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Biological Control 

Programmes against 

Insects and Weeds 

in Canada 1969-1980 

EDITED BY J.S. KELLEHER AND M.A. HULME 

@ COMMONWEALTH AGRICULTURAL BUREAUX

Commonwealth Agricultural Bureaux 

Farnham Royal 

Slough SL2 3BN 

England 

Tel. Farnham Common 2281 

Telex 847964 

ISBN 085198536 X 

© Commonwealth Agricultural Bureaux, 1984. All rights 

reserved. No part of this publication may be reproduced in any 

form or by any means, electronically, mechanically, by photocopying, 

recording or otherwise, without the prior permission 

of the copyright owner. 

The Executive Council of the Commonwealth Agricultural 

Bureaux is signatory to the Fair Copying Declaration, details 

of which can be obtained from The Royal Society, 6 Carlton 

House Terrace, London SWI Y SAG. 

Printed by Page Bros (Norwich) Ltd

CONTENTS 

Contents iii 

Page 

FOREWORD vii 

GENERAL INTRODUCTION ix 

PART I - Biological control of agricultural insects in Canada, 1969-1980 

Chapter 1. Current approaches to biological control of agricultural insect pests 3 

Chapter 2. Acyrthosiphon pisum (Harris), Pea Aphid (Homoptera: Aphididae) 7 

Chapter 3. Adelphocoris lineolatus (Goeze), Alfalfa Plant Bug (Heteroptera: Miridae) 9 

Chapter 4. Agromyza frontella (Rondani), Alfalfa Blotch Leafminer (Diptera: 11 

Agromyzidae) 

Chapter 5. Artogeia rapae (L.), Imported Cabbageworm (Lepidoptera: Pieridae), 15 

Trichoplusia ni (HObner), Cabbage Looper (Lepidoptera:Noctuidae), 

and Plutella xylostella (L.), Diamondback Moth (Lepidoptera: 

Plutellidae) 

Chapter 6. Culex pipiens L., Northern House Mosquito (Diptera: Culicidae) 19 

Chapter 7. Culiseta inornata (Williston) a Mosquito (Diptera: Culicidae) 23 

Chapter 8. Cydia pomonella (L.), Codling Moth (Lepidoptera: Tortricidae) 25 

Chapter 9. Delia antiqua (Meigen), Onion Maggot (Diptera: Anthomyiidae) 29 

Chapter 10. Entomoscelis americana Brown, Red Turnip Beetle (Coleoptera: 31 

Chrysomelidae) 

Chapter 11. Euxoa messoria (Harris), Darksided Cutworm (Lepidoptera: Noctuidae) 33 

Chapter 12. Forficula auricularia L., European Earwig (Dermaptera: Forficulidae) 39 

Chapter 13. Hypera postica (Gyllenhal), Alfalfa Weevil (Coleoptera: Curculionidae) 41 

Chapter 14. Lygus spp., Plant Bugs (Heteroptera: Miridae) 45 

Chapter 15. Mamcstra configurata Walker, Bertha Armyworm (Lepidoptera: Noctuidae) 49 

Chapter 16. Manduca quinquemacu/ata (Haworth), Tomato Hornworm (Lepidoptera: 57 

Sphingidae) 

Chapter 17. Melanoplus spp., Camnu/a pellucids (Scudder), and other Grasshoppers 61 

(Orthoptera: Acrididae) 

Chapter 18. Musca domestics L., House Fly (Diptera: Muscidae) 63 

Chapter 19. Dulema melanopus (L.), Cereal Leaf Beetle (Coleoptera: Chrysomelidae) 65 

Chapter 20. Phyllonorycter blancardella (F.), Spotted Tentiform Leafminer, (Lepidoptera: 69 

Gracillariidae) 

Chapter 21. Phyllotreta spp., Flea Beetles (Coleoptera: Chrysomelidae) 73 

Chapter 22. Tetranychus urticae Koch, Twospotted Spider mite (Acarina: Tetranychidae) 77 

Chapter 23. Thymelicus lineola (Ochsenheimer), European Skipper (Lepidoptera: 79 

Hesperiidae) 

Chapter 24. Tipu/a pa/udosa Meigen, European Cranefly (Diptera: Tipulidae) 85 

Chapter 25. Tria/eurodes vaporariorum (Westwood), Greenhouse Whitefly (Homoptera: 89 

Aleyrodidae)

iv Contents 

PART II - Biological control of weeds in Canada, 1969-1980 

Chapter 26. Current Approaches to Biological Control of Weeds 

Chapter 27. Acroptilon repens (L.) DC., Russian Knapweed (Compositae) 

Chapter 28. Ambrosia artemisiilolia L., Common Ragweed (Compositae) 

Chapter 29. Artemisia absinthium L., Absinth (Compositae) 

Chapter 30. Carduus nutans L., Nodding Thistle and C. acanthoides L., Plumeless 

Thistle (Compositae) 

Chapter 31. Centaurea diffusa Lam. and C. maculosa Lam., Diffuse and Spotted 

Knapweed (Compositae) 

Chapter 32. Cirsium arvense (L.) Scop., Canada Thistle (Compositae) 

Chapter 33. Clrsium vulgare (Savi) Ten., Bull Thistle (Compositae) 

Chapter 34. Convolvulus arvensis L., Field Bindweed (Convolvulaceae) 

Chapter 35. Euphorbia esu/a-virgata complex, Leafy Spurge and E. cyparissias L., 

Cypress Spurge (Euphorbiaceae) 

Chapter 36. Hypericum perforatum L., St. John's-wort (Hypericaceae) 

Chapter 37. Linaria vulgaris Miller, Yellow Toadflax, and L. dalmatica (L.) Mill., 

Broad-leaved ToadOax (Scrophulariaceae) 

Chapter 38. Opuntia polyacantha Haworth, Plains Prickly-pear Cactus (Cactaceae) 

Chapter 39. Rhamnus cathartica L., Common or European Buckthorn (Rhamnaceae) 

Chapter 40. Salso/a pest/fer A. Nels., Russian Thistle (Chenopodiaceae) 

Chapter 41. Senecio jacobaea L., Tansy Ragwort (Compositae) 

Chapter 42. Silene cucubalus Wibel, Bladder Campion (Caryophyllaceae) 

Chapter 43. Sonchus arvensis L., Perennial Sow-thistle, S. oleraceus L., Annual Sowthistle, 

S. asper (L.) Hill, Spiny Annual Sow-thistle (Compositae) 

Chapter 44. Verbascum thapsus L., Common Mullein (Scrophulariaceae) 

PART III - Biological control of forest insect pests in Canada 1969-80 

Chapter 45. Biological Control of Forest Insect Pests in Canada 1969-1980: 215 

Retrospect and Prospect 

Chapter 46. Adelges piceae (Ratz.), Balsam Woolly Adelgid (Homoptera: Adelgidae) 229 

Chapter 47. Choristoneura fumiferana (Clemens), Spruce Budworm (Lepidoptera: 235 

Tortricidae) 

A. Field Development of Bacillus thuringiensis Berliner in Eastern Canada, 238 

1970-80 

B. Viruses: Application and Assessment 248 

C. Application of Microsporidia and Fungi, and of Genetic Manipulation 260 

D. Testing of Parasitoids 267 

E. Review of Biological Control Opportunities against Spruce Budworm, 273 

Choristoneura fumiferana 

Chapter 48. Choristoneura occidentalls Freeman, Western Spruce Budworm (Lepidoptera: 277 

Tortricidae) 

Chapter 49. Coleophora laricella (Hubner), Larch Casebearer (Lepidoptera: 281 

Coleophoridae) 

95 

105 

111 

113 

115 

127 

139 

147 

155 

159 

171 

179 

183 

185 

191 

195 

203 

205 

211

Chapter 50. Coleophora serratella (L.), Birch Casebearer (Lepidoptera: Coleophoridae) 

Chapter 51. Fenusa pusilla (Lepeletier), Birch Leafminer (Hymenoptera: 

Tenthredinidae) 

Chapter 52. Gilpinia hercyniae (Hartig), European Spruce Sawfly (Hymenoptera: 

Diprionidae) 

Chapter 53. Leucoma sa/icis (L.), Satin Moth (Lepidoptera: Lymantriidae) 

Chapter 54. Lymantria dispar (L.), Gypsy Moth (Lepidoptera: Lymantriidae) 

Chapter 55. Malacosoma disstria HObner, Forest Tent Caterpillar (Lepidoptera: 

Lasiocampidae) 

Chapter 56. Neodiprion abietis (Harris), Balsam Fir Sawfly (Hymenoptera: Diprionidae) 

Chapter 57. Neodiprion lecontei (Fitch), Redheaded Pine Sawfly (Hymenoptera: 

Diprionidae) 

Chapter 58. Neodiprion sertifer (Geoffroy), European Pine Sawfly (Hymenoptera: 

Diprionidae) 

Chapter 59. Neodiprion swainei (Middleton), Swaine Jack Pine Sawfly (Hymenoptera: 

Diprionidae) 

Chapter 60. Operophtera bruceata (Hulst), Bruce Span worm (Lepidoptera: Geometridae) 

Chapter 61. Operophtera brumata (L.), Winter Moth (Lepidoptera: Geometridae) 

Chapter 62. Orgyia leucostigma (J.E. Smith), Whitemarked Tussock Moth (Lepidoptera: 

Lymantriidae) 

Chapter 63. Orgyia pseudotsugata (McDunnough), Douglas-fir Tussock Moth 

(Lepidoptera: Lymantriidae) 

Chapter 64. Pristiphora erichsonii (Hartig), Larch Sawfly (Hymenoptera: Tenthredinidae) 

Chapter 65. Pristiphora geniculata (Hartig), Mountain-ash Sawfly (Hymenoptera: 

Tenthredinidae) 

Chapter 66. Rhyacionia buoliana (Schiff.), European Pine Shoot Moth (Lepidoptera: 

Tortricidae) 

APPENDIX - Addresses of contributors 

INDEX OF SPECIES 

Contents v 

285 

291 

295 

299 

303 

311 

321 

323 

331 

341 

349 

353 

359 

363 

369 

381 

387 

395 

397

Foreword 

Foreword vii 

The CIBC Technical Communication series was initiated to provide an outlet for 

regional reviews on biological control. This review, the 8th in the series and the 3rd prepared 

by Canadian scientists, points to the importance which Canada attaches to biological 

control and reflects the volume of Canadian activity in this field. 

Canada continues to support an active classical biological control programme, relying 

on the Commonwealth Institute of Biological Control to undertake most of its foreign 

exploration and research. The collection and redistribution of natural enemies successfully 

established earlier to hasten control has continued. However, the current volume 

indicates an acceptance of biological control in its wider context as a component, 

albeit a very important one, of integrated pest management. Increasing attention and 

interest are being focused on other biological control approaches, i.e., augmentative 

and inundative releases as well as amelioration of the environment. The value of food 

plants or nectar sources for adult parasitoids has been demonstrated. 

To date, augmentative and inundative releases in Canada have involved pathogens, 

both introduced and native, rather than parasitoids or predators. The period under 

review has seen the implementation, by large field trials, of microbial control, utilizing 

both bacterial and viral preparations for the control of forestry pests. The use of 

Bacillus thuringiensis has involved the large-scale production of "tailor-made" formulations 

by the agro-chemical industry and provides a preferred, although more 

expensive, alternative to the former wide-scale use of chemical pesticides for the 

control of spruce budworms. B.thuringiensis is fully registered as a pesticide in 

Canada for use against several lepidopteran defoliators. Similarly, research on viruses 

of neodiprionid sawflies has led to practical field application, with some degree of 

carry-over from year to year. 

The first book reported introductions of control agents against two weeds; the 

second reviewed attempts against four additional species or species complexes 

whereas in the present volume, thirty agents have now been released against fourteen 

weed species in Canada. Increasing efforts have been made to evaluate or quantify the 

gains which have been or might be derived from biological control of weeds. 

The book is timely; by its preparation, scientists and administrators can take stock of 

achievements to date and thus will be better placed to plan for the future. As M.A. 

Hulme and G.A. Green point out, the scope for research opportunities is limited not by 

lack of suitable problems but by the resources available to devote to biological control. 

The economic climate in Canada, as elsewhere, dictates that emphasis be given to 

developing management strategies for the pests causing the greatest economic losses 

and, as pointed out by Dr. P. Harris, proposals for future funding for biological control 

must, in order to convince administrators to release funds, provide quantitive 

assessment of the losses inflicted by the target pest or weed and thereby demonstrate 

the financial benefit which will result if the project is successful. This book attempts to 

provide an evaluation of each control attempt, and administrators and scientists now 

should be in a good position to plan for the future. 

F.D. Bennett 

Director 

Commonwealth Institute of 

Biological Control

General Introduction 

Gcncrallntroduction ix 

This book is the third review of Canadian biological control work published by the 

Commonwealth Agricultural Bureaux. It is compiled and edited by Dr. M.A. Hulme 

and Dr. J .S. Kelleher. Dr. P. Harris coordinated preparation of the section on biological 

control of weeds. 

The first compilation, "A Review of the Biological Control Attempts Against Insects 

and Weeds in Canada" was published in 1962 and dealt with control attempts against 

agricultural pests and weeds up to 1959 and against forest insects from 1910-1958. In 

1971 a sequel was published entitled ''Biological Control Programmes against Insects 

and Weeds in Canada 1959-1968"; this volume had separate sections on agricultural 

insects, on weeds, on forest pests, and on the organization of Canadian biological 

control research. During the late 1970s, a further sequel was proposed and preparation 

began in 1980. This volume is the end result. 

Like its immediate predecessor, this review has two main functions. First, it collates 

Canadian biological control attempts against insects and weeds from 1969 to 1980, and 

thus provides a permanent record of otherwise diffuse and relatively inaccessible data. 

Secondly, it attempts to provide an evaluation of each control attempt in terms of 

reasons for success or failure, and hence develops recommendations for future work. 

Terminology used in biological control research can, at times, be ambiguous. The 

simple term "parasite" can be particularly troublesome and as an aid to readers its usage 

is defined more precisely. More effort has been devoted to entomopathogens during 

the current review period and in some cases both microbial parasites and insect 

parasites have been examined from the same host insect. To avoid confusion when 

referring to these entomogenous and entomophagous parasites, the latter have been 

termed parasitoids or insect parasites rather than just parasites. A parasitoid, 

following the definition of DeBach, is an insect that develops as a larva on or in a single 

host insect from eggs laid on, in or near the host; it usually consumes most of the host's 

tissues and it kills the host. Phytophagous insects that feed on plants regarded as 

weeds are thus termed parasites, whereas those feeding on crop plants, including trees, 

are referred to as pests (emphasizing their relationship with man rather than with the host 

plant). 

The term ''biological control" also requires some explanation. In the present context 

the term refers to an applied control strategy that involves the manipulation of living 

natural enemies for the purpose of regulating the abundance of pest populations. The 

regulation may be short or long term and the manipulation may include release 

strategies ranging from spot-introductions to widespread inundation. Introductions of 

sterile individuals are thus included here; but the use of semiochemicals, notably 

kairomones and pheromones, is included only where these chemicals influence 

predator or parasitoid behaviour. Pheromone confusion trials on the pest insect are 

excluded since they involve direct chemical manipUlation of the pest. The use of 

insect growth regulators is similarly excluded. 

The book is divided into three sections which cover agricultural insects, weeds, and 

forest insects; chapters within each section are generally listed in the alphabetical 

order of the insect's or weed's generic name; and each of the three sections begins with 

an overview of the chapters that follow. Addresses of contributors are listed in the 

Appendix. The book does not include an updated synopsis of the organization and 

accomplishments of Canadian biological control research in a separate section 

equivalent to Part IV of the 1971 volume. Accomplishments are summarized in the 

overview chapter beginning each section and the organizational observations in the 

1971 synopsis remain equally valid today without need for further elaboration.

x Gcncrallntroduction 

Several changes in the organization of Canadian biological control research have 

taken place since publication of the 1971 book. The Research Institute of Agriculture 

Canada at Belle .. ille, Ontario, which had played a pivotal role in importation and 

applied research of biological control organisms was closed in 1972 and its staff was 

relocated. The Biocontrol Unit was formed in Ottawa by Agriculture Canada to coordinate 

importations. Material is imported through the Biocontrol Unit, and through 

Macdonald College in Quebec, the Forest Pest Management Institute and the 

University of Guelph in Ontario, and the Regina Research Station of Agriculture 

Canada in Saskatchewan. The Department of Fisheries and Forestry became part of a 

new Department, Environment Canada, in 1971. Forestry research is conducted by the 

Canadian Forestry Service within this Department; biological control research is still 

carried out at the same laboratories as those listed in the last review but establishment 

names have been modified to reflect the new organization. 

Many people assisted in the preparation of this review. Special acknowledgement is 

extended to Ms. R. Boyle and Ms. P. Loshak for helping in correcting the text. Dr. F.D. 

Bennett, Director, Commonwealth Institute of Biological Control, initiated the 

preparation, Dr. 0.1. Greathead, Assistant Director and Mr. 0.1. Girling, Information 

Officer, assisted in its publication, and Mrs. A.H. Greathead read the proofs and 

completed the index.

PART I 

BIOLOGICAL CONTROL OF 

AGRICULTURAL INSECTS IN 

CANADA 1969-80

Chapter 1 

Current Approaches to Biological 

Control of Agricultural Insect Pests 

1.S. KELLEHER 

This part covers the biological control of insect and mite pests of crops, fruit trees, and 

ornamentals. As in the previous review (Kelleher 1971) it includes inoculation 

(introduction), augmentation, and inundation, using beneficial insects, entomopathogens, 

and autocidal methods. 

Some organizational changes have occurred since the last review. In 1972, the 

Research Institute at Belleville, Ontario, was closed and the staff transferred to 

Research Stations in other parts of Canada. The service function, of obtaining 

infonnation and collections of biological control organisms from abroad was transferred 

to Ottawa. The programme on the biological control of weeds was moved to the Regina 

Research Station. An Integrated Pest Control Section was fonned at Winnipeg with 

many of the scientists from Belleville. Other individuals were stationed at Summerland, 

Saskatoon, Harrow, and Ottawa. 

The adoption of integrated pest management (IPM) systems has placed biological 

control in a much more important role than before. At one time it was considered as an 

alternative to chemicals i.e. complete control was necessary. Now, however, our 

knowledge of insect population dynamics has increased, and it is now considered that 

even a small additional percentage mortality can have a profound effect on the overall 

reduction of an insect population. 

The initial stages of an IPM programme involve a reduction in pesticide usage, by 

monitoring pest infestations so that chemicals are applied only when necessary. As a 

consequence, natural control factors are not so suppressed and are able to exert 

additional mortality on the pest population. But there will be a point where very little 

more can be obtained from the systems available and additional factors must be added 

to attain a greater reduction in pesticide use. This can come in many forms but the 

introduction of new natural enemies should be an important consideration in many 

instances. 

Most of the studies reported in this part have utilized introduced species of 

parasitoids, or entomopathogens (Bacillus thuringiensis Berliner (B.t.), fungi, viruses). 

Other aspects of biological control such as mass releases of parasitoids e.g. Trichogramma 

species, have been largely neglected. However reports from the USSR, 

China, and South American countries have attributed considerable successes with this 

approach and are prompting some consideration of initiating similar work in Canada. 

Much may depend on the development of techniques to provide a large number of 

parasitoids during a relatively short period for any particular insect. The main 

emphasis will be on production and storage but consideration should also be given to a 

number of target pests whose susceptible stages occur at different times. 

Increased awareness of the value of natural enemies has led to research on the 

differential effects of pesticides on natural enemies. Although pesticides usually affect 

a wide spectrum, some taxa are less affected by them than others. A working group of 

the West Palaearctic Regional Section of the International Organization for Biological 

Control has taken an organized and coordinated approach to this subject. Members of 

this group have standardized the culturing of various taxa of beneficial insects and are 

adopting standardized methods for testing the effects of pesticides on these insects in 

the laboratory and in the field. Eventually these data will be available as recommendations 

3

4 J. S. Kelleher 

Table 1 

to be placed on the label of pesticide containers and ill the bulletins of official agencies. 

The following 24 chapters in this part have been arranged in alphabetical order using 

the scientific name of the pest species. An evaluation of the programme is given in 

Table 1. Only 10 of the pests were included both in this review and the last one. It can 

be concluded that no other information is available on the other target pests. This 

indicates the transient nature of many of the agricultural projects, in contrast to those 

on forest insects and weeds. 

Evaluation of biological control measures against agricultural insect and mite pests 

Pest Method Agent 

Acyrthosiphon pisum (Harris) Adventitious Predator 

Adelphocoris lineolatus (Goeze) Inoculation Parasitoid 

Agromyza frontella (Rondani) Inoculation Parasitoid 

Artogeia rapae (L.), Trichoplusia 

ni (Hilbner), & Plutella Inundative Virus, B.t. 

xylostella (L.) Inoculation Parasitoid 

Culex pipiens L. Augmentation Planaria 

Culiseta inornata (Williston) Augmentation Fungus 

Cydia pomonella (L.) Inundation Virus 

Delia antiqua (Meigen) Autocidal 

Entomoscelis americana Brown·· 

Euxoa messoria (Harris) Augmentation Virus 

Forficula auricularia (L.) Inoculation Parasitoid 

Hypera postica (Gyll.) Adventitious Fungus 

Lygus spp. Inoculation Parasitoid 

Mamestra configurata Walker·· 

Manduca quinquemaculata (Haworth) Inundation B.t. 

Melanopus spp., Camnula pellucida 

(Scudder) & other grasshoppers Inundation Protozoa 

Musca domestica L. Integration Parasitoid 

Oulema melanopus (L.) Inoculation Parasitoid 

Phyllonorycter blancardella (Fabricius) Inoculation Parasitoid 

Phyllotreta spp. Inoculation Parasitoid 

Tetranychus unicae Koch· Integration Predator 

Thymelicus lineola (Ochs.) Inundation B.t. 

Inundation Virus 

Inoculation Parasitoid 

Tipula paludosa (Meigen) Inoculation Parasitoid 

Trialeurodes vaporariorum (Westwood)· Integration Parasitoid 

Measures started during or extending into period 1969 to 1980 

·Greenhouse 

··Exploratory studies - no. released 

•• • Degree of Success: 

- No control or not yet known if established 

+ Slight pest reduction or too early for evaluation of control 

+ + Local control; distribution restricted or not fully investigated 

+ + + Control widespread but local damage occurs 

+ + + + Control complete 

Degree of 

Success··· 

+ 

+ 

++++ 

++ 

+++ 

+ 

+ 

+ 

+ 

+++ 

++++ 

+++ 

++++ 

++++ 

+ 

+++ 

++++ 

+++ 

+ 

++++

Literature Cited 

Current approaches to biological control of agricultural insect pests 5 

In the last Review, the use of a nematode, DD-136, was reported (Welch 1971) 

against several crop pests. This work was not continued although there are still several 

avenues to explore. Hopefully this will be done in the future. It will also be noted from 

Table 1 that predators were used in only 2 instances - one adventitiously, the other in 

a greenhouse situation. Possibly this group is less favored because the members tend 

to be less specific than parasitoids. However for reasons considered above, even 

relatively small degrees of mortality can effect population reductions on a much larger 

scale. But it would also be important to determine if there would be a net increase in pest 

mortality or if it would be merely compensatory. 

Of the 26 agents used, 11 were by inoculation with parasitoids and 7 by inundation 

with pathogens. Inoculations gave high success in 2 cases; others could not be 

evaluated as it was too early or recoveries had not yet been made. In contrast, 5 of the 

7 pests were controlled well by inundation with pathogens. However this method is 

primarily for short-term stage control whereas inoculation of new natural enemies is a 

long-term population control measure. 

In many cases, establishment of exotic natural enemies may be hampered by the low 

numbers available for release e.g. against Adelphocoris lineolatus (Goeze), Phyllotreta 

spp., and Thymelicus lineola (Ochs.). Propagation has been difficult or unattainable. 

Sometimes mortality has been high in rearing andlor storage. This has required intense 

efforts by the CIBC to increase the number of individuals obtained. Some new 

techniques have been considered e.g. leaving an area undisturbed on the premise that 

parasitoid populations would increase. Increasing host populations by the addition of 

their eggs from other areas has also been tried successfully in some cases although the 

danger of introducing more virulent strains has restricted the use of this technique. 

In addition to the work reported in the following chapters there have been some 

minor efforts which did not warrant separate sections. These are as follows: Mantis 

religiosa L. ootheca were collected near Belleville, Ontario, in 1971 and 1972 and 

released near St. John's, Newfoundland against various grasshopper species (Acrididae); 

no recoveries have been recorded (R. Morris, 1981, personal communication). 

Coccinella septempunctata L. was found in northern New Jersey, in 1973 apparently 

as an adventitious introduction (Angalet & Jacques 1975). They were redistributed to 

various states in subsequent years and to Nova Scotia in 1981. The species had been 

reported from various parts of Quebec (Larochelle 1979) and was found in New 

Brunswick in 1981 (P.W. Schaefer, 1981, personal communication). 

As in previous reviews, this publication has been possible only through the cooperation 

of those who performed the work. In this part. 28 authors have contributed. Their efforts 

are gratefully acknowledged. as well as those of editors and typists who are too numerous 

to name individually. 

Angalct. G. W.; 1 acquest R.L. (1975) The establishmcnt of Coccinella septempunctata L. in thc continental Unitcd Statcs. USDA Cooperative 

Economic Insect Report 25, 883-884. 

Kcllchcr. 1.S. (1971) Current approachcs to biological control of agricultural insect pests. In: Biological control programmes against insects 

and weeds in Canada 1959-1968. Commonwealth Institute of Biological Control Technical Communication 

4.1-3. 

Larochellc, A. (1979) Les coleoptercs Coccinellidac du Quebec. Cordulia. Supplement 10. I-Ill. 

Wclch. H.E. (1971) Various target species allcmplS with 00-136. In: Biological control programmes against insects and weeds in Canada 

1959-1968. Commonwealth Institute of BiologiClll Control TechniCIJI Communication 4. 62-66.

Blank Page 

6


Chapter 2 

Acyrthosiphon pisum (Harris), Pea Aphid 

(Homoptera: Aphididae) 

B.D. FRAZER 

Coccinella undecimpunctata L. was first encountered in pea aphid, Acyrthosiphon 

piswn (Harris), infested alfalfa in May 1972. Since then it is routinely found on low-growing, 

aphid infested plants including cereals, strawberries, and vegetables in numbers 

about equal to the predominant native species, C. californica and C. trifasciata. C. 

undecimpunctata is one of the first coccineJlids to be found in spring. They appear to 

be adapted to cooler cJimates than the lower mainland of British Columbia as there are 

few aphids available when they are first seen. The effect of their predation in reducing 

spring aphid numbers can greatly reduce the rate of increase of aphids (Frazer & 

Gilbert 1976) and thereby extend the time before pesticides are required. Later in the 

season the effects of C. undecimpunctata alone are smalJ because losses from the large 

number of predators in alfalfa, at least, are compensatory (Charnov et al. 1976). If C. 

undecimpunctata were added to a field without them, their aphid consumption would 

simply result in less for the other competing predators with no net increase in aphid 

mortality. 

Frazer, B.D.; Gilben. N. (1976) Coccinellids and aphids: a quantitative study of the impact of adult ladybirds (Coleoptera: CoccineUidae) preying 

on field populations of pea aphids (Homoptera: Aphididae). Journal of the Entomological Society of 

British Columbia 73, 33-56. 

Charnov, E.; Frazer, B.D.; Gilbert. N.; Raworth. D. (1976) Fishing for aphid - the exploitation of a natural population. JourfllJl of Applied 

Ecology 13. 379-389. 

7

Blank Page 

8

\0 C. H. Craig and C. C. Loan 

Recommendations 


development at intended liberation sites in western Canada. However, 47 P. ade/phocoridis 

were released near Clavet, Saskatchewan, latitude 52°N, in alfafa containing a 

second and third instar A. Iineo/alllS nymph population of 2 per sweep. A total of 29 P. 

ade/phocoridis and 49 P. rubricol/is were released in a similar situation near Shellbrook. 

Saskatchewan. latitude 53°N. Liberations in 1981 included 16 P. ade/phocoridis at the 

same site at Saskatoon and 12 of the species at Shellbrook. The first attempt to recover 

these introduced parasitoids at the liberation sites will be made in 1981. 

The introduction and release of P. ade/phocoridis and P. rubricol/is against A. 

lineo/atus in western Canada will continue through 1982 or 1983 when the impact of the 

programme will be assessed. Because A. Iineo/alllS is an excellent candidate host for 

introduced parasitoids. it is recommended that a search be made for other specific 

parasitoids of A. lineo/atus in Europe to increase the probability of successful 

establishment in western Canada. 

Bilewicz·Pawinska. T. (1975) Distribution of the insect parasites Peristenus Foerster and Mesochorus Gravenhorst in Poland. Bulletin de 

I'Academie Polonaise des Sciences Closse II Serie des Sciences Biologiques 23. 823-827. 

Craig. C.H. (1971) Distribution of Adelphocoris lineolatus (Heteroptera: Miridae) in western Canada. CanadUJn Entomologist 103. 280-81. 

Craig, C.H. (1963) The alfatra plant bug, Adelphocoris lineolatus (Goeze) in northern Saskatchewan. Canadian Entomologist 95.6-13. 

Loan. C.C. (1965) Life cycle and development of Peris/enus pal/ipes (Curtis) (Hymenoptera: Braconidae. Euphorinae) in five mirid hosts in the 

Belleville district. Proceedings of the Entomological Society of Ontario (1964) 95. 115-121. 

Loan. C.c. (1979) Three new species of Peristenus Foerster from Canada and western Europe (Hymenoptera: Braconidae. Euphorinae). 

Natura/iste Canadian 106.387-391.

Pest Status 

Background 

Chapter 4 

Agromyza frontella (Rondani), Alfalfa 

Blotch Leafminer (Diptera: 

Agromyzidae) 

J.C. GUPPY, D.G. HARCOURT, M.O'c. GUIBORD and 

L.S. THOMPSON 

The alfalfa blotch leafminer, Agromyza frontella (Rondani), was introduced from 

Europe to the north eastern United States during the late 1960s (Miller & Jensen 1970) 

and first appeared in Canada at St-Armand, Quebec, in 1972 near the United States 

border (Harcourt 1973). The insect spread rapidly throughout eastern Canada from 

Prince Edward Island to Ontario (Thompson 1974, Guppy & Harcourt 1977), and by 

1979 it had threatened to become the most important pest of alfalfa in the 10 eastern 

counties of Ontario (Harcourt & Binns 1980) and in the other eastern provinces. It has 

continued to spread westward in Ontario and damaging levels were recorded in 

Hastings County in 1980 (Guppy 1981). 

Hosts include: Medicago, Melilollls, and Trifolium, but alfalfa, Medicago sativa L., 

is apparently preferred (Steyskal 1972, Spencer 1973). The insect overwinters as a 

partially developed pupa and the adult emerges about mid-May to oviposit in the firstgrowth 

alfalfa. In eastern Canada there are three complete generations a year (Guppy 

1981), but a few individuals may complete a fourth. The crop is attacked by both the 

adults and larvae, but most of the damage is done by the larvae which feed on the 

mesophyll tissues forming blotch mines each of which represents about 27% of the 

leaflet area. 

The crop is attacked throughout the growing season but damage is more severe in 

the first and second cuttings; during the past 4 years, the percentage of leaflets mined 

in eastern Ontario averaged 70% and 58%, respectively. 

Seven parasitoid species native.to eastern Canada have been reared from larvae of A. 

frontella, all of them are hymenopterous species of the family Eulophidae. Diglyphus 

websteri (Crawford) and D. begini (Ashmead) were recorded in eastern Ontario and 

these two plus D. pulchripes (Crawford) in Quebec. In Prince Edward Island, five 

species were found, namely, D. begini, D. intermedius (Girault), Notanisomorpha sp., 

Pnigalio maculipes (Crawford), and Pnigalio n. sp. One larval-pupal parasitoid 

Cyrtogaster sp. (Hymentoptera: Pteromalidae) emerged from puparia in Ontario. 

Assessment of parasitism has shown that the native species are of little importance 

in suppressing alfalfa blotch leafminer populations. However, a hemipteron species 

Nabis ferus (Linnaeus), common to eastern Canada, appears to be an important 

predator of the larvae. At Ottawa, incidence of attack increases with each generation, 

averaging about 60% in the third. 

The Beneficial Insects Research Laboratory, Newark, Delaware, United States 

Department of Agriculture imported 14 parasitoid species from Europe from 1974 to 

1978 for release in the United States (Hendrickson & Barth 1979). By 1978 three 

hymenopterous species, Dacnusa dryas (Nixon) (Braconidae), Chrysocharis punctifacies 

Delucchi (Eulophidae), and Miscogaster hortensis Walker (Pteromalidae), were 

11

12 J. C. Guppy, D. G. Harcourt, M. O'c. Guibord and L. S. Thompson 

established at the Delaware field plots. These were recolonized in other northeastern 

states, where they became established (Hendrickson & Barth 1979, and personal 

communication), and imported for release into eastern Canada. A fourth species, 

Diglyphus isaea (Walker) (Eulophidae), was shipped to Quebec for release in 1975; 

establishment was not successful in either country apparently because it crossed with 

native species of Diglyphus and further attempts of establishment were abandoned 

(R.M. Hendrickson 1976, personal communication). 

Releases and Recoveries D. dryas, C. punclifacies, and M. hortensis are solitary endoparasitoids. The host is 

attacked during the larval stage and the parasitoids complete their development during 

Table 2 

the pupal stage. 

All releases in Canada were of adults, laboratory reared in Newark, Delaware, or 

field collected there or in other northeastern States by cooperators and shipped to 

Canada directly to release points or for distribution through Agriculture Canada, 

Research Branch, Biological Control Unit, Research Program Service. Release and 

recovery data are given in Table 2. D. dryas, the only species thus far recovered, 

Releases and recoveries of parasitoids against the alfalfa blotch leafminer, Agromyza 

fronlella (Rondani), in Canada. 

Releases 

Species and Province Year Number Y car of recovery 

Chrysocharis plillctifacies 

Prince Edward Island 1978 4 


Ontario 1980 150 

Quebec 1979 249 

Quebec 1980 90 

DaClIlIsa dryas 



Prince Edward Island 1979 546 1980 

Ontario 1979 586 1979 

Quebec 1979 16 

Quebec 1980 378 1981 

Dig/ypllUs isaea 

Quebec 1975 900 

Miscogasler IlOrlellsis 


appears to be firmly established in eastern Canada. In eastern Ontario, it was reared 

from third generation pupae in the year of release, 1979, and from each generation in 

1980 after overwintering successfully in diapausing pupae. It was also collected in 

sweepnet samples throughout the growing season in 1980 at Ottawa.

Blank Page 

14

Pest Status 

Use of Bacillus thuringiensis 

Chapter 5 

Field Plot Introductions of Viruses 

Artogeia rapae (L.), Imported 

Cabbageworm (Lepidoptera: Pieridae), 

Trichoplusia ni (Hiibner), Cabbage 

Looper (Lepidoptera: Noctuidae) and 

Plutella xylostella (L.), Diamondback 

Moth (Lepidoptera: Plutellidae) 

R.P. JAQUES and J.E. LAING 

Artogeia rapae (L.), the imported cabbageworm, causes damage to cole crops 

practically wherever these crops are grown in Canada. The pest is quite susceptible to 

certain chemical insecticides and to insecticides containing Bacillus thuringiensis 

Berliner and, therefore, populations of larvae are usually retained at acceptable 

densities by recommended control programmes. Trichoplusia ni (Hiibner), the cabbage 

looper, is not as widespread but, because it is less susceptible than A. rapae to 

registered insecticides, it is considered to be the more important pest of cole crops, 

especially in southern Ontario. Plutella xylostella (L.) is not considered to overwinter 

in Canada and thus does not become a pest on cole crops until late in the season. 

Formulations of B. thuring;ensis (B.t.) containing B. thuringiensis var. kurstaki, a 

high-potency strain of B.t., were registered in Canada in 1972 for use against A. rapae, 

T. ni, and P. xylostella on cole crops and other crops. The new formulations (Thuricide® 

HPC, Sandoz Crop Protection Inc.; and Dipel® HD-l, Abbott Laboratories Ltd.) 

replacing formulations registered previously, protected cole crops equally as well as or 

better than did chemical insecticides. These formulations of B.I. are now used quite 

extensively. 

The native parasitoid complex of the imported cabbageworm (Michalowicz 1980) 

and the diamondback moth (Butts 1979, Bolter 1982) have been studied intensively. 

Two species, Apanteles rubecula Marsh. which parasitizes A. rapae and Apanleles 

plulellae (Kurdj.) a parasitoid of diamondback moth, have been imported and released 

in southwestern Ontario. 

The granulosis virus of A. rapae (ARGV), a naturally occurring virus (Jaques & 

Harcourt 1971) that often causes high mortality in populations of larvae of A. rapae 

late in the growing season, was evaluated by bioassays and plot tests as an introduced 

pathogen. In addition, three viruses that kill larvae of T. ni were assessed in laboratory 

and field studies. Two of these viruses, the single-embedded nuclear polyhedrosis 

15

16 R. P. Jaques and J. E. Laing 

virus of T. n; (TNNPV-SEV), the predominant naturally occurring virus of T. ni 

(Jaques 1970a) , and the nuclear polyhedrosis virus of Autographa cali/orn;ca 

(ACNPV), a virus that kills T. n; and that closely resembles the multiple-embedded 

nuclear polyhedrosis virus of T. ni (TNNPV-MEV), are considered as candidates for 

development as microbial insecticides for use against T. n;. 

Efficacy of the viruses of A. rapae and T. n; was assessed in 1970-80 using field 

plots of cabbage (each 24-32 m2) Jaques 1970b, 1972, 1973, 1977; Jaques & Laing 

1978). 

In these tests: 

(1) ARGV (7.5 x 10 12 granular inclusion bodies (GIBlha) applied to foliage 4 to 6 

times during the growing season reduced populations by 95 to 100% and protected the 

crop as well as did chemical insecticides applied at the recommended rates. 

(2) TNNPV-SEV, TNNPV-MEV and ACNPV were about equally effective against 

the cabbage looper. Four to 6 applications of 1.5 x lOll polyhedral inclusion bodies 

(PIB)lha during the growing season reduced populations of T. n; on cabbage by about 

75% and protected the crop as well as did methomyl or B.t. but not as well as 

permethrin applied at recommended rates. 

(3) Reduced-dosage mixtures of ACNPV, ARGV, andlor B.t. with chlordimeform 

were as effective against A. rapae and T. ni as were the microbial or chemical 

insecticides applied alone at the full rate (Jaques & Laing 1978). Mixtures of the 

viruses or B.t. and permethrin at 114 or 112 full rate were equally as effective as 

permethrin applied alone in protecting the crop. 

(4) The efficacy of ACNPV propagated ;n vitro was similar to that of ACNPV 

propagated ;n vivo. 

(5) Because the viruses persist in soil (Jaques 1974a, 1974b), application of a high 

dosage of ARGV and ACNPV when plants were transplanted, suppressed populations 

of A. rapae and T. n; on cabbage plants and lessened the frequency of use of insecticides 

later in the season. 

Predation and Parasimm The native parasitoid complex of the imported cabbageworm and the diamondback 

moth have been studied intensively (Butts 1979, Michalowicz 1980, Bolter 1982). 

Major mortality factors for A. rapae at Cambridge, Ontario during 1977-78 were 

Apanteles glomeratus (L.), Phryxe vulgaris (Fallen), Compsilura concinnata (Meigen), 

and Pteromalus puparum L. Major changes in the population occurred during the 

pupal stage and the key factor responsible for these changes was the pupal parasitoid, P. 

puparum. A. glomeratus which parasitizes the larvae of A. rapae also contributed 

substantially to the total mortality. However, rates of parasitism by both species of 

parasitoids only reached high levels late in the growing season and did not prevent A. 

rapae from reaching densities which were injurious to the cabbage crop (Michalowicz 

1980). 

Major mortality factors of the diamondback moth larvae in Ontario are the larval 

parasitoids, M;croplitis plutellae (Mues.) and Diadegma insulare (Cress.), and the 

pupal parasitoid, D;adromus subti/icornis (Grav.) (Butts 1979, Bolter 1982). In three 

of four years in which parasitoids were monitored from 1977-81 in Cambridge, 

Ontario, D. insulare was the dominant parasitoid while D. subtilicornis was the 

dominant parasitoid in one of the four years. 

In a study of the competition between the larval parasitoids D. insulare and M. 

plutellae (Bolter 1982), it was shown that female D. insulare produced an average of 

814 eggs in a lifespan of 26 days at 23°C, while female M. plutellae produced an average 

of 318 eggs in a lifespan of 20 days at 23°C. D. insulare avoided superparasitism and 

multiple parasitism of hosts already parasitized by M. plutellae. M. plutellae generally

Artogeia rapae (L.). 17 

avoids superparasitism. but cannot detect eggs of D. insulare in the host for at least 12 

hours after they were oviposited. However, the first-instar larva of M. plutellae was 

shown to be intrinsically superior to the first-instar larva of D. insulare. 

The native parasitoid complex of the diamondback moth does not provide adequate 

control of diamondback moth on Brussels sprouts late in the season when conditions 

favour an increase in the host population. 

Parasitoid Introductions Apanteles rubecula a larval parasitoid of A. rapae was introduced from British 

Columbia to Richmond, Ontario by Harcourt in 1970 and 1971. Establishment of the 

parasitoid was in doubt. However, four specimens of A. rubecula were recovered from 

a garden plot in Ottawa in 1982. A small number of A. rubecula. originally obtained 

from British Columbia, were released in Guelph, Ontario (40 99 and dd in 1978, 85 99 

and 120 dd in 1979), Harrow, Ontario (180 99 and 120 dd in 1978) and Cambridge, 

Ontario (165 99 and 175 o'd in 1979). Although pupae of A. rubecula were observed in 

the field in the fall during the year of each release, no A. rubecula have been recovered 

from the release areas during 1980-82. 

A second strain of A. rubecula obtained from north eastern China in 1981 was 

released at Guelph during 1982, but establishment of the parasitoids is unknown at the 

time of this report. 

Apanteles plutellae (Kurdj.) a larval parasitoid of the diamondback moth, native to 

Europe was imported to Guelph in 1981 from the CIBC laboratory in Trinidad. It is 

presently in culture at the University of Guelph and will be released in Guelph during 

1982. 

Host-Parasitoid-Pathogen Interactions 

The host-parasitoid-pathogen interactions between the parasitoid Apanteles glomeratus, 

a granulosis virus (GV), and their lepidopteran host Artogeia rapae larvae 

depended on the length of time between oviposition by the parasitoid and time of 

ingestion of the virus by the host. Parasitoids did not survive in hosts which ingested 

virus on or before the fifth day post-parasitism. Percentage survival of parasitoids 

gradually increased from 26% when oviposition by parasitoids occurred six days prior 

to GV infection, to 90% when oviposition by parasitoids occurred nine days prior to GV 

infection. Survival of parasitoids in non-virus treated hosts remained consistently 

above 95%. The degree of host infection was strongly correlated with survival of 

parasitoids: the heavier the host's GV infection, the fewer parasitoids that emerged 

from the host to pupate and that emerged from the pupae as adults (Levin et al. 1981). 

After prior oviposition in GV-infected A. rapae larvae, A. glomeralUS transmitted 

GV to healthy A. rapae larvae 73% of the time. Ninety per cent of parasitoids 

transmitted GV to at least one recipient larva. A. glomeralus which developed in and 

emerged from GV-infected A. rapae larvae, transmitted GV to 84% of the larvae in 

which they initially oviposited. Discrimination between healthy and diseased A. rapae 

larvae by female A. glomeralus was not observed. This lack of discrimination is likely 

to contribute to the dissemination of GV from host to host by A. glomeralUS in the field 

and to mortality of the parasitoid's progeny. Thus, the parasitoid is at a disadvantage 

when competing with GV in the field for hosts (Levin el al. 1979, 1983).

Pest Status 

Background 

Chapter 6 

Culex pipiens L., Northern House 

Mosquito (Diptera: Culicidae) 

1.A. GEORGE 

The northern house mosquito, or rain barrel mosquito, Culex pipiens L., has long been 

known to live in close proximity to humans in southern Ontario (Wood el al. 1979). 

Larvae occur most commonly in stagnant water polluted to some degree with varying 

amounts of decaying organic matter such as vegetation or sewage. C. pipiens larvae 

are usually associated with, or follow the earlier occurring larvae of Culex resluans 

Theobald. Adult populations of C. pipiens reach a peak in August, and though 

breeding continues until October, females begin entering diapause in late August and 

will not take a blood meal until the following spring (Madder el al. 1980, Madder 1981). 

Mated females spend the winter in any protected shelter available to them. About mid 

May females seek their first blood meal and deposit the first egg rafts during the third 

week of May at Guelph (Madder el al. 1980). Thoughfemales prefer the blood of birds 

to that of mammals (Hayes 1961), they will, when abundant, invade homes and feed on 

humans. 

C. pipiens has been implicated in the spread of St. Louis encephalitis (SLE) and it, 

along with Culex resluans (Madder el al. 1980), is assumed to be the vector of this 

virus in eastern North America (Wood el al. 1979). The first recorded epidemic of SLE 

occurred in southern Ontario in 1974-75 and stimulated investigations on surveillance 

for,and abatement of this insect (Mahdy el al. 1979, Helson el al. 1980). 

Four years (1977 -80) of identifying mosquito larvae by the author for the Middlesex 

London District Health Unit, London, Ontario survey crews, has helped to establish 

catch basins, designed to drain away surface water, as major breeding sites for C. 

pipiens in this area. In 1979 catch basins accounted for 96% of all breeding sites found 

by the survey crew (Pringle el al. 1978). Moreover, on randomly selected streets in 

Brampton, Clarkson, Streetsville, and Port Credit, 70% of the catch basins examined 

contained Culex larvae (Hill, 1978, personal communication). 

Catch basins not only provide water high in organic matter throughout the summer, 

but, in addition, the underground pipes into which they drain provide ideal protected 

sites for the females to spend the winter months. In addition, the street locations of 

most catch basins puts them in close proximity to human dwellings. Finally, some 

catch basins form a part of many farm drainage systems. These also support Culex 

larvae. Thus, the drainage systems, established throughout southern Ontario to 

remove surface water, provide ideal breeding conditions for C. pipiens and C. 

resluans, the suspected vectors of SLE. 

The planarian flatworm, Dugesia ligrina (Girard) (Tricladida, Turbellaria), has been 

known to be a predator of mosquitoes since Lischetti (1919) reported it to consume 

mosquito larvae (Jenkins 1964). A larger species, Dugesia dorolocephala (Woodworth), 

has recently been shown also to act as an effective predator of mosquito eggs, larvae, 

and pupae in California (Legner & Medved 1972, 1974, Medved & Legner 1974, Yu & 

Legner 1976). Small Merosloma species, under 1 mm in length, of planaria in the order 

Rhabdocoelida, kill mosquito larvae in the rice fields of California (Case & Washino 

1979). 

19


Acknowledgement 


Culex pipiens L.. 21 

basins can readily be inoculated with reared planaria or more simply by transferring 

floats with planaria to new catch basins. 

Research on the abatement of Culex spp. in catch basins is required to enable intelligent 

control measures to be implemented if Culex-transmitted SLE virus reappears in 

Ontario. A study of the ability of predaceous planaria to survive year round in catch 

basins is under way. A search for Merostoma species should be conducted in Ontario. 

If planaria fail, the next most promising control in catch basins appears to be a 

means of slow release of B.t.;' or methoprene. 

This research was assisted by the Ontario Ministry of the Environment through the 

Ontario Pesticide Advisory Committee. 

Case. T.; Washino. R.K. (1979) Flatwonn control of mosquito larvae in rice fields. Science 206. 1412-1414. 

George. J.A. (1978) The potential of a local planarian. Dugesia tigriM (Tricladida. Turbellaria). for the control of mosquitoes in Ontario. 

Proceedings of Ihe EntomologicDl Society of Ontario 109.65-69. 

Hayes. R.O. (1961) Host preferences of Culiseta melanura and allied mosquitoes. Mosquito News 21. 179-187. 

Helson. B. V.; Surgeoner. G.A.; Wright. R.E. (1980) The seasonal distribution and species composition of mosquitoes (Diptera: Culicidae) 

collected during a St. Louis Encephalitis surveillance program from 1976 to 1978 in southwestern Ontario. 

Canadian Entomologist 112. 865-874. 

Jenkins. D.W. (1964) Pathogens. parasites and predators of medically important anhropods- Annotated list and bibliography. Bulletin of 

the World Heallh Organization Supplement to vol 30. 

Legner. E.F.; Medved. R.A. (1972) Predators investigated for the biological control of mosquitoes and midges at the University of California. 

Riverside. Proceedings of the California Mosquito Control Associotion 40. 109-111. 

Legner. E.F.; Medvcd. R.A. (1974) laboratory and small-scale field experiments with planaria (Tricladida. Turbellaria) as biological 

mosquito control agents. Proceedings of the Califomio Mosquito Control Association 42. 79-80. 

Uschelli. A.B. (1919) Un venne del genero Planoria. enemigo natural de las larvas del mosquito. Physis. Buenos Aires. 4.591-595. 

Madder. D.J. (1981) Biological studies on Culex pipiens L. and Culex restuans Theo. (Diptera. Culicidae) in southern Ontario. Ph.D. Thesis. 

University of Guelph. 125 pp. 

Madder. D.J.; MacDonald. R.S.; Surgeoner. G.A.; He/son. B.V. (1980) The use of oviposition activity to monitor populations of Culex 

pipiens and Culex restuans (Diptera: Culicidae). Canadian Entomologist 112. 1013-1017. 

Mahdy. M.S.; Spence. L.; Joshua. J.M. (Eds) (1979) Arboviral encephalitides in Ontario with special reference to St. Louis encephalitis. 

Ontario Ministry of Health, 364 pp. 

Medved. R.A.; Legner. E.F. (1974) Feeding and reproduction of the planarian Dugesia dorotocephala (Woodworth). in the presence of 

Culex peris Speiser. Environmental Entomology 3, 637-641. 

Pringle. T.; Ryan. S.; Smith. L. (1978) Middlesex County mosquito·bome encephalitis control programme (1978). Report of Middlesex 

London District Health Unit, London. Ontario. 36 pp. 

Wood. D.M.; Dang. P.T.; Ellis. R.A. (1979) The insects and arachnids of Canada. Part 6. The mosquitoes of Canada. Diptera: Culicidae. 

Agriculture Canada Publication 1686. 390 pp. 

Yu. Hyo-sok; Legner. E.F. (1976) Regulation of aquatic Diptera by planaria. Entomophaga 21. 3-12.

Blank Page 

22

Pest Status 

Background 

Host Specificity 

Chapter 7 

Culiseta inornata (Williston), a Mosquito 

(Diptera: Culicidae) 

J .A. SHEMANCHUK, H.C. WHISLER and S.L. ZEBOLD 

Culiseta inomata (Williston) is a very common mosquito species in the Prairie 

Provinces of Canada. It is found not only in the open country but also in the aspen 

grove regions. Females of this species pass the winter as fertilized females in rodent 

burrows, caves, root cellars, rock piles, and abandoned buildings. Generally, the 

species does not appear in large numbers until late July. There are several generations 

in a season. C. inomata is a common pest of livestock and occasionally of man, and is 

a vector of western equine encephalomyelitis and California encephalitis (Morgante & 

Shemanchuk 1967, Shemanchuk & Morgante 1967). 

Concern about the environmental contamination with pesticides has led many 

countries to examine the use of biological agents for the control of mosquitoes. An 

aquatic fungus, Coelomomyces psorophorae Couch (Chytridiomycetes: Blastocladiales), 

parasitic on larvae of C. inomata was discovered in the irrigated areas of southern 

Alberta in 1956 and has been found there every year since. Larval mortalities up to 

80% have occurred in some of the breeding ponds. This fungus was also found 

infecting C. inornata larvae in the irrigated areas of Saskatchewan, which indicates a 

wide geographic distribution. 

The persistence of this fungus in the irrigated areas of southern Alberta and 

Saskatchewan and the ability to colonize the host species of mosquitoes in the 

laboratory prompted us to study further this particular host-parasite combination. 

Laboratory experiments resulted in the discovery of a previously unknown obligate 

alternate host the copepod, Cyclops vernalis, in the life-cycle of Coelomomyces 

psorophorae (Whisler et al. 1974, 1975). In the life-cycle, the zygote seeks out and 

attaches to the intersegmental membranes of the mosquito larva and penetrates the 

cuticle leading to the development of hyphal bodies, mycelium, and ultimately thickwalled 

resistant sporangia in the coelom of the larva, which kill the larva. Under 

appropriate conditions, these sporangia release zoospores of opposite mating type 

which infect the alternate host, Cyclops vernalis. Each zoospore develops into a 

thallus and eventually gametangia. Gametes of opposite mating type fuse either in or 

outside of the copepod to form the mosquito-infecting zygote. 

The discovery of the life-cycle led to the development of a successful laboratory 

procedure for the propagation of the fungus and to a better understanding of its basic 

biology. 

With the reliable technique which was developed for consistent and significant 

infections in C. inornata in the laboratory, host specificity studies of Coelomomyces 

psorophorae were possible. The possibility of infecting Aedes vexans (Meigen) 

received particular attention because larvae of this mosquito with light infections of 

Coelomomyces psorophorae have occasionally been found in field sites where heavily 

infected larvae of C. inornata were also found. Larvae of A. vexans, A. dorsalis 

23

24 J. A. Shemanchuk. H. C. Wisler and S. L. Zebold 

Field Trials 



(Meigen), and A. flavescens (Muller) were exposed to zygotes of Coelomomyces 

psorophorae, but, despite repeated attempts, infections by this strain were never 

attained. C. inornata larvae in the same experiment were infected (Zebold et al. 1979). 

These results seemed to support the prevailing opinion that Coelomomyces is a 

highly specific parasite. In further tests, however, infection was achieved in Culex 

pipiens L., C. quinquefasciatus Say, A. aegypti (L.), A. sierrensis (Ludlow), A. 

triseriatus (Say), and C. inornata (Louisiana strain). 

A. aegypti larvae were more susceptible than the other species, but maximum 

resistant sporangia production was consistently best in the original host species, C. 

inornata. 

In 1979, a preliminary field trial was conducted at 8-Mile Lake near Lethbridge using 

laboratory-cultured Coelomomyces psorophorae. Six artificial pools were established. 

One pool was inoculated with zoospores and copepods, one received copepods that 

were infected in the laboratory and were ready to release the zygotes, two pools 

received zygotes from laboratory-infected copepods, and two pools that received no 

fungal inoculum served as controls. Into each of the pools, first instar laboratoryreared 

larvae of C. inornata were introduced and exposed for 24 hours after which 

they were brought back to the laboratory for rearing to final instar and for observation 

for infection. 

The results from this test confirmed our field observation that the fungus is an 

effective killer of C. inomata larvae. The fungus was most effective when introduced 

into mosquito habitats in the zygote stage and produced a 64% kill. 

These results further indicate that this fungus will have practical application in 

controlling C. inornata as a short-term microbial pesticide and as a long-term inoculum 

in mosquito-breeding habitats where the fungus does not occur naturally. 

(1) Expand research on the design and development of techniques for large-scale 

production and long-term storage of Coelomomyces psorophorae. 

(2) Evaluate Coelomomyces psorophorae as a short-term microbial pesticide and as a 

long-term inoculum in mosquito-breeding habitats in the irrigated areas and in areas 

where the fungus does not occur. 

(3) Continue searching for Coelomomyces infections in other species of mosquitoes 

and define their life-cycles. 

(4) Search for other aquatic fungi that might be domesticated and manipulated for the 

control of mosquitoes. 

Morgante. 0.; Shemanchuk. J.A. (1967) Virus of California Encephalitis Complex; isolation from Cuiisela inornata. Science 157. 692-693. 

Shemanchuk. J.A.; Morgante. O. (1967) Isolation of Western Encephalitis virus from mosquitoes in Albena. Canadian JoumJll of 

Microbiology 14.1-5. 

Whisler. H.C.; Zebold; S.L.; Shemanchuk. J.A. (1974) Alternate host for mosquito parasitic Coelomomyces. Nature 251. 715-716. 

Whisler. H.C.; Zebold. S.L.; Shemanchuk. J.A. (1975) Life history of Coelomomyces psorophorae. Proceedings of the National Academy 

of Sciences 72. 693-696. 

Zcbold. S.L.; Whisler H.C.; Shemanchuk. J.A.; Travland. L.B. (1979) Host specilicity and penetration in mosquito pathogen Coe/omomyces 

psorophorae. Canadian Journal of Botany 57. 2766-2nO.

Pest Status 

Background 

Orchard Tests 

Table 3 

Chapter 8 

Cydia pomonella (L.), Codling Moth 

(Lepidoptera: Tortricidae) 

R.P. JAQUES and J.E. LAING 

The codling moth, Cydia pomonella (L.), is a major pest of apple in most areas of 

Canada in which the crop is grown. Several chemical insecticides, notably phosmet, 

azinphos-methyl, and permethrin, are effective against the pest. Nevertheless, protection 

of apples against the codling moth is a major concern in development of integrated 

pest management programmes for apples, not only because of the importance of the 

pest, but also because the broad-spectrum insecticides used to control it are detrimental to 

the predaceous and parasitic arthropods in orchards. 

A granulosis virus discovered by Tanada (1964) has been shown to be highly infectious 

for C. pomonella larvae in laboratory tests (Keller 1973, Laing & Jaques 1981). The 

virus was quite effective against the pest in apple orchard tests in Germany (Huber & 

Dickler 1977), reducing damage 10 fruit by C. pomonella by as much as 89%. Falcon el 

al. (1968) obtained similar crop protection in tests in California but the virus was less 

effective in orchard tests in Ohio (Sheppard & Stairs 1976). 

The granulosis virus of C. pomonella (CPGV) was applied to apple trees at four 

locations in Canada between 1974 and 1980 in orchard tests on effectiveness of the 

virus against the codling moth (Jaques el al. 1977, 1981). 

Seven-tree plots were sprayed at rales of 1 x 10 9 to 3 X 10 10 GIB of CPGV or 0.5 g 

azinphos-methyl per litre of spray in a 4-year test (1975-78) carried out at the 

Research Station at KentviJIe, Nova Scotia. A summary of results (Table 3) indicated 

that CPGV was not as effective as azinphos-methyl in protecting apples against 

damage by larvae of C. pomonella. Total damage to picked and dropped apples 

harvested from plots treated with CPGV was reduced by an average of 95.5%. 

Injury to apples by larvae of Cydia pomonella (L.) in a 4-year orchard test at KentviJIe. 

Nova Scotia, on efficacy of a granulosis virus· 

Material 

Virus 

Azinphos-methyl 

Check 

Injury by C. pomonellallOO apples 

Picked fruit Picked + Dropped fruit 

SE" DE-· SE DE 

1.6 1.0 1.7 1.6 

0.1 0.1 0.2 0.4 

1.2 3.0 1.3 12.1 

·Tests were carried out in cooperation with C.R. MacLellan and K.H. Sanford, 

Research Station, Agriculture Canada. Kentville, N.S. 

··SE and DE refer 10 "shallow-entry" and "deep-entry" injury, respectively. 

25

26 R. P. Jaques and J. E. Laing 

Table 4 

Evaluation of Control Attempts 

The granulosis virus was applied to plots in apple orchards at the Research Station, 

Summerland, British Columbia, in 1975 and 1976; at the Research Station, Vineland 

Station, Ontario, in 1974, 1977, and 1978; and at the University of Guelph, Guelph, 

Ontario, in 1976-80; Table 4 lists data from some of the tests. 

Injury to apples by larvae of Cydia pomonella (L.) in orchard tests on efficacy of C. 

pomonella granulosis virus'. 

Materialllitre Applica.tionsl Injury by c.!omonellallOO 

of spray generatIon apples picke at harvest 

1st 2nd SE·· DE** 

Summerland, British Columbia 

1975 

CPGV 3.2-7.3 x lO9 GIB 2 2 55 32 

Check 0 0 22 71 

Vineland Station, Ontario 

1974 

CPGV 3.5-6.5 x 10 9 

GIB 3 2 21 5 

Phosmet 3.1 g 2 1 2 I 

Check 0 0 5 22 

Guelph, Ontario 

1979 

CPGV 3.3xlO'o GIB 3 3 9 2 

Check 

1979 

0 0 11 14 

CPGV 3.6xlO'o GIB 2 2 11 2 

3 4 8 0 

Check 0 0 7 11 

·Tests were carried out in cooperation with M.D. Proverbs, Research Station 

Summerland, British Columbia, and E.A.C. Hagley and R. Trottier, Research 

Station, Vineland Station, Ontario. 

"SE and DE refer to "shallow-entry" and "deep-entry" injury. respectively. 

Total damage to apples in plots treated with CPGV was not reduced appreciably in 

many of the tests. Deep-entry (D.E.) damage was reduced by 55% to 100%, approaching 

the reductions noted in plots treated with a chemical insecticide. It is noteworthy that 

shallow entries (stings) (S.E.) were higher in apples from plots treated with the virus 

than in nontreated apples in some tests, e.g. 1975 Summerland test, presumably 

because larvae infected by the virus died after they had entered the apple. 

The 1979 test at Guelph indicated superior crop protection with increased numbers 

of applications of the virus. In a plot test in 1980 at Guelph, CPGV was applied 2 or 4 

times for each of the two generations of C. pomonella larvae; however, crop 

protection was not increased by the higher frequency of application. 

The granulosis virus of C. pomonella did not protect the crop as well as did chemical 

insecticides in these tests. However, the virus is considered to have substantial 

potential in integrated pest management because it is specific for the target insect.

Cydia pomollella (L.). 27 

Further studies will emphasize timing and dosages of application, persistence of the 

virus in the orchard habitat, and application of the virus in combination with low 

dosages of chemical insecticides as means of increasing effectiveness. 


Falcon. L.A.; Kane. W.R.; Bethell. R.S. (1968) Preliminary evaluation of the granulosis virus for control of the codling moth. Journal of 

Economic Entomology 61. 1208-1213. 

Huber. J.; Dickler. E. (1977) Codling moth granulosis: Its efficacy in the field in comparison with organophosphorous insecticides. Journal of 

Economic EnlOmology 70. 557-561. 

Jaques. R. P.: Maclellan. C. R.; Sanford. K. H.; Proverbs. M.D.; Hagley. E.A.C. (19n) Preliminary orchard tests on control of codling moth 

larvae by a granulosis virus. Canadian Entomologist 109. 1079-1081. 

Jaques. R.P.; Laing. J.E.; Maclellan. C.R.; Proverbs. M.D.; Sanford. K.H.; Trottier. R. (1981) Apple orchard tests on efficacy of the 

granulosis virus of the codling moth. Laspeyresia pomonella (Lepidoptera: Olethreutidae). Ento· 

mophaga 26. 111-117. 

Keller. S. (1973) Mikrobiologische Bekiimpfung des Apfelwicklers Laspeyresia pomonella (L.) (= Carpocapsa pomonel/Q) mit spezifischen 

Granulosisvirus. Zeit.schrift fiir angewandte Entomologie 73. 137-181. 

Laing. D.R.; Jaques. R.P. (1981) Codling moth: techniques for rearing larvae and bioassaying granulosis virus. Joumal of Economic 

Entomology 73. 831-853. 

Sheppard. R.E.; Stairs. G.R. (1976) Effects of dissemination of low dosage levels of a granulosis virus in populations of the codling moth. 

Jou",al of Economic Entomology 69, 583-586. 

Tanada. Y. (1964) A granulosis virus of the codling moth. Carpocapsa pomonella (Linnaeus) (Olethreutidae, Lepidoptera). Journal of Insect 

Pathology 6.378-380.

Blank Page 

28

Chapter 9 

Delia antiqua (Meigen), Onion Maggot 

(Diptera: Anthomyiidae) 

F.L. McEWEN 

The onion maggot, Delia anliqua (Meigen), is the most destructive pest of onions 

throughout the temperate regions of the northern hemisphere and in Canada causes 

losses of 50-90% (Finlayson 1959). Effective control was not achieved until the late 

1940s when the cyclodiene insecticides became available. These, when applied in the 

furrow with the seed, provided excellent control of the first generation and additional 

treatments of DDT against the second and third generation adults reduced damage to a 

minimum. Resistance to these insecticides developed and the cyclodienes were 

replaced about 1960 by such organophosphorus components as ethion and diazinon. 

Subsequently chlorfenvinphos, fensulfothion, carbofuran, fonofos, and chlorpyrifos 

have been used in the seed furrow; and parathion, diazinon, naled, or malathion have 

been used as sprays against the adults of the second and third generation. Resistance 

to several of these insecticides has developed and, while the level of resistance has not 

been as great as with the cyclodienes, commercial control is becoming increasingly 

difficult (Harris & Svec 1976). 

The use of the sterile-male approach for insect control was first successfully applied 

(Knipling 1960) against a livestock pest and since then its use has been explored for 

many insect species. In the case of the onion maggot, McClanahan & Simmons 

(1966) and Noordink (1966) showed that the insect could be sterilized without serious 

effects on the longevity of the adult. In Holland, Noordink and his associates 

continued studies on the sterile-male method for control, and by 1980 had completed 

laboratory and field testing to the point where a commercial venture in marketing the 

programme to the growers is now in place (Noordink 1971, 1974; Ticheler el al. 1974; 

Loosjes 1976). 

In Canada, research on sterile-male control for the onion maggot began as a 

cooperative venture between Agriculture Canada (C.R. Harris) and the University of 

Guelph (F.L. McEwen) in 1971. In the initial stages of the study, mass rearing 

procedures were perfected (Harris & Svec 1976), and laboratory tests determined that 

when pupae reared under diapausing conditions were irradiated (Cobalt 60) after 6 

days post-diapause (24°C) at 2 or 4 krad, the males were sterilized and the females 

made unreproductive. Tests established that males produced from these pupae were 

competitive and lived about as long as those emerging from non-irradiated pupae. 

Initial field releases of sterilized pupae were begun in 1973 and, using fluorescent 

dyes as markers on released flies, the field distribution pattern was also determined. 

The survival of released flies was monitored and eggs collected in the field and hatch 

determined. The initial results indicated that the flies did not disperse widely (most 

recaptures were within 75 m of release site) and that the hatchability of eggs in the 

release area was reduced. In addition, an economic study was undertaken that showed 

that if the sterile-male programme was effective, it was an economically sound 

approach (King 1973). 

Field tests were expanded with 6000000 pupae released in 1974 and 10 000 000 in 

1975. While it was clear that egg hatch was reduced, bird predation on released pupae 

and immigration of wild flies into the release area resulted in inconsistent results. 

Extensive monitoring indicated, however, that when the ratio of wild to released flies 

approached 1: I, the egg hatch was reduced near 50%. 

29

30 F. L. McEwen 


Since rearing facilities for continuing field releases at the 1974 and 1975 levels were 

no longer available, the release portion of the programme was curtailed in subsequent 

years and efforts concentrated on learning more about the field ecology of wild and 

released flies, studying mating habits and determining a release procedure in which 

bird predation would not be such an important negative factor on the programme. 

These studies have demonstrated that the pupae can be released by air or as adults by 

air and, hopefully, will not be so subject to predation as ground release of pupae in 

designated sites. It has been shown also that the female fly mates only once (Martin 

1981) and that in the field, much of the survival of third generation larvae to 

overwintering pupae results from cull and volunteer onions left in the field after 

harvest. Thus fall sanitation is an essential component in a programme to reduce onion 

maggot populations. 

Future plans are to release approximately 100 000 000 sterilized flies in an isolated 

onion-growing area containing about 300 ha of onions in each of the years 1982 and 

1983. To accommodate this, a new biological control laboratory has been built at the 

University of Guelph with major facilities and space for mass rearing the onion 

maggot. These releases will be closely monitored and serve as a demonstration project 

to determine the feasibility of the sterile-male method of control. If successful on the 

limited area chosen, the programme will be expanded to the major onion areas in 

Ontario. 

Finlayson, D.G. (1959) Chemical control of the onion maggot in onions grown from seed in various types of soil in Northwestern America in 

1955-56. Journal of Economic Entomology 52, 851-856. 

Harris, C.R.; Svec, H. (1976) Onion maggot resistance to insecticides. Journal of Economic Entomology 69, 617-620. 

King, D.L.J. (1973) An economic appraisal of the sterile-male technique of onion maggot control on the Holland Marsh of Ontario. M.Sc. 

Thesis, University of Guelph, 176 pp. 

Knipling, E.F. (1960) The eradication of the screw-worm Oy. Scientific American 203, 54-61. 

Loosjes, M. (1976) Ecology and genetic control of the onion Oy Delia antiqua Meigen. Wageningen, PUDOC; 94 pp. 

Martin, J.S. (1981) Mating beha\;our of the onion maggot Oy Hylemya antiqua (Meigen) in laboratory conditions. M.Sc. Thesis, University 

of Guelph, 43 pp. 

McCIanaham, R.J.; Simmons, H.S.(1966) Sterilization of onion maggots by irradiation with cesium-137. Canadian Entomologist 98, 931-935. 

Noordink, J.Ph.W. (1971) Irradiation, competitiveness, and the use of radioisotopes in sterile-male studies with the onion Oy, Hylemya 

antiqua M. In: Sterility principle forinsect control or eradication. International Aromic Energy:Agency, 

232-328. 

Noordink, J.Ph.W. (1974) Onderzoek met behulp van radiactivc isotopen. Jaarversl. 1973. Mededelingen Instituut voor Plantenziektenkundig 

Onderzoek, Wageningen, 119-121. 

Ticheler, J.; Loosjes, M.; Noordink, J.Ph. W.; Noorlandcr, J.; Theunissen, J. (1974) Field experiments with the release of sterilized onion 

Dies Hylemya antiqua (Meig.). In: The sterile-insect technique and its field of applications International 

Atomic Energy Agency, 103-107.

Pest Status 

Background 

Chapter 10 

Entomoscelis americana Brown, Red 

Turnip Beetle (Coleoptera: 


G.H. GERBER 

The red turnip beetle, Entomosce/is americana Brown, is an oligophagous insect 

which feeds on Cruciferae and is an occasional pest of rape, Brassica campestris L. and 

B. napus L., mustard, B. juncea (L.) Czern. and B. Itirta Moench, and cruciferous 

garden crops in western Canada (Stewart 1973, Gerber & Obadofin 1981a, 1981b). The 

larvae and adults feed on seedling plants in May and June before the adults aestivate in 

July, and the adults feed on mature plants in August and September after aestivation. 

The only damage of economic significance is caused by the adults in June (Gerber 1974, 

1976). 

The red turnip beetle is native to North America and in Canada occurs south of the 

Arctic climatic zone and west of longitude 96°W (Stewart 1973). The beetle overwinters in 

the egg stage on the surface of the soil. The eggs hatch in late April and early May, 

shortly after the snow has melted, but usually before rape, mustard, and cruciferous 

garden crops are planted (Gerber & Obadofin 1981a). Larval development normally is 

completed by the end of May. The larvae feed on volunteer rape and mustard 

seedlings, and on cruciferous weeds in fields that contained these plants the previous 

year (Tumock et al. 1979). The adults emerge during the first 3 weeks of June and feed 

for 2-3 weeks, usually in the same fields in which the larvae fed. If the supply of food 

plants is not adequate. the adults will move into nearby new fields containing their host 

plants. At the end of June, the adults enter the soil to aestivate for about a month. They 

reappear in late July and August; disperse to new fields of rape, mustard, or garden 

Cruciferae; and mate and lay eggs until late October. 

The only known natural enemies of E. americana attack the adult stage: a pathogen 

(microsporidia (Gerber 1975» and a predator (adults of the carabid beetle, Pterosticltus 

adstrictus (W.J. Tumock, 1975. personal communication». These two natural enemies 

have been encountered on only a few occasions in the field and consequently are not 

considered to be important control agents. 

Manolache (1941) reported two tachinid parasitoids in the larvae and pupae of a 

European species of Entomoscelis (E. adonidis Pall.) in Romania: Meigenia mllIabilis 

Fall. and Marcltantia clta/cltonta Meig. However, the incidence of parasitism by M. 

mutabilis was low «6.0%) and Manolache considered E. adonidis to be only a 

secondary host for this tachinid (a heteroxenous species). Manolache did not report on 

the abundance and importance of the other tachinid. Brovdii (1977) found up to 38% of 

the last instar larvae of E. adonidis parasitized by tachinids in the Ukraine. but the 

tachinids were not identified. 

Studies were initiated in 1973 to identify the natural enemies of E. adonidis in 

Europe and to determine whether there are any parasitoids of this beetle which are 

suitable for introduction into Canada as control agents for E. americana. The 

parasitoids of E. adonidis were considered to be potential control agents for E. 

americana, because the life histories, phenology. and host plants of these two species 

31

32 G. H. Gerber 



are similar (Manolache 1941; Stewart 1973; Brovdii 1977; Gerber & Obadofin 1981a, 

1981b). These studies have not been successful, because populations of E. adonidis 

have been extremely scarce outside of the Soviet Union since 1973. Only a small 

number of specimens of a species of Meigenia have been found parasitizing the larvae. 

Collections of E. adonidis have not yet been made in the Soviet Union. 

It is recommended that every attempt be made to collect additional larvae and adults of 

E. adonidis from Europe, especially from the Soviet Union, to identify the parasitoids 

of this beetle. If M. mutabilis is the only parasitoid which can be collected in sufficient 

number for release in Canada, research is needed to determine its life history and 

whether it is truly heteroxenous. If M. mutabilis is heteroxenous, it would not be a 

suitable control agent for E. americana. 

Efforts also should be made to collect another species of Entomoscelis, E. suturalis, 

which occurs on Cruciferae in Europe. The life history of E. suturalis is similar to 

those for E. americana and E. adonidis (Brovdii 1977), but there is no information in 

the literature on its natural enemies. 

Brovdii, V.M. (19n) Fauna of the Ukraine - Chrysomelinae leaf beetles. Ukrainian S.S.R. Academy of Sciences. Institute of Zoology. 

Naukova Dumka. Kiev 19(16), 1-388. (In Ukrainian). 

Gerber, G.H. (1974) Red turnip beetle on rape. Canadex 149.622. 

Gerber, G.H. (1975) Occurrence of a microsporidian infection in the red turnip beetle. Entomo.fcelis americana (Coleoptera: Chrysomelidae). 

Canadian Entomologist 107, 1081-1082. 

Gerber. G.H. (1976) Effects of feeding by adults of the red turnip beetle, Entomosctlis americana Brown (Coleoptera: Chrysomelidae). during 

late July and August on the yield of rapeseed (Cruciferae). Manitoba Entomologist 10,31-35. 

Gerber, G.H.; Obadofin. A.A. (198Ia) Growth, development and survival of the larvae of the red turnip beetle, Entomoscelis americana 

(Coleoptera: Chrysomelidae) on Brassica campestris and B. napus (Cruciferae). Canadian Entomologist 

lB. 395-406. 

Gerber. G.H.; Obadofin. A.A. (198lb) The suitability of nine species of Cruciferae as hosts for the larvae of the red turnip beetle. Entomosctlis 

americana. (Coleoptera: Chrysomelidae). Canadian Entomologist 113.407-413. 

Manolache. F. (1941) Research on the morphology. biology. and control of the insect, Entomoscelis adonidis Pall .• in Romania. Methods. 

Guidance and Investigations. Institute of Agronomic Research Romania (Bucharest) 71. 1-205. (In 

Romanian). 

Stewan. D.B. (1973) The red turnip beetle. Entomoscelis americana Brown (Coleoptera: Chrysomelidae). biology and plant relationships. 

M.Sc.Thesis, University of Albena. Edmonton, 86 pp. 

Tumock. W.J.; Gerber, G. H.; Bickis, M.; Bennett. R.B. (1979) The applicability of X-ray energy-dispersive spectroscopy to the identification 

of populations of red turnip beetle. Entomoscelis americana (Coleoptera: Chrysomelidae). Canadian Ento· 

mologist 111. 113-125.

Pest Status 

Background 

Chapter 11 

Euxoa messoria (Harris), Darksided 

Cutworm (Lepidoptera: Noctuidae) 

H.H. CHENG 

The darksided cutwonn, Euxoa messoria (Harris), is the most destructive insect pest 

of tobacco in Ontario and indeed throughout most tobacco-growing areas of Canada. 

It is a northern species which has also done great damage to a variety of crops. The 

principal injury is caused by larvae which attack the newly transplanted tobacco 

seedlings and damage the leaves or growing points and sometimes notch or sever the 

plants. If left uncontrolled, a low to moderate population level of this pest has resulted 

in 20-48% damaged plants and 14-25% loss of yield (Cheng 1971a, 1971b, 1973c, 

1975, 1980a). In the tobacco-growing areas, large populations of this pest are 

produced in the rye rotation crop, but invasion by migrating larvae is always a problem 

(Bucher & Cheng 1970). 

The bionomics of the darksided cutworm in Ontario has been published (Cheng 

1973a). It has one generation a year and overwinters as an egg in the soil from 6 to 12 mm 

below the surface. Depending upon the weather, overwintered eggs begin to hatch 

from the end of March to early April. Larvae in the early instars feed on the rye 

rotation crop, later they attack newly transplanted tobacco seedlings. The duration of 

the larval stage is about 3 months. The mature larvae cease feeding and transform to 

pupae in the soil from late July to mid-August. The pupal stage lasts from 18 to 28 days. 

The adults emerge from mid-August to October and lay their eggs in the soil during the 

same period. These eggs are completely developed before winter and hatch in the 

following spring. 

Research on darksided cutwonn control in Canada in the past 10 years has centered 

in two areas: (1) selection and evaluation of the more effective and safe chemical 

insecticides (Cheng 1979, 1980a, 1980b), and (2) search and evaluation of effective 

biological control agents (Bucher 1970, 1971; Cheng 1973b, 1977). These approaches 

are reviewed in this chapter. 

As more information becomes available on the hazards involved in the agricultural use 

of insecticides, there is a greater demand for alternative methods for controlling 

insect pests. Consequently, laboratory and field tests with virus pathogens and 

Bacillus rhuringiensis preparations were conducted from 1968 to 1972 at the Research 

Station, Delhi, Ontario (Bucher 1970, 1971, Cheng 1973b). The results indicated that 

these pathogens were significantly less effective than chemical insecticides against E. 

messoria larvae in the field (Cheng 1973b). 

Studies on the biology and collection of parasitoids, predators, and diseases of E. 

messoria have also been conducted by Agriculture Canada at the Delhi Research 

Station. The degree of the influence of various biotic factors on E. messoria 

populations and the importance and possible roles of the natural enemies in the 

tobacco crop and pest relationship have been discussed (Bucher & Cheng 1971, 

Cheng 1973a, 1977). In general. larval mortality in E. messoria from natural enemies 

was low. 

Tobacco is the number one cash crop in Ontario. Because of the high value of the 

crop and the insufficient pressure of the various biotic factors on the dark sided 

33

34 H. H. Cheng 

Parasitoids 

Predators 

cutworm, the use of chemical insecticides for control of this pest is vital to tobacco 

production. Persistent chemical insecticides, such as DDT and endosulfan (Thiodan®, 

Niagara Otemicals) cannot be used on tobacco because of the danger of environmental 

contamination and undesirable residues in tobacco (Cheng & Braun 1977, Frank et al. 

1977). Therefore, research in the evaluation of insecticidal control of cutworms in 

tobacco has been directed towards the more effective and safe chemical insecticides 

(Cheng 1973c, 1975, 1979, 1980a, 1980b). For example, the broad-spectrum pyrethroids, 

permethrin, and cypermethrin are very toxic to the cutworm larvae and nonhazardous, 

and have been registered and recommended for both preplanting (on the 

rye cover crop or on soil surface) and postplanting (on tobacco plants) for control of 

cutworms. 

From 1973 to 1977, 14 species of insect parasitoids were reared from E. messoria 

larvae or pupae in Ontario; they all were primary and internal parasitoids, namely, 

Apanteles laeviceps Ashmead, A. militaris Walsh, Meteorus communis (Cresson) and 

M. levil'entris (Wesmael) (Hymenoptera: Braconidae); Arenetra rufipes vernalis 

Walley, Campoletis flavicinctus (Ashmead), Campoletis sp., Enicospilus sp., and 

Eutanyacra sllturalis (Say) (Hymenoptera: Ichneumonidae); Copidosoma bakeri 

(Howard) (Hymenoptera: Encyrtidae); Muscina stabulans (Fall.) (Diptera: Muscidae); 

Linnaemya compta (Fall.), Winthemia rll/opicta (Bigot), and W. deilephilae (O.S.) 

(Diptera: Tachinidae). Of these 14 species, Arenetra rufipes vernalis, Copidosoma 

bakeri, and Enicospilus sp. were the most common species reared from E. messoria 

larvae and were present in considerable numbers every year. The total parasitism by 

these three species was about 22% (Cheng 1977) and were considered to be the most 

important parasitoids of E. messoria. 

From the economic point of view, A. rllfipes vernalis is considered to be the most 

effective parasitoid of the darksided cutworm in the current generation in Ontario. It 

kills the sixth-instar larvae and essentially prevents the cutworm from causing the 

maximum damage to the tobacco crop, because the seventh instar of this pest does 

more damage to the tobacco crop than all the other instars combined. Enicospi/us sp. 

kills its host in the seventh instar or prepupal stage, and it reduces some losses caused 

by the cutworm. Conversely, C. bakeri increases the crop losses by the current 

generation, because the cutworms attacked by C. bakeri consumed 27.5% more food 

than did normal cutworms (McMillan 1930); however, it will reduce the population 

levels of the following generation of this pest. The rest of the parasitoids were present 

in small numbers or reared only once during the period of this study and it is likely that 

they are not important. 

Several birds, insects, and spiders were observed to attack the larvae and adults of the 

dark sided cutworm (Cheng 1973a). Birds periodically landed in the fields in search of 

larvae in the early morning; most frequently recorded were starlings and grackles. Two 

species of ground beetles, Calosoma calidum (F.) and Harpalus caliginosus F. 

(Coleoptera: Carabidae), were the most important insect predators. Both the adults 

and larvae of the ground beetles destroyed a large number of cutworms. Moths of the 

darksided cutworm were preyed upon by spiders, which were identified as Leiobunum 

vittatum (Say), Phalangium opilio (L.), Hadrobllnus maculostlS (Wood), and Odie/lus 

pictus (Wood), as the moths rested in their hiding places. However, definitive studies 

on the effectiveness of these predator complexes in the regulation of E. messoria 

populations are lacking. Nevertheless, they are assumed to be valuable biological 

control factors.

Diseases 

Microbial Insecticide 

EIlXO(l messoria (Harris). 35 

Several insect pathogens have been isolated from the diseased larvae of E. messoria 

collected in the fields at Delhi, Ontario (Bucher & Cheng 1971). The bacterial diseases 

are common and the bacteria most commonly isolated from infested larvae are Bacillus 

cereus Frankland & Frankland, Enterobacter cloacae (Jordan), Enterobacter aerogenes 

(Kruse), Klebsiella pneumoniae (Schroeter), Streptococcus faecalis (Andrewes 

& Horder), Pseudomonas j1uorescens Migula, Pseudomonas spp., Bacillus splraericus 

Neide, and Achromobacter spp. The infected haemocoels of cutworm larvae usually 

contained one or a mixture of two or more bacterial species. B. cereus is a well-known 

pathogen of many insects (Heimpel & Angus 1963); E. aerogenes and P. fluorescens 

have been considered as potential pathogens of a number of insects (Bucher 1963); the 

pathogenicity of the other species is very questionable and they probably occurred by 

chance in the haemocoel of sick larvae of E. messoria. The microsporidial disease, 

Nosema sp., is less common; the fungus disease, Sorosporella uvella (Krass.), is rare; 

and the virus diseases are virtually absent. 

Although larvae of E. messoria collected in the fields in Ontario are free from virus 

diseases, they are susceptible to two virus diseases, nuclear polyhedrosis and 

granulosis virus, originally isolated from a related cutworm, E. ochrogaster (Guenee) 

(Bucher 1970). In cooperation with Dr. G.E. Bucher of Agriculture Canada Research 

Institute, Belleville, Ontario, field tests using preparations of nuclear polyhedrosis 

virus and granulosis virus were conducted in 1969 and 1970 at the Research Station, 

Delhi, Ontario. These tests showed that both viruses would protect tobacco seedlings 

from severe cutworm damage when applied on the green rye in high concentrations, 

but they were less effective than chlorpyrifos (Dursban® or Lorsban l8l , Dow Chemical 

of Canada Ltd.) treatment and better than the untreated control. 

In 1971 and 1972, attempts were made to introduce both virus diseases into healthy 

populations of E. messoria by spraying the virus suspensions on tobacco trap-plants 

growing in a rye field. Consequently, a considerable number of E. messoria larvae 

collected with tobacco trap-plants from areas where viruses were introduced in 1971 

and 1972 were infested with virus. This indicated that a large amount of virus survival 

occurred and that virus introduction is feasible. Unfortunately, this programme was 

discontinued after the Research Institute, Belleville, Ontario, closed in the fall of 1972. 

In 1969, laboratory experiments were conducted to determine the susceptibility of the 

various larval stages of E. messoria in Ontario to four commercial preparations of 

Bacillus thuringiensis Berliner: Thuricide® 9OTS, Thuricide® HP, Biotrol l8l BTB 183, 

and Dipel® (Sandoz Canada). In these experiments, first-instar to third-instar larvae 

that fed on rye leaves treated with all four B. thuringiensis preparations were found to 

be susceptible at all rates applied (Cheng 1973b). Mortality of fourth-instar to seventhinstar 

larvae fed treated tobacco leaves was low. 

From the results of laboratory experiments, it was apparent that preparations of B. 

thurittgiensis showed potential as a possible alternative to chemical insecticides for the 

control of the early instar larvae of E. messoria. Therefore, a field test was conducted 

in 1970 at the Agriculture Canada Research Station, Delhi, Ontario, to determine 

whether these preparations could be as effective as chlorpyrifos for control of this pest 

when applied on the rye cover crop in spring. Data showed that B. tlruringiensis 

preparations as applied in the field for control of E. messoria larvae were relatively 

ineffective as compared with chlorpyrifos (Cheng 1973b). The failure of these 

preparations in the field trial is probably attributable to the different environmental 

conditions and the much more complex ecosystem in the field than in the laboratory.

Blank Page 

38

Pest Status 

Background 

Releases and Recoveries 



Chapter 12 

Forficula auricularia L. , European 

Earwig (Dermaptera: Forficulidae) 

R.F. MORRIS 

This report is an update on the European earwig, Forficula auricularia L., and its 

parasitoid, Bigonichela selipennis (Fallen), in Newfoundland as last reported by 

Morris (1971). This pest continued to spread throughout Newfoundland, and is now 

found in the following communities: St. John's, Wedgewood Park, Mt. Pearl, Kilbride, 

Petty Harbour, Logy Bay, Topsail, Long Pond, Torbay, Renews, Bay Roberts, 

Clarkes Beach, Grand Bank, Fortune, Grand Falls, Stephenville. 

The European earwig was first discovered in Newfoundland at St. John's in 1948. The 

parasitoid, Bigonichela selipennis, was introduced from British Columbia to Newfoundland 

in 1951, 1952, and 1953. It was successfully established but parasitism was 

extremely low during the period 1955-59 (Morris 1971). Because of a slow build-up, 

supposedly hardier strains of the parasitoid were obtained by the Research Institute at 

Belleville from Sweden and Switzerland and released at St. John's in 1959, 1961, and 

1963. 

The use of traps and attractants to complement earwig control with parasitoids were 

investigated and reported on by Morris (1965). 

No additional releases of Bigollichela selipennis have been made since those recorded 

by Morris (1971). Studies on its establishment and population increase were continued 

during the period from 1969 to 1978. Results are shown in Table 5. 

The introduced parasitoid, Bigonichela selipellllis, has successfully established itself 

with a maximum parasitism of 16.4% in 1973. Although the initial parasitism was low, 

4.4% in 1969, a steady increase was observed until 1973. There has been a considerable 

reduction in earwig populations in the study area since 1972, making it impossible to 

collect as large samples (4000 earwigs) as were used in the earlier years, and this 

reduction is no doubt due to the high levels of parasitism during the 1972-76 period. 

There has been a continuing spread of earwigs from the original site in St. John's with 

populations now established 420 km and 775 km from St. John's. Studies should be 

initiated to determine if the parasitoid has been introduced with its host to Grand 

Bank, Fortune, Grand Falls, and Stephenville. If it has not been introduced naturally, 

steps should be taken to artificially introduce Bigonichela selipellnis to these areas. 

39

Pest Status 

Background 


Parasitoids 

Pathogens 

Chapter 13 

Hypera postica (Gyllenhal), Alfalfa 

Weevil (Coleoptera: Curculionidae) 

D.G. HARCOURT and J.e. GUPPY 

Since its invasion of the mid-Atlantic States during the early 1950s, the eastern strain 

of the alfalfa weevil, Hypera pos/iea (Oyll.), has become the most important pest of 

alfalfa in eastern North America. Of Eurasian origin, this biotype spread rapidly 

northward and in little more than a decade reached Ontario and Quebec where it began 

to alarm dairy farmers in the lower Great Lakes region. From 1967 to 1974, 

populations spread throughout southern Ontario, increasing at geometric rates. 

However, by the mid-seventies. this pattern of unregulated growth had been checked 

by the combined action of natural enemies, and during the past 5 years numbers of the 

pest have been constrained at a density level that fluctuates about the economic 

damage threshold. As a result. outbreaks have been restricted. However, scattered 

epicentres of infestations still exist and sudden population flare-ups are prone to occur. 

In 1957. the Beneficial Insects Research Laboratory. Northeastern region, 

U.S.D.A .• began to make releases of exotic parasitoids against the weevil. A total of 

13 species was released, several of which became established (Abu & Ellis 1976). 

Discovery of the pest in Ontario in 1967 prompted recolonization here, of those species 

that had become established in the northeastern United States (Williamson 1971, 1972). 

Six species of parasitoids were released in various localities in Ontario during 1970 and 

1971 (Williamson 1971, 1972): Bathyplectes anurus (Thomson), B. eureulionis 

(Thomson), B. slenosligma (Thomson), Mieroelonus aelhiopoides Loan, M. coles; 

Drea, and Telras/jehus ineertus (Ratzeburg). Recoveries in 1971 included all species 

except M. eolesi which was not found until 1978. B. slenostigma was not found in 

follow-up years but all other species became firmly established. Although B. anurus 

was recovered the first year after its release. it has been slow to establish and spread, 

and its incidence of parasitism is of little importance. 

The egg parasitoid, Palasson luna (Girault) was not released in Ontario but has 

spread across the province with its host. 

In 1973. an infectious disease caused by the fungus Entomophthora phytonomi Arthur 

(Harcourt et al. 1974) was discovered in the Bay of Quinte area of southern Ontario 

where it caused a spectacular epizootic in populations of the weevil. New to the insect 

in North America. it was soon found throughout Ontario and in adjacent parts of the 

United States (Muka & Oyrisco 1976). 

41

Hypem poslica (GyllcnhaJ). 43 

I-Iarcourt. D.G.; Guppy. J.C.; Macleod. D.M.; Tyrrell. D. (1974) The fungus Emomopill/wrtl pi,ylollomi pathogenic to the alfalfa weevil. 

Hypera postim. Catracliatr Emomologisl 106. 1295-1300. 

Harcourt. D. G.; Guppy, J.c.; Binns, M. R. (1977) TIle analysis of inlrageneration change in eastern Ontario populations oflhc alfaUa weevil. 

Hypera postiCCl (Coleoptera: Curculionidae). Canadian Elllomologist 109, 1521-1534. 

Harcourt. D.G.; Ellis, C.R.; Guppy. J.C. (1980) Distribution of Microclonlls aelltiopoitles.1I parusitoid of the alfalfa weevil (Coleoptera: 

Curculionidlle) in Ontario. Proceedings of tlte Emomologicltl Society of Omario (1979) lID, 35-39. 

loan. C.C. (1971) SitOIlCl cylindricollis Fahr., sweelclover weevil, and Hypera postica (Gyll.) •• lIf.llfll weevil (Coleoptera: Curculionidae). In: 

Biological conlrol progrummcs against insects and weeds in Cllnadll 1959-68. Commonwealtll blStitl4le 

of Biological COlllml Technical Commwlicatiotl 4. 43-46. 

Muka. A.A.; Gyrisco, G.G. (1976) Report presenled III 13th Northeast Regional Alfalfa Insects Conference, Newark, Delaware. 

Williamson, G.D. (1971) Insect liberalions in Canada, 1970. Parasites and predators. Canacia AgricllllIlre Liberatioll Bulietin 34. 16 pp. 

Williamson. G.D. (1972) Insect liberations in Canada. 1971. Parasites and predators. Canacia Agrialllllre LiberatiOlJ Bulietin 35. 16 pp.

Blank Page 

44

Pest Status 

Background 

Chapter 14 

Lygus spp., 

Miridae) 

C.H. CRAIG and c.c. LOAN 

Plant Bugs (Heteroptera: 

About 30 species of Lygus are known to occur from coast to coast in Canada (Kelton 

1975). Most of the species feed on a variety of herbaceous and woody plants. some are 

host specific or are limited to related plant species. Many species of Lyglls are 

economically important as pests of fruits. vegetables. and tobacco crops, and of legume 

crops. primarily those grown for seed. Of the dozen species found on alfalfa the most 

abundant and important as pests are L. borealis Kelton and L. lineo/aris (Palisot de 

Beauvois), with L. unctuosus (Kelton). L. desertinus Knight, and L. shulli Knight of 

lesser importance. 

Lygus overwinter as adults in the shelter of plant litter on the soil surface. In spring 

they feed on the early plants and move to alfalfa when it becomes suitable for feeding 

and oviposition. 

In Canada the number of generations of Lygus per year is not well documented 

because nymphal taxonomy is not known. It is generally conceded. however. that the 

species are univoltine in northern latitudes and bivoltine. or largely so. south of about 

latitude 51°N. 

Lygus feeding injures the vegetative and reproductive parts of the plant causing 

stunting. bud-blast and premature nower drop. and reduced yield and quality of seed. 

In most years and in most alfalfa seed fields. Lygus infestations exceed the economic 

threshold and control measures are essential. 

In Poland. Lygus rugulipennis Poppius. the dominant species on alfalfa. is parasitized 

by the braconids PeristemlS digoneUlis Loan. P. stygicus Loan. and P. rubricol/is 

(Thomson). The former two are bivoltine and attack both generations of host; the 

latter is univoltine and attacks only the first generation host (Bilewicz-Pawinska 

1969. 1975). 

In Canada, at Belleville. Ontario. L. lineo/aris. in the first generation on forage 

legumes. is parasitized by Peristenus pal/ipes (Curtis) and in the second generation on 

several weed species. by P. pseudopal/ipes (Loan) (Loan 1965. 1970). 

In 1975 in a survey of first-generation Lygus populations in alfalfa seed fields in 

Saskatchewan and Alberta. P. pal/ipes was the only euphorine parasitoid recovered. 

Incidence ranged from 3% to 49%. with an average of 21 % in the southern shortgrass 

prairie region. 28% in the central mixed prairie region, and 11% in the northern 

parkland-mixed forest region (Loan & Craig 1976). Surveys since that time have noted 

the occurrence of euphorine parasitism probably by P. pallipes, in second-generation 

Lygus in the southern prairie region (Craig. 1980. unpublished data). 

45

46 C. H. Craig and C. C. Loan 



Table 6 

A programme to supplement the natural parasitism in Lygus populations in western 

Canada was started in 1977 with the first collection and shipment to Ottawa of parasitoids 

of European Lyglls, and in 1978 with the first liberations of these in western 

Canada. Table 6 shows the progression of liberations in the period 1978-81 inclusive. 

Liberations of Peristenus spp. in alfalfa against Lygus spp. in western 

Canada. 

Date of liberation Location of liberation site 

7 June 1978 

9 June 1978 

13 June 1978 

21 June 1978 

14 June 1979 

21 June 1979 

29 June 1979 

29 May 1980 

3 June 1980 

10 June 1980 

10 June 1980 

6 June 1981 

6 June 1981 

! 

} 

Moose Jaw, Saskatchewan; 50 o N; 

shortgrass prairie; dry 

Saskatoon, Saskatchewan; 52°N; 

mixed prairie; dry 

Tilley, Alberta; 50 0 30'N; 

shortgrass prairie; 

irrigated 

Shellbrook, Saskatchewan; 53°N; 

parkland-mixed forest; dry 

Ardath, Saskatchewan; 51°30'N; 

mixed prairie; dry 

Shellbrook, Saskatchewan 

(supplement to 1979 release) 

Saskatoon, Saskatchewan 

mixed prairie; irrigated 



Yellow Creek, Saskatchewan; 

53°N parkland; dry 



Species 

P. digoneLltis 


P. digoneutis 

P. stygicus 


P. srygicus 


P. digoneutis 

P. digoneutis 

P. digoneutis 

P. digoneutis 

P. digoneutis 

Number 

The imported parasitoids were released into Lygus populations breeding in alfalfa 

fields used for seed production. The lifespan of the sites for sampling purposes is about 

5 years, and during that time they are subject to normal alfalfa seed cropping practices. 

Intensive sampling for presence of adult Peristenus and mass collection of host 

nymphs for parasitoid rearing was started the year follOwing the initial liberations and 

continued for at least three ensuing years. In 1979-80, a total of 274 parasitoid adults, 

either captured at the liberation sites or reared from Lygus hosts collected from alfalfa 

at the liberation sites, were the native species, Peristenus pallipes. No introduced 

parasitoids have been recovered. 

The introduction and liberation of Peristenus parasitoids will terminate in the spring of 

1981. During the next few years attempts will be made to recover the introduced 

parasitoids and to evaluate the programme. 

197 

177 

541 

41 

159 

23 

167 

261 

80 

138 

125 

115


Lyglls spp., 47 

Bilewicz-Pawinska. T. (1969) Natural limitation of LygllS TIlgu/ipel"'is Popp. by groups of UiophTon pallipes Curtis on the rye crop fields. 

Ekologia /'olska, Series .. 1 17.811-815. 

Bilcwicz-Pawinska. T. (1975) Distribution of insect parasites l'eristellllS Foerster lind MesochoTlis Gravenhorst in Poland. Bulletin lie 

I'ACtldemie Polonaise des Sciences 23. 823-827. 

Kelton. L.A. (1975) The LygllS bugs (genus Lygus Hahn) of North America (Heteroptera: Miridac). Memoirs o/tlle Entom%gielll Society of 

Canada 95, 101 pp. 

Loan. C.C. (1965) Life cycle and development of LeiopilTonpllllipes Curtis (Hymenoptera: Braconidae. Euphorinae) in five mirid hosts in the 

Belleville district. Proceedi/lgs of tile ElllomologiCtlI Society of Ontario (1964) 95, 115-121. 

Loan. C.C. (1970) The new parasites of the tarnished plant bug in Ontario: Leioplirol/1JSlmdopallipes and Euphoriantllygivora (Hymenoptera: 

Braconidae. Euphorinae). Prm:eel!i'lgs af the Elllolllological Society of Olllario 100, 188-195. 

Loan, C.C.; Craig. C.H. (1976) Euphllrine parasitism of Lyglls spp. in lllflllfil in western CllOllda (Hymenoptera: Braconidae; Heteroptem: 

Miridac). NtltllTll/iste Cal/aditlll 103, 497-500.

Blank Page 

48

Introduction 

Pest Status 

Background 

Chapter 15 

Mamestra configurata Walker, Bertha 

Armyworm (Lepidoptera: Noctuidae) 

W.J. TURNOCK 

The bertha armyworm, Mamestra configllrata Walker, was first recognized as a major 

pest of the rapeseed and canola crops, Brassica nap"s (L.) and B. campestris L., on the 

Canadian prairies in 1971. Little was known of the life history and natural control of this 

species. In 1972, research programmes were initiated at Agriculture Canada Research 

Stations in western Canada. Soon after, the Commonwealth Institute of Biological 

Control station at Delemont. Switzerland, began a study of the closely related European 

species, Mamestra brassicae (L.). To date, no decision has been made to introduce 

parasitoids of M. brassicae to Canada. This report summarizes information on the 

natural enemies of M. configllrata and M. brassicae and suggests future actions in 

biological control of the former species in Canada. 

M. configurata is native to North America and in Canada occurs from Manitoba to 

British Columbia (Wylie & Bucher 1977). Its native hosts are unknown, but it has been 

reported to feed on a wide variety of cultivated plants and introduced weeds (Beirne 

1971). On the Canadian prairies sporadic infestations occurred on various crops before 

1940. Since then attacks have largely been confined to fields of rapeseed and canola 

(Turnock & Philip 1979). From 1940 to 1970 the outbreaks were local and of short 

duration. From 1971 to 1974 an outbreak of unprecedented severity occurred from 

western Manitoba across the parkland region to Edmonton, and from Lethbridge to 

the Peace River District in Alberta. Insecticides were applied to about 38 000 ha 

(17.7% of the seeded area) in 1971, and about 31000 ha (23.3% ofthe seeded area) in 

1972. The outbreak declined in 1973 and damaging infestations were absent by 1975. 

Populations increased again in 1978 and 1979, and in 1980 about 49 000 ha (2.4% of the 

seeded area) were sprayed. 

The bertha armyworm is univoltine in Canada and overwinters in the pupal stage. 

Adults emerge from the first week of June to early August, in most years 50% of the 

adults have emerged by mid-July. Egg-laying, on the underside of the leaves of host 

plants, begins soon after emergence and the eggs hatch about 1 week later. There are 

six larval instars. The larvae feed mainly on the leaves, but the older instars may 

damage flowers and pods. Fully-fed larvae enter the soil in late August and September 

and pupate at depths down to 15 cm. 

The early reports of bertha armyworm infestations do not include lists of parasitoids or 

diseases (Wylie & Bucher 1977). Since 1972, collections of larvae have yielded 15 

species of parasitoids (Table 7). Wylie (1979) reared an additional 3 species from larvae 

and 5 species from pupae that had been held in field cages in an area where the bertha 

armyworm has never been found. Neither egg nor pupal parasitoids has been found in 

field collections. 

49

50 W. J. Turnock 

Table 7 

Table 8 

Parasitoids recovered from field-collected larvae of Mamestra eonfigllrata 

Walker in Canada. 

Hymenoptera 

Ichneumonidae 

Banehlls f1aveseens Cress. (M,S,A)· 

Braconidae 

Apanteles xylinlls (Say) (M) 

Cotesia laevicips (Ashm.) (M) 

Eulophidae 

Elllophlls nr. nebillosus (Prov.) (M) 

Eupleetrus bieolor Swed. (M) 

Diptera 

Tachinidae 

Athrycia cinerea (Coq.) (M,S,A)· 

Mericia ampeius (WIK.) (M,S,A) 

Exorista mella (Wlk.) (S.A) 

Phryxe peeosensis(Tnsd.) (M) 

P. vulgaris (Fall.) (M) 

Chaetogena sp. (A) 

C. sp. (c1aripennis (Macq.) group) (A) 

Lespesia sp. (A) 

Winthemia rufopieta (Bigot) (M) 

W. qlladripustulata (F.) (M) 

• Location of collection points in parenthesis. (M = Manitoba, S = Saskatchewan, 

A = Alberta). 

Banehus f1aveseens Cress. was the most abundant species regardless of host 

abundance (Table 8). This univoltine parasitoid lays its eggs in the early larval instars 

and completes its development before the host would normally pupate. 

Parasitism ('Yo) by Banehus f1aveseens Cress., Athrycia cinerea (Coq.), Mericia ampelus 

(Wlk.), and other species on Mamestra eonfigurata Walker in Manitoba, Saskatchewan, 

and Alberta, 1972-80. 

Parasitism ('Yo) 

Year(s) Province No. No. Banehus Athrycia Mericia Other 

Fields Larvae 

1972-74 Manitoba 119 1915 28.3 20.7 0.4 0.1 

Saskatchewan 1 59 47.5 1.7 3.4 1.7 

Alberta 5 506 42.5 21.7 2.4 0 

1975-78 Manitoba 152 100 44.0 25.0 0 2.0 

1979 Manitoba 43 410 6.1 9.3 0 1.7 

Saskatchewan • 2 1273 14.0 29.0·· 

1980 Manitoba 51 2154 26.3 6.2 0.04 0.3 

Alberta 3 775 25.3 4.4 0 0 

Data provided by A.P. Arthur, Agriculture Canada, Research Station, Saskatoon . 

•• Mainly A. cinerea. 

Athrycia cinerea (Coq.) usually was less abundant than B. f1al'eseens when host 

populations were low (Table 8). but it may be as abundant in some fields during 

outbreaks. A. cinerea is univoltine in the Prairie Provinces. The eggs arc attached to 

the integument of larvae in the fourth to sixth instars. the larvae usually develop 

gregariously, and they mature before the host completes its feeding (Wylie 1977a).

MameSlra configurara Walker, 51 

Mericia ampelus (W1k.) was found in a very small percentage of bertha armyworm 

larvae collected during outbreaks, but has not been collected between outbreaks 

(Table 8). This species attaches its eggs to the leaves of plants and the larvae hatch 1-2 

minutes after oviposition. It appears to be bivoltine in Canada, but only the second 

generation parasitizes bertha armyworm. Larval survival is low, suggesting that Mamestra 

configurala is not a preferred host (Wylie 1977b). 

Pathogens have not been a major cause of mortality in the bertha armyworm. Wylie 

& Bucher (1977) identified fungus pathogens of the genus Entomophthora and a 

nuclear polyhedrosis virus as the main larval diseases in 1972. In addition, a protozoan 

parasite, possibly of the genus Nosema, was recovered from a few larvae. 

The cabbage moth, Mameslra brassicae (L.), is similar to M. configurala in its life 

history and phenology. M. brassicae feeds on a wide range of plants and is a major pest 

of cabbage in northern Eurasia. In western Europe (Switzerland, Austria, Germany) 

and in the warmer climatic zones of the Soviet Union (Kiev, Kharkov, Voronetz, and 

Krasnodar regions), it is bivoltine (CIBC Annual Project Statements 1974-80, 

Dzhuran 1979, Agarkov 1974, Stenin 1974, Drozda & Garnaga 1978, Tsybul'ko 1973). 

In cooler parts of the Soviet Union (Moscow, Gorky, Leningrad, Volgoda (Perm), 

Tomsk, Altai, Irkutsk, and Sakhalin regions), it is univoltine (Hori 1935, Kopvillem 

1960, Shchetinin 1974, Prokov'cva 1976, Kostylyova 1979). The univoltine populations 

lie north and the bivoltine populations lie south of the annual isotherm for 2 200" days 

over lOoC (Fig. 1). 

The parasitoid complex of M. brassicae consists of 47 species, of which 20 occur in 

the USSR (Razumov 1972, Kopvillem 1962). However, only 23 species are reported in 

the CIBC Annual Project Statements and recent literature from the Soviet Union 

(Table 9). Only two species, ErneSlia consobrina (Mg.) and Exelastes cinclipes (Retz.), 

are abundant in both areas. 

Ernestia consobrina occupies a similar position in the guild of parasitoids to that 

occupied by Mericia ampeills in North America. E. consobrina larviposits on the food 

plant of the host. Parasitism is most successful in third·instar larvae and M. brassicae is the 

major host (Kopvillem 1960, 1962, CIBC Annual Project Statement 1974); E. consobrina 

is the most important parasitoid of Mameslra brassicae in most of the Soviet Union 

(KopviJIem 1962), but not in western Europe (CIBC Annual Project Statements 

1974-80). It docs not occur in Primorskiy (far east) (Slabospitskii 1980). In the areas of 

the Soviet Union where both host and parasitoid are bivoltine, it appears to have 

problems in synchronization with its host. In the Kicv region, Dzhuran (1979) reports a 

large decrcase in parasitism from the first to the second host generation while Drozda 

& Garnaga (1978) note an increase in the second generation. In univoltine areas, E. 

consobrina appears to be a more effective parasitoid than in bivoltine areas. High 

levels of parasitism are reported from the Leningnld, Moscow. and Volgoda (Perm) 

regions (Kopvillem 1960), the Gorky region (Razumov 1972), and the Irkutsk region of 

western Siberia (Shchetinin 1974). 

Exelastes cinclipes occupies a similar position in the guild of parasitoids to that 

occupied by B. f/al'cscens in North America. E. cinclipes is bivoltine in western 

Europe, where it parasitizes larvac of the second generation (CIBC Annual Project 

Statement 1974). In the Moscow region. it is univoltine (Kopvillem 1960). This ichneumon 

mainly parasitizes third·instar larvae and appears to be well synchronized with its 

host (Kopvillem 1960). E. cinclipes is a common parasitoid in both western Europe and 

the Soviet Union. In westcrn Europc and areas of the Soviet Union with bivoltine hosts, 

it is more important than E. cOllsobrina (Tsybul'ko 1973. Agarkov 1974, CIBC Annual 

Project Statements 1974-78). but in cooler parts of the Soviet Union it is less abundant 

(Kopvillem 1962. Razumov 1972. Shchctinin 1974). 

Microplilis mediator (Hal.). like B. flal't'scens in North America. attacks host larvae 

in the early instars but unlikc it. M. mediator is multivoltine (CIBC Annual Project

Table 9 

Mamestra configurata Walker. 53 

Insect parasitoids of Mamestra brassicae Walker in western Europe and the USSR (See 

Fig. 1 for location of regions in the USSR). 

Family and Species 

Tachinidae 

Erneslia eonsobrina (Mg.) 

Phryxe vulgaris (Fall.) 

Alhrycia impressa (Wlp.) 

A. erYlhroeera R.D. 

Sip/rona erislala (F.) 

S. flavifrons Staeger 

Winlhemia quadripuslulala (F.) 

Exorisla larvarum (L.) (Taehina 

larvarum (L.» 

Blondelia nigripe.f (Fall.) 

Ceromasia sp. 

Ichncumonidae 

E.wasles cinelipes (Rctz.) 

Therion giganteum (Grav.) 

Campoplegini sp. 

Sleniehnellmon eulpalor (Schrank) 

Braconidac 

Microplilis mediator (Hal.) 

M. tubereulifer (Wcsm.) 

COlesia eongesla (Nees) 

C. glomerala (L.) 

MeleOru.v leviventris (Wesm.) 

Eulophidae 

ElllopllUs larvarllm L. 

Ellpleclrus sp. 

Eupleelrlls bieolor Swcd. 

Trichogrammatidae 

Triehogramma evaneseens Wcstw. 

Host Bivoltinc 

W. Europe. Krasnodar. 

Kiev. Saratov 

W. Europe 

Primorskiy 

W. Europe 

Krasnodar. Veronezh 

W. Europe 

W. Europe 

W. Europe. Kharkov 

Krasnodar 

W. Europe 

W. Europe 

Kharkov. Primorskiy 

Krasnodar. Voronezh 

Krasnodar 

Krasnodar. Kharkov 

W. Europe. Krasnodar. 

Voronezh. Kharkov. Kiev 

Region of Occurrence 

Host Univoltine 

Leningrad. Volgoda. 

Moscow. Gorky. Tomsk 

Tomsk 

Tomsk 

Tomsk 

Tomsk 

Moscow 

Moscow 

Moscow 

Sakhalin 

Moscow. Gorky. Tomsk. 

Sakhalin 

Sakhalin 

Gorky 

Sakhalin 

Sakhalin 

Gorky. Irkutsk. Altai 

Statement 1978). M. mediator is the most abundant parasitoid of Mamestra brassicae in 

Europe (CIBC Annual Project Statements 1974-80) but is not reported from the Soviet 

Union. It does not enter dispause to overwinter (CIBC Annual Project Statement 1980) 

and this characteristic may explain its absence from the Soviet Union. Microplitis tuberculifer 

(Wesm.) was the most abundant parasitoid in far eastern regions (Slabospitskii 

1980). where Mamestra brassicae is bivoltine. M. brassicae is univoltine on the island of 

Sakhaline and is attacked by 5 species of parasitoids (Hori 1935). Only one of these. E. 

cinctipes. also occurs in other parts of the Soviet Union (Table 7). 

An egg parasitoid. TricllOgramma el'anescens Westw., occurs in western Europe 

and the Voronezh. Kharkov. Krasnodar, Gorky. Irkutsk. and Altai regions of the USSR 

(Razumov 1972. Tsybul'ko 1973. Agarkov 1974. Prokoreva 1976, CIBC Annual Project

54 W. J. Turnock 


Acknowledgements 

Statement 1978, Kostylyova 1979). In the regions where the host is univoltine, T. evanescens 

generally is very rare (Prokoreva 1976). It is used as an inundative biological 

control agent in the USSR. 

The major components of the parasitoid guilds of M. configurata and M. brassicae 

attacking the early instar larvae include one ichneumon, B. f1avescens, in Canada; and 

two ichneumons, E. cintipes and Microplitis mediator, and one tachinid, E. consobrina, 

in western Europe. In Canada. one tachinid, A. cinerea, attacks the late instar larvae of 

Mamestra cotlfigurata but no species of comparable effectiveness is reported from Eurasia. 

No egg parasitoids occur in Canada whereas T. evanescens occurs at generally low levels 

in Eurasia. 

The differences in the major components of the parasitoid guilds of M. configurata and 

of M. brassicae lead to the following recommendations for parasitoid introductions into 

Canada: 

(1) Parasitoids attacking the early larval ins tars 

(a) Ichneumons: B. f1avescetls in Canada is more effective than either E. cinctipes 

or Microplitis mediator in Eurasia. M. mediator does not go into diapause and does not 

occur in those parts of the Soviet Union where Mamestra brassicae is univoltine. Neither 

E. cinctipes nor Microplitis mediator should be considered for introduction into Canada. 

(b) Tachinids: Mamestra configurata does not have an effective species attacking the 

early larval instars as Mericia ampe/us is poorly adapted. E. consobrina is an important 

parasitoid in Eurasia. It successfully parasitizes Mamestra configurata in the laboratory 

(Wylie 1977a) and has potential as a biological control agent. Material for releases in 

Canada should be obtained from areas where M. brassicae is univoltine. 

(2) Parasitoids attacking late larval instars 

In Canada, A. ci1lerea is common, particularly during outbreaks, but no equivalent 

species is reported as a major parasitoid of M. brassicae in Eurasia. A. cinerea could 

be considered for introduction into the Soviet Union, perhaps as part of an exchange of 

material involving E. C01lsobri1la. M. brassicae was a suitable host for A. cinerea in 

laboratory tests (Wylie 1977a). 

(3) Egg parasitoids 

The very low level of egg parasitism in M. brassicae does not suggest that T. evanescens 

would contribute significantly to the control of M. configurata in Canada. However, the 

local form of T. evanescens reported from the Irkutsk region (Kostylyova 1979) should 

be further investigated. If Canada should develop facilities for producing Trichogramma 

for inundative release, importation of the "Irkutsk" form would be desirable. 

Copies of the cited literature from the USSR were made available through the efforts 

of Mr A.1. Sylchenko, Ministry of Agriculture, Moscow, and Dr G. Tsubulskaja, 

Ukrainian Plant Protection Research Institute, Kiev. Their cooperation is greatly 

appreciated. Dr A.P. Arthur, Agriculture Canada, Saskatoon, kindly permitted the use 

of his data on parasitism of M. configurata in Saskatchewan.


Mamestra con/igurata Walker, 55 

Agarkov. V.M. (1974) Effect of entomophages on the abundance of the cabbage moth during'l period of low abundance. Bulletin oftht All· 

Union Scientific Re.rearch in.rtitllle for the PrOlectioll of Plants 27. 3-6 (Translated from Russian). 

Beirne. B.P. (1971) Pest insects of annual crop plants in Canada. Memoirs of the Enwmological Society of Canada 78. 124 pp. 

Central Intelligence Agency (1974) USSR agriculturallllias. U.S. Government Printing Office. 59 pp. 

Drozda. V.F.; Garnaga, N.G. (1978) Some biological and ecologic;11 char;scteristics of the t'lchinid Oy. Ernestia consobrina (Mg.). a parasite 

of the cabbage moth caterpill;sr. Scientific Pap'" of the Ukrainian Agrietlltural Academy 2(19. 23-25 

(Translated from Russian). 

Dzhurnn. V.N. (1979) The development of biological mcans for controlling the cabbage moth. Scientific Pap'" of the Ukraillian Agrimltural 

Academy 230. 25-26 (Translated from Russian). 

Hori. M. (1935) The cabbage moth (Barathra bra.uicae L.) in southern Saghalien. Report of the Saghalietr Central Experiment Station 

Sen-ice 1(3) (Translatcd from Japanese). 

Kop\;lIem. Kh.G. (1960) Parasites ofthe cabbage moth (Barathra brassicae L.) and the diamond· back moth (Pllllelia maculipennis Cun.) in 

the Moscow region. Entomologicl'l.'skol' Oboul'nil.' 39. 584-592. 

Kop\;lIem. Kh.G. (1962) Parasites of the cabbage moth and diamondback moth in the Moscow Region. Biological Methods of Controlling 

Pests and Discascs of Agricultural Crops I. 89-113 (Translated from Russian). 

Kostylyova. Ye.V. (1979) Experimental application of Trichogramma 'Igainstthe caggage moth in the Bratsk district of the Irkutsk region. 

In: Problems of Plant Protection in Eastern Siberia. Irkutsk. USSR. p. 34-39 (Translated from Russian). 

Prokofeva. N.A. (1976) Trichogramma in cabbage fields. Zaschita Rastenii 9. 19-20 (Translated from Russian). 

Razumov. V.P. (1972) Parasites of tbe cabbage moth (Maml'stra brassicae (L.)) in Gorky Oblasl. Proceedings of the Gorky Agricultural 

Institute 53.9-12 (Translated from Russian). 

Shchetinin. Yu.V. (1974) Parasites of the cabbage moth and diamond· back moth in the Tomsk region. In: The problems of entomology in 

Siberia. Novsibirsk. USSR. pp. 131·132 (Translated from Russian). 

SlabospilSkii. A.I. (1980) (Insect enemies of cabbage pests.) Zashchita Rastenii 5. 23 (in Russian). 

Stenin. V.I. (1974) The parasites. predators and polyhedrosis of the cabbage moth in the Kuban. Proceedings of the Kuibyshtl- Agricultural 

Institllle 125. 53-55 (Translated from Russian). 

Tsybul'ko. V.l. (1973) The main entomophages of the cabbage moth in Kharkov Province. Proceedings of the Kharkov Agricultural Institute 

182. 15-25 (Translatcd from Russian). 

Tumock. W.J.: Philip. H.G. (1979) The outbreak of benha armyworm. Maml'stra configurata (Noctuidae: Lepidoptera) in Albena 1971 to 

1975. Manitoba Entomologi.fl I I( 1977). 10-21. 

Wylie. H.G. (l977a) Observations on Athrycia cinerea (Diptera: Tachinidae). a parasite of Mamestra configurata (Lepidoptera: Noctuidae). 

Canadian Entomologist 109. 747-754. 

W)·lie. H.G. (1977b) Obsen'ations on Mericia ampe/us (Diptera: Tachinidae). an occasional parasite of hcnha armyworm. Mamestra 

configurata (Lepidoptera: Noctuidae) in western Canada. Canadian Entomologist 109. 1023-1024. 

Wylie. H.G. (1979) Insect parasites reared from artificial field populations ncar Winnipeg. Manitoba. Manitoba Entomologist 11(1977). 

SO-55. 

Wylie. H.G.; Bucher. G.E. (1977) The benha armyworm. Mamestra configurata (Lepidoptera: Noctuidae). Monalit), of immature stages on 

the rape crop. 1972-1975. Cantldian Entomologist 1119.823-837.

Blank Page 

56

Pest Status 

Background 

Chapter 16 

Manduca quinquemaculata (Haworth), 

Tomato Hornworm (Lepidoptera: 

Sphingidae) 

H.H. CHENG 

The tomato hornworm. Manduca quillquemaculata (Haworth). is principally a pest of 

tomato and tobacco plants in Canada. The distribution of this species is North and South 

American. On tobacco. the first-instar and second-instar larvae make many small holes 

in the leaves, later they eat larger areas of the lamina. and by the last instar the larvae 

may strip the top and mid-leaves of the plants leaving only the midribs and main leaf 

veins. In Canada. a moderate to high population level of this pest may cause 0.5% to 

2.7% loss of the marketable tobacco in untreated fields (Cheng 1977a). 

The tomato hornworm has one complete generation and part of a second generation 

each year under southwestern Ontario climatic conditions. Only the first generation of 

this species causes appreciable damage to tobacco. The insect overwinters as a pupa in 

the soil. Moth emergence occurs from late June to September. The adults fly at dusk and 

lay their eggs on the under side of the tobacco leaves during the same period. Eggs hatch 

within four to six days and the larvae dig into the soil to a depth of 10 to 12 cm and pupate. 

Most of the pupae remain in the soil until the following year. but some moths may 

emerge from late August to September to start a second generation. Ten-year blacklight 

trap studies showed that population levels of M. quillquemacu[ata in southwestern 

Ontario are generally low to moderate (unpublished data). 

The tomato hornworm can be successfully controlled using a number of different 

chemical insecticides, however. the use of chemical insecticides on tobacco presents a 

number of problems that may assume greater importance in the future. In particular. 

applications of certain insecticides on tobacco during late July and August result in 

insecticide residues (Cheng & Braun 1977). which have undesirable effects on the 

quality of tobacco and may put the Canadian tobacco export trade in serious jeopardy. 

Consequently. a search for and development of alternative control methods for hornworms 

has been carried out during the past 20 years. Among the more promising of the 

biological agents tested for the control of this pest are strains of the spore forming bacterium 

Bacillus thurillgiensLr Berliner. which was found to be as effective as chemical 

insecticides. and has been used successfully for controlling hornworms on tobacco 

(Guthrie et al. 1959. Creighton et al. 1961. Begg 1964. Bucher & Cheng 1971, Cheng 

1973. 1977b. 1978). 

Two commercial preparations of B. tllllrillgimsis, Dipe1® and Thuricide®-HPC, have 

been registered and recommended for use in controlling hornworms on tobacco since 

1973 (Anonymous 1973). A survey conducted in southwestern Ontario in 1977, 1978. and 

1979 indicated that about 20% of growers applied B. thuringiensis preparations for 

control of horn worms. When aphids and hornwormsoccurred in the same period, most of 

the growers would apply chemical insecticides or a tank mix combination of B. thurillgiensis 

preparation for hornworm and a chemical insecticide for aphids because B. thuringiensis 

preparations 'gave almost no control of aphids. 

57

58 H. H. Cheng 




The most important insect parasitoids of the tomato homworm are Apanteles spp., 

which parasitize 10-20% of the hom worm larvae in tobacco fields each year. 

Apanteles spp. kill the fourth-instar and fifth-instar larvae and essentially prevent 

the homworm from causing maximum damage to the tobacco crop. 

Preparations of B. thllringiensis control tomato hornworms as well as chemical 

insecticides (Bucher & Cheng 1971. Cheng 1973. 1977b, 1978) and for approximately 

the same cost of $20 to $25 per hectare for the material. B. thllringiensis has the merits 

of being nontoxic to man. plants, and non-target animals including beneficial insects 

such as parasitoids and predators. Thus it should be used by growers when an 

economic population level of the tomato horn worm larvae occurs in the tobacco fields. 

Under the present system of annual cropping of Due-cured tobacco in Ontario, 

sequential applications of insecticides for homworm control and of sucker control 

agents within short periods are common practices in tobacco production. To reduce the 

cost of control measures, attempts have been made to mix recommended insecticides 

and sucker control agents in the same tank and apply them to tobacco plants for 

control of hornworms and suckers in one spray operation. Five year tests indicated that 

all recommended insecticides used for homworm control can be mixed with sucker 

control agents in the same tank before application without losing their efficacy and 

caused no effects on the yield and quality of Due-cured tobacco in Ontario (Cheng 1977b, 

1978, 1980). 

At the Delhi Research Station, monitoring and economic threshold data have been 

developed for M. qllinquemaculata (Cheng 1977a). Since this pest overwinters as a 

pupa in the soil, early detection methods involve the capture of moths in light traps. 

Larval densities are monitored from mid-July to mid-August and insecticide applications 

are recommended when 5 or more large larvae (larger than 3 cm) are found per 100 

plants. Generally. M. qllinqllemacillata can be controlled for the whole growing season 

by a single application of B. thllringiensis or one of the recommended chemical 

insecticides. 

Detailed studies on the bionomics of the tomato hornworm in Ontario should be 

conducted. Although preparations of B. thuringiensis have provided excellent control of 

the hornworm larvae, the rapid drop of larvae from plants treated with chemical insecticides 

is much more dramatic than the cessation of feeding and the slow death of B.t.infected 

larvae. Growers, therefore, should be better informed ofthe merits of B. thuringiensis 

to offset their natural preference for a chemical insecticide that has more 

spectacular effects. A similar approach should be made in other areas of Canada where 

the tomato hornworm is a problem. 

Anonymous (1973) 1973 Tobacco production recommendations. Ontario Ministry Agriculture and Food, Pub!. 298. 32pp. 

Begg, J.A. (1964) Microbial and chemical control of homworms attacking tobacco in Ontario. Journal of Economic Entomology 57, 646-649. 

Bucher, G .E.; Cheng, H. H. (1971) Comparison of Bacillus Ihuringiensis preparations with carbaryl for homworm (Lepidoptera: Sphingidae) 

control on tobacco. Canadian Entomologist 103, 142-144. 

Cheng. H.H. (1973) Microplot test using microbial and chemical insecticides for control of tomato homworms on tobacco in Ontario. The 

Lighter 43(3). 10-13.

Mtmduca qllillqllemaclliata (Haworth), 59 

Cheng, H.H. (1977a) F1ue-cured tobacco losses caused by the tomato hornworm, Manduca quinquemaculala (Lepidoptera: Sphingidae), at 

various infestation levels in Ontario. Canadian Entomologist 109,1091-1095. 

Cheng, H.H. (1977b) Insecticides and sucker control chemicals: compatibility and effects on green peach aphid, tomato hornworm and 

suckers on flue-cured tobacco in Ontario. Tobacco Science 21, 108-111. 

Cheng, H.H. (1978) Pesticides play important role. Canadian Tobacco Grower 26(8),31-33. 

Cheng, H.H. (1980) Erfects of tank-mixed combinations of insecticides and sucker control agents on efficacy and on the yield and quality of 

flue-cured tobacco. Proceedings of the Entomological Society of Ontario Ill, 7 -12. 

Cheng, H.H.; Braun, H.E. (1977) Chlorpyrifos, carbaryl, endosulfan, leptophos, and trichlorfon residues on cured tobacco leaves from fieldtreated 

tobacco in Ontario. Canadian 10urnal of Plant Science 57,689-695. 

Creighton, C.S.; Kinard, W.S.; Allen, N. (1961) Effectiveness of Bacillus tlluringiensis and several chemical insecticides for control of 

budworms and hornworms on tobacco. 10urnal of Economic Entomology 54, 1112-1114. 

Guthrie, F.E.; Rabb, R.L.; Bowery, T.G. (1959) Evaluation of candidate insecticides and insect pathogens for tobacco hornworm control, 

1956-1958. 10urnal of Economic Entomology 52, 798-804.

Blank Page 

60

Chapter 17 

Melanoplus spp., Camnula pellucida 

(Scudder), and other Grasshoppers 

(Orthoptera: Acrididae) 

A.B. EWEN and M.K. MUKERJI 

Grasshoppers have been important destructive pests since crop production began on the 

Canadian prairies. Four species: the migratory grasshopper. Melanoplus sanguillipes 

(Fab.); the twostriped grasshopper, M. bivittatllS (Say); the Packard grasshopper, M. 

packardii Scudder; and the c1earwinged grasshopper, Camnllia pellucida (Scudder); 

generally arc considered to be the most important. Natural enemies and weather 

conditions cause marked fluctuations in their populations from year to year from one 

area to another, and several population peaks have been recorded during the more than 

thirty years that grasshopper surveys have been conducted in Saskatchewan (Gage & 

Mukerji 1977). High populations and significant damage to crops have been associated 

with early egg hatch due to an early, warm, and dry spring (Randell & Mukerji 1974). 

Grasshoppers host a variety of pathogenic micro-organisms including fungi, bacteria, 

viruses, and protozoans. Epizootics of fungal pathogens can produce drastic reductions 

in grasshopper populations. Pickford & Riegert (1964) showed that Emomophlhora 

grylli Fres. was a major factor responsible for significant reductions in grasshopper 

populations, espciaJly C. pellucida, in Saskatchewan in 1963. Although there have 

been other incidents of fungal epizootics, these pathogens have not given consistent 

control of grasshopper populations because of their restrictive requirements of specific 

moisture and temperature conditions for initiation and dissemination of infection in the 

host populations (Henry 1970). Most bacteria associated with grasshoppers are 

facultative pathogens which cannot multiply in the host gut but require direct passage 

into the haemocoele (Bucher 1960). Also. bacteria and many of the fungi pathogenic in 

grasshoppers are not suitable microbial control agents because they are associated 

with or pathogenic in other insects and animals (Henry 1970). 

Viral and protozoan pathogens have received more attention as potential biological 

control agents for grasshoppers. An entomopox virus (Henry & Jutila 1966) and a 

crystalline-array virus of the picornovirus group (Jutila et al. 1970) have been isolated 

from M. sangllinipes and M. bivittatus, respectively. Although these viruses arc 

uncommon in grasshoppers under normal conditions, observations indicate that they 

may be capable of lowering the population density of their hosts. Prolonged effects of 

these pathogens have yet to be assessed. Of the protozoans, Malameba locustae (King 

& Taylor), several species of grcgarincs, three species of Nosema (N. locuslae Canning. 

N. acridophagus Henry, and N. cuneatum Henry), and a number of other microsporidians 

have been reported or described in grasshoppers. Malameba locustae and the 

gregarines (the most common protozoans in grasshoppers) cause chronic infections but 

have little immediate effect on their hosts. 

Most research effort in recent years has been directed towards using the Nosema 

spp. as biological control agents for the management of grasshopper populations and, 

of these. N. loclIstae has received the most attention. In 1980 a quantitative study of 

the effect of N. /ocuslae as a control agent against grasshopper populations was 

carried out in a short grass pasture in east central Saskatchewan (Ewen & Mukerji 

1980). The predominant grasshopper species were M. sangllinipes, M. packardii. and 

C. pellucida, and about 50% of these populations were infected between 4 and 5 weeks 

61

62 A. B. Ewen and M. K. Mukcrji 


after application of 2.5-5.0 .x 10' spores of N. iocustae per ha. Maxima of 95-100% 

infection were evident between 9 and 12 weeks after application for all three 

grasshopper species. This increase in prevalence of infection throughout the season 

probably was due to the fact that feeding grasshoppers tend to consume grasshopper 

cadavers that they find, and data (Ewen & Mukerji 1980) indicate that most cadavers 

would contain mature spores of N. iocllStae later in the season. 

M. sanguinipes showed the greatest vulnerability to N. iocllStae infection among the 

three predominant grasshopper species in the Saskatchewan study (Ewen & Mukerji 

1980). At a 50% level of infection. its population was reduced 26%, significantly more 

than either M. packardii (20%), or C. pellucida (8%). Overall, the treated populations of 

M. sanguinipes and M. packardii were reduced by about 20%, 4 weeks after spore 

application and by about 60%,8 weeks later. On the other hand, the population of C. 

pellucida, although showing about the same prevalence of infection as the MeianopillS 

populations, was reduced overall by only 28%. 12 weeks after application of N. iocllStae 

spores. It seems that the Cyrtacanthacridinae are more vulnerable to N. iocllStae 

infection than are the Oedipodinae. 

Grasshoppers that survived to lay eggs appeared to be infected to the extent that their 

fecundity was reduced. This was especially true of M. packardii, where the females laid 

about 65% fewer eggs than untreated populations (Ewen & Mukerji 1980). Egg production 

by the treated M. sanguinipes populations also was reduced markedly when 

compared to the control populations. Not enough data were collected to evaluate the 

effect of the pathogen on fecundity of C. pellucida. Data show that mature spores of N. 

iocllstae can overwinter (presumably in cadavers,) but it is not known if sufficient 

numbers survive to adequately infect the next year's populations. 

Applications of N. iocllStae spores in Saskatchewan were made to grasshopper 

populations that were predominantly in the third nymphal instar (Ewen & Mukerji 1980). 

Applications to younger populations resulted in the insects being killed at much lower 

levels of infection. and this could have important implications for grasshopper control in 

crop land. Crop defoliation could be reduced by killing the grasshoppers when they were 

first-instar or second-instar nymphs. but then fewer spores would be produced for infection 

of other grasshoppers. Thus. reducing the grasshopper populations earlier would 

better protect the crop. but a second application of spores a week or two later would be 

necessary because considerable recruitment would still be possible in these younger 

populations. 

Bucher. G.E. (1960) Potcntial bacterial pathogens of insects and their characteristics. Journal of Insect Pathology 2. 172-195. 

Ewen. AI B.; Mukerji. M.K. (1980) Evaluation of Nmema locus/ae (Microsporidia) as a control agent of grasshopper populations in 

Saskatchewan. JOIlrtral of Invertebrate Pathology 35. 295-303. 

Gage. S.H.; Mukerji. M.K. (1977) A perspective of grasshopper distribution in Saskatchewan and interrelationship with weather. 

Environmental Entomology 6. 469-479. 

Henry. J.E. (1970) Potential microbial control of grasshoppers and locusts. Proceedings of the International Study Conference. Current & 

Future Problems of Acridology. pp. 465-468. 

Henry. J.E.; Jutila. J.W. (1966) The isolation of a polyhedrosis virus from a grasshopper. Journal of Invertebrate Pathology 8.417-418. 

Jutila. J.W.; Henry. J.E.; Anacker. R.L.; Brown. W.R. (1970) Some properties of a crystallinc-array virus (CAV) isolated from the 

grasshopper Melanoplus biviltatus (Say) (Orthoptera: Acrididae). Journal of invertebrate Pathology 15. 

225-23\. 

Pickford. R.; Riegert. P. W. (1964) The fungous disease eaused by Entomophthora grylfi Fres .• and its effects on grasshopper populations in 

Saskatchcwan in 1963. Canadian Enlomologist 96. 1158-1166. 

Randen. R.L.; Mukcrji. M. K. (1974) A technique for estimating hatching of natural egg populations of Melanoplus sanguinipes (Orthoptera: 

Acrididae). Canadian EnlOmologift 106. Sot -SI2.

Chapter 18 

Musca domestica L., House Fly (Diptera: 

Muscidae) 

R.A. COSTELLO 

Aies, particularly Musea domes/iea L., associated with egg producing operations have 

become an increasing problem in British Columbia's Fraser Valley in recent years. 

Conflicts between farmers and their nonfarming neighbours have intensified with the 

encroachment of urban development on agricultural areas. Flies can also be a considerable 

annoyance to farm operators and their families and employees. 

Certain parasitoid wasps have been found effective in suppressing nuisance fly populations 

in egg producing operations in California (Legner & Dietrick 1972, Legner e/ al. 

1975). A commercial insectary in that state provided the parasitoids for this study. The 

pupal parasitoid Spa/angia endius Walker (Hymenoptera: Pteromalidae) was selected 

for this trial because of its tendency to burrow deeper into manure than other available 

parasitoids in search of pupae (Legner 1977). Pre-release sampling indicated that more 

than 90% of the pupae were further than 3 cm below the surface. 

In 1978, a total of 400000 Spa/angia endius, in the form of parasitized house fly pupae, 

were released into a deep pit layer barn in Aldergrove, British Columbia. The barn, 

measuring 91 m by 12 m, contained 27 000 layers. The pit contained a 9 month accumulation 

of manure at the start of the trial. Four releases of 100 000 parasitoids each were 

made at 3 week intervals commencing 20 April. No other control methods were applied 

in this barn. Fly numbers, as indicated by "spot cards" (Rutz & Axtell 1979). were 

compared to those in a bam 30 m away where fly control consisted of chemical insecticides 

applied as space sprays. residual surface sprays, and floor baits. The spot cards 

consisted of white 7.6 x 12.7 cm unlined file cards. These were pinned to posts in the 

barns, collected weekly. and the fecal and regurgitation marks counted. 

Levels of parasitism were measured by collecting manure samples once a week. 

floating out fly pupae, and holding them at 30"C until either flies or parasitoids emerged. 

This also provided an indication of the fly species involved and all pupae collected were 

Musca domes/iea. 

Ay numbers were monitored in both barns from 25 April to 13 June. The spot card 

counts were similar for the first weeks, averaging 45.3 per card in the bam using 

chemical control methods and 35.7 in the barn where parasitoids were released. By the 

end of the third week, mean spot card counts rose to 390.2 in the chemical control barn 

and fell to 26.9 in the barn containing Spa/angia endius. Repeated applications of 

pyrethrum as a thermal fog resulted in a reduction of the mean spot card count to 213.2 

by the end of the 6th week when the manure was removed and spot card counts were 

discontinued. Spot counts in the barn using parasitoids averaged 20 to 25 during the 4th, 

5th and 6th weeks of the trial. 

Six weeks after the initial introduction of parasitoids 63% of the fly pupae separated 

from manure samples contained Spa/angia endius larvae and pupae. This was the highest 

level of parasitism found during the sampling period. 

House fly numbers in the barn containing parasitoids rcmnincd nt acceptnble levels 

throughout the trial and the remainder of the fly senson, while flies in the bam employing 

chemical control methods were intolerably abundant and eventually necessitated 

removing the manure to relieve the problem. The commercial value of the parasitoids 

used in this study was approximately $800, about the same as the operator spent on 

chemicals the previous year. 

63

64 R. A. Costello 


Further laboratory and field studies are being carried out to develop an integrated 

approach to fly control in egg layer barns entailing parasitoid introductions, manure 

management, and chemical insecticides. 

Legner. E.F. (1977) Temperature. humidity and depth of habitat influencing host destruction and fecundity of muscoid fly parasites. 

Entomophaga 22. 199-206. 

Legner. E.F.; Dietrick. E.J. (1972) Inundation with parasitic insects to control filth breeding flics in California. Proceed;II8s o/the CalifornitJ 

Mosquito Control Association 40, 129-130. 

Legner. E.F.; Bowen. W.R.; Rooney. W.F.; McKeen, W.O.; Johnston. G.W. (1975) Integrated fly control on poultry ranches. California 

Agriculture 29(5). 8-10. 

RUll. D.A.; Aldell, R.C. (1979) Sustained releases of Muscidifurru raptor (Hymenoptera: Pteromalidae) for house fly (Musca domestica) 

control in two types of caged·layer poultry houses. Environmellta/ Entomology 8. 1105-1110.

Pest Status 

Background 

Chapter 19 

Releases and Recoveries in Ontario 

Oulema melanopus (L.), Cereal 

Leaf Beetle (Coleoptera: Chrysomelidae) 

D.G. HARCOURT, J.e. GUPPY and C.R. ELLIS 

During the early and mid 1970s, the cereal leaf beetle (eLB), Oulema melanopus (L.), 

began to threaten the production of small grains in Ontario. Following its initial 

discovery in Essex County near the border of Michigan in 1965, it spread rapidly 

eastward and by 1975 it had occupied most of Ontario south of Hwy 17. Populations 

reached economic levels in 1973, and in 1974 chemical treatment was required in ca. 75 

fields within the triangular area bounded by the counties of Lincoln, Grey, and 

Durham (Bereza 1974). In 1976, it occurred in damaging numbers on Manitoulin Island 

and, in 1977, it was found north of Lake Huron in the districts of Algoma, Sudbury, 

and Nipissing (Ellis et al. 1979). 

Like many of our introduced pests, the cereal leaf beetle is rarely troublesome in its 

native Europe where it is attacked by a complex of natural enemies. One of these, the 

larval cndoparasitoid Tetrastichus julis (Walker) was introduced against the beetle by 

research workers in Michigan in 1967. It was recovered in low numbers in 1969 (Stehr 

1970) and was extensively recolonized in 1971, when further releases were made in 

Michigan, Indiana, Ohio, West Virginia, and New York (Dysart et 01. 1973). 

T. julis is mostly bivoltine in Michigan (Gage & Haynes 1975). It emerges from its 

overwintering sites in late May and flies to nearby grain fields where it deposits its eggs 

in the first host larvae that appear. The gregarious parasitoid larvae grow slowly within 

their host while it is feeding. As soon as the host larva enters the soil and forms its 

pupal cell, the parasitoids quickly complete their development and form naked pupae 

within the cell. Diapause is facultative, but the incidence increases as the season 

progresses. Some adults emerge in early summer and give rise to a second generation. 

The remainder of the first generation and all of the second overwinter as last instar 

larvae inside the pupal cells of their hosts. In Michigan, roughly 80% of the population 

enters a second generation; this generation is poorly synchronized with populations of 

its host since at the time of emergence relatively few beetle larvae are available for the 

adults to attack (Gage & Haynes 1975). 

Studies in Michigan during the early seventies indicated that T. julis had poor 

powers of dispersal (Haynes et -al. 1974). Natural spread was slow and rates of 

parasitism in the United States midwest remained well below that needed to maintain 

populations at subeconomic levels. 

Large-scale releases of T. julis were made at 4 sites in southcentral Ontario in June 

1974 when parasitized host larvae were set out in fields of oats and barley (Harcourt et 

al. 1977). This has been the only parasitoid released in the province. 

In 1975, life table studies of the host in the Quinte area of southern Ontario showed 

that 55% and 43% respectively of the pupal cells in study plots in Northumberland and 

65

66 D. G. Harcourt, J. C. Guppy and C. R. Ellis 

Table 10 

Current Status of T. julis 

Hastings Counties (Harcourt et al. 1977) contained larvae of T. julis. These findings, 

which were unexpected in light of the Michigan experience, prompted closer examination 

of larval collections made during the course of annual CLB population surveys by Ontario 

Ministry of Agriculture and Food personnel at 8 sites within the province during 1975. 

The surveys consisted of 250 net sweeps from each of 30 fields of spring grain located 

within a 75 km! area. Eight such areas were sampled in late June following the 

accumulation of 475°D>9°C. 

Table 10 shows that T. julis had dispersed widely across Ontario by 1975. Rates of 

parasitism were highest in southwestern Ontario, lowest in eastern Ontario, and 

intermediate in other parts of the province. Overall parasitism was 84%. The number 

of parasitoids per host ranged from 1 to 44 and averaged 5.9. The four host instars were 

parasitized in roughly the same proportion (75, 87, 84,84), suggesting that the larvae 

were attacked when small. 

Parasitism of the cereal leaf beetle, 

(Walker) in Ontario, 1975. 

County Township No. host 

larvae collected 

Oulema melanopus (L.), by Tetrastiehus julis 

Kent Merlin 894 95.0 

Middlesex Glencoe 212 91.9 

Essex Malden 526 88.6 

Wellington Fergus 227 83.7 

York Whitchurch 143 83.2 

Ontario Brock 15 73.3 

Bruce Mildmay 156 68.6 

Renfrew Bromley 147 15.0 

TOTALS 2320 84.4 

% parasitized 

Sweepnet samples of spring grain on Manitoulin Island in early July 1976 showed that 

the parasitism rate was 87% (Ellis et al. 1979). 

Since 1974, there have been no reports of economic damage by the cereal leaf beetle in 

Ontario other than on Manitoulin Island. In most fields of spring grain it has been 

difficult to find larvae. This raised fears that the host population might become too low to 

maintain the parasitoid which would set the stage for a resurgence of the pest. For this 

reason, extensive sampling has been carried out in representative sites in Ontario since 

1977. Rates of parasitism in the past 4 years have ranged from 31-68%, indicating that T. 

julis has the capacity to maintain itself as an effective biological control agent at very low 

host densities. There has been no indication of resurgence of CLB populations and no 

damage from the pest was reported in Ontario during the 1977-80 period. 

Because the distribution of T. julis in 1975 was more extensive than the area of the 1974 

releases and because its population density at most sites was inexplicably high, it is 

concluded that the parasitoid spread into Ontario as a result of the earlier releases in 

Michigan and other parts of the United States. It is also clear that the parasitoid has 

better powers of dispersal than originally reported.



Ou/ema me/at/opus (L.). 67 

We believe that there are two reasons for the spectacular success of T. iulis in Ontario 

relative to that in Michigan. First, the larval period of the cereal leaf beetle occurs after 

the seasonal accumulation of 235°0>9°C (Fulton & Haynes 1975) throughout its range, 

and this is therefore later in Ontario than in the United States midwest. Since the 

developmental threshold of T. iu/is resembles that of its host (Gage & Haynes 1975), it 

similarly emerges later in its northern range and its larvae complete their development 

later in the season. Hence, a greater proportion of the first generation enter diapause. 

Second, in deference to the harsher climate than in the United States midwest, agricultural 

practice in most parts of Ontario favours spring grains as opposed to winter wheat. 

These frequently grow in rotation with, and as a nurse crop for, alfalfa and other 

legumes. Hence, the field is left untilled after harvest and host pupal cells below soil 

level are not disturbed by plowing and disking, a practice which can destroy more than 

95% of the parasitoid population (Haynes et al. 1973). 

In view of the potential importance of the cereal leaf beetle to culture of spring grains in 

Canada, rates of attack of T. iulis relative to numbers of its host should be monitored at 

regular intervals throughout its range. 

Bereza. K. (1914) Ontario insects. Canadian Agricultural/nseet Pest Review 52. 16. 

Dysan. RJ.; Maltby. H.L.; Brunson. M.H. (1913) Larval parasites of Oulema melanopus in Europe and their colonization in the United 

States. Entomophaga 18. 133-161. 

Ellis. e.R.; Harcoun. D.G.; Dubois-Martin. D. (1919) The current status in Ontario of Tetrastichus julis (Hymenoptera: Eulophidae). a 

parasitoid of the cereal leaf beetle. Proceedings of the Entomological Society of Ontario 109. 23-26. 

Fulton. W.e.; Haynes. D.L. (1915) Computer mapping in pest management. Environmental Entomology 4.357-360. 

Gage. S. H.; Haynes. D. L. (1975) Emergence under natural and manipulated conditions of Tetrastichus julis. an introduced larval parasite of 

the cereal leaf beetle. with rcCerence to regional population management. Environmental Entomology 4. 

425-434. 

Harcourt. D. G.; Guppy. J .C.; Ellis. C. R.E. (1917) Establishment and spread of Tetrastiehus julis (Hymenoptera: Eulophidae) a parasitoid of 

the cereal leaf beetle in Ontario. Canadian Entomologist 109, 473-476. 

Haynes. D.L.; Brandenburg. R.K.; Fisher, P.D. (1913) Environmental monitoring network for pest management systems. Environmental 


Haynes. D.L.; Gage. S.H.; Fulton. W. (1974). Management of the cereal leaf beetle pest ecosystem. Quaestiones Entomologieae 10, 

165-176. 

Stehr. F. W. (1910) Establishment in the United States of Tetrastiehus julis. a larval parasite of the cereal leaf beetle. Journal of Economic 

Entomology 63.1968-1969.

Blank Page 

68

Pest Status and Background 

Chapter 20 

Phyllonorycter blancardella (F.), Spotted 

Tentiform Leafminer (Lepidoptera: 

Gracillariidae) 

J.E. LAING 

The spotted tentiform leafminer (STLM). Phyllonorycler blancardella (F.). is an indirect 

pest of apple in eastern Canada and the United States. This species probably 

entered North America from Europe early in the 1900s. Severe infestations (> 20 mines 

per leaf) may cause early leaf drop. stunting of terminal growth. premature fruit 

ripening, and fruit drop with a resultant decrease in yield and reduction of fruit set the 

year following the infestation (Pottinger & LeRoux 1971. Johnson 1975). There are three 

generations of the leafminer per year throughout its range in North America. The 

leafminer overwinters as a pupa. emerges in May. and begins to oviposit first-generation 

eggs. Adults of the first generation are present in orchards from mid-June through July. 

Second-generation adults appear in August (Johnson 1975. Laing 1977). 

Although many species of parasitoids have been recorded from STLM (Pottinger & 

Le Roux 1971. Johnson el al. 1978). this species is able to reach damaging levels in some 

orchards each year by the third or overwintering generation. Because of the cryptic 

feeding habits of the larvae. chemical controls must be either systemic or timed to 

coincide with adult emergence. The latter has been facilitated by the synthesis of a sex 

attractant for STLM (Roelofs el al. 1977) and the development of heat unit requirements 

above a threshold of approximately 7°C for emergence of the adults (Johnson el 01. 

1979). Although individual growers may obtain good control of STLM at times. reinvasion 

of commercial orchards likely occurs from hedgerow and abandoned or poorly 

maintained orchards. 

The following parasitoids have been reported from STLM in Ontario and Quebec 

(Pottinger & LeRoux 1971. Johnson el al. 1978): 

Braconidae Apanteles ornigis Weed 

Eulophidae Sympiesis marylandensis Girault 

Sympiesis bimaculatipennis Girault 

Sympiesis sericeicornis (Nees) 

Sympiesis conica (Provancher) 

Pnigalio maculipes (Crawford) 

Pnigalio flavipes (Ashmead) 

Pnigalio uroplatae (Howard) 

Chrysocharis cuspidogaster (Yosh.) 

Chrysocharis Iricinclus Ashm. 

Chrysocharis laricinellae (Ratz.) 

Tetrastichus sp. 

Cirrospilus cinclilhorax (Girault) 

Zagrammosoma mullilinealum (Ashmead) 

Horismenus Jraternus (Fitch) 

Eupelmidae Eupelmella vesicularis (Retzius) 

The most abundant parasitoids of STLM are the braconid Apanteles ornigis Weed in 

the first and third generations. and the chalcids Sympiesis marylandensis Gir. and S. 

69

Ph yJlollorycter blallcardelltr (F.) , 71 

Johnson. E.F .• Trouier. R.: L.'1ing. J.E. (1979) Degree-day relationships to the development of Lilhocollelis blancardella (Lepidoptem: 

Gracillariidae) and its parasite Apenlldes mnigis (Hymenoptera: Braconidae). Canadiall EtJlonrologisl 

III, II77- IIs... 

Laing. J.E. (l9n) Spotted tentifonn Icafminer. Ontario Ministry of Agriculture and Food, Agdex Factshcct. 3 pp. 

Laing. J.E.; Her:lty. J.M. (1981) Establishment in Canada of the parasite "'pallldes pedias Nixon on the spotted lenliform leafminer 

Phyllonorycler blancardella (Fabr.). EIII'irtmmelllal Emomology 10, 933-935. 

Nixon, G.E.J. (1973) A revision of Ihe north-western Europc.1D species of Ihe "ilripemlis, pallipes, octonariw, triallgulator, fratermlS, 

foniosllS, parasilellae, melacarpalis, and cirC/tt1lscripIILf-groups of ApatJIeles Forster (Hymenoptera: 

Braconidae)_ Bullelill of EIlIt}IJwltlgictz/ Research 63, 169-228. 

POllinger, R. P.; Le Roux, E.J. (1971) The biology and dynamics of Lil/mcolletis IJIclllcelrdelia (Lepidoptera: Gracillariidae) on apple in 

Quc!bec. Memoirs of Ihe ElllolllologiclIl Sociely of Calltlda 77, 437 pp. 

Roelofs, W.L.: Reissig, W.H. Weires, R.W. (1977) Sex auractalll for the spoiled tentiform learminer moth Lithocolletis b/allcardelltl. 

Environlllellla/ Etllolllolog}, 6, 373 - 374. 

SWilD, D.1. (1973) Evalualion of biologicnl conlrol of Ihe ouk Icafminer I'lzyllrmor},ctermessalliella (Zeit) (Lepidoptera: Gracillnriidae) in 

New Zealand. Bulletill of Elllr1lTwlogiCll/ Re.rI!rlrclz 63, 49-55.

Blank Page 

72

Pest Status 

Background 

Chapter 21 

Phyllotreta spp., Flea Beetles (Coleoptera: 


H.G. WYLIE, W.l. TURNOCK and L. BURGESS 

Damage to rape crops in western Canada by flea beetles is caused primarily by adults of 

two species, Phy/lotreta crllciferae (Goeze) and Phyl/otreta strio/ata (F.). A third flea 

beetle, Psylliodes puncru/ata Melsh., occurs in virtually all seedling rape crops on the 

prairies but by itself does not constitute a serious problem. Phyllolrela robusta Lee. and 

Phyllolrela a/bionica (Lee.) occur occasionally on rape crops in Saskatchewan (Burgess 

1977a) and three other described crucifer-feeding species in the genus Phyllotreta are 

known to occur in that province (Burgess 1981b). 

P. cruciferae was introduced on the west coast of North America in the early 1920s 

(Milliron 1953) and was abundant on crucifers in the Prairie Provinces by the late 1930s 

and early 1940s (Westdal & Romanow 1972). P. cruciferae has usually been the 

dominant flea beetle in rape fields across the prairies, particularly in the more southerly 

parts of the rape-growing area. 

P. slrio/ala apparently was introduced to North America before 1801 (Chittenden 

1923) and was present in Canada from the Atlantic provinces to British Columbia by the 

early 1900s (Burgess 1977a). This species infests rape crops across the parkland 

agricultural area from southern Manitoba to north of the Peace River in Alberta (Burgess 

1977a). P. strio/ata has recently gained in relative importance as a pest in both Saskatchwan 

and Alberta, being more abundant than P. cruciferae in some Saskatchewan rape 

fields after 1976 (Burgess 1981a) and in some fields in central Alberta since 1979 (H.G. 

Philip 1981 personal communication). 

Flea beetle problems in rape crops have increased in severity in the past decade. In 

Manitoba and Saskatchewan most fields of rape are threatened annually by these 

insects. In Alberta, flea beetle problems have tended to be less acute than in Saskatchewan 

and Manitoba, but in 1979 and 1980 heavy infestations were reported from 

most rape-growing areas (H.G. Philip 1981 personal communication). The estimated 

percentages of rape acreage treated with insecticides in 1979 were 75% in Manitoba, 

59% in Saskatchewan, and 45% in Alberta (Turnock & Samborski 1980). Although yield 

loss due to flea beetle damage is difficult to estimate. yield reductions of 15-50% have 

occurred in untreated plots in insecticide trials (Turnock & Samborski 1980). The 

combination of flea beetles and poor conditions for germination that occurred in 1975 

and 1980 in Manitoba completely destroyed many fields of rape. 

This is the first biological control programme set up against flea beetles of the genus 

Phyllotreta. The programme was initiated because of the low level of natural control of 

P. cruciferae and P. strio/ata and because these are introduced species. Studies in 

Manitoba since 1975 confirmed only three native parasitoids of rape-infesting flea 

beetles: a braconid. Microctonus \'ittatae Mues.; a mermithid; and an allantonematid. 

Howardu/a sp. M. viltatae parasitizes adults of both P. cruciferae and P. strio/ala. but 

the incidence of parasitism is usually less than 5%. Various factors limit the impact of 

this braconid in Manitoba. including its short adult life and low oviposition rate. and 

poor temporal synchronization with the host's population in mid-summer. Neither the 

mermithid nor the allantonematid is sufficiently abundant to limit populations of the 

73

74 H. G. Wylie, W. J. Turnock and L. Burgess 


Table 11 

rape-infesting species. Occasional predation of flea beetle adults by adults of Collops 

viltalllS Say (Coleoptera: Melyridae) and Geocoris bullalus (Say) (Hemiptera: 

Lygaeidae) and by larvae of Chrysopa sp. (Neuroptera: Chrysopidae) have been reported 

(Gerber & Osgood 1975; Burgess 1977b, 1980). 

In Europe, a large complex of flea beetle species infest rape and other crucifers. 

Usually, the most destructive species are Psylliodes chrysocepha/a (L.) and Phyllolrela 

undu/ala Kutsch. (Carl 1973, Carl & Sommer 1975). Neither species occurs in Canada; 

P. chrysocepha/a was recorded once in Newfoundland (Anon. 1953) but apparently did 

not become established. Neither P. slrio/ala (sometimes called P. vinala F. by European 

entomologists; see Barber 1947) nor P. cruci/erae is considered to be an important pest 

in Europe. P. strio/ala is usually more abundant than P. erueiferae (Carl & Lehmann 

1980). 

Studies in Austria, Germany, and Switzerland identified three species of euphorine 

braconids, three mermithid species, and an allantonematid, Howardu/a phyllolrelae 

Oldham, as parasitoids of Phyllolrela spp. Although H. phyllolrelae parasitized up to 

70% of the flea beetle adults and reduced oviposition by parasitized females, it had little 

or no effect on beetle survival (Carl & Sommer 1975). The impact of the mermithids was 

also negligible. One of the braconid species was uncommon and was not identified. A 

second species, Microclonus sp. Z (Sommer 1981) which parasitized less than 10% of 

the flea beetles, was morphologically indistinguishable from M. villalae (C.c. Loan 

1981 personal communication). The third braconid species, Mieroetonus bie%r 

Wesm., parasitized up to 50% of the flea beetle adults in summer. Small numbers of this 

braconid that were imported in Canada in 1977, and tested in the laboratory at Winnipeg, 

parasitized adults of P. eruci/erae and P. slrio/ala and developed on both species. 

Therefore, M. bie%r was considered to be a suitable candidate species for importation 

and release. 

Parasitoid cocoons received from the European Laboratory of the Commonwealth 

Institute of Biological Control were reared at the Research Program Service, Central 

Experimental Farm, Ottawa. Those cocoons which produced hyperparasites of 

the genus Mesoehorus were destroyed, and adults of Mieroetonus bie%r and M. vittalae 

were shipped by air express to Winnipeg. 

Details of releases of Mieroetonus bie%r Wesm. are shown in Table 11. Parasitoids 

were released in the open in experimental plots of rape, Brassica napus L., cv. Tower, at 

the Glenlea Field Station of the Agriculture Canada Research Station, about 20 km south 

of Winnipeg. With the exception of three small releases, one in July 1979 and two in July 

1980 when host numbers were low, all parasitoids were released in May, June, August, 

or September when the plots were heavily infested by P. eruei/erae and lightly infested 

by P. strio/ata. No insecticides were applied to the plots each year for several weeks 

before the parasitoids were released, and none were applied after releases began. 

Open releases and recoveries of parasitoids of Phyllolreta spp. 

Species and Province 

M icroctonus bie%r Wesm. 

Manitoba 

Year Origin 

1978 Austria 

1979 Austria 

1980 Austria 

Number 

182 

375 

653 

Year of Recovery

Table 12 

Phyllotreta spp.. 75 

Several attacks by the parasitoid females on adults of P. strio/ata were observed on rape 

plants in the plots during releases. 

Flea beetles from the release sites were collected in 1979 and 1980 and reared in the 

laboratory for evidence of parasitoid establishment. Numbers collected were 8502 P. 

eruciferae, 261 P. strio/ata, and smaller numbers of other rape-infesting beetles in June 

1979 from the 1978 release site; 3082 P. cruciferae and 674 P. siriolaia during July 

October 1979 from the 1979 release site; and 5039 P. siriolaia and 418 Psylliodes 

punetlllata Melsh. in April 1980 from overwintering sites adjacent to the 1979 release 

site. No M. hieolor emerged from these beetles. 

Some adults of M. bicolor and M. sp Z were retained for laboratory studies (Table 12). 

These studies showed that females of ,H. bicolor parasitized more P. striolClla than P. 

cruciferae when equal numbers of the two hosts were present. 

Imported parasitoids of Phyllolrela spp. used for laboratory studies 

Species 



Microetonus hieolor Wesm. 

Mieroelonus sp. Z 

Year Origin 

1977 Germany 

1978 Austria 

Switzerland 

1979 Austria 

1980 Austria 

1977 Germany 

1978 Switzerland 

1979 Austria 

1980 Austria 

Number 

Several factors have limited the probability of establishment. First, small numbers of 

parasitoids were released. Second. scarcity ofthe preferred host. P. striolala. at Glenlea 

may have limited oviposition by the females after release. Third. dispersal of the beetles 

in autumn to overwintering sites and in spring in search of food, scattered the population 

of parasitized beetles and thereby reduced the probability of female parasitoids that 

emerged in the spring being fertilized. If M. hieolor has become established, the small 

numbers released and scattering of the population would minimize our chances of 

detecting establishment until the incidence of parasitism has increased substantially. 

Larger colonies of M. bieolor (> 50() females per colony) should be released. Although 

large numbers of parasitized flea beetles have been collected by the CIBC. only small 

numbers of parasitoid adults have been reared and female colony size has never exceeded 

100. There are two reasons for the small parasitoid colonies. First. many of the 

immature parasitoids enter diapause and eventually die when the hosts are reared in 

cages in Europe. Second. parasitoid emergence from cocoons obtained in Europe has 

usually been less than 50%. The possibility that higher temperature and longer photoperiod 

prevent diapause should be investigated. as well as the factors responsible for 

poor survival of the parasitoid larvae and pupae in cocoons. 

The possibility of obtaining additional candidate parasitoid species for release in 

Canada should be investigated in discussions planned in 1981 between staff of the CIBC 

and scientists from the USSR. 

43 

131 

20 

26 

8 

9 

2 

13 

I

Pest Status 

Background 


Chapter 22 

Tetranychus urticae Koch, Twospotted 

Spider mite (Acarina: Tetranychidae) 

R.J. McCLANAHAN 

The twospotted spider mite. Tetranychus urticae Koch, continues to be a major problem 

in greenhouse crops, particularly cucumbers, chrysanthemums, and roses. The floral 

crops are fairly well protected by granular applications of the systemic insecticide 

aldicarb, but cucumber growers are having a difficult time keeping mites under control. 

Resistance to dicofol and Pentac® (Zoecon Industries Ltd.) has developed in some 

greenhouses. The effective material oxythioquinox was withdrawn from use on cucumbers 

in 1974. 

The predaceous mite Phytoseiulus persimilis Athias-Henriot has been the only biological 

control agent seriously considered for control of T. urticae in greenhouses, 

although other mite predators are effective in orchards. The European workers have had 

encouraging results with P. persimilis and mass rearing is carried out at a number of 

government and commercial establishments. Russian sources report a production of 83 

million P. persimilis per year from one rearing unit (Askretkov & Tolmacheva 1980). 

Probably the most extensive use of P. persimilis on greenhouse crops is in the Netherlands 

where some 400 ha (60% of total production) of cucumbers is protected by the 

predator (Koppert 1980). 

Research on the interaction of prey mites and P.persimilis has mostly been reported 

from Europe. Methods of introduction have been worked out for tomatoes (French et 

al. 1976) and cucumbers (Gould 1977), while the optimum conditions of temperature and 

humidity were defined by Stenseth (1979b) in Norway. Many references pertain to the 

compatibility of various insecticides and fungicides and the use of P.persimilis (e.g. 

Jeppson et al. 1975), but these results were superseded by investigations using a strain of 

P. persimiiis resistant to phosphate insecticides (Stenseth 1979a). 

At Harrow, laboratory studies proved that some acaricides were selective in favor of 

the predator (McClanahan 1971). However, the best materials were experimental or not 

widely accepted by growers for twospotted mite control. Since then oxythioquinox has 

been withdrawn from use on greenhouse cucumbers, and the twospotted mites have 

developed varying degrees of resistance to acaricides (McClanahan 1980). 

It is difficult to detail releases of P. persimilis in Canada, since there are several sources, 

including commercial enterprises, and only part of the production is used in Canada. A 

colony has been maintained at the Harrow Research Station for many years, and limited 

numbers are available on request by research establishments or educational projects. 

Acknowledgements of such shipments usually record successful establishment. P. 

persimilis are reared and sold by Better Yield Insects in Ontario and by Applied Bio 

Nomics Ltd. in British Columbia. The number of predators available at the release point 

is dependent on the number of prey mites in the shipment and on the interval between 

77

78 R. J. McClanahan 



packaging and releasing. Thus the number actually released can be much different than 

the number shipped, but under favorable conditions reproduction is very rapid with a 

generation in 5 days. 

Four commercial greenhouses near Leamington were used in a demonstration experiment 

in 1980. Two P. persimilis were placed on each mite-infested cucumber plant in 

February. Control of T. urlicae was achieved and maintained until late May, but then a 

change in greenhouse environment favored the pest mite and the growers had to switch 

to chemical control. Probably the humidity was lowered when vents were open 

throughout the day and this prevented P. pers;milis eggs from hatching. 

Techniques of using P. pers;milis in Canadian greenhouses will have to be refined and 

adjusted to greenhouse conditions. Introduction of predators onto the fall crop of 

cucumbers might avoid a resurgence of T. urticae. 

Research projects could include modification of the greenhouse environment by 

misting to produce favorable conditions for the predator, or spraying only a portion of 

the cucumber plants with an acaricide while predators were active on the unsprayed 

portion. 

Rearing under artificial conditions, as carried out in Russia (Storozhkov & Kamacheeva 

1980) should be tried in Canada for increased mass production. 

Askretkov. A.V.; Tolmacheva, KP. (1980) A sovkhoz biolaboratory. Zoshchita Rostenii 2,36 (in Russian). 

French, N.; Parr, W.J.; Gould. H.J.; Williams, J.l.; Simmonds, S.P. (1976) Development of biological control methods for the control of 

Tetranychus urticae on tomatoes using Phytoseiu/us persimilis. Annals of Applied Biology 83, In-189. 

Gould, H.l. (1977) Biological control of glasshouse whitefly and red spider mite on tomatoes and cucumbers in England and Wales 1975 -76. 

Plant Pathology 26. 57-60. 

Jeppson, L.R.; McMurtry. 1.A.; Mead, D.W.; Jesser. M.J.; Johnson, H.G. (1975) Toxicity of citrus pesticides 10 some predaceous 

phytoseiid mites. Journal 01 Economic Entomology 68, 707-710. 

Koppen, P.C. (1980) Biological control in glasshouses in the Netherlands. Proceedings of the International Symposium on Integrated 

Control in Agriculture and Forestry, Vienna 1979. p. 484. 

McClanahan, RJ. (1971) Selective acaricides for integrated control of Tetranychus urticae. International Organization for Biological 

Control. West Palearctic Regional Section. Proceedings of a Conference on Integrated Control in 

Glasshouses. pp. 13-22. 

McClanahan. R.J. (1980) Why has integrated control practice levelled off in Canada" Bulletin SROP 19801111, 141-144. 

Stenseth, C. (1979a) Effect of fungicides and insecticides on a resistant strain of Phytostiulus persimilis Athias-Henriot (Acarina: 

Phytoseiidae). Forskning og Forsok i Landbruket 30,77-83. 

Stenseth, C. (1979b) Effeet of temperature and humidity on Ihe development of Phytoseiulus persimilis and its ability to regulate populations 

of Tetranychus urtkae (Acarina: Phyloseiidae, Telranychidae). Entomophaga 24, 311-318. 

Storozhkov, Yu.V.; Kaznacheeva, V.P. (1980) Rearing of Phytoseiu/us in hydroponic greenhouses. Zoshchita Rostenii 2,34 (in Russian).

Pest Status 

Background 

Chapter 23 

Thymelicus lineola (Ochsenheimer), 

European Skipper (Lepidoptera: 

Hesperiidae) 

J.N. McNEIL 

In the last review dealing with the European skipper. Thymelicus lineola (Ochs.), Arthur 

(1971) reported that the distribution of this insect in Canada was limited to Ontario, 

Quebec. New Brunswick. and Nova Scotia in the east. with one localized population at 

Terrace, British Columbia. At that time economic losses caused by T. Iilleola had been 

recorded in Grey and Hastings Counties. Ontario. The distribution of the skipper has 

increased considerably and is now found in Prince Edward Island (Thompson 1974). 

Newfoundland (Jackson 1978). and in Manitoba (Preston & Westwood 1981). Also the 

population in British Columbia has now spread into the Lake Shuswap area (J. Proctor. 

1982. personal communication). 

Important hay losses have been recorded in Ontario (K. Bereza & W. Riley, 1978, 

personal communication. Quebec (McNeil et al. 1975), and Prince Edward Island 

(Thompson 1977). establishing it as a major pest species oftimothy in the more northerly 

areas of its distribution. While the skipper is present throughout most northeastern 

states (Arthur 1971) the only incidence where T. lineola has reached pest status occurred 

in northern Michigan (R.F. Ruppel, 1977. personal communication). 

Bacillus thurillgiellSis Berliner. has proven effective in controlling larval skipper populations 

(Arthur & Angus 1965. Arthur 1968. McNeil et al. 1977) and is now recommended 

by the Conseil des productions vegetales du Quebec (1 x 10 10 I.U./ha) if control measures 

are required. It not only offers satisfactory foliage protection when compared with chemical 

insecticides (Thompson 1977. Letendre & McNeil 1980), but also reduces the possible 

impact on non-target species, such as bees. 

The discovery of a nuclear polyhedrosis virus (NPV) affecting a high percentage of larval 

populations around Normandin. Quebec (Smimoff 1974) stimulated research to evaluate its 

potential as a biological control agent for T. lineola. Smimoff et al. (1976) and Duchesne 

(1980) demonstrated the efficacy of this virus. however its action is much slower than B. 

thurillgiellSis. Following an aerial application of B. thllringiellSis 1 x 10 10 I.U. at 18.71 

l/ha. infected larvae were observed within 2 days and 100% mortality was obtained in 6 

days (Fig. 2a). Defoliation levels at the time of harvest were 20%. the same a'i pre-treatment 

levels. while in the controls defoliation averaged 90%. By comparison an aerial application 

of the NPV. 5 x 10 6 polyhedra/ml at 18.71 l/ha. gave the same mortality but required 

considerably more time (Fig. 2b). Also defoliation at harvest was 50%, and while being 

lower than the 100% in the controls, was significantly higher than the pre-treatment level of 

20%. Thus the virus has less potential than B. thllrillgiensis as a curative means of control, 

but could be introduced as a preventative measure if populations are beginning to increase 

but have not reached very high larval densities. This would be advantageous as the virus 

persists in the population and has an effect over several years (Duchesne 1980). While few 

other pathogens have been found infecting skipper larvae in Quebec. two entomopathogenic 

fungi ZoophtJlOra radicans and Entomophthora egressa have been isolated from larvae 

collected at Amqui in 1977 and 1978 (McNeil & MacLeod 1982). 

79

Imported Parasitoids 

Thyme/iells /it/('o/a (Ochsenheimer), 81 

Sixteen species of parasitoids have been reared from skipper populations in Quebec 

since 1972 and only 3 species are common to the 22 species found in Ontario (Arthur 

1962). As reported for Ontario total parasitism levels are very low and the only parasitoid 

recovered consistently in any numbers is Itoplectis cotlquisitor (Say). Based on 

observations over the last 7 years the importance of indigenous parasitoids in the 

population dynamics of T. lin eo/a would have to be considered as negligible. While the 

diversity of parasitoid species was lower in Europe, Carl (1968) reported high levels of 

parasitism and felt that the principal larval parasitoids Pllryxe vulgaris Fall. and Rogas 

tristis Westm., as well as the major pupal parasitoid Syspasis (=Slenichneumon) 

scutellator (Grav.) would be suitable candidates for introduction into Canada. He 

believed that S. scutellator would be the most promising due to the fact that it was well 

synchronised with the skipper and, as it is univoltine, would not require alternate hosts 

as do the larval parasitoids. 

Specimens of P. vulgaris have been received regularly from Europe since 1972 (Table 

13), but unfortunately shipments usually arrived when local skipper populations had 

already pupated. Thus efforts were made to maintain laboratory cultures using Arlogeia 

rapae (L.) larvae as an alternate host. Female parasitoids readily oviposted and parasitoid 

larvae developed successfully, however difficulties in maintaining healthy host 

colonies inhibited successful mass rearing of the parasitoid. In 1974, adults arrived soon 

enough to be released directly in the field at Normandin (Table 14), but no P. vulgaris 

have been recovered in the area. Releases of adults and parasitized A. rapae larvae were 

made at Rawdon in 1974 and 1975 (Table 14), but were too late to coincide with the 

presence of skipper larvae. However cabbages were quite widely cultivated around the 

release site and an abundance of imported cabbageworm larvae were available as 

alternate hosts. In subsequent sampling no skipper larvae parasitized by P. vulgaris were 

recovered. It is of interest to note that P. vulgaris is an indigenous species and has been 

reared from A. rapae in Ontario (Harcourt 1966), yet has never been reported attacking 

T. lineola in either Ontario or Quebec. Carl (1968) suggested that different geographic 

races of P. vulgaris, with restricted host ranges may exist, which would explain this 

situation. 

Shipments of S. scutellator have been received from Delemont since 1974 and as seen 

in Tables 13 and 14, numbers were rather low in 1974 and 1975 but increased subsequently. 

In an effort to increase the numbers collected, Dr Carl treated fifth-instar skipper larvae 

with fluorescent powder and released them at the collection site at Plancher-Bas. It was 

felt that as the last larval skin remains attached to the pupae individuals could be easily 

located using a black light. While the recovery of marked individuals was poor, it was 

observed that skipper pupae that had been parasitized were more readily located with a 

black light than unparasitized ones, even without marking. Using this technique, night 

time collections yielded higher numbers than in previous years. Adults held under 

laboratory conditions throughout the winter (Table 13) were kept at 2 ± 1°C in plastic 

boxes containing leaf litter and peat moss. Males died rapidly and although females lived 

much longer only one survived until spring but died before T. lineola pupae were 

available. From 1977 all adults not used in open releases were held on arrival in an 

insectary and supplied with a 10% sugar solution as well as water. By mid-September all 

males and some females had died. At this time all surviving females were placed in large 

field cages containing logs, hay bales, and leaf litter. In 1977-78 there were no survivors 

while in 1978-79 we recovered 5 of the 200 females in mid-June. These were fed and 

held in the insectary until skipper pupae were available. One female stung the first pupa 

that she encountered, remaining 45 minutes with her ovipositor in the host and upon 

withdrawal, died. The stung pupa was held but no parasitoid emerged. The other 4 

females however, showed no interest in skipper pupae. New hosts were provided each 

day until the parasitoids died. All exposed pupae were held but only T. lineola adults 

emerged. In 1979 the holding cages were destroyed during a storm and most parasitoids

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84

Pest Status 

Background 

Chapter 24 

Tipula paludosa Meigen, European 

Cranefly (Diptera: Tipulidae) 

A.T.S. WILKINSON 

The early history of the European crane fly, Tipula paludosa Meigen, in Canada has 

been recorded already (Fox 1957. Wilkinson & MacCarthy 1967. Wilkinson 1971). In 

Nova Scotia, this pest peaked about 1965 (Creelman 1971) but had declined to a low level 

by 1971. High populations of the larvae (Ieatherjackets) damaged golf courses and lawns 

around St. John's, Newfoundland until 1970 (Creelman 1969, 1970). In the lower Fraser 

Valley of British Columbia, it has spread as far east as Hope. On Vancouver Island, it 

was found near Duncan and Victoria in 1972 and caused damage to golf courses and 

lawns in Victoria in 1976. It damaged lawns in Nanaimo in 1978 and in Alberni in 1979. In 

1980. it damaged lawns and a golf course in Prince Rupert (Fig. 3). Populations were 

highest when the pest was first found in 1965, but as the infestation was spread by gravid 

females from the introduction sites near Vancouver into the lower Fraser Valley and 

south into Washington State, populations declined, damage became less, and chemical 

controls became unnecessary. When new isolated infestations such as those on Vancouver 

Island and at Prince Rupert occur, they behave like those near Vancouver did 

and require control measures, at least in the first few years. The spread south in 

Washington was recorded by Jackson & Campbell in 1975, when crane flies had been 

found 180 km south of the British Columbia-Washington border. 

No indigenous parasitoids have been found in larvae of T. paludosa but many predaceous 

ground beetles and birds have been observed feeding on them. The starling 

continues to be the best predator of both the larvae and adults. Many birds feed on the 

adults. 

One disease, or combinations of the many diseases found in the larvae, may have been 

responsible for reducing populations and keeping them below the economic level, but 

this has not been proven. The following diseases have been identified in T. paludosa 

larvae from the Vancouver area by Dr. P.L. Sherlock, Rothamsted Experimental 

Station, Harpenden, Herts., England: Gregarina longa Leger, Hirmocystis venlricosa 

(Leger) Labbe, AClinocephaius lipuiae (Hammerschmidt) Leger, DiplocySlis sp. and 

Nosema binucleatum Weissenberg. All except N. binucleatum were also found in 

larvae from Newfoundland. In British Columbia, up to 50% of the larvae examined 

harbour all protozoans mentioned. 

The literature indicated that the parasitoid Siphona geniculata De Geer was considered 

the primary control agent of T. paludosa. In England, Rennie & Sutherland (1920) 

recorded 21.3% and IS.9% parastism for 2 consecutive years for the first generation and 

27.7% parasitism for the second generation. The latter was based on a low host population. 

Parasitism by S. geniciliala in other parts of Europe was not as high as that reported by 

Rennie & Sutherland. The Commonwealth Institute of Biological Control was retained 

by Agriculture Canada, Research Branch, in 1967 to study natural controls in Germany 

where T. paludosa occasionally causes damage in pastures. Populations of T. paludosa 

examined for parasitoids in 3 sites in Germany by Carl (1972) showed parasitism of 15.5, 

O.S, and 6.0% for the first generation and 4.9, 4.5, and 4.0% for the second generation. S. 

genicuiala has been recorded in Europe from Mamestra brassicae (L.), T. oleracea L., T. 

85


Tipilia pailldosa Mcigen. 87 

fllivipennis De Geer. T. viltala Meigen. T. sllbnodicornis Zetterstedt. T. monlillm Egger. 

and T.maxima Poda (Rennie & Sutherland 1920. Chiswell 1956, Coulson 1962, Alma 

1975) as well as from T. pailldosa. It has been reared from only T. pailldosa in British 

Columbia. 

A phorid, Megaselia pailldosa (Wood), was found in T. pa/udosa by Coggins (1970) and 

by Carl (1972). It is rare in Europe and requires damp conditions. 

Many insecticides tested for the control of leatherjackets were effective. but only 

diazinon. chlorfenvinphos, and parathion were registered. Diazinon is used primarily on 

home and public lawns and the other two are used on pastures. Except in the more recent 

infestations at Nanaimo, Pon Alberni, Prince Rupen, and Victoria. there is very little 

need for chemical control. If these infestations follow the pattern of those in the lower 

Fraser Valley. populations will decline and chemical controls will no longer be needed. 

The B-exotoxin of Bacillus thuringiensis Berliner and the DD-136 nematode of 

Neoplectana carpocapsae Weiser were investigated by Lam & Webster (1972) as possible 

controls for T. pailldosa. Both B-exotoxin and DD-136 were successful in killing 

leatherjackets in the laboratory, but the experimental evidence suggests that the heavy 

application required to achieve high mortality would not be practical for control of T. 

paludosa in the field. 

Carter (1973a. 1973b) showed that Tipula iridescent virus (TIV) can be transmitted 

when healthy larvae feed on a TIV-infected larva. Field trials by Caner (1978) showed 

that TIV can be introduced into field populations of T. paludosa but with low efficiency. 

In 1968. 331 adult S. geniculata were received from the Commonwealth Institute of 

Biological Control (CIBC). Switzerland. from which 565 adults were reared and released 

near Cloverdale. British Columbia. Between 1971 and 1975 an additional 7000 S. 

geniculata received from the CIBC or reared at the Vancouver Research Station were 

released in the lower Fraser Valley. A technique for breeding S. geniculata was developed 

by Carl (1972). Leatherjackets were inoculated with larvae dissected from fieldcollected 

or laboratory-reared gravid females of S. geniculata. The first recovery was in 

1972 when 4 flies were reared from puparia attached to a leatherjacket cadaver. Counts 

of leatherjackets and parasitism were taken from January to August at Cloverdale from 

1974 to 1977 and at Ladner from 1975 to 1979. Parasitism was never very high. At 

Cloverdale. the highest parasitism recorded for the first generation (December to 

March) was 4.3% with an average of 1.6%, and for the second generation (June and July) 

the highest parasitism recorded was 5.1 % in 1974 and for the 4 years parasitism averaged 

2.4%. At Ladner during 5 years the highest parasitism was 3.3% for the winter generation 

with an average of2.3%. and for the second generation the highest parasitism recorded was 

6% with an average of 2.8%. As in Europe. the percent parasitism determined for the 

second generation was based on low numbers of the host because of the marked 

decrease in the larval population late in the season. 

In 1973. 100 S. geniculata adults were air expressed to Newfoundland; 79 survived 

and were released. In 1974. 600 were sent and released. None has yet been recovered. 

Megaselia pa/udosa was found in some of the leatherjackets received at the Vancouver 

laboratory from CIBC. Switzerland. It was reared for several generations but the 

colony died and the parasitoid was never released. 

Tipll/a iridescent virus-infected larvae were released near Ladner in 1975 but the virus 

has not been found in any larvae examined from this area.

Pest Status 

Background 

Chapter 25 

Trialeurodes vaporariorum (Westwood), 

Greenhouse Whitefly (Homoptera: 

Aleyrodidae) 

R.J. McCLANAHAN 

The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), can be a problem 

wherever greenhouse vegetable and flower crops are grown. In major greenhouse areas 

of Canada, the damage has been alleviated considerably by extensive use of the 

parasitoid Encarsia formosa Gahan. When whiteflies are not controlled they cause 

reduction in plant vigour, formation of sooty mould on leaves and fruit, and reduced 

yield. Insecticide sprays, particularly the synthetic pyrethroids, are effective against the 

adults but repeated applications are required to keep the population at sub-economic 

levels. 

Much of the increased acreage under plastic and glass in the 1970s has been used for 

flower crops and bedding plants. These products may be infested with whitefly when 

they leave the greenhouse, in which case they have a lower value as well as serving to 

spread whitefly into new areas. Greenhouse whiteflies are also a problem in small hobby 

greenhouses or solar rooms of houses in which plants are grown. Biological control is 

the best means of combatting the pest in these situations. 

A research project on control of whiteflies was conducted at the Harrow Research 

Station from 1966 to 1974. An integrated control schedule was devised in which E. 

formosa were released, then sprays of oxythioquinox were applied to keep whiteflies 

under control until the parasitoids were established (McClanahan 1970, 1972). The 

withdrawal of oxythioquinox in 1974 shifted the emphasis to biological control alone. By 

this time mass rearing was well established and sufficient parasitoids were available to 

provide good whitefly control on greenhouse tomatoes and cucumbers (McClanahan 

1973). 

In Europe, renewed interest in biological control of whiteflies was generated by a 

need for control methods compatible with the use of Phytoseiulus persimilis Athias 

Henriot for twospotted mite control. Extensive research was conducted in England and 

Holland on the interaction between E. formosa and whiteflies. A good review of this 

European research was given by Vet et al. (1980). Although there has been interest 

expressed in finding a whitefly parasitoid more effective than E. formosa at low 

temperatures, none has been found to date. 

The greenhouse whitefly was introduced to Japan about 1974 and within 4 years it 

became an important pest of greenhouse crops. A number of native parasitoids were 

found, not including E. formosa (Nakazawa & Hayashi 1977). Biological control is being 

considered in Japan. 

89

90 R. J. McClanahan 


Table 15 


The use of E. fonnosa for whitefly control is so extensive that it is difficult to estimate 

the numbers released (Table 15). In the early 19705 production and distribution were 

handled by the Harrow Research Station. Parasitized whiteflies on tobacco leaves were 

packaged in lots estimated to contain 2, 5, or 10 thousand. 

A number of small businesses have been involved in E. fonnosa production and sales. 

Greenhouse Bio-Controls (1972-77) mainly supplied hobby greenhouse owners, with 

most sales to points in the United States. In 1973 and 1974 Greenhouse Bio-Controls 

supplied some of the needs of the Ontario Greenhouse Vegetable Producers' Marketing 

Board (OGVPMB) members, with 650000 and 947 000 parasitoids sold to the Board and 

distributed by them. This accounts for the increased Canadian distribution from this 

source in those years. In 1974-75, OGVPMB contracted E. formosa production to a 

grower, but that was not as successful as a subsequent arrangement whereby they 

provided partial salary for a technician supervised by Ontario Ministry of Agriculture 

and Food, with the rearing done in an isolated greenhouse at the Harrow Research 

Station. 

Releases of Encarsia formosa Gahan in Canada against Trialeurodes vaporariorum 

(Westwood). 

Source Numbers released- (thousands) 

1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 

Harrow Research Station 10 150 943 3133 2148 1485 1157 6 IS 12 19 

Greenhouse BiD-Controls 14 886 1028 47 41 81 

OGVPMB" 500 750 2065 2160 lOSS 1265 550 

Beller Yield Insects 2S 40 

Applied Bio-Nomics 450 1750 588 

* Parasitized whitefly pupae from which there is 90-98% emergence of adult parasitoids. 

** Ontario Greenhouse Vegetable Producers' Marketing Board. 

In 1979 a similar arrangement was set up in British Columbia so growers there and in 

Alberta are supplied with E. formosa from Applied Bio-Nomics Ltd. The rearing 

facilities were supplied by Agriculture Canada and technical support was given by the 

British Columbia Department of Agriculture. 

Better Yield Insects was recently established in Ontario to produce and sell E. 

fonnosa and other biological control agents_ This source serves mainly hobby greenhouse 

owners in the United States, but plans were made to supply greenhouse vegetable 

growers in Ontario through OGVPMB, in 1981. 

Most releases have resulted in establishment, as judged by the very few failures 

reported. There have been cases where parasitoids were eliminated by an insecticide 

application, but with just one spray they have survived in the pupal stage and continued 

to multiply on the surviving whiteflies. 

The overall incidence of whitefly in Essex County has been reduced to the point where it 

is no longer a limiting factor in greenhouse tomato and cucumber production, and it is 

seldom a problem on field vegetables. E. formosa are easily found outdoors every 

summer.

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92

PART II 

BIOLOGICAL CONTROL OF 

WEEDS IN CANADA 

1969-80

Blank Page 

94

Success of the Programme 

Chapter 26 

Current Approaches to Biological Control 

of Weeds 

P. HARRIS 

A total of 30 agents has been released against 14 weed species in Canada. A third of 

the agents have failed to become established, a third are established but inflict 

relatively minor damage to the weed, and a third inflict major damage. This gives a 

crude measure of the success of the programme, but it is not adequate to determine 

whether investment in biological control of weeds is justified in economic terms. The 

opportunity is taken in this chapter to discuss this and other current issues. 

The success of any pest control programme depends on a combination of its 

effectiveness and its cost. In biological control both of these vary greatly with the 

agent selected. It is easiest to predict the cost of an agent; so other things equal, the 

least expensive agent is the best one. Indeed, van Lenteren (1980) suggested that there 

are too many variables and unknowns to enable an effective agent to be selected on a 

scientific basis. Scientific or not, there are rules of thumb for increasing the chances of 

success: matching the climate of the collection and release area (Wapshere 1980), 

collecting from the host plant species or strain on which the agent is to be released, and 

Harris (1973) suggested a number of desirable agent characteristics. These approaches 

can now be tested and modified against the record in Julien's (1982) world catalogue of 

releases. The procedures that work in practice can then be followed, even if the 

reasons for success are not understood. 

Biological control of weeds, in common with government sponsored chemical weed 

control programmes such as those against leafy spurge and knapweed in Canada, has 

been derelict in not evaluating the benefits of the programme in economic terms. 

Without economic cost:benefit data it is difficult to determine whether a particular 

strategy against a weed makes economic sense or it is being pursued for political, 

philosophical, or historical reasons. Several chapters in this section represent initial 

evaluation of the prospective cost:benefits of biological control of possible target 

weeds. Hopefully, this is a step towards substantiating the intuition that biological 

control is economically superior to any other method of control for certain types of 

weed problems. 

The usual practice in biological control is to rate individual agents as failures, partial 

or complete successes depending on their impact on the density of the host (see Laing 

& Hamai 1976). This is neat, but a problem, because it is sometimes the combined 

cropping pressure of several agents on a weed that achieves its density reduction; also 

the effects on weed density are often delayed by the seed accumulated in the soil so 

that the project cannot be rated until several years after the agent has achieved its 

maximum effect. I suggest that it is more useful to rate biological control agents of 

weeds in terms of the proportion of the annual production removed or destroyed. The 

agents are similar in effect to cows in a pasture: if consumption is below a certain level, 

future yield is not reduced. Thus the good farmer restrains utilization of grasses to 

40-60% of annual production depending on the species and area. The good biological 

control worker, on the other hand, must try to exceed the threshold for the target weed 

(which might be determined by clipping tests). Most forbs are less tolerant than grasses 

to utilization (Jameson 1963), but many shrubs will tolerate browsing up to 75% of 

95

96 P. Harris 

Table 16 

annual production (Ellison 1960). If the threshold of a target weed is assumed to be 

50% of annual production. it will not be controlled by an agent that removes 30% of 

production. Nevertheless the addition of new defoliators, seed or root feeders, will 

normally increase the total amount of the weed consumed. Thus the practice is to add 

agent species until the threshold is exceeded. For this reason I consider any agent that 

has become numerous enough to remove a substantial proportion of annual production 

as a success. I would prefer to rate them by the actual amount removed but do not 

have the data for all the species established in Canada. 

The successes of the Canadian programme are listed in Table 16. Several of the 

Agents removing a substantial proportion of the annual production of the target weed in 

one or more regions of Canada. 

Target Weed 

Carduus nutans L. 

Centaurea diffusa Lam. 

e. maculosa Lam. 

Cirsium vulgare (Savi) Ten. 

Euphorbia cyparissias L. 

Hypericum per/oratum L. 

Senecio jacobaea L. 

Agent 

Rhinocyllus conicus Froel. 

Urophora affinis Frfld. 

U. quadri/asciata (Mg.) 

Urophora sty lata L. 

Hyles euphorbiae (L.)* 

Anaitis plagiala (L.) 

Chrysolina hyperici (Forst.) 

C. quadrigemina (Suffr.) 

Tyria jacobaeae L. 

Longitarsus jacobaeae (Wat.) 

• The inclusion of this insect is possibly an optimistic estimate of its effect. 

Country 

Screening Agent 

Canada 






Australia 

Australia 

New Zealand 

United States 

agents have in fact achieved density reductions of the target weed that have solved 

some of the problems from it. For example, the seedhead weevil, Rhillocyllus conicus 

FroeI., has reduced the density of Carduus nutans L. sufficiently on Saskatchewan 

rangeland that it does not threaten the cattle stocking rate. On the other hand, the 

thistle remains numerous on disturbed sites such as gravel pits, and even at low 

densities can be a nuisance in parks and around beaches. Similarly Hypericum 

perforatum L. presently has little effect on the stocking rate of British Columbia 

rangeland: the dense stands at Elko, British Columbia, are not of concern for cattle 

production as stocking is kept low to retain the area as a wildlife overwintering refuge. 

The weed, however, is still perceived to be a problem by the ranchers, possibly 

because they fear its spread. 

The initial work on four of the successful agents (Table 16) was done by other 

countries. Insects successful in Australia or California, such as Chrysolina quadrigemina 

(Suffr.), have tended to be successful in Canada despite differences in climate and the 

converse is true of Canadian pioneered species such as R. conicus. Indeed, the most 

effective and widely employed technique for selection of an effective agent is to choose a 

proven winner. Such agents are also inexpensive as most of the pre-release studies 

required by Canada have been done. Stock for the Chrysolina spp. established in 

Canada was obtained from California following success there. It would almost certainly 

have achieved an impact on the weed in Canada sooner if the releases had been made 

with climatically pre-adapted stock; but there is a trade-off between speed of success 

and cost. In North America, savings can be achieved on weeds common to both Canada

Table 17 

Current approaches to biological control of weeds 97 

and the United States by demonstrating the effectiveness of the agent in one country and 

only distributing those that are successful. 

There are 11 agent species established in Canada that are not removing a substantial 

proportion of the host plant production (Table 17). The reasons for their failure to 

increase to a high population density vary. Some were released so recently that there has 

not been time. Sphenoptera jugosfavica Zell. which was released in 1977 has increased 

to a high density within 0.25 km of the release point but is still too restricted in 

distribution to be included in Table 16. Other species may require a period of climatic 

adaption through selection. Studies on the successful agents Tyria jacobaeae L., Hyles 

euphorbiae (L.), and Chrysolina quudrigemina indicated that a period of 2-13 generations 

of natural selection was required to produce a population adapted to the release 

area. Thus several of the insects in Table 17 are possible successes. 

Agents established in Canada but not removing a substantial proportion of annual 

production of target weed. 

Target Weed 

Carduus nutans L. 

Centaurea diffusa Lam. 

C. maculosa Lam. 

Acroptilon repens (L.) 

Cirsium arvense Scop. 

Euphorbia esula-virgata 

complex 

Hypericum perforatum L. 

Linaria vulgaris Mill. 

Sonchus arvensis L. 

Carduus acanthoides L. 

Agent 

Trichosirocalus ho"idus Panz. 

Sphenoptera jugoslavica Zell. 

Metzneria paucipunctella Zell. 

Paranguina picridis Kirj. & Ivan. 

Ceutorhynchus litura F. 

Urophora cardui (L.) 

Oberea erythrocephala Schr. 

Aphis chloris (Koch) 

Calophasia lunula (Hufn.) 

Cystiphora sonchi (Bremi) 

Rhinocyllus conicus Froel. 

Year Established 

1978 

1977 

1974 

1977 

1968 

1976 

1981 

1981 

1966 

1982 

The failure of R. conicus to attack a high proportion of Carduus acanthoides L. flower 

heads seems to be related to a poor adaptation to this thistle. The weevil was a success 

on C. nutans in Canada, the host plant from which it was collected in Europe. The 

association of both specialized insects and pathogens with a host plant is an extremely 

stable relationship. The completion of a number of generations on a marginal host 

normally does not improve survival unless the genetic potential to overcome host 

resistance already exists in the agent population. There are host races of R. conicllS on a 

number of European thistles (Zw6lfer & Preiss 1983); but it is uncommon on C. 

acanthoides and was not found in the samples examined by Zw6\fer (1965). Thus the C. 

nutans strain of R. conicus is likely to remain marginal on C. acanthoides as the species 

does not have the genetic potential to exploit it successfully. 

Two of the 12 failures listed in Table 18 have been established in Canada on the plant 

from which they were collected in Europe. Thus only ten or a third of the agents have 

failed to become established at all. This compares with a failure rate of about two thirds

Number of Phytophages and Weed Control 


depressed by overgrazing or disturbance. Canadian examples are H. perfora/um, 

Centaurea diffusa Lam., C. maculosa Lam. in the grasslands of the interior of British 

Columbia; Carduus nlllans in the mid-grass prairie of Saskatchewan; Euphorbia esulavirgala 

complex in Manitoba; and E. cyparissias L. on limestone soils in 

Ontario, North American plants such as Solidago gigantea Ait, behave similarly in 

parts of Europe. These plants do not form extensive monocultures in their native region 

where they are cropped by phytophages. For example, E. cyparissias normally forms 

only a small portion of the herbaceous community on limestone soils in Europe compared 

to 25-50% at Braeside, Ontario. The introduction of phytophages against H. 

perforalum in British Columbia and Ontario reduced it to a small percentage of its 

former abundance at most sites, and C. nlllans has been reduced to less than 10% on 

Saskatchewan rangeland. In part, the effectiveness of a control agent depends on the 

level of competition from other plants (Harris 1981a) which is normally greatest in 

uncultivated habitats and least in disturbed sites. 

Specialized phytophages and their hosts normally have a mutual density dependence. 

Thus cropping pressure is high when the plant is abundant and low when it is scarce and 

vice versa for the mortality of the phytophage. The result is that neither becomes 

exterminated. A Canadian biological control example is the cinnabar moth, Tyria 

jacobaeae, on Senecio jacobaea L. in British Columbia in which the moth has 

tracked the density of its host (Lakhani & Dempster 1981). Similarly Ralph (1977) found 

that the highest densities of milkweed (Asclepias syriaca L.) supported the highest 

densities of Oncopellus fasciatus (Dall.), and that below a certain density that plant 

escaped attack. This has been called 'escape in space' by Feeney (1976). 

To summarize, classical biological control of weeds is most appropriate in terms of its 

impact and its effects against introduced weed species that dominate large areas of range 

or other uncultivated land. 

Cropping pressure on a weed can be increased by establishing several phytophage 

species on it (Harris 1981a). Even two closely competing seed head flies on C. diffusa 

reduced seed production more when together than either did alone (Myers & Harris 

1980). Internationally, introductions have tended to continue over a period of years until 

an average of four species has been established on the weed (Harris 1979). This process 

of adding agents can only go so far as there is a species area-asymptote: the number of 

phytophagous insects and pathogens cropping a plant species varies with the log of its 

abundance (Lawton & Schroeder 1977, Strong & Levins 1979). That is to say the 

number of phytophages that can be supported by a plant species doubles for every 

tenfold increase in its abundance. In southern Britain five continental species of Heteroptera 

have become established on pine following large plantings. The pines displaced 

juniper and as a result one juniper-feeding Heteroptera, which formerly existed in 

sizeable colonies, has become extinct (Southwood 1957). Simberloff (1978) achieved 

similar results experimentally by altering the size of mangrove islands. In some plants an 

expansion of range is matched by an increase in the species consuming it. The recruits 

are derived from other plants in the new range or from the host in the native habitat. This 

occurred within 50 years on cacao (Strong 1974). With other introduced plants such as E. 

cyparissias in North America, there has been negligible recruitment of insect consumers 

even after a hundred years. Presumably most native insects are unable to overcome the 

physical and chemical defenses of the plant and the infestations are too remote for 

specialized insects to reach them from Europe.

100 P. Harris 

The number of niches available to insect species is partly a function of the plant 

architecture, so a species native to several parts of the world tends to support similar 

numbers of leaf chewers, stem borers, and insects in other guilds throughout its range, 

even though the insects may be in different taxonomic orders (Lawton 1978). The niches 

can be regarded as sites at which the nutrient pool in the plant can be tapped. The pool 

normally cannot be drained through anyone tap but they all lower its level. This implies 

competition between agents in different niches. For example, Moran & Southwood 

(1982) found that there was interaction between chewers and sap suckers on the tree 

species studied. 

The best targets for classical biological control are introduced plants on which the 

consumer pressure is below that found in the native region. It should be possible to raise 

consumption to at least the native region level although the number of phytophages that 

can be established will be lower as their density will not be depressed by specialized 

parasites. Probably each agent established on a weed increases the difficulty of establishing 

additional species so those with the most potential should be introduced first. 

It is unlikely that native weeds can be controlled by classical biological control unless 

their abundance has increased. This has occurred with ragweed, Ambrosia artemis;;folia 

L. (Harris & Piper 1970). If the phytophage-ragweed area asymptote is below that 

of ragweeds that have not increased since European settlement, it should be possible to 

establish additional agents from South America; however the increased consumer 

pressure on the weed may not reduce allergenic hay-fever since the symptoms in man 

are relatively dose independent. Usually the best hope for the biological control of a 

native weed is the periodic application of an agent (probably a native pathogen) to keep it 

at an artificially high level. This is called augmentative biological control and is discussed 

under the heading 'The Future'. Hall et al. (1980) found no significant difference in 

the success of biological control against native and exotic insect pests, but whether the 

native pests had increased in adundance with modem agriculture was not considered. 

Demonstration that Candidate Agents are not a Threat to Desirable Plants 

The use of a plant species as a host by a phytophage depends on its suitability as a 

nutrient source and as a place to live, the opportunity of reaching the plant, and the 

survival advantage of using it (Harris 1981b). If one of these requirements is 

unfavourable, the agent will not reach high levels on it. The strategy is to show that the 

organism cannot develop on any plant outside a taxonomic group that does not contain 

desirable species (Harris & Zwolfer 1968, Zwolfer & Harris 1971, Wapshere 1974). 

Unfortunately in the laboratory, organisms develop on a broader range of plants than 

they attack in nature. It is then necessary to show that the organism either does not 

have the opportunity of establishing on the desirable plant in nature or that individuals 

doing so are at a selective disadvantage. In effect there is a 3 tier system of testing: 

desirable plants that fail the first test because they will support development, are 

considered at the next tier of opportunity and if this is positive, at the last, and most 

difficult, tier of advantage. 

The opportunity of an insect to attack a plant within its distributional range normally 

depends on the presence in the plant of sensory tokens for attraction and acceptance 

by the ovipositing female. This is the result of many generations of selection to 

optimize survival and is not easily changed. Indeed, it is often difficult to establish an 

agent if the strain or species of the target weed is different from the one on which it was 

collected. This is evident in the programme for the biological control of leafy spurge in 

Canada. Similarly Goeden (1978) found that the race of R. conicus established on C. 

nutans in North America did not attack Silybum marianum (L.) Gaertn. in the field,


although a strain collected from this plant established readily. This programming of an 

insect for a particular plant tends to break down in the laboratory and so is best field 

tested in the native region. 

In contrast to the active dispersal of most insects, the passive dispersal of pathogens 

and to a slightly lesser extent certain insects like aphids, results in their deposition on 

many plant species which they will frequently attempt to attack. The host range of 

pathogens is normally genetically stable so most of the pathogen propagules landing on 

other plant species are lost. However, if the genetic capacity (possibly as a result of 

hybridization) to attack another plant species exists in a pathogen popUlation, the 

occasionally successful individual can, by asexual reproduction, increase rapidly. It is 

not a good omen for biological control if dense stands of a desirable plant on which a 

pathogen can develop in the laboratory, grow near the target weed. 

The advantage of a particular host species to a phytophage depends on its potential for 

increase on it. The innate reproductive capacity of the phytophage on various plants can 

be measured in the laboratory, but the rate of increase in the field is influenced by 

mortality, competition from other consumers, the density of the host, and other factors 

that cannot be measured in the laboratory. Thus a good laboratory host is not necessarily at 

risk in nature, and a relatively poor laboratory host might be regularly damaged if there 

are large amounts growing as a monoculture. This is hard to determine experimentally in 

the new habitat without danger that the organism will escape. For this reason the 

development of the organism on an introduced crop plant in the laboratory is justification 

for rejecting it as a biological control agent; but development on a native wild plant is less 

cause for concern. For example, the European moth Plryllonorycter blancardella 

(Fabr.) attacks Cratueglls spp., apple, and several related plants in its native range but, 

where it has been introduced into Quebec, Pottinger & LeRoux (1971) were unable to 

find it on Cratueglls spp., an abundant native, although it was common on the introduced 

apple. Similarly Moran (1982, personal communication) found that insect pests on South 

African crops derived from native plants were, with rare exceptions, attacked by native 

species. On the other hand, introduced crops were attacked by both native and introduced 

insects. 

There are examples in which introduced insects and pathogens have become pests of 

native plants. These phytophages are either polyphagous, like the gypsy moth, so they 

readily accept and develop on a wide range of plants; or the native lacks resistance, as in 

the case of the chestnut blight, so the organism has a higher reproductive capacity on it 

than on the original host. The best indication of the genetic capability of phytophages to 

utilize plants in the new habitat is their host range in the native region, and if necessary 

desirable plants of the new habitat can be tested there by planting them at their normal 

density. Thus a species such as Lema cyan ella L., which in Europe is only found on 

Cirs;llm arvense (L.) Scop. (Peschken & Johnson 1979) is unlikely to attack native 

North American thistles to any extent even though it will accept them in the laboratory. 

Selection of Target Weeds for Classical Biological Control 

Classical biological control cannot escape some measure of politics because it depends 

on public funding. Also, as an agent will spread over many properties, it has to be 

introduced as a matter of public interest. 

Originally the priorities for biological control in Canada were largely determined by 

popular demand: the squeaky wheel approach. This did not necessarily target the best or 

the most urgent weeds for biological control as is evident from some of the examples in 

this volume.

102 P. Harris 

The Future 


It is axiomatic that biological control is only justified if it is likely to produce a 

satisfactory return on investment which is greater than can be obtained by other means 

of control. The biological control of a suitable target weed is likely to require 20 scientist 

years ($2 million at present costs) (Harris 1979). These costs are less if host specificity 

testing has been done elsewhere. Determination of benefit requires quantification of 

savings and increased yields minus any detrimental effects of control such as the 

reduction of a nectar source. Costs and benefits that cannot be quantified in monetary 

units should be expressed in ecological terms. The study should be published before 

biological control is started. This gives an opportunity for objections to be voiced and 

the proposal debated. 

Classical biological control of weeds is likely to continue to be directed primarily against 

introduced species that form extensive dense stands on uncultivated land. For this type 

of problem there is a hgh rate of success and the return is excellent, particularly when 

considered on.a national or a continental basis. There are, however, a limited number of 

weed species that are prime targets in Canada. As work on these is completed or the 

possibilities for biological control are exhausted, as is happening for C. arvense, the 

programme will be directed increasingly against weeds of more minor importance. One 

way of maintaining a favorable benefit-cost ratio is to tackle them as joint projects with 

the United States or other countries so that the costs are shared and the benefits accrue 

on an international scale. At present international cooperation is informal and this will 

probably need to be replaced by more formal cooperative agreements against specific 

target weeds. 

There is room to increase the rate at which present projects are completed but the 

long-term prospect is for a continued small Canadian participation in classicial biological 

control of weeds. There has been an increase in staffing since the 1968 review (Harris 

1971) that reflects the economic seriousness of some of the projects such as knapweed 

and leafy spurge. Thus Agricultural Canada has increased its participation from 2 to 4 

full-time scientists; McGill University (Macdonald College) has an active programme 

that emphasizes pathogens; the Province of Alberta is recruiting a scientist, and the 

University of British Columbia has a programme elucidating the effects of some of the 

agents. The programme will probably stay at this level with more emphasis placed on the 

selection of both the target weeds and the agents. 

The main area for expansion is in augmentative biological control in which a pathogen 

is applied periodically as a bioherbicide. Two centres, Macdonald College and the 

Regina Research Station have started investigations in this area. The work has not been 

reported in this review as it has yet to lead to the licensing of a bioherbicide in Canada. 

The few bioherbicides currently in use in the United States are for weeds of crops that 

are hard to control by other means (Templeton 1982). One ofthe attractions of bioherbicides 

is that they can be produced in small amounts at a reasonable cost. Thus they can 

be used for weed problems of minor crops in which the area involved does not justify the 

development of a specific herbicide. The method has a profit potential so it is likely to be 

developed primarily by industry and this could occur rapidly. The main obstacle to date 

has been the lack of licensing regulations. These have now been drafted in the United 

States and it is probable that Canada will adopt similar requirements. There is an initial 

role for government research to get the industry started. Subsequently the government 

role may be largely regulatory. 

Ellison, L. (1960) Influence of grazing on plant succession of range plants. Botanical Review 26, 1-66. 

Feeney, P. (1976) Plant apparency and chemical defense. In: Wallace, l.W.; Mansell, R.L. (Eds.). Biochemical interactions between plants 

and insects. Recent Advances in Phytochemistry 10, 1-40. New York; Plenum Press.

Blank Page 

104

Pest Status 

Background 

Chapter 27 

Acroptilon repens (L.) DC., Russian 


A.K. WATSON and P. HARRIS 

Acrop,ilon repens (L.) DC. (Centaurea repens L.) is native to Mongolia. Western 

Turkestan, Iran, Turkish Armenia and Asia Minor (Moore & Frankton 1974). and was 

first introduced into Canada about 1900 as a contaminant of Turkestan alfalfa seed (Groh 

1940). Russian knapweed is now widespread in the southern parts of the four western 

provinces and is also found in southern Ontario. although most infestations are relatively 

small (50% of infestations in Saskatchewan are less than one acre in size) (Watson 1980). 

This noxious weed has a well developed, extensive root system which is the major 

means of reproduction and spread (Frazier 1944). It forms dense infestations in cultivated 

fields, in grain and alfalfa fields. in pastures, along roadsides and irrigation ditches and in 

waste places. Russian knapweed is apparently indifferent to crop association and is able 

to survive in almost any crop in tillable soil (Rogers 1928). Infested fields commonly 

have knapweed densities of 100-300 shootslm 2 which suppress and essentially eliminate 

other plant growth (Selleck 1964). In addition to its intense competitive ability, Russian 

knapweed is poisonous to horses (Younget al. 1970). Actual crop losses and other losses 

due to Russian knapweed have not been determined nor estimated in Canada. 

Because of its serious threat to Canadian agriculture, Russian knapweed was designated 

as a "prohibited noxious weed" in the Federal Seeds Act (Agriculture Canada 

1967). The benefit of this is debatable as it is difficult to collect viable seed in Canada 

(Watson 1975) and germination rarely occurs in the field (Selleck 1964). Control of this 

persistent perennial weed is difficult as its extensive root system is not adversely 

affected by cultivation and the weed is relatively resistant to commonly used herbicides. 

Picloram (4-amino-3,5.6-trichloropicolinic acid) and glyphosate [N-(phosphonomethyl) 

glycine) are two of the more effective herbicides for Russian knapweed control (Alley & 

Humberg 1979). The biology of Russian knapweed has recently been reviewed (Watson 

1980). 

In North America, Russian knapweed is relatively free of specialized parasites and is not 

extensively attacked by polyphagous feeders, but in its native range, Russian knapweed 

is the host of a number of specialized organisms (Watson 1980). The potential biological 

control agents of Russian knapweed include seven organisms that attack the seed head: 

a seed gall mite (Aceria acropliloni V. Shev. & Kov.), three Diptera (Dasyneura sp., 

Urophora maura (Frfld.), Urophora kasochstanica V. Richter) and three Coleoptera 

(Larinus bardus Gyll., Larinus jaceae Fabr., Rhynchaenus dislans Faust); a stem gall 

former (Aulacida acroptilonica Beliz); a leaf and stem rust (Puccinia acroptili Syd.); and 

a leaf and stem gall nematode (Paranguina picridis Kirj. & Ivan.) (Watson 1980). 

105

108 A. K. Watson and P. Harris 

Table 21 

Table 22 

Recovery of P./Jicridis Kirj. & Ivan. on Russian knapweed, A. repem (L.) DC., at the 

Regina Research Station. 

Precipitation 

Year Galls/m: P. picridislm: A. repetls stems/m: September-May (mm) 

1977 0 

1978 0.67 

1979 3.0 

1980 no obvious 

galls but some 

swollen stems 

1981 0.63 

0 

2.9 

3599 

16 

15.0 

52.0 

18.6 

167.5 

212.5 

213.0 

145.7 

108.6 

The nematode population declined in the springs of 1980 and 1981, which was likely the 

result of the dry conditions. In the five years from release, no P. picridis were found in the 

control strip of knapweed planted 3 m away from the test plots. 

At the Ste-Anne-de-Bellevue site, 6 m l plots were established in the early spring of 

1977 and 100 000 nematodeslm l were inoculated in three of the plots. Russian knapweed 

was transplanted into all plots and eight crop species were sown in rows between the 

Russian knapweed plants in 1977. In 1978. globe artichoke and safflower were sown in 

all plots. A few nematode galls were observed on Russian knapweed in 1977 and heavy 

galling occurred on Russian knapweed in 1978, 1979, and 1980. In 1981, gall formation on 

Russian knapweed was reduced. Galls did not develop on any of the tcst plant species in 

1977, 1978, or 1979. 

Effect of P. picridis Otl the ktlapweed 

P. picridis was innoculated into 3 m l plots of pure Russian knapweed at Jenner, Alberta. 

at a rate of 30 Ooo/ml, and three control plots were established with a 50 em buffer zone 

from the treated area. 

No galls were found on the knapweed in the 1978 growing season even though the 

nematodes had been kept in soil for six weeks before release. However, in the spring of 

1979, most of the knapweed shoots in the treated plots were galled, although those 

appearing later in the summer were not infected. The plots were sampled at the end ofthe 

growing season, the knapweed counted. weighed, and the nematodes extraced (Table 

22). The results show that, apart from distorting the knapweed stems, the nematode had a 

negligible effect. This is in contrast to the results reported from the USSR (Kovalev et 01. 

1973). The other notable feature about the results is that in spite of the close proximity of 

the treated and control plots, there had been little movement of the nematode into the 

control plots. 

This trial was terminated at the end of 1979, as the knapweed on the surrounding area 

has been treated with glyphosate and apparently eliminated. 

Effect of P. picridis Kirj. & Ivan. on A. repetls (L.) DC. at Jenner, Alberta in 1979. 

No. stems! No. seed headsl Dry weight of No. nematodes! 

Treatment 0.25 ml 0.25 m l fohage/0.25 m l 0.25 m: 

P. picridis 25.3 ± 3.9 73 ± 20.7 42 ± 6.2 2259 ± 163 

Control 33.2 ± 4.3 55 ± 16.0 44.8 ± 7.0 5.7 ± 3.9




Acropli/on repms (L.) DC.. 109 

Fears were expressed following submission of the laboratory screening tests that if P. 

picridis was able to adapt to attack desirable knapweeds or even globe artichoke. it 

might be extremely difficult to eradicate. The results from the persistence trials and the 

lack of movement of the nematode from the treated to control plots indicate that these 

fears are groundless. Removal of the host plant for two growng seasons will result in 

eradication of the nematode with little likelihood of reinfestation from surrounding 

populations without human assistance. Furthermore, the host range under field conditions 

was narrower than in the laboratory. Thus, there were no galls found on Cynara 

scolymus in the plots in either Saskatchewan or Quebec, and at Regina stray plants of 

Carduus nulans and Cirsium arvense that appeared in the treated plots were also not 

infected. Lettuce was not a host under laboratory conditions (Watson 1975) and the two 

small swellings were almost certainly from some other cause, as no nematodes were 

found in them. From a safety point of view. the nematode should be no problem to any 

plant except Russian knapweed and it can be easily eradicated if desired. 

The effectiveness of P. picridis is another matter. The lack of movement in or on the 

soil suggests that it would have to be spread thoroughly over a knapweed stand in much 

the same manner as a granular herbicide. The nematode also requires moist spring 

conditions and there is no purpose in using it on the Canadian prairies unless the area to 

be treated normally receives a good winter snow cover. The nematode requires a winter 

before it will infect Russian knapweed, so the fall seems to be the best time for 

application. 

The lack of knapweed suppression in the plots treated in Alberta was disappointing. 

Almost certainly the effect would have been larger if the knapweed had some grass 

competition, as this would have helped suppress the later growing shoots. However, the 

main reason for lack of an effect is that the impact may be delayed for a year. The stem 

growth in the current year depends on the root reserves of the previous year. The 

nematode creates a metabolic sink in the stem that will tend to divert reserves from the 

roots so the plant should be less robust for the following year. 

1 The nematode, P. picridis, should be released on selected major natural infestations 

of Russian knapweed in British Columbia, Saskatchewan, and Manitoba. 

2 Since Russian knapweed populations in Canada do not reproduce extensively 

from seed, the importation of biological control agents that attack the seed head is not 

justified. 

3 Since biological weed control programmes usually require more than one biological 

control agent to be successful (Harris 1979) and since P. picridis may not provide 

sufficient stress to control Russian knapweed in all habitats, studies could be initiated to 

evaluate the potential of the stem gall former Aulacida acroplilonica and the potential of 

the rust Puccinia acroplili as possible additional biological control agents of Russian 

knapweed. 

Agriculture Canada (1967) Seeds Act and Regulations. Ottawa: Quecn's Printer. 50 pp. 

Alley, H.P.; Humburg. N.E. (1979) Research in weed science. 1978. AgricullUral Experiment Station of the University of Wyoming 

Research Journal 137.98 pp. 

Frazier. J.C. (1944) Nature and rate of development of the root system of Centaurea picris. Botanical Gazelle (Chicago) 105.345-351. 

Groh. H. (1940) Turkestan alfalfa as a medium of weed introduction. Scienct' in Agriculture 21. 36-43.

Blank Page 

111

Blank Page 

112

Pest Status 

Background 

Chapter 29 

Artemisia absinthium L., Absinth 

(Compositae) 

M.G. MAW and D. SCHROEDER 

Artemisia absinthium L. is indigenous to temperate Europe and Asia and was introduced to 

North America as a medicinal and flavoring herb some time before 1832. By 1841. 

absinth had escaped from gardens and was recognized as an established weed in the 

United States (Mitich 1975). The weed was first recorded in Canada at Fort Garry. 

Manitoba in 1860 (Scoggan 1957). By 1883, absinth was considered to be naturalized in 

numerous locations from Newfoundland to western Ontario (Mitich 1975). Although it is 

abundant in the Prairie Provinces. it was not recognized as a serious weed until 1954 

(Frankton & Mulligan 1970). 

Absinth can now be found in all provinces of Canada and in many of the northern 

states but with few exceptions it is confined to farm yards, around grain elevators, and 

along the edges of fields, railways, and roadsides. It is controlled by cultivation but can 

be spread into pastures, hayfields, and crop lands. Rapid increase in the spread of the 

weed on the prairies is associated with relatively moist conditions (Selleck & Coupland 

1961). 

Although absinth may flavor milk, and grain from infested fields may be rejected 

because the flour might be tainted (Selleck & Coupland 1961), such occurrences are 

rare. Cattle will not graze on absinth by choice, but may inadvertently consume it in hay. 

Absinth is a health hazard as the odor can cause illness in those working in infested 

fields. and its pollen causes great discomfort in those sensitized by it. 

While absinth is controlled by cultivation, the farming techniques of minimal or zero 

tillage might permit the weed to become a serious problem in some areas. 

At Canada's request. surveys of absinth insects in Europe were undertaken by the 

Commonwealth Institute of Biological Control. A literature review suggested that 

Euzophera citlerosella (Zeller) (Lepidoptem: Pyralidae), a stem and root miner, was 

specific to A. absimhillm (Miotk 1973). Field surveys in Austria, Germany, France, and 

the Swiss Valais showed that E. cinerosel/a occurs in most populations of absinth 

throughout its European mnge, and that it causes serious damage to its host (Schroeder 

1979). 

E. cillerosella emerges about the end of May to the end of July and mating takes place 

within 24 hours of the female's emergence. Males mate several times; females just once. 

Oviposition starts the day following mating with 12 eggs laid daily for the first four days. 

Over 100 eggs may be laid during June and half that number during July. 

The eggs arc deposited on the lower leaves and hatching occurs in 8-10 days. The 

young larvae commence to feed on the upper cuticle of the leaf but soon bore into the 

leaf petiole destroying the bud in the leaf axil, then downwards, feeding on the vascular 

tissue of the shoots. As the season advances, the larvae reach the roots and destroy 

the outer parts before mining into the woody tissue. The winter is passed as hibernating 

larvae and puplltion takes pl.lce in the spring within a silken cocoon in a pupal cell near 

the root crown. 

Damllge to the host plant depends on the development of the larvae. First and second 

instars clluse little damage. but third and fourth instars mine the cambium and vascular 

113

Pest Status 

Chapter 30 

Carduus nutans L., Nodding Thistle and 

C. acanthoides L., Plume less Thistle 

(Compositae) 

P. HARRIS 

Carduus nwaftS L. and C. acanlllOides L. are thistles of European origin that form dense 

stands on dry uncultivated grasslands in many parts of North America. Three interbreeding 

subspecies of C. nWans occur in Canada (Moore & Frankton 1974) which arc 

treated as full species by some authors (Kazmi 1964). There is also some hybridization 

between C. mllaftS and C. aca""lOides (Mulligan & Frankton 1954). however. as far as 

the practical aspects of biological control are concerned there are two species: C. nulaftS 

with large heads (2-7 cm diameter) and a relatively short but intense flowering period 

that, on Saskatchewan rangeland, is largely finished by the end of July; C. aca",hoides 

with small heads (1.2-2.5 cm diameter) and a prolonged flowering period that. in 

southern Ontario. produces a succession of flower heads from early June until the plant 

is killed by frost in October or later. The seed of both thistles germinates as conditions 

permit throughout the growing season and they may be summer annuals. winter annuals. or 

biennials. The flowering height in C. nWans ranges from a few centimeters to over 2 m. 

so there is considerable plasticity in the species as well as genetic variability as the result 

of hybridization. 

Distribution of the thistle on the Canadian prairies is limited by a need for winter 

protection of the rosettes and relatively low grass competition for seedling establishment. 

Thus it is mainly found on light soils in the mid-grass prairie vegetation zone. in 

places that are covered by snow drifts in winter. such as gullies. fence lines. brush 

patches. and the lee side of stone piles. The dead stems also trap the snow in winter. 

Established stands tend to be self-perpetuating as the death of the flowering stems in 

August creates a seedbed largely devoid of competing vegetation. The occurrence of the 

thistle on heavier soils is a sign that the site was disturbed within the past few years. 

The status of C. nwaftS has changed in Saskatchewan since the establishment of the 

seed-head weevil. Rhinocyllus conicllS Froel.. for its biological control. In 1970, stands 

of 150 OOOlha of flowering C. nWans plants were common in pasture and extended for 

many kilometers in roadside borrow pits. At this density. there is no grazing within the 

stand. In 1980. the thistle was largely restricted to breaks in the pasture sward such as 

ground squirrel diggings and along cattle trails. Stands of over 15 000 plantslha were 

uncommon and small roadside stands that used to be a feature of the landscape have 

been reduced to scattered plants. On the 4 point scale. modified from Vere & Medd 

(1979). the most densely infested region has declined from category 4 to categories 1-2: 

1 = no C. nmans, 2 = scattered thistles or 

standslha.4 = continuous thistles or >50 stands/ha. There was negligible grazing loss 

from category 2 infestations in Australia. a loss of 8.3% from category 3. and 16.7% loss 

from category 4. No comparable data are available for Saskatchewan but the loss is 

presumably similar. Currently there is little grazing loss from C. mllaftS on permanent 

pasture although dense patches remain on recently disturbed and abandoned ground 

which is often on roadsides. At low densities it is still a nuisance in some places such as 

parks. C. nmans continues to spread in the mid-grass prairie zone but on a narrower 

range of sites. 

115


Rhinocynus conicus 

(Froel.) (Coleoptera: 

Curculionidae) (a) Ecology 

Trichosirocalus 

horridus (panz.) 

(Coleoptera: 

Curculionidae) 

Carduus IIutans L., 117 

The biology and host specificity of R. conicus has been treated in detail by Zw61fer & 

Harris (in press). The weevil is native to Europe, western Asia, and North Africa 

between latitudes 30 0 

N and SooN. Its main host is C. nutans but there has been race 

formation on other thistles in the genera Carduus, Cirsium, Silybum, and Onopordum. 

Teneral R. conicus emerge in July to early August in southern Ontario and August in 

Saskatchewan. The weevil has a second generation if the day length is over 16 hrs. 

Individuals released in a cage in southern Ontario on the 27 June when the day length was 

15 hr 48 min did not breed, but those released in mid-July in Saskatchewan with a day of 

16 hr 5 min did so. Laing & Heels (1978) reported a second generation from weevils 

released in southern Ontario in August, but these were mated in the laboratory. presumably 

under long day conditions. Normally, in Canada, there is a single generation emerging 

after mid-summer and then hibernating in the soil litter. They appear again in the spring 

to feed on the leaves of bolting thistles and oviposit on the involucral bracts of the flower 

buds. Oviposition starts slightly before the buds are available in the spring with some 

wastage of eggs on the leaves enclosing the terminal flower bud and the first heads receive 

an abundance of eggs. Rees (1977) counted over 500 eggs on a single head. 

The eggs are covered with a cap of chewed thistle and the larva bores directly into the 

flower bud from under the cap. It mines the receptacle and sometimes the peduncle as 

well as feeding on the young ovules. Typically the receptacle mine fills with callus on 

which the larva feeds (Shorthouse, 1982, personal communication). Thus, like a gallformer, 

the larva stimulates production of its food supply. The mature larva forms a 

hard pupal chamber in the thistle head which remains after emergence so the number 

that developed in a head can be counted. 

(b) Releases 

Most of the R. conicus stock established in Canada was collected from C. nwans growing in 

the French Rhine Valley around Mulhouse. As the initial results with this stock on C. 

acanthoides were disappointing, additional weevils were imported from the smallheaded 

thistle C. personata (L.) Jacquin as well as stocks from Cirsium spp. Day length 

at the release date probably prevented many of the colonies from breeding until the year 

following release (Table 23). With hindsight, it would have been better to have held them 

in laboratory storage until the following spring or mated them under long day conditions 

in the laboratory before release. 

(a) Ecology 

The biology of T. horridus was reported by Trumble & Kok (1979) and a bibliography 

of the weevil compiled by Trumble & Kok (1980). The weevil is found from Italy to 

Poland, in Turkey and the USSR. The adults have been found feeding on a number of 

thistle genera and the larvae developed on several of these in the laboratory (Kok 1975), 

however, in the thistle garden at the Regina Research Station, they have only been found 

on Carduus spp. and not on either European or native Cirsium spp. Thus the field host

118 P. Harris 

Table 23 Open releases and recoveries of R. conicllS Froel. against Cardlllls spp. 

Release Initial 

Province Host date Place Source Number recovery 

Saskatchewan C. "Ulans 26.7.68 Aylesbury 400 1969 

16.7.69 1898 

C. "Ulans 16.7.69 Findlater 1897 1969 

Ontario C. acamhoides 25.7.68 Read (site A) 320 1969 

23.5.69 1 282 

10.6.70 2 350 

5.10.69 Read (Site B) 3 74 

5.10.69 1 80 

31.6.70 Read (Site C) 1 3500 1971 

22.5.69 Stoco Lake 1 350 1970 

11.7.69 Roslin I 4320 1970 

22.5.70 1 1500 

1.5.70 Moira 4 200 

C. acamhoides 3.6.70 Flesherton 1 250 not checked 

xc. "utans 

C. "ulans 9.6.75 Guelph 5 2185 1976 

Manitoba C. "Ulans 17.6.74 Somerset 5 500 1975 

4.9.74 Darlingford 5 4000 1975 

Quebec C. "ulans 17.6.74 Lac St-Jean 5 1100 1975 

C. acanthoides 23.7.78 Huntingdon 5 7731 1982 

16.6.80 5 10130 

British Columbia C. nUlans 16.7.79 Williams Lake 5 2600 site 

destroyed 

1. Mulhouse, France ex C. nutans 

2. St. Hippolyte, France ex C. personala 

3. Krymsk, USSR ex Cirsium spinosllm 

4. Nantes, France ex C. vulgare 

5. Findlater. Saskatchewan ex C. nutans 

range of the strain introduced is more restricted than that of R. conicus. Under field 

conditions in Virginia, United States, it had a strong preference for C. nutans over C. 

acanlhoides and was more readily established on stands of the former species (Sieburth 

& Kok 1982). On C. nUlans, high densities of T. IIOTTidus and R. conicus were found in 

the same stands (Kok 1980). 

In Canada, the adult weevil overwinters in the soil litter. It becomes active in early 

spring to lay in the mid-vein of large CardullS leaves. This differs from the life cycle in 

Rome, Italy, where the weevil starts ovipositing in October and continues over winter 

(Bolt & Campobasso 1981). The larva bores down the mid-vein into the crown and 

develops just below the apical leaves. This causes the plant to produce several lateral 

shoots, which in Saskatchewan may be attacked again when about 15 cm high; the larvae 

are also sometimes found in the lateral vegetative buds. The result is to produce a bushy 

thistle in which flowering is probably delayed. The larvae pupate in the soil and emerge 

as adults in reproductive diapause in the early summer. They feed on the thistle leaves 

until the fall and can be frequently found on the bracts of the flower buds. 

(b) Releases 

The stock released at Aylesbury, Saskatchewan, was collected in eastern Austria. around 

Morel, Switzerland, and Neuenburg, Germany (Table 24). In addition, 22 weevils from

Table 24 


Carduus IIll1allS L., 119 

Neuenburg, released on a 4 m 2 stand of C. IIll1allS maintained at the Regina Research 

Station, were the source of the stock released elsewhere in Canada. At Regina, survival 

of the weevil was most easily confirmed by removing the apical rosette leaves to expose 

the larvae during the spring wheat seeding period, usually around mid-May. Later in the 

year, the weevil was hard to find and even its damage was obscure. Thus, it was hard to 

confirm establishment at Aylesbury as the road to the site was often impassable until late 

May. It is suspected that the reason that this cryptic weevil has not been reported 

established at other sites is that the thistles have been inspected too late in the season. 

Open releases and recoveries of T. horridlls (Panz.) against CardulLf spp. 

Province Site Host Year Source Number Recovery 

Saskatchewan Aylesbury C. flUlaflS 1975 Austria-Germany- 

Switzerland 

65 1979 

Aylesbury C. flUians 1979 Saskatchewan 36 

Regina C. nUians 1975 Germany 22 1976 

Quebec Huntingdon C. acanthoides 1977 Saskatchewan 26 

Huntingdon C. acallthoides 1980 Saskatchewan 6 

Ontario West 

Huntingdon C. acallthoides 1978 Saskatchewan 33 

British 

Columbia 

Williams 

Lake C. nutans 1979 Saskatchewan 22 

site 

destroyed 

Manitoba Snowflake C. nutans 1980 Saskatchewan 16 

Density of R. conicus 

The general effects of R. conicus on C. lIlllans in Saskatchewan have been described in 

the Pest Status section. More detailed studies were done at the Findlater and Aylesbury 

release sites (Table 25 and 26). Findlater was an unused gravel pit and Aylesbury a gully in 

a permanent pasture. Both sites were sampled in early August: Findlater on a permanent 

transect along the spoil pile, and Aylesbury in four directions from the release point. The 

density of flowering thistles was determined with m 2 samples taken at 5 or 10 m intervals, 

or they were calculated by the distance between nearest neighbour for a population with a 

uniform distribution (Southwood 1978). The latter estimates are indicated by the absence 

of an error term in Table 26. In 1978 and 1979, the estimates obtained from the nearest 

neighbour method were: Aylesbury 1.4, 1.0, and at Findlater 48.2, 8.3/m 2 • These are 

similar to the values obtained from counting on the m 2 plots (Table 26). However, in 1976 

at Aylesbury, the distribution was clumped with most of the site free of thistles but some 

patches containing up to 651m 2 • In this year the nearest neighbour method, assuming a 

uniform distribution, gave a density of 2.7/m 2 compared to 6.6/m 2 obtained by averaging 

the m l samples. All heads were clipped from the thistle nearest to the right comer of the 

plot, the receptacle diameter of each head was measured, and the number of R. conicus or 

its pupal chambers were counted. Ifthere were not enough thistles in the transect samples 

to determine weevil density, the thistle nearest to each sampling interval was used. 

At Findlater, the density of R. coniClLf maturing in the flower heads climbed steadily 

from the second year to reach a plateau of 3.4 to 6.4 weevilslhead (Table 25). The weevils 

released in 1968 at Aylesbury (Table 23) received a day of less than 16 hrs in length and 

so probably did not breed until the following year. Thus the initial increase at Aylesbury 

was similar to that at Findlater; but after reaching a peak in 1975, the density fell. This

120 P. Harris 

Table 25 

may have been caused by cattle consuming the terminal flower heads, which contained 

the highest numbers of R. conicus. The cattle did this to an increasing extent as the 

density of the stand declined. The site was not grazed in 1982 and the density of weevils 

increased. 

Establishment pattern of R. conicus Froel. on C. acantlloides L. and C. nutans L. 

C. acantlloides (Site A) at Read, Ontario. Released 320 R. conicus 25 July 1968,282 on 

23 May 1969, 350 on 10 June 1970. 

Calc. R. coniclls 

Year Eggsffhistle per head No. thistles sampled 

1968 0 0 

1969 0.29 0.017 1453 

1971 0.38 0.023 285 

C. acantlloides at Roslin, Ontario. Released 4320 R. conicus on 11 July 1969. 

Calc. R. conicus 

Year Eggs/thistle per head No. thistles sampled 

1969 0 0 

1970 0.52 0.03 1531 

1970· 1.56 0.09 50 

1971 0.18 0.01 1272 

• On scattered C. nutans in C. acantlloides stand. 

C. nutans at Aylesbury, Saskatchewan. Released 400 R. conicus 26 July 1968, 1898 On 

16 July 1969. 

Year R. conicuslhead No. heads sampled 

1969 0.08 317 

1970 0.04 1055 

1971 0.06 688 

1972 0.26 847 

1973 0.79 956 

1974 2.72 311 

1975 3.68 288 

1976 1.43 182 

1977 0.43 353 

1978 2.70 251 

1979 0.86 349 

1980 0.40 293 

1981 0.06 54 

1982 3.18 105

Table 25 

continued 

CtmillllS IIlllatl.f L.. 121 

C. ,wlans at Findlater. Saskatchewan. Released 1897 R. conicus on 16 July 1969. 

Year R. conicllslhead No. heads sampled 

1969 0.03 119 

1970 0.002 509 

1971 0.01 194 

1972 0.19 241 

1973 0.46 168 

1974 1.45 211 

1975 4.53 52 

1976 4.01 96 

1977 1.84 99 

1978 3.38 86 

1979 5.02 177 

1980 3.65 373 

1981 3.51 59 

1982 6.36 375 

Laing & Heels (1978) reported achieving similar population densitites on C. n!llans 

in Ontario and the initial results reported by Letendre el al. (1976) for Quebec followed 

the same pattern. Thus the Saskatchewan impact of R. coniclls on C. nWans is probably 

representative of populations elsewhere in Canada except for British Columbia where the 

release site was destroyed by road building. 

Density of C. tllllans 

The density of C. tlllIans declined at Aylesbury from 15.7 flowering plantslm 1 in 1969 to 

0.5/ml in 1982 (Table 26). The habitat was initially invaded by Russian pigweed, Axyris 

amarantlroides L., and stinkweed, Thlaspi arvense L. The stinkweed was cropped by 

the red turnip beetle. Entomoscelis americana Brown, which also developed on C. 

mllans rosette leaves during this transitional period. Finally perennial grasses. Agropyron 

repens (L.) Beauv. and Sripa comata Trin. & Rupr.. occupied the area and the 

thistle was confined to breaks in the sward. 

At Findlater. the density of the thistle fluctuated from dense. following a moist fall 

and/or spring. to sparse when it was dry (Table 26). The invasion of the transect on the 

spoil pile by other plants was slow, so after dry winters the site remained open for 

recolonization by C. nlllans when conditions were more favourable for its seedlings. 

Gradually clumps of crested wheat grass, Agropyron crisralllm (L.) Gaertn .• appeared 

and by 1982 covered the transect. The C. nWans stand was then confined to the southwestern 

slope of the spoil pile. which was still free of grass. 

The decline of C.nlllans stands in Virginia, United States. occurred more rapidly than 

in Saskatchewan (Kok & Surles 1975). The summer rainfall was greater and its distribution 

more even so that there would be a greater growth of grass. Thus both studies 

support the conclusion that control of C. nutans has been achieved by a combination of 

R. conicus and competition from other plants. 

At neither Saskatchewan site has the lowered density of the thistle reduced the 

numbers of R. cotliells/head. Scattered thistles often escape attack and the weevil may 

not be able to maintain itself on them. For example, 120 R. conieu.s released in 1974 on a 

stand of C. mllans in Regina that consisted of 368 scattered phtnts at 0.07 plantslm 1 bred 

in 1975 but not in 1976 when the density was 0.02 plantslm 1 • However, the weevil

122 P. Harris 

Table 26 C. flU/ailS L. stands at Aylesbury and Findlater following establishment of R. coniclls 

Froel. (± S.E.M.). 

Year No. C. tIIltallS/m 2 No. heads/plant Head diameter No. plants sampled 

Aylesbury 

1969 15.9 ± 1.7 5.7 ± 0.8 2.87 ± 0.02 56 

1970 11.8 ± 1.1 7.5 ± 0.9 1.68 ± 0.03 125 

1971 6.8 ± 0.7 6.2 ± 0.8 2.02 ± 0.03 100 

1972 604 ± 0.8 8.0 ± 0.9 1.65 ± 0.02 106 

1973 704 ± 1.1 1.79 ± 0.02 129 

1974 4.1 6.6 ± 1.3 1.73 ± 0.02 47 

1975 4.9 404 ± 0.7 1.94 ± 0.02 65 

1976 6.6 ± 104 304 1.73 ± 0.01 54 

1977 1.3 ± 0.3 6.0 ± 0.3 1.55 ± 0.02 60 

1978 1.2 ± 0.5 4.3 ± 0.8 1.52 ± 0.03 58 

1979 104 ± 004 3.9 ± 0.7 1.38 ± 0.02 89 

1980 1.9 ± 0.7 2.3 ± 0.1 1.16 ± 0.05 124 

1981 0.9 ± 0.4 1.5 ± 0.1 1041 ± 0.02 60 

1982 0.5 ± 0.1 2.8 ± 0.5 1.56 ± 0.04 38 

Findlater 

1969 l3.5 ± 2.6 11.9 ± 1.8 1.80 ± 0.04 10 

1970 19.1 ± 2.5 10.0 ± 1.3 1.98 ± 0.02 51 

1971 19.8 ± 2.8 4.9 = 0.5 1.69 ± 0.04 40 

1972 8.0 ± 1.2 6.9 = 0.7 1.70 ± 0.02 35 

1973 5.3 = 1.0 1.87 ± 0.04 32 

1974 19.9 5.9 ± 1.2 1.95 ± 0.01 35 

1975 52.1 2.9 ± 0.7 1.86 ± 0.06 18 

1976 7.2 4.2 ± 0.6 1.81 ± 0.03 24 

1977 0.4 ± 0.2 5.2 ± 0.2 2.03 ± 0.03 19 

1978 33.9 ± 5.7 2.3 ± 0.3 lAO ± 0.05 38 

1979 6.7 ± 0.1 5.2 ± 0.8 1.19 ± 0.03 33 

1980 3.0 ± 0.7 3.6 ± 0.3 1.19 ± 0.03 104 

1981 0.6 ± 0.3 4.0 ± 1.6 1.39 ± 0.06 24 

1982 0.03- 11.6 ± 1.8 1.83 ± 0.02 32 

- 1 thistle in 37 m 2 

persisted at another site in Regina on a 10 m 2 stand of C. nlltallS with around SO flowering 

thistles. If the weevil requires dense stands, even if they are confined to a few m 2 , the 

roadside and gravel pit stands may be necessary for maintaining a population. 

Size of C. nU/alls 

The size of flowering C. 'IlltallS plants as indicated by the number of heads/plant 

declined (Table 26). The slope of the decline was not significantly different at Aylesbury 

and Findlater, so the data were combined for the regression in Table 27 (Equation 1). 

The only major departure from the regression was the 1982 value from Findlater. This 

value was not used for the regression as it was not from the permanent transect. The 

equation shows that on the average a plant produced 0.34 fewer heads each year. Thus

Table 27 

Table 28 

Carduus lIU1tl1lS L. . 123 

thistle size has declined more than its density. For example at Aylesbury. the density of 

the thistle in 1982 was 97% less than in 1969. but the number of heads had declined by 

nearly 99%. 

Regression equations of the effect of R. con;cus Froel. on C. nUiallS L. 

1. Average no. heads/plant at Aylesbury 

and Findlater 

2. Average head diameter at Aylesbury 

3. Average head diameter at Findlater 

x = no. years r = correlation coefficient 

dJ. 

= 994.5 - 0.50 x 26 

= 79.8 - 0.40 x 12 

7.3 - 2.89 x 13 

r 

-0.79 

-0.71 

-0.38 

p 

124 P. Harris 

Reasons for the impact of R. conicus 

Lashley (1969) and Sagar (I972) calculated that over 98% of the seed would have to be 

destroyed to achieve control of C. nutans if 50% of the seed was viable and 10% of the 

plants survived. At Aylesbury 80.6% ± 3.6 of the plump seed germinated on moist filter 

paper at room temperature, so the viability factor they used was low. Regression 

equations of seed production per head versus head size and the number of R. conicus 

gave reductions that varied from 5 to 25 seeds per weevil. The variation may arise from 

the formation of callus tissue acting as a metabolic sink in the heavily attacked heads; 

but even the highest estimate would only reduce seed production by around 50%. 

Analysis of one year's results of a four year study of thistle survival at Aylesbury 

indicated that no seedlings survived in a grass sward. Presumably the stand became 

established initially after a natural or man-made disturbance exposed the ground. The 

thistle then perpetuated itself and even at the stand margin spread by producing enough 

plants to smother the site. A constant percentage of plants was lost through the growing 

season regardless of their density or age and around 3% survived to the flowering stage. 

Apparently the weevil reduced seed production to the point at which the thistle was not 

able to completely occupy the site at all times. This allowed the entry of competing 

vegetation which eventually displaced the thistle. Further reductions of C. nUians can 

almost certainly be achieved by pasture improvement to reduce the number of bare spots. 

Effect of R. coniclls on C. acanthoides 

C. acanthoides has remained a problem in Ontario since the introduction of R. conicus. It 

is known that the weevil has persisted on the thistle as there is no difficulty in finding 

flower heads with eggs on them in the early spring; however, it is probable that seed 

production is reduced by a minor amount. In Virginia, only 12.4% of C. acanthoides 

heads are attacked compared to 81.4% ofthose on C. nlltans (Surles & Kok 1977). Much 

of this difference relates to the synchronization of egg production with flowering. In 

Saskatchewan, oviposition covers the flowering period and both are largely completed in 

July. In contrast, on 7 August 1969 at Read, Ontario, after R. conicus had ceased 

oviposition, 22% of the heads of C. acanthoides had finished flowering and would have 

been available to R. conicus, 7% were in bloom, and 70.7% were still in bud (unpublished 

data, T. New). Thus, 78% of the heads produced by C. acanthoides were not available to 

R. conicus. Similarly in Virginia, Surles & Kok (1977) found 19.1% of the heads were 

available to the weevil. 

Dowd & Kok (1981) found a density-related weight reduction of R. conicus in C. 

acanthoides that did not occur in C. n14tans. Also, the weevil responded to C. nutans 

more readily than to C. acanthoides for oviposition: in Table 25 there was a 3-fold 

difference in the numbers of eggs laid on the two species while Surles & Kok (1977) 

found a 4-fold difference. The difference in flower head size does not seem to be the 

important factor as some races of R. conicus achieve high densities on the small-headed 

thistles, C. pycnocephalus and C. ten14iflorus. 

R. conicus has not adapted to C. acanthoides in Europe: Batra et al. (1981) found it 

rarely on the thistle in France and it was not recorded in the surveys on C. acanthoides 

by Zw6lfer (1965). In my opinion, it is unlikely to adapt to become an effective control 

agent of the thistle in North America. 

Effect of T. horrid/IS 

No assessment of the impact of T. horridus on C. nil tans was made at Aylesbury beyond 

the fact that few plants are attacked. There are no reports on the value of the more dense

126 P. Harris 

Laing. J.E.: Heels. P.R. (1978) Establishment of an introduced weevil. Rhinoc}'lIlls conicllS (Coleoptera: Curculionidae) for the biological 

control of nodding thistle. Cardull.f nlltans (Composit3e) in southern Ontario. Proceedings of the 

ElIlomological Societ}' of On",rio 1119. 3-8. 

Lashley. R. (1969) Musk thistle control. Proceedings of Ihe North Ctlltral Weed Control Conference 24. 99-100. 

Letendre. M.e.: Ritchot. 1'01.: Guibord. O·e.: Leduc. e. (1976) Essai d'cradication du chardon penche. CardullS nutans L.. oj I'aide du 

charanllon Rhinoc}'lIlls conicus Fmc!. Ph}'toprotection 57. 47-54. 

Moore. R.J.: Frankton. C. (1974) The thistles of Canada. Canadian Department of Agriculture Monograph 10. Ottawa. III pp. 

Mulligan. G.A.: Frankton. e. (195-1) The plumeless thistles (Cardlms spp.) in Canada. Canadian Field·Naluralist68. 31-36. 

Myers. J.H.: Harris. P. (1980) Distribution of Urophora galls in nower heads of diffuse and spotted knapweed in British Columbia. Jourtullof 

Applied Ecolog}' 17.359-367. 

Puttler. B.: Long. A.H.: Peters. E.J. (1978) Establishment in Missouri of Rhinocyllus conicllS for the biological control of musk thistle 

(Carduus nu",IIS). Wud Science 26. 188-190. 

Rees. N.E. (l9n) Impact of RhinoC)'lIus COIliCIlS on thistles in southwestern Montana. Em'ironmental Entomology 6. 839-842. 

Rees. N.E. (1978) Interactions of Rhinocyllus ccmicus and thistles in the Gallatin valley. 31·38. In: Frick. K.E. (Ed.) Biological control of 

thistles in the genus Card,ms ill the United States. Stoneville. Miss.: USDA. 50 pp. 

Sagar. G.R. (1972) On the ecology of weed control. In: Jones D.P.: Solomon M.E. (Eds.) Biology in pest and disease control. British 

Ecological Society. 42-50. 

Siebunh. P.J.: Kok. L.T. (1982) Oviposition preference of Tricllosirocalus Irorridus (Coleoptera: Curculionidae). Canadian Entomologist 

114. 1201-1202. 

Southwood. T.R.E. (1978) Ecological methods. Chapman & Hall. 52-1 pp. 

Surles. W. W.: Kok. L.T. (1977) Ovipositional preferences and s)'nchronization of Rlrinocyllus conicus with Carduus nutans and C. 

acantlroides. Em·ironmental ElIlomolog}, 6. 222-22-1. 

Trumble. J.T.: Kok. L.T. (1979) Celltorhynchidius horridus (Coleoptera: Curculionidae): life cycle and development on Carduus thistles in 

Virginia. Annals of tht Entomological Society of America n. 563-564. 

Trumble. J.T.: Kok. L.T. (1980) A bibliography of Ceuthorhynchidius horridus (Panzer) (= Trichosirocalus horridus (Panzer»). an 

introduced weevil for the biological control of Carduus thistles. Bulletin of the Entomological Sociery of 

America 62.464-467. 

Vere. D.T.; Medd. R.W. (1979) Estimating the economic loss caused by Carduus nutans in New South Wales. Proceedings of the 7th Asian· 

Pacific Weed Science Conference. 421-423. 

Ward. R. H.; Pienkowski R.L.: Kok. L. T. (1974) Host specificit)· of the first·instar of Cellthorhynchidius horridus. a weevilforthe biological 

control of thistles. Journal of Economic Entomology 67, 735 -737. 

Zw6ICer, H. (1965) Preliminary list of phytophagous insects attacking wild Cynareae (Compositae) species in Europe. Commonwealth 

Instilllte of Biological Control Technical Bulletin 6. 81-154. 

Zw6lfer, H.; Harris, P. (in press) Biology and host specificity of Rhinocyllus conicllS, (Froel.) (Col.: Curculionidae), a successful biocontrol 

agent of the thistle Carduus nutans L. Zeirschrift fiir angewandte Entomologie. 

Zw61fer, H.; Preiss. M. (1983) Host selection and oviposition bchaviour in west· European ecotypes of Rhinocyllus conicus FroeJ. (Col.: 

Curculionidllc). Zeitsclrrift fiir angewandte Entomologie 95, 113·122.

Pest Status 

Chapter 31 

Centaurea diffusa Lam. and C. maculosa 

Lam. s. lat., Diffuse and Spotted 


P. HARRIS and I.H. MYERS 

Diffuse and spotted knapweed are herbaceous plants introduced from Europe to the dry 

grasslands of western Canada and other parts of North America. The combination of 

their allelopathic properties (Fletcher & Renney 1963), low forage value. and drought 

adaptation have allowed these two knapweeds to displace most other herbaceous plants 

over large areas. 

Diffuse knapwced is typically a biennial. The species was recorded in Washington State 

in 1907 (Howell 1959) and early Canadian herbarium specimens suggest a northward 

spread into British Columbia: Oyama 1936, Penticton 1939, Grandforks 1940 (Groh 

1943); however, it may also have been introduced directly into the province with Turkestan 

alfalfa from the Caspian Sea region. Renney (1959) suggested that the weed occurred at 

Pritchard and Lytton, British Columbia, prior to 1930 and certainly other weeds from 

southern USSR were recorded at Kamloops (near Pritchard) as early as 1920 (Groh 

1940). From these beginnings the weed spread by 1972 to infest 25 952 ha of dryland range 

and roadside in British Columbia as well as small areas in Alberta (Watson & Renney 

1974). Distribution of diffuse knapweed in 1977 is shown in Fig. 4. In 1981 about 25 ha of 

diffuse knapweed, 8 heavily infested. were found on one farm near Morden, Manitoba 

(B. Todd, 1982, personal communication). Harris & Cranston (1979) predicted that the 

relatively high availability of summer moisture in Manitoba would put it beyond the range 

of the weed. It is now not clear whether the potential of the weed was seriously 

underestimated or the infestation merely represented a local site anomaly as it was on a 

light soil with a southern exposure and dry. In 1982 several kilometers ofrailway track 

were found to be infested at Walsh, Saskatchewan. This is only a slight extension of the 

range from the stand at Irvine, Alberta (Fig. 4); but a small stand was also found on the 

railway track at Colonsay, Saskatchewan, which is southeast of Saskatoon (S. McKell, 

personal communication). Distance spread ofthe weed across the prairies often seems to 

be associated with railway ties or treated bridge timbers from British Columbia. 

It appears that diffuse knapweed will continue to spread until it dominates the herbaceous 

community in open uncultivated sites in the brown chernozem and brunisol soils of 

southern British Columbia and the brown soils of Alberta and Saskatchewan. This 

involves about 7.5 million ha (Harris & Cranston 1979). 

Spotted knapweed is a short lived perennial. The first Canadian specimen was collected 

by McCoun from Victoria, British Columbia, in 1893 (Groh 1943). By 1972, it was 

estimated to have infested 2410 ha in British Columbia as well as several small stands in 

Alberta (Watson & Renney 1974); but these amounts are small compared to the estimated 

800000 ha in Montana, United States (Maddox 1979). The western Canadian distribution 

of the weed in 1977 is shown in Fig. 5. 

It is predicted that spotted knapweed will spread to dominate the herbaceous community 

in open uncultivated or lightly forested sites at the dry end of the Douglas fir zone 

in British Columbia and in the dark brown soils of Alberta and Saskatchewan. About 3.2 

million ha are vulnerable to invasion (Harris & Cranston 1979). 

Assuming that the two knapweeds spread to their predicted limits of approximately 10 

million ha. the loss in terms of dry native pasture species would be 2.5 million tonnes/year 

127

130 P.I-htrrisandJ. H. Myers 


Urophora aflinis 

Frfld. (Diptera: 

TephrUldae) 

Urophora quadr1fBSCiata 

Mg. 

(Dlptera: 

Tephritidae) 

Cumm. The urediospores of P. jaeeae and P. eentaureae are similar in electron photomicrographs 

(Traquair el al. 1981), but are different from those of P. earlham; (Traquair 

1982 personal communication). 

It has recently been realized that because of different taxonomic treatments of spotted 

knapweed in Europe and North America, the problem species of British Columbia has 

been largely missed in the surveys done in Europe for possible biological control agents. 

Dostal (1976) recognizes 14 European species in the section Maculosae, whereas Moore 

& Frankton (1974) classified all the knapweeds in the section that have been introduced 

to North America as C. maeulosa. According to Dostal, C. maeulosa is diploid 

(2n= 18), whereas the problem knapweed of British Columbia is tetraploid (2n=36) and 

seems to be referable to C. biebersleinii D.C. C. biebersleinii is endemic to central and 

southeast Europe, but most of the survey was done on the more western species of C. 

valles;aea (D.C.) Jordan, C. maculosa Lam. s. SIr., and C. rhenana Bor. 

U. a/finis oviposits into immature flower heads of diffuse and spotted knapweed. The 

preferred head in diffuse knapweed is 5.5 to 7.5 mm long (Berube 1980). The larva 

stimulates gall formation from the receptacle tissues and feeds on enlarged and modified 

parenchyma cells within the gall. The number of galls that can develop in a 

head is proportional to the receptacle area, so the heads of spotted knapweed tend to 

have more galls than those of diffuse knapweed (Harris 1980a). The mature larva 

overwinters in the gall in the seed-head and its emergence in the spring is synchronized 

with the appearance of the first flower buds which are usually all attacked. In British 

Columbia, the partial second generation of U. affinis is too small to fully utilize the 

diffuse knapweed flower heads produced later in the summer (Roze 1981). However, 

spotted knapweed heads tend to be produced concurrently in early summer so that a 

smaller proportion escape attack. 

The releases of U. affinis are listed in Table 32. U. affinis established readily on both 

spotted and diffuse knapweed in British Columbia (Harris 1980a). It increased to a 

density of up to 3000 gallslml and spread widely throughout British Columbia to substantially 

reduce knapweed seed production. In Hastings County, Ontario, some galls 

were found in the year following release but heavy grazing destroyed most of the 

knapweed heads and the site has not been surveyed since. In Alberta, there was a 

change in policy which resulted in the treatment of all knapweed infestations with 

picloram. Flies became established on at least one site but we assume no colonies 

currently survive. The Quebec colonies released in 1980 were still present in 1981 and 

appear to be established (Watson 1981 personal communication). 

U. quadri/asciala is bivoltine and like U. affinis forms galls in the flower heads of a 

number of knapweed species. It emerges at the same time as U. affmis in the spring but 

oviposits into slightly more mature heads (7.5-9.5 mm in diffuse knapweed (Berube 

1980». The gall is fonned from the ovary wall tissues; several galls are nonnally found in 

a head and can develop in the same head as U. affinis. Both U. affmis and U. 

quadri/asciala increased rapidly after release, but at the original release sites U. quadrifasciala 

has since declined to low numbers, while U. affinis has stabilized at moderate 

levels of attack (Fig. 6). U. quadri/aseiata has spread more widely and rapidly than U. 

affinis and is now found on even small remote stands of knapweed in British Columbia. 

Berube (1980) suggested that U. quadrifaseiata has been less successful because heads

132 P. Harris and J. H. Myers 

Metzneria 

paucipuncteJJa 

Zell. (Lepidoptera: 

Gelechiidae) 

Table 29 

The life cycle of the moth on C. vaJlesiaca in the Swiss Rhone Valley (the source of the 

stock released in British Columbia) is reported by Englert (1971, 1972). The moth is 

univoltine and emerges at the end of May. It lays 60-100 eggs with a maximum ofthree eggs 

on an individual flower head base or adjacent stem. A single larva survives to develop in a 

head where it feeds principally on the achene while the seed coat is still soft. The mature 

larva overwinters in the seed head which in spotted knapweed remains standing all winter 

having shed its seed in the fall. Up to nine seeds are eaten by a larva and in 83 attacked 

heads of C. vaJlesiaca, 95% of the viable seed was destroyed. Usually one-third to one-half 

of the heads were attacked even though the plants were widely scattered. Approximately 

20% of the eggs and 30-40% of the larvae were parasitized in Europe. Field records of the 

moth are restricted to knapweeds in the section MacuIosae, although in the laboratory it 

developed on C. diffusa. 

Adult M. paucipunctella were released (Table 32) in 1973 and 1974 at Castelgar airport 

and Westwold, British Columbia. M. paucipunctella has not been recovered from 

Castelgar; the number released was slightly less than at Westwold (73 in 1973 and 76 in 

1974) and in 1974, the flowering plants were mown shortly afterthe release was made. At 

Westwold, the initial establishment was tenuous with only four larvae found at the 

release point in August 1973. By the following year, larvae were found up to 20 m away 

(Table 29) and in 1976, they had spread a radius of at least 50 m. By 1979, the population 

was evenly distributed within a 50 m radius and by 1981, M. paucipunctella had spread at 

least 0.5 km. 

Establishment of M. paucipunctella Zell. on spotted knapweed, C. maculosa Lam., at 

Westwold, British Columbia. 

Year 

(fall) 

1973 

1974 

1976 

1977 

1978 

1979 

1980 

Radius Sampled 

(m) 

25 

20 

50 

30 

25 

50 

15 

No. Heads 

Examined 

4351 

2999 

485 

1443 

1719 

531 

443 

% heads with a M. 

paucipunctella larva 

0.1 

0.7 

2.0 

3.7 

27.5 

20.3 

37.7 

The population growth of M. paucipunctella has reflected the winter mortality of 

larvae in the previous year. For example 68% of the larvae survived the winter of 

1977-78 compared with only 28% in 1978-79. The reason for the mortality is not clear. 

The larvae can survive colder temperatures than they experience at Westwold; survival in 

the mild humid winter of Vancouver in 1977-78 was 82%, and it was 78% in the dry cold 

winter of Walachin, British Columbia. Possibly larvae are affected by a combination of 

moisture and cold and the rate of onset of cold weather. Larvae absorb and lose moisture 

readily: 14 overwintering larvae dissected from knapweed heads and put on moist filter 

paper at 1000C in 3 days increased their weight by 50% (from 3.17±0.56 g to 4. 79± 1.13 g). 

After 16 days in a desiccator, they had returned to their original weight of 3.11±0.66 g. 

Less than 1% of the larvae are parasitized by an Elachertus sp. (Chalcidae) and some 

larvae are eaten by mice which feed on the seed heads particularly in the late summer. 

The percentage of seed destroyed by M. paucipunctella in Canada is much lower than 

the 95% reported by Englert (1971). However, C. biebersteinii heads at Westwold

Sphenoptera 

jugoslav/ca Obenb. 

(Coleoptera: 

Buprestidae) 

Table 30 


Centallrea diffllsa Lam. and C. maclllosa Lam. s. lat., 133 

contain an average 17 seeds compared with the 9-10 seeds for C. vallesiaca in the Swiss 

Rhone Valley. Only one M. paucipunctella larva develops in a head and destroys 

approximately four seeds or about one quarter of the production in a head at Westwold. 

However, at Westwold, M. paucipunctella does coexist in the same heads with U. 

quadrifasciata and there was no significant difference in the number of galls in heads 

with and without M. paucipunctella. Certainly U. quadrifasciata is adding to the seed 

destruction by M. paucipunctel/a but the moth larvae destroy U. affinis galls in the head. 

The biology and host specificity of S. jugoslavica were studied by Zw61fer (1976). The 

beetle is indigenous to the Balkans where it is found only on C. diffusa and C. jurineafolia. 

The adults feed on the knapweed foliage and do relatively minor damage. The female 

oviposits between the bases of tightly appressed rosette leaves, and if rosette growth 

occurs during the egg stage, the larva is unable to penetrate into the root crown. Thus the 

beetle is restricted to regions with a reliable summer drought during this stage. From the 

root crown a single larva bores into the root leaving a cylinder of cortex undamaged. The 

rosette continues to live, but in Europe often does not flower in the following year and so 

is subject to a second attack by S. jugoslavica. Up to 70% of the larvae in Europe are lost 

to parasitoids, predators, and competitors, but they were able to coexist with insects 

that feed on the outside of the knapweed roots. The beetle is univoltine and produces 

33-65 eggs/female. 

S. jugoslavica was released at Grandforks (51 adults) and White Lake, British 

Columbia (188 adults) in 1976 (Table 32). No survivors were found at Grandforks, but 

the colony at White Lake increased to infest 25-50"10 of the rosettes within a 250 m 

radius in 1981, and over half the flowering plants had been attacked (Table 30). 

Proportion of diffuse knapweed plants, C. diffusa L., attacked by Sphenoplera at the 

White Lake Observatory release site. 

Year Distance From Release Site Total· 

II 3m 6m 10 m 13 m 26 m 39 m 52 m 65 m 

Stem 

PlantslO.25 ml X ±S.D. n 

1977 .13 (40)·· 

1978 .38 (52) .29 (17) .07 (41) 

1979 .39 (18) .SO (5) .29 (7) .05 (20) 

1980 .40 ( 5) .SO (34) .46 (13) 

1981 .59 (94)in 23 quadrates 0-250 m 

• Ungrazed area only 

•• Number of flowering plants 

10.11 

3.1 

.SO (IS) .52 (23) .57 (21) .29 (14) .33 (9) 6.5 

4.3 

Predictions of the eventual effects of the knapweed gall flies, U. affinis and U. quadri· 

fasciata, are conflicting. The immediate effects of the flies on the study sites at Kamloops 

have been a decline in seed production from around 25 000 to 1 SOO/m l and a reduction in 

the biomass of the weed, but the number of plants per unit area has remained the same. 

Obviously any effects of seed destruction would be masked for several years by the seed 

bank in the soil which, under dense stands of knapweed, is massive. Survivorship 

studies by Roze (1981) indicate that 1 500 seedslm l should be enough to maintain the 

7.6 

3.5 

4.2 

1.8 

11 

IS 

8 

23


Table 31 

density of the weed, so no decline should be expected. On the other hand, Berube & 

Myers (1982) suggested that the knapweed would be controlled on sites where there 

was a high seedling loss either from drought or in moist sites from strong competition 

from other vegetation. In a later study, Myers & Berube (in press) found that the 

number of knapweed plants surviving to the flowering stage was directly proportional to 

the number of seedlings over a wide range of knapweed densities. If the results of this 

study are generally applicable, the flies should eventually achieve a large decline in 

knapweed density. The difference in the two predictions may be related to the study 

methods. ROle (1981) achieved a low knapweed density by removing seedlings from 

plots of almost pure knapweed. This had the effect of temporarily reducing the competition 

for the remaining knapweed. In the Myers & Berube (in press) study, the 

knapweed was always in competition: with itself at high densities and with grass at low 

densities. 

The effect of the beetle S. jugoslavica on diffuse knapweed was not studied in detail as 

until recently the colony was too small for destructive sampling. That the beetle tends to 

reduce seed production is evident from Table 31. Its effect may be much greater if it 

Effect of S. jugoslavica Obenb. on diffuse knapweed, C. diffusa L., seed production 

per flowering plant at White Lake, British Columbia 

Attacked Unattacked 

Year X ±SD n X ±SD n 

1977 18.6 13.4 5 20.4 14.8 28 

1978 69.1 45.9 26 73.5 55.7 82 

1979 38.9 33.9 10 66.5 80.4 16 

1980 31.6 24.4 25 54.3 52.5 27 P 0.05 U Test 

tends to prevent rosettes from bolting: approximately 20% of the rosettes in the fenced 

area had been attacked in the previous year, so they had passed at least two years 

without flowering. No previously attacked rosettes were found in the grazed area but the 

significance of this is not known, nor is the percentage of rosettes that normally take two 

years to flower. There was an indication that S. jugsolavica had a synergistic effect on 

seed reduction in plants stressed by drought or attacked by the seed-head gall flies. Both 

gall flies were present on the site, and in the autumn of 1981, there was an average of 

1.63 ± 1.43 (S.D.) galls in the five distal heads on 23 plants; but whether a combination of 

S. jugoslavica and the flies reduce seed production below the level needed for 

maintenance of the knapweed stand remains to be seen. 

The effect of M. paucipunctella on spotted knapweed was less than expected from 

European studies as a different species of knapweed appears to be involved in British 

Columbia. Also, the overwintering larvae at Westwold, British Columbia, have suffered 

a periodic large and unexplained winter mortality that has prevented the rapid increase 

and spread of the species. However, without releases in other knapweed stands, it 

should not be assumed that this mortality occurs throughout the spotted knapweed 

region of North America. The ability of M. paucipunctel/a or the seed fly U. 

quadrifasciata to survive in the colder parts of the Canadian prairies is doubtful. In 

the winter of 1981, spotted knapweed heads containing overwintering larvae of the three 

seed-head insects were tied to a stake at normal plant height at Regina. Only U. affinis 

larvae were alive in the spring. If large stands of the weed became established on the 

prairies, it might be possible to select cold hardy strains of the insects but in the meantime

Table 32 


Centaurea diffusa Lam. and C. maculosa Lam. s. lat., 135 

the safest course of action is to chemically treat stands of the weed as they appear and are 

still small. 

Auld et al. (1979) pointed out that the best control strategy against a weed on either a 

farm or regional basis depends on the rate at which it spreads. The faster the rate, the 

greater the necessity to treat the source area while for slowly spreading weeds, containment 

is the most economic course of action. The seed reduction achieved by the 

biological control agents already established in British Columbia should have decreased 

the rate of knapweed invasion from headlands onto tame pasture as well as the spread to 

new regions within western Canada. Unfortunately, the benefits from this reduced rate 

of spread will not be reflected in the chemical control programme until this is done on a 

strictly costlbenefit basis. To reduce knapweed with biological control agents to the 

point where the publicly funded chemical control programme becomes clearly unnecessary 

will require the establishment of more biological control agents on knapweed in 

Canada. 

Open releases and recoveries of insects against Centaurea diffusa L. and C. maculosa 

Lam. s. lat. 

Control Agent Province Released Year Origin Number Year of Recovery 

C. I1Ulcu/o5a 

Urophora affinis Ontario 1970 France 694 1971 

British Columbia 1970 France 297 1971 

Ontario 1971 France 97 


British Columbia 1972 British Columbia 1472 

British Columbia 1974 British Columbia 550 

Alberta 1976 British Columbia 200 Site treated with herbicide 

Quebec 1979 British Columbia 950 

Quebec 1980 British Columbia 345 

Urophora quadrifa5c",ra Quebec 1979 British Columbia 950 

Merzneria paucipuncrel/a British Columbia 1973 Switzerland 197 1974 

British Columbia 1974 Switzerland 177 1975 

British Columbia 1979 British Columbia 180 Overwintering test 

C. diffusa 

Urophora affinis British Columbia 1970 France 284 1971 


British Columbia 1972 USSR 797 1973 

Alberta 1977 British Columbia 681 Site treated with herbicide 

Quebec 1980 British Columbia 

Urophora quadrifa5ciara British Columbia 1972 USSR 50 1973 

Sphenoprera jugol/avica British Columbia 1976 Greece 239 1977 

(1) The effects of S. jugoslavica on diffuse knapweed in British Columbia should be 

determined. If the beetle adds to the seed reduction that is achieved by the seed-head 

gall flies. it should be established throughout the diffuse knapweed region. 

(2) The susceptibility of M. paucipunctella to winter mortality should be detennined for 

a number of places within the spotted knapweed region and the moth established in 

favorable sites. 

(3) Additional species of biological control agents should be established on both 

spotted and diffuse knapweed in Canada as soon as they can be screened and approved




for release. In particular. studies should be completed on the root-feeding moth Agapeta 

zoegana for spotted knapweed. and Pelochrisla medullana for diffuse and spotted 

knapweed. 

(4) The possibility of using or enhancing pathogens already on knapweed in North 

America. particularly SclerOlina sclerotiorum and Puccinia jaceae should be explored. 

Although S. scleroliorum is a major pest of vegetable crops. its presence on knapweed 

infested rangeland should not aggravate the problem on cultivated land. 

Aspects of the biological control of knapweed have been the subject of Ph.D. studies at 

the University of British Columbia (U .B.C.) by Liga Roze and Peter Morrison. of undergraduate 

or technical studies. from U.B.C. by Barbara Rawlek. Woody Bennet. Sandy 

Ockenden and from Regina by Julie Soroka. Their work and ideas have been used extensively 

in preparing this review. Thanks are also due to Peter Morrison and Julie Soroka 

for reviewing and suggesting changes in the manuscript. 

Auld. B.A.; Coote. B.G.; Menz. K.M. (1979) Dynamics of plant spread in relation to weed control. ProCt'edings of 'he 7,h Asian Pacific 

Weed Science Conference. 399-402. 

Berube. D. E. (1980) Interspecific competition between Urophora affinis and U. quadrifascia,a (Diptera: Tephritidae) for ovipositional sites 

on diffuse knapweed (Centaurfa difflLta Compositae). ZeiLtclirif' far angewand'e Entonwlogie 90. 

299-306. 

Berube. D.E.; Myers. J.H. (1982) Suppression of knapweed invasion by crested wheatgrass in the dry interior of British Columbia. Journal of 

Range Matlagemen' 35. 459-461. 

Cummins. G.B. (1977) Nomenclature changes and new species in the Uredinales. Myco,axotl 5. 398-408. 

Dostal. J. (1976) Cen'aurea L. p. 254-301. In: Flora europaea. vol 4. Cambridge University Press. 505 pp. 

Englen. W. (1971) Me'Ztleria paucipunc,ella Zell. (Ge1echiidae. Lepidoptera): a potential insect for the biological control of Cenlaurea 

s,oebe L. in Canada. Commotlweal,h Ins'i'u'e of Biological Cotllrol Progress Repor' 28. 12 pp. 

Englen. W.O. (1972) Revision der Gallung Me,zneria Zeller (Lepidoptera. Gc1echiidae) mit Beitriigen zur Biologic der Anen. Zeitscllrif' far 

angewand'e Entomologie 75.381-421. 

Fletcher. R.A.; Renne)" A.J. (1963) A growth inhibitor found in Centaurea spp. Canadian I(}urnal (}f Plant Science 43.475-481. 

Groh. H. (1940) Turkestan alfalfa as a medium of weed introduction. Science in Agricul,ure 21.36-43. 

Groh. H. (1943) Canadian weed survey. 2nd Annual Repon of the Canadian Department of AgriCUlture. 74 pp. 

Harris. P. (1979) Cost of biological control of weeds by insects in Canada. Weed ScienCt' 27. 242-250. 

Harris. P. (19800) Establishment of UropllOra affitlis Frnd. and U. quadrifascia,a (Meig.) in Canada for the biological control of diffuse and 

spOiled knapweed. Zeitschrif' fiir atlgewand'e En'(}m(}logie 89. 504-514. 

Harris. P. (1980b) Effects of Urophora affinis Frnd. and U. quadrifascia,a (Meig.) (Diptera: Tephritidae) on Om'al/rea diffusa Lam. and C. 

maclliosa Lam. (Compositae). Zei'schrif' far angewatld'e En'omologie 90. 190-210. 

Harris. P.; Cranston. R. (1979) An economic evaluation of control meusures for diffuse and spOiled knapweed in western Canada. Canadian 

10llmal of I'latl' Scitnce 59. 375-382. 

Howell, J.T. (1959) Distributional data on weedy thistles in western North America. Leafle, of Wes'ern Bo'any 9.17-29. 

Jeffrey. C. (1967) Notes on Compositae: 111. The Cynareae in cast tropical Africa. Kew Bulle,in 22, 107-140. 

Maddox, D.M. (1979) The knapweeds: their economics and biological control in the western States. U.S.A. Rangelatlds I. 139-143. 

Moore. R.J.; Frankton. C. (1974) The thistles of Canada. Calladiotl Drpar'menl of Agricul,ure Motlonograph 10. Ottawa. 111 pp. 

Myers. J. H.; Berube. D. E. (in press) Diffuse knapweed invasion into rangeland in the dry interior of British Columbia. Canadian Journal of 

Plan' Science. 

Myers. J.H.; Harris, P. (1980) Distribution of Uroplwra gulls in nower heads of liffuse and spotted knapweed in British Columbia. JOl/rnal of 

Applied Ecol(}gy 17.359-367. 

Renney. A.J. (1959) Centaurea spp. infestation in British Columbia. Proceedinll$ of a Joint Meeting of the North Central Weed Control 

Conference 16 and the Western Canada Weed Control Conference 10. 18-19. 

Roze. L. (1981) The biological control of Centaurea diffll.ta Lam. and C. maclIl(}.ra Lam. by Uropllora affitlis Frauenfeld and U. 

quadriflLrcia'a Meigel! (Diptera: Tephritidae). Ph.D. thesis. University of British Columbia. 

Savile. D.B.O. (1970a) Some Eurasian Puccinia species allacking Cardueae. Canadian 10llmal of BOIony 48. 1553-1566. 

Savile. D.B.O. (1970b) Autoecious Pllccinia species al1acking Cardueae in North America. Canadian loumal of Bo'any 48. 1567-1584.

Celltaltrea diffusa Lam. and C. macltlosa Lam. s. lat., 137 

Traquair, J.A.; Kokko, E.G.; Harris, P. (1981) Urcdiniosporc morphology of two rust fungi on Cellllllm:ll (knapweed). Almrllcls ollile 

Cll/ladiall 80latlical Assoeiatioll Amlllaf Meelitlg 1981. 

Watson, A.K.; Alkoury, I. (1981) Response of safflower cultivars to Pllceillia jaceae collected from diffuse knapweed in eastern Europe. 

Proceeditlgs olllle 5111 Itilemuliolllif SymptJSillt1l 1m Ille Biological Cotllml of Weeds, 301-305. 

Watson, A.K.; Copeman, R.J.; Relllley A.J. (1974) A first record of Scleroliml sclerotio",,,, and Microsplllleropsis cetllllllreac on CCtllllllrell 

diffllsa. Call1ldiatl Jmmlllfl11 Botatly 52. 2639-2640. 

Watson, A.K.; Renney, AJ. (1974) The biology of Canadian weeds, 6. Celllmlreu diffiLm ,lIId C. Itrllcillosa. Camldiutl JOllmal of PfulI/ 

SciC/lce 54,687-701. 

Watson, A. K.; Schroeder, D.; Alkoury, I. (1981) Collection (If Pllccitlill specics [rom diffusc knapweed in eastern Europe. Call1uli,m JOllmaf 

01 Plam Palhology 3.6-8. 

Zwolfer H. (1976) Investigations on SplJetloplera (Cllilo.rletlla) jllgosfal·ica Obenb. (Col. Bupreslidac), a possiblc bioconlrol agent of the 

weed CetililllTeU diffllsil Lalli. (Colllpositac) in Canada. ZcilSc/rrifr liir Iltlgewalldre EII/oltralogie SO, 

170-190.

Blank Page 

138

Pest Status 

Background 


Altics csrduorum 

Guer. (Coleoptera: 


Chapter 32 

Cirsium arvense (L.) Scop., Canada 

Thistle (Compositae) 

D.P. PESCHKEN 

New data have been published on the pest status of Canada thistle, Cirsium arvense (L.) 

Scop., since the previous ten year review (Peschken 1971). Thomas (1980) summarized 

the abundance of Canada thistle on cultivated land in Canada. This is a particularly 

serious weed in the three Prairie Provinces, especially in the black soil zone and in 

Manitoba. In this province it ranked fifth and sixth in abundance in 1978 and 1979 

respectively; ninth and twelfth in Saskatchewan from 1976 to 1979; and on the average 

thirteenth in Alberta from 1973 to 1979. Of their most troublesome weeds, farmers in 

Alberta, Saskatchewan, and Manitoba ranked Canada thistle second, fifth, and third 

respectively, i.e. considerably higher than the rank based on relative abundance (Thomas 

1980). Peschken et al. (1980) estimated the loss in yield of wheat in Saskatchewan based 

on the sampling estimate of the density of Canada thistle in wheat fields (Thomas 1976) 

and estimates of the reduction in yield of wheat at various density levels of Canada 

thistle. Assuming the 10 year average yield of 1607 kg per ha and a price of$14.7 per 100 

kg, Saskatchewan farmers lost 24 300 t of wheat or $3 600 000 in the reduction of yield of 

wheat alone due to Canada thistle in 1976. The costs of chemical and cultural control of 

Canada thistle are high. Thus the total cost of Canada thistle in terms of cost of control 

and losses to all crops is a multiple of the $3 600 000 estimated for wheat. 

Natural enemies of Canada thistle and the initial stages of the biological control work 

were discussed in the previous review (Peschken 1971). Work on the biological control 

of Canada thistle has also been done in the United States with Altica carduorum Ouer. 

(Coleoptera: Chrysomelidae), Urophora cardui (Diptera: Tephritidae), and Ceutorhynchus 

Iitura (Coleoptera: Curculionidae) (Andres 1980, Schaber et al. 1975, Story 

1980). The latter species is established in Idaho, South Dakota, and Montana (Julien, 

1982). Baker et al. (1972) reported on releases of A. carduorum against Canada thistle in 

England. Ward & Pienkowski (1978a, 1978b), working in the state of Virginia, United 

States, investigated the biology and mortality of Cassida rubiginosa Muell. (Coleoptera: 

Chrysomelidae) which has been accidentally introduced into eastern North America. 

One insect was screened but not released. The only confirmed host plant of Tingis 

ampliata H.-S., (Heteroptera: Tingidae) in its native habitat in Europe is C. arvense. 

However, in the laboratory it developed fertile eggs on several other plants. including 

the cultivated globe artichoke (Cynara scolymus L.) and safflower (Carthamus tinctorius 

L.). Therefore, T. ampliata was not recommended for release (Peschken 1977). 

(a) Ecology 

Baker et al. (1972) showed that the development ofthe immature stages of A. carduorultl 

is slightly faster at 100% relative humidity (r.h.) than at 97%. At an average temperature 

139

140 D. P. Peschken 

Ceutorhynchus 

lItura (F.) 

(Coleoptera: 

Curcullonidae) 

of 15°C, development was not completed. while at 22.5°C to 25°C. it was completed in 33- 

38 days. Thus high temperatures and humidities are needed for an optimal rate of 

development. This agrees with the coastal Mediterranean and Atlantic native distribution 

of the beetles (Peschken 1971). 

(b) Releases 

Releases up to and including 1968 were reported by Peschken (1971). The colony at 

Lacombe, Alberta survived until 1971. In addition, 170 were released in 1969 at Fon 

Vermilion, Albena (58°28' N), which is the most northern and coolest of all release sites 

of A. carduorum in Canada (Table 33). In 1970, 1018 beetles were released at Essex, 

Ontario (42° 22' N), which is the most southern and warmest of all release sites. Both 

releases were made early in the spring which prevented overdispersal in high 

temperatures (Peschken 1977). Predation of eggs and larvae was severe at Essex and less 

severe at Fort Vermilion. In the fall of the respective release years, 18 adults were found 

at Fon Vermilion and only one at Essex, although six times as many beetles had been 

released at the latter site. At Essex, the carabid beetle Lebia viridis Say, was implicated as 

a main predator of eggs and larvae. In feeding tests it consumed 0.7 eggs and larvae per 

hour (Peschken 1971). No A. carduorum were found in subsequent years. 

(a) Ecology 

The ecology of this stem-mining weevil was summarized by Peschken (1971). Since then 

Peschken & Beecher (1973) and Peschken & Wilkinson (1981) have published additional 

information. The weevil larvae feed on the parenchyma tissue of the stem and avoid the 

vascular bundles. In Canada, the females oviposit from early May until the beginning of 

June. The new adults copulate and feed heavily during sunny, late summer and early fall 

days ",ith temperatures over 18°C, but do not oviposit. At this time, males outnumber 

females 2: 1. 

In spring, females outnumber the males 1.6: 1. In the laboratory females laid an average 

of 122 eggs in temperatures varying from 17°C to 27°C during a 16.5 hour day and 7°C to 

17°C during a 7.5 hour night. An average of 80% of the eggs hatched. 

(b) Releases 

A total of 1188 weevils was released in five provinces at 11 release sites (Table 33). 

The insect became established at nine sites in varying climates in four provinces of 

Canada. It spread slowly, 2.9 km in 12 years in Ontario, 90 m and 75 m in six and four 

years respectively at two release sites in Saskatchewan. The length of mines varied on 

the different release sites from 5 to 23 cm. The short, 5 cm, mines were found at 

Lacombe, Albena where almost all of the thistles were smooth-leaved, resembling 

those of C. arvense var. integrifolium Wimm. & Grab. The weevil preferred dense 

patches of thistle. 

Mined shoots were from 1.09 to 1.96 times taller than unmined ones in the fall 

(Peschken & Wilkinson 1981). This is explained as follows: early emerged, unattacked 

thistle rosettes grow into taller shoots by fall than later emerged ones (Peschken & 

Wilkinson 1981). The weevil oviposits into the early emerged rosettes and it is

Urophora cardui 

(L.) (Diptera: 

Tephritidae) 

Cirsium arvense (L.) Scop.. 141 

assumed that larval mining does not prevent the early emerged rosettes from growing 

into taller shoots. This also means that damage to the thistles is light. 

The development of the weevils and thistles was monitored in detail at one release 

site in Ontario. The weevil was released on a dense patch of Canada thistle, and 

eventually it spread to other more or less contiguous thistle patches on the same 

permanent pasture covering about 1 ha. On the original release patch, the level of 

mined stems peaked at 72% in the fifth growing season with an average of 2.75 larvae 

per stem, and thistle density subsequently diminished to zero (Peschken & Beecher 

1973, Peschken & Wilkinson 1981). However, on another patch in the same pasture, 

thistle density did not diminish although 77-91 % of the stems were mined for four 

years, while on a third thistle density declined to zero per m 1 with only up to 2% of 

the stems being mined. Thus no consistent correlation between an increase in the 

weevil population and a decline of the thistles was observed. The rust Puccinia 

punctiformis (Str.) Roh!. and the thistle feeding beetles Cleonus piger Scop. (Coleoptera: 

Curculionidae) and Cassida rubiginosa Muell. (Coleoptera: Chrysomelidae) were also 

present on this release pasture, and dense thistles tend to decrease to scattered shoots 

behind an advancing front (Amor & Harris 1975). It is assumed that the decline of 

thistles on some of the patchcs was caused by one or a combination of these factors. 

Similarly, the fluctuating thistle densities at release sites in western Canada could not 

be associated with levels of weevil infestation. 

(a) Ecology 

This gall fly occurs from France in the west (ZwOlfer 1967) to near the Crimea 

(Oirlbeck & Oirlbeck 1964) and Siberia in (he east (Leclercq 1967), and from Sweden 

in the north (Zetterstedt 1847) to the Mediterranean in the south (Zwolfer 1967). 

Areas in half shade seem to be preferred over those in full sun (ZwOlfer 1967). 

The fly is monophagous on Canada thistle and oviposits into the vegetative buds of 

the main or side shoots. In Saskatchewan, the oviposition period extends from the end 

of May to the third week in July. The larvae overwinter and pupate in spring inside a 

multi-locular lignified gall. There is a strong correlation in the number of larvae and the 

size of field collected or laboratory produced galls (Pesch ken et al. 1982). 

(b) Releases 

A total of 4932 flies and 290 galls was released in 14 locations in the four western 

provinces of Canada and in 10 locations in Ontario, Quebec, and New Brunswick (Table 

33). In western Canada, galls were usually produced in the year of the release, and on 

two sites it survived for two and three years respectively. However, the fly died out in 

western Canada except for a very small colony at Camrose, Alberta. 

In contrast, U. cardu; is established at five locations in Ontario, Quebec, and New 

Brunswick. Near Sussex, New Brunswick, the fly had been released at two locations, 

4.5 km apart. The population of one release had spread over 1000 ha by 1980, but only 

6% of the shoots were galled in anyone thistle patch. By 1981, populations of the two 

release sites had merged and spread over 3000 ha. On some thistle patches up to seven 

galls were found on one thistle shoot and there was an average of three on the attacked 

shoots (O.B. Finnamore. 1981. personal communication). In 1979. 13% of a sample of 

larvae was diagnosed to contain Nosema sp. (Microsporidia) spores and the percentage 

was higher in dead than in live larvae. Three percent of the larvae were parasitized by 

Habrocyrus elevatus Walker (Hymenoptera: Pteromalidae). In 1980, only 3% of the

142 D. P. Pcschken 

Lema cyanella 

(L.) (Coleoptera: 


larvae contained Nosema spores and 1.3% were parasitized by an as yet unidentified 

hymenopterous parasite. In Saskatchewan and Alberta, the mortality was higher: 35% 

of a total of 402 larvae collected in the spring of 1975, 1976, and 1977 was dead. 

Comparing only those thistles that emerged during the oviposition period of the fly, 

shoots with galls on the main shoot were 57% shorter, and those with sideshoot galls 

were 10% shorter than ungalled shoots in Quebec when growing on an uncultivated site 

with competing vegetation. However, in Saskatchewan even an average of 13 galls per 

shoot did not reduce the height, dry weight, number of seed heads or the dry weight of 

new shoots produced by thistles growing in the absence of competition on heavy fertile 

soil with sufficient moisture (Peschken et al. 1982). 

(a) Ecology 

This leaf-feeder is widely distributed in Europe and A!>ia between latitudes 35°N and 

65°N and occurs about three-quarters of the range of C. arvense (Peschken & Johnson 

1979). It is rare in Germany, Austria, Czechoslovakia, and Poland and is more frequent 

in western Europe (Zwolfer & Pattullo 1970, Winiarska 1973). Collection records 

indicate that moist habitats are preferred (Winiarska 1973, ZwOlfer & Pattullo 1970, 

Lopatin 1960, Peschken unpublished). 

The adult beetles hibernate and in Europe they appear on the thistle rosettes at about 

the end of April. They oviposit in May and the new generation of adults can be observed 

from the end of June until August. There is one generation per year. 

(b) Host specificity 

The only confirmed breeding host in Europe is C. arvense (Zwolfer & Pattulo 1970, 

Peschken & Johnson 1979). In the screening tests for host specificity, it did not feed on 

any cultivated plants but on several Cirsium spp. native to North America (Peschken & 

Johnson 1979). One of these, Cirsium drummondiiT. & G., was even preferred in favour 

of Canada thistle in choice tests in the laboratory. In a field cage, however, the females 

laid most eggs on those thistles which were most prevalent in terms of biomass of leaves 

and stems (Peschken unpublished). 

(c) Releases 

The releases listed on Table 33 were made for the purpose of testing the host preference 

of L. cyanella in the more natural environment of a field cage, not for establishment in 

the field. In the course of these field cage studies, 4 out of 28 beetles survived the 1978n9 

winter. In subsequent years the beetles were collected in the fall and overwintered in the 

laboratory. However, another adult was collected in the field in the spring of 1981. Thus 

L. cyan ella can survive the winter in Saskatchewan. No larvae were found in 1981. The 

release of L. cyanella with the intent of establishment has not yet been approved out of 

concern for the Cirsium species of our native North American flora.

Table 33 Open releases and recoveries of insects against Cirsium arvense (L.) Scop. 

Cirsium arvense (L.) Scop.. 143 

Year of 

Species and Province Origin Year Number Recovery 

Altica carduorum (Guerin-Meneville) 

British Columbia Switzerland· 1969 5534 

Alberta Switzerland· 1969 170 1971 

Ontario Switzerland • 1970 1018 

France 1970 345 

TOTAL 7067 

Ceutorhynchus litura (F.) 

British Columbia Germany, Switzerland 1975 69 1976-80 

France, Italy 

Alberta Germany, Switzerland 1975 57 1976-80 

France, Italy 

Indian Head, Saskatchewan 1978 280 1979-80 

Saskatchewan Switzerland· 1973 70 1974-80 

Switzerland· 1974 30 1975-80 

Germany, Switzerland 1975 41 1976-80 

France, Italy 

Switzerland· 1976 56 

Switzerland • 1978 25 1979 

Indian Head, Saskatchewan 1979 228 1980 

Ontario Switzerland·· 1966 56 

New Brunswick Indian Head, Saskatchewan 1978 276 1981 

TOTAL 1188 

Urophora cardui (L.) 

British Columbia Germany 1974 274 

Germany 1975 98 

France. Austria 1976 199 

plus lab. reared 

from French stock 

Alberta Germany 1975 100 1976 

Austria, France 1976 472 



Lab. reared from stock 1977 406 1978-81 

collected in Canada 

Saskatchewan Germany 1974 625 

Germany, plus lab. 1975 274 1976-80 

reared from German stock 

France, Austria 1976 915 1977-78 



Lab. reared from stock 1977 392 


Ontario Germany 1975 81 1976-80 



from French stock


Table 33 continued 



Species and Province Origin Year Number Recovery 

Quebec Germany 1975 96 




Lab. reared from stock 1977 99 


Field collected 1979 290 1981 

at Compton, Quebec galls 

New Brunswick France, Austria 1976 191 1977-82 



Lab. reared from stock 1977 207 1978-82 


TOTAL 4932 flies 

plus 290 

galls 

Lema cyanella (L.) 

Switzerland· 1978 28 1979 

1979 68 

1980 35 1981 

1982 31 1982 

TOTAL 162 

• These were laboratory reared beetles from stock collected in Switzerland . 

.. Not reported in Peschken 1971. 

The cool climate combined with predation prevented establishment of A. carduorum. 

The weevil, C. litura, is established in four provinces and probably can be colonized in 

all agricultural areas of Canada. However, damage to Canada thistle by larval mining is 

small. Furthermore, Canada thistle is a major weed in the grain belt of the three Prairie 

Provinces, where destruction of eggs and larvae by cultivation of thistles along field 

margins prevents the buildup of dense populations. U. cardu; is not established in 

western Canada (except for a small colony at Cam rose , Alberta), but it can probably be 

established anywhere in the agricultural areas of eastern Canada. The galls do cause 

noticeable stress to thistles growing in competition with other vegetation (Pesehken el 

al. 1982). Overdispersal prevented the buildup of dense populations and reduced 

effectiveness so far. It is not known why U. cardu; did not become established in western 

Canada. The 35% rate of mor.tality alone does not explain the failure of the release 

colonies, many of which bred well in the year of their release. Possibly severe spring 

frosts during the pupation period were a problem. Most release stock originated from the 

upper Rhine Valley which is considerably warmer and moister than the Prairie Provinces. 

Lalonde & Shortbouse (1982) suggest that inadequate moisture on the release sites in 

western Canada prevented the breakdown of the callus plug in the exit channel out of the


Ferdinandsen. C. (1923) Biologiske Undersogelser over Tidselrust (puccinia sual'eolens (Pers. Rostr.». Beretning om Nordi.rke jordbrllgsforskeres 

forenings Kongres 5-8, 475-487. 

Julien, M.H. (Ed.) (1982) Biological control of wceds: a world cataloguc of agents and their target weeds. Commonwealth Agricultural 

Bureaux. 108 pp. 

Lalonde. R.O.; Shorthousc, J.D. (1982) Exit strategy of Urophora cardui (Diptera: Tephritidae) from its gall on Canada thistle. Canadian 

Entomologist 114. 873-878. 

Leclercq. M. (1967) Contribution it I'etude des Trypetidae (Diptera) palearctiques et de leurs relations avec les vegetaux. Bulletin des 

Recherches Agronomiques de Gembloux (N.S.) 2, 64-105. 

Lopatin, I.K. (1960) Data on the fauna and ecology of leaf-beetles (Coleoptera: Chrysomelidae) on the southern rear bank of the Dnieper 

River. Entomologicheskoe Obozrenie 39(3).447-457. 

Peschken. D.P. (1971) Cinium arvense (L.) Scop .• Canada Thistle. In: Biological control programmes against insccts and weeds in Canada 

1959-1968. Commonwealth InstitUle of Biological Control Technical Communication 4. 79-83. 

Peschken, D.P. (1977) Host specificity of Tingis ampliata (Tingidae: Heteroptera): a candidate for the biological control of Canada thistle 

(Cirsium arvense). Canadian Entomologist 109.669-674. 

Peschken. D.P.; Beecher. R.W. (1973) Ceutorhynchus lilllra (Coleoptera: Curculionidae): biology and first releases for biological control 

of the weed Canada thistle (Cirsium arvense) in Ontario. Canada. Canadian Entomologist 105. 

1489-1494. 

Peschken, D.P.; Finnamore D.B.; Watson, A.K. (1982) Biocontrol of the weed Canada thistle (Cirsium arvense): releases and 

development of the gall fly Urophora cardui (Diptera: Tephritidae) in Canada. Canadian Entomologist 

114.349-357. 

Peschken. D.P.; Hunter. J.H.; Thomas. A.O. (1980) Damage in dollars caused by Canada thistle in wheat in Saskatchewan. Proceedings of 

the Canada Thistle Symposium, Regina, p. 37-43. 

Pesehken, D.P.; Johnson, O.R. (1979) Host specificity and suitability of Lema cyanella (Coleoptera: Chrysomelida). a candidate for the 

biological control of Canada thistle (Cirsium arvense). Canadian Entomologist III. 1059-1068. 

Peschken. D.P.; Wilkinson. A.T.S. (1981) Biocontrol of Canada thistle (Cinium arvense): releases and effectiveness of Ceutorhynchus 

litura (Coleoptera: Curculionidae) in Canada. Canadian Entomologist 113, 777-785. 

Schaber. B.C.; Balsbaugh. E.U .• Jr.; Kantack, B.H. (1975) Releases of Altica carduorum (Col.: Chrysomciidae) on Canada thistle (Cirsium 

arvense) in South Dakota. Entomophaga 20, 325-335. 

Story. J.M. (1980) Biological control of Canada thistle in Montana. Proceedings of the Canada Thistle Symposium. Regina. p. 128-129. 

Thomas. A.O. (1976) Weed survey of cultivated land in Saskatchewan. Weed survey series, Publication 76-1, 93 pp. 

Thomas. A.O. (198O) Relative abundance of Canada thistle on cultivated land in Canada. Proceedings of the Canada Thistle Symposium, 

Regina. p. 167-181. 

Ward, R.H.; Pienkowski, R.L. (1978o) Biology of Cassida rubiginosa, a thistle-feeding shield beetle. Annals of the Entomological Society 

of America 71(4). 585-591. 

Ward. R.H.; Pienkowski, R.L. (1978b) Mortality and parasitism of Cassida rubiginosa, a thistle-feeding shield beetle accidentally 

introduced into North America. Environmental Entomology 7(4),536-540. 

Wilson, R.O. (1981) Effect of Canada thistle residue on growth of some crops. Weed Science 29(2), 159-164. 

Winiarska, W. (1973) Observations on the biology of Lema cyanella L. Chrysomelidae, Criocerinae. Polskie Pismo Entomologiczne 43(2). 

373-382 (in Polish). 

*Zetterstedt, J.W. (1847) Diptera Scandinavia. V. VI. Lund. p. 2163-2580. 

Zwolfer, H. (1967) Observations on Urophora cardui L. (Trypctidae). Weed projects for Canada. Commonwealth Institute of Biological 

Control Progress Report 14. Delemont. 11 pp. 

Zwolfer, H. (1969) Experimental feeding ranges of species of Chrysomelidae (Col.) associated with Cynareae (Compositae) in Europe. 

Commonwealth Institute of Biological Conrrol Technical Bulletin 12. 115-130. 

Zwolfer, H.; Pattullo. W. (1970) Zur Lebensweise and Wirtsbindung des Distel-Blattkiifers Lema cyanella L. (puncticollis Curt.) (Col. 

Chrysomelidae). Anzeiger fur Schiidlingskunde. Pj1anzenschutz, UmweltschUlz. 43(4). 53-59 

* The article has not been seen by the author.

Pest Status 

Background 


Chapter 33 

Urophora sty/ala 

F. (Diptera: 

Tephritidae) (a) Ecology 

Cirsium vulgare (Savi) Ten., Bull Thistle 

(Compositae) 

P. HARRIS and A.T.S. WILKINSON 

Cirsium vulgare (Savi) Ten. is a biennial of Eurasian origin that propagates itself only by 

seed. It is found in all regions of southern Canada but is most abundant in Quebec, 

Ontario, and British Columbia (Moore & Frankton 1974) on recently disturbed uncultivated 

ground or overgrazed permanent pasture. In southern British Columbia, it occurs 

along roads, ditches, dykes and fences, and on pastures or range where the sward has 

been broken; it is often troublesome in forage crops in the second year after planting. 

The thistle does not withstand cultivation so it is not a pest in arable crops. It may have 

one to several flowering stems, usually 0.5 to 2 m high but sometimes 3 m. Plants can be 

up to one meter in diameter with as many as 343 seed heads. The sharp prickles on the 

leaves discourage livestock from grazing it. 

Bull thistle can be controlled with 2,4-D or MCPA at 1 kg/ha; mowing is also effective 

if it is done when the plant is reaching maturity; but if cut too early the plant regrows and 

sets seed before frost. In spite of the ease of control, bull thistle persists as a common 

weed although it is a minor problem compared with the other thistles targeted for biological 

control in this volume. 

Surveys of the European insect fauna on C. vulgare were made by Zw6lfer (1965) as part 

of a broad study of thistle insects that might be used for biological control in Canada. In 

North America, the flower buds of C. vulgare are attacked by the artichoke plume moth, 

Platyptilia carduidactyla (Riley) (Pterophoridae), and the vegetative parts by Entylia 

carinata (Forst.) (Membracidae) as well as by a number of more polyphagous insects. 

There was an absence of specialized insects such as Urophora stylata F. (Tephritidae) in 

the seed heads. As a result of studies by Zw6lfer (1965), Persson (1963), and Redfern 

(1968), it was apparent that U. stylata was a promising biological control agent. Thus its 

screening and introduction to Canada was partly opportunistic. The lack of screening 

and release of other agents for the control of C. vulgare reflects the relatively minor pest 

status of the thistle. 

The biology of U. stylata is reported by Redfern (1968) and ZwOlfer (1972). The mature 

larvae overwinter in the seed heads of C. vulgare and pupate in the spring. The univoltine 

adults emerge in early summer (June) and the males establish territories on bolting thistle 

plants. Shortly before the thistles start to bloom the female visits the plants, mates, 

oviposits into the flower buds at a precise stage of maturity, and then leaves for another 

147

148 P. Harris. and A. T. S. Wilkinson 

Table 34 

thistle. The eggs are laid in small groups through the bracts at the top of the bud. A 

second-instar larva hatches in 5-8 days and bores down a corolla tube into the ovariole. 

The ovariole and the adjacent receptacle become enlarged and the larva feeds inside this 

gall. Lignified tissues which develop on the outside of the gall gradually coalesce with 

those of adjacent galls so that the larvae are eventually enclosed in a hard multilocular 

gall. 

Zwolfer (1972) and Redfern (1968) reported that approximately one quarter of the C. 

vulgare heads collected in their studies in western and central Europe were attacked by U. 

stylala. This is much lower than the population reached at the best site in British 

Columbia. On the European continent, 37% of the larvae were parasitized (Zw6lfer 

1972) and 24% in Britain (Redfern 1968). No larval or pupal parasitoids were encountered in 

Canada. In certain regions of Europe, strains of U. stylala are specialized on certain other 

thistles, but no attack of other thistles by the strain released has been found in Canada. 

(b) Releases 

The releases of U. stylala are summarized in Table 34. The fly established itself readily 

at sites with a dense stand of C. vulgare. It has subsequently declined or disappeared 

where the thistle became sparse following the reestablishment of grasses and other 

herbaceous perennials as has happened at Danville and lie Jesus, Quebec, and Cranbrook, 

British Columbia. At aka, Quebec, the thistle was mowed one year after release 

and the colony disappeared. The release sites at Nanaimo and at Cloverdale, British 

Columbia, were also destroyed but the fly can be found in the surrounding area. The 

current status of the other release sites is unknown. The results of establishment suggest 

that fly dispersal is slow and they require a relatively stable and dense stand of C. 

vulgare for survival. 

Open releases and recoveries 

(Savi) Ten. in Canada. 

of Urophora stylala F. on Cirsium vulgare 

Year Location Origin No. released Year of recovery 

1973 Nanaimo, Germany - 174 adults 1974 (site cleared 

British Columbia Switzerland and mowed in 1975) 

1973 Westham Isle. Germany - 462 adults 1974 

British Columbia Switzerland 

1973 Cloverdale, Germany - 132 adults 1974 

British Columbia Switzerland 

1973 Cranbrook, Germany - 459 adults 1974-1976 (no 

British Columbia Switzerland thistles or U. 

stylala in 1981) 

1976 aka, Quebec France - 132 adults Site mowed - no 

Austria establishment 

1977 Danville, Quebec British Columbia 157 adults 1978 

1977 lIe Jesus, Quebec British Columbia 248 adults 1978 

1978 New Denver, British Columbia 957 pupae 1979 

British Columbia 

1978 Williams Lake, British Columbia 2000 pupae 1979 


(lots 6069, 7017, 69)

Table 35 

Cirs;llm I'ulg(lre (Savi) Ten. , 149 

The establishment and build-up of U. stylata populations were followed in more detail 

at Cranbrook, Nanaimo. and particularly Cloverdale and Ladner. British Columbia 

(Table 35). The Cranbrook site was along a power right-of-way through forest; Cloverdale 

was a permanent pasture on black muck soil in the Fraser delta on which the thistle 

grew where the cattle hooves broke the sward. The site was destroyed for development 

in 1980, but the fly survives in the area. At Ladner, also in the Fraser delta. the thistle 

was confined to the edge of a drainage ditch through an intensely cultivated area used 

largely to grow seed sugar beet and carrots. The populations were followed by sampling, 

at the end of the summer, all the seed heads on thistle plants growing at approximately 5 

m intervals in 4 directions from the release point. The exception was the linear stand at 

Ladner. Samples were taken to the edge of the colony or the site. whichever was least. 

Size and spread of U. stylata F. colonies at release sites in British Columbia. 

Heads/plant No. heads % heads No. larvaeJgall Colony Distance (m) to near- 

Location Year ± S.E.M. sampled galled ± S.E.M. radius m est thistle ± SD 

Cranbook 1973 21.2 ± 6.0 525 6.7 20 II.R ± 11.1 

197-1 12.1 ± 1.8 320 2.8 2.1 ± 0.4 100 2.9 ± 2.9 

1976 6.2 ± 1.11 19-1 3.6 2.0 ± 0.4 80 thistle scarce 

19111 No thistles prescnt and no U. srylata found on nearby roadside C. vulgart' 

Nanaimo 1973 9.4 ± 2.1 113 3.5 30 0.7 ± 0.8 

1974 8.7 ± 1.5 180 42.8 3.0 ± 0.3 100 0.2 ±0.3 

1975 Area bulldoled, sown to grass and surrounding thistle cut 

Cloverdale 1973 53 30.2 3.0 ± 1.1 

1974 29.3 ± 3.5 299 41.5 3.2 ± 0.2 

1975 32.2 ± 5.0 10M 15.9 140 2.4 ± 3.4 

(299 plantslha) 

1976 39.7 ± 9.7 1110 65.3 140 + 36.1 ±5.2 

1977 39.8 ± 5.9 1\53 84.7 9.1 ± 0.3 200 + 3.5 ± 4.1 

1978 38.4 ± 5.7 1283 95.8 13.7 ± 0.6 250+ 2.4 ± 0.4 

1979 34.7 ± 7.2 520 92.7 

1980 Site destroyed 

(site 2) 1978 511.0 ± 19.4 5811 92.2 

1979 60.1 ± 14.5 402 83.6 

Ladner 1973 22.5 ± 4.7 -149 12.2 3.1 ± 0.3 100 0.3 ± 0.3 

1974 Not sampled - all but 2 thistles mowed 

1975 54.1 ± 9.2 1165 24.4 125 1.0 ± 1.1 

1976 38.6 ± 6.9 1313 5.7 3!!6+ 2.8 ± 6.3 

1977 80.6 ± 15.7 2338 6.0 160 + 1.7 ± 1.7 

19711 59.7 ± 10.6 1851 31.7 ISO + 11.9 ± 1.3 

1979 61.2 ± 10.9 2348 46.3 14.2 ± 5.2 

1980 41.8 ± 5.9 1918 39.9 

1981 55.3 ± 11.8 775 26.3 

1982 39.6 ± 9.0 912 38.8 

The results (Table 35) show that at Cloverdale the fly population increased to attack 

over 90% of the heads formed. The number of larvae per head increased with the percentage 

of heads attacked (Equation 8. Table 36). This is also apparent from Table 35: at 

low densities of the fly. a density of 2-3 larvae per gall was found. but at high fly 

densities the average increased to around 14 larvae per gall with maximum numbers of 

over 30 larvae. Presumably the high larval numbers are the result of multiple ovipositon. 

The data for Ladner were excluded from this analysis where it is suspected that the 

inability of the fly to attack more than half the heads resulted from their loss over the 

surrounding fields which were treated with insecticide during the season. Thus although

150 P. Harris and A. T. S. Wilkinson 

Table 36 


ElTects of U. stylata 

on the number of 

seed heads on 

C. vulgare plants 

the high number of larvae/gall in 1979 indicated a high density of flies in early summer. 

the percentage of heads attacked suggests that those forming late in the season escaped 

the fly. 

The average distance of the sampled thistle to its neighbour (Table 35) gives an idea of 

density although. except in one instance. this cannot be related to the number of thistles 

per unit area as the distribution contagion was not measured. No effect of the fly on the 

distance between thistles was apparent; however as C. vulgare seed was found to be still 

viable after approximately 36 years under forest cover (Harrington 1972). it will take a 

number of years of reduced input into the soil seed-bank before the density of the thistle 

is affected. 

Evaluation of the effect of U. stylata F. on C. vulgare (Savi) Ten. 

Regression 

1. No. heads on unattacked plants 0.40 x + 2.0 

2. No. heads on attacked plants 0.32 x + 6.2 

3. No. plump seedlhead from unattacked plants 3.66 r - 18.7 

4. No. plump seedlhead from attacked plants -0.12 r + 67.7 

5. Mean no. larvaelhead in head size classes 0.16 r - 1.2 

6. Maximum number of larvaelhead in head 

size cI asses 0.24 r + 2.8 

7. Live larval weight in mg -0.08 n + 9.5 

8. No. larvaclgall 0.11 z + 0.3 

9. No. larvaelhead -0.006 x + 9.6 

10. Total seed production from unattacked plants 55.51 x + 235.2 

11. Total seed production from attacked plants 17.69 x + 571.4 

Where x = dry weight of plant in g 

r = radius of receptacle attachment to the involucre in nun 

z = the percentage of heads attacked 

n = no. larvae/head 

Cor.Coef. n P 

0.97 25

The number of seeds 

per head vs. head 

size and the number 

of U. sty/ala 

larvae present (a) Methods 

Cirsium vulgare (Savi) Ten.. 151 

recorded for each plant, as well as the number of heads attacked, and the number of U. 

stylolo larvae per gall. Attack by U. stylala enlarges the receptacle but does not affect 

the base where it is attached to the involucre, so its diameter was used to compare the 

size of the productive heads on the attacked and un attacked plants. 

(b) Results 

An average of 88% of the productive heads was galled on the attacked plants. This 

percentage is higher than that obtained from the transect samples (Table 35), but as a 

range of thistle sizes was selected from near the center of the colony, it was not a random 

sample. The 564 galled heads contained an average of 10.3 ± 0.3 SEM larvae. This is also 

slightly higher than the mean in Table 35. 

Plant weight accounted for most of the variation in the number of seed heads on both 

the attacked and unattacked plants (Equations 1 and 2. Table 36). The level of attack on 

individual plants ranged from an average of 1. 7 larvae/head to 18.1 larvae/head, but the 

attack level was not affected by plant size (Equation 9, Table 36). The slopes of the 

regression lines (Equations 1 and 2) suggest that attack reduced the number of heads: 

plants of 100 g had 9.5% fewer and those of 200 g had 14.6% fewer than the unattacked 

plants. However, the slopes were not significantly different and the differences in the 

averages were partly balanced by a slightly larger head size on the attacked plants 

(average diameter 13.7 ± 0.07 mm compared with 12.8 ± 0.06 for the unattacked plants). 

It is concluded that the receptacle area in the two groups of plants was practically identical. 

This was in contrast to the results of the seed-head Urophora spp. on diffuse knapweed 

(Harris 1980) where the number of heads and plant size were reduced by attack. 

Heads from both attacked and unattacked plants were bagged shortly before the pappus 

was ready to fly. Seed head size was measured as the radius of the receptacle attachment 

to the involucre as previously described, and the plump seed. separated with a blower, 

was counted for each head. Plump seed rather than germinated seed was used for 

regression analysis: both produced similar trends but the correlations were higher with 

the former. Part of the problem was a high variability of germination between heads. 

Anderson (1968) reported 40% germination at 20°C although this was increased to 80% 

with temperatures alternating between 20-30°C. We obtained 66.2 ± 2.0% germination 

of plump seed from unattacked plants at room temperature and 52.4 ± 4.8% from 

attacked plants. 

(b) Results 

On unattacked plants, large heads produced more plump seed than did small ones 

(Equation 3, Table 36) as is normal in composites. In contrast on the attacked plants, 

seed production decreased with head size (Equation 4, Table 36) although the slope and 

the correlation coefficient were so low that the production of 62 seeds for an average 

head of 13.7 mm diameter can be used as a constant for all heads. This means that for the 

plant it is now more productive to develop several small heads rather than a few large 

ones.

152 P. Harris and A. T. S. Wilkinson 

Calculation of seed 

production by 

attacked and 

unattacked plants 



The effect of head size on seed production in the attacked plants is nullified because 

the number of U. sty/ala also increases with head size (Equation 5, Table 36). The mean 

number of larvae per head was considerably lower than the maximum number in the 

heads of each size (Equation 6, Table 36). Thus for a head with a diameter of 14 mm the 

average number from the regression was 6.6 larvae while the maximum was 14.6 larvae. 

Thus the larval population is well below the physical limits of the thistle heads. There 

was a rather small effect of crowding on larval weight. A regression of live weight of 980 

larvae from heads with 1-33 larvae in a gall showed that one larva per gall averaged 9.4 

mg compared with 6.7 mg for those in heads with 33 larvae. The slope of the regression is 

highly significant, although as indicated by the small correlation coefficient there was a 

large variation in larval weights at all densities (Equation 7, Table 36). For the purpose of 

the calculations in this paper the size and hence the effect of a larva was assumed to be 

the same whether it was single or crowded. 

(a) Methods 

Seed production for each head on the unattacked plants was determined from regression 

Equation 3 (Table 36). These were summed and the total for each plant regressed on 

plant weight so that average production could be determined for a plant of any size. The 

same was done for the attacked plants except that the heads were assumed to produce 62 

seeds regardless of size. 

(b) Results 

The production of 4398 seeds for a plant of 75 g (Equation 10, Table 36), is close to the 

figure of 4000 seeds/plant given by Salisbury (1964) for the thistle in Britain. The attacked 

plant of this size produced 1898 seeds (Equation 11, Table 36), a reduction of 

57%. For a plant of 150 g, the reduction was 62%. 

The calculations were made for a U. Sly/ala population infesting 88% of the thistle 

heads. This is slightly below the population plateau at Cloverdale, so the reduction in 

plump seed production at this site should be at least 60%. If the difference in the germination 

between attacked and unattacked plants is accepted, the reduction is over 65%. 

Under field conditions germination and seedling survival seem to depend on breaks in 

the sward rather than competition within the C. vulgare population. This means that the 

reduction in thistle density should be similar to the reduction of seed as soon as the soil 

seed-bank has reached its new equilibrium. 

(1) U. stylala should be distributed to sites across Canada with stable populations of 

C. vulgare; but there is little point in releasing it against temporary outbreaks. 

(2) The introduction of additional biological control agents does not appear to be 

warranted as most of the problems with C. vulgare are either temporary following the 

clearing of land or the result of poor farming practice. 

Anderson. R.N. (1968) Germination and establishment of weeds for experimental purposes. Weed Science Society of America, 636 pp. 

Harrington. J.F. (1972) Seed storage and longevity. In: Kozlowski T.T. (Ed.) Seed biology vol. III. Academic Press. pp. 145-245.

CiTSiu11I J'lllgaTe (Savi) Ten. , 153 

Harris, P. (19BO) Effects of UropllOra affillis Frlld. and U. lfuaelrifruciata (Meig.) (Diptera: Tephritidae) on Centaurea diffusa Lam. and C. 

maculosa Lum. (Composilae). 'Zritse/rri[t frlr allgewalldte Emomologie 90, 190-210. 

Moore, R.J.; Frankton, C. (1974) TIle thistles of Canuda. Agricullllre CU/lelda MOllograplr 10, 111 pp. 

Persson, P.I. (1963) Studies on the biology and huvill morphology of some trypetids (Dipt.). Opuscula Entomologica 28, 3-69. 

Redfern, M. (1968) The natural history of spear thistle hends. Field SlIldies 2.669-717. 

Salisbury. E. (1964) Weeds lind aliens. Collins, 384 pp. 

Zwolfer, H. (1965) A prcliminary list of phytoplurgous insects IIttllcking wild Cynareae species in Europe. Commonwealtll Instillete of 

Biellogical Control Tee/mimi B,llielill 6, 81-154. 

Zwolfer. H. (1972) Invcstiglltions on Ur(lplwra sty/ala Fabr •• a possible agent for Ihe biological control of Cinium vIClgare in Canada. 

Weed projects for C:lDmJa. Commollwcallir /tlStilllle of Biological Control Progress Report 29. 20 pp.

Blank Page 

154

Pest Status 

Background 

Biological Control 

Chapter 34 155 

Convolvulus arvensis L., Field Bindweed 

(Convolvulaceae) 

M.G. MAW 

Field bindweed. Convolvulus arvensis L.. a deep rooted perennial of Eurasian origin. is 

a serious problem in many areas and has been classed as the worst weed of the prairie 

and the Great Plains States (Bakke et al. 1939). It is a serious weed in Ontario and 

Quebec. especially in corn. and although it is of less importance in the western provinces 

some local areas are badly infested. 

Losses from bindweed competition vary with the crop and cultural methods. Rye 

yields may be reduced by 20% while grain sorghum yields may be reduced by 78% . On 

bindweed free land, wheat. barley. and oats yielded respectively 350.576. and 515 kg per 

ha more than on infested fields (Wiese & Phillips 1976). Fast growing crops that shade 

the ground may compete effectively with the weed. and winter wheat on the drier parts 

of the Great Plains is a good competitor because winter and spring growth occurs when 

bindweed is dormant. Summer crops may however be severely stunted or even killed by 

severe bindweed competition (Weise & Phillips 1976). 

Field bindweed was first noticed in America in Virginia as early as 1739. and by 1900 it 

was well established and recognized as a serious weed in most of the western states. In 

addition to a progressive spread across America. the weed may have been introduced 

several times. For example. it may have been introduced directly into Kansas with 

wheat brought from the Ukraine by immigrants about 1875 (Weise & Phillips 1976). 

Bindweed is difficult to control because of its extensive root system and prolific seed 

production. Roots and rhizomes may cover an area up to 6 m in diameter (Frazier 1943) 

and extend down 9 m below the soil surface (Phillips 1978). In addition roots store a 

range of sugars. starches. and proteins that can support the plants over long periods 

even though top growth may be repeatedly destroyed (Weise & Phillips 1976). Over 11 

million seeds may be produced per hectare and they may remain viable in soil for up to 30 

years (Timmons 1949). 

Seedlings develop deep taproots in a few weeks and in 9 to 11 weeks spread radially by 

lateral roots. Within one season a single plant may form a patch of more than 3 m in 

diameter (Weise & Phillips 1976). 

Control of bindweed but not eradication can be achieved through an integrated programme 

of frequent cultivation and selected herbicides. However, with the growing 

concern of the overload of chemicals in the environment, their cost. the cost of energy, 

and costs in lost production there has been interest in biological control. Mohyuddin 

(1969) listed the insects from Calystegia spp. and Convol"lIll1s spp. found by him in 

Ontario and by others in other parts of the world. and the University of California and 

the USDA jointly mounted a project to survey the Mediterranean area for natural 

enemies of Convolvulus (Rosenthal 1980). In all, 140 species of insects. three species of 

mites, and three fungi were found attacking C. arvensis and other closely related Convolvulaceae. 

Of these, a mite, Eriophyes sp.; a bruchid. Spermophagus sericelts Geoff.; a

156 M. G. Maw 

Discussion 

Table 37 

Table 38 

chrysomelid. Ga/eruca TUfa Germ.; and a mildew. Erysiphe convolvuli DC.. showed the 

most potential as control agents (Rosenthal 1980). None. however. was found to be 

strictly monophagous. 

Little biological control work has been done in Canada. However. limited attempts to 

augment existing populations or to establish new colonies in Alberta and British 

Columbia with insects from Saskatchewan and Ontario (Table 37 and Table 38) were not 

successful. 

Collection and release in Canada of chrysomelid insects in control of COlU'O/VIl/US arvensis 

L. projects 

Species Number Year Source Release or Lab Study 

Chirida guttala 114 1969 Canada British Columbia (study) 

(01.) 125 1970 Ontario British Columbia (study) 

236 1979 Saskatchewan Alberta (release) 

C/lelymorpha cassidea (F.) 97 1979 Saskatchewan Alberta (release) 

Melriona bie%r (F.) 18 1969 Canada British Columbia (study) 

7 1970 Ontario British Columbia (study) 

Metriona purpurata Boh. 224 1979 Saskatchewan Alberta (release) 

Collection and release in Canada of chrysomelid insects in control of Convo/vulus sepiwll 

L. projects 

Species 

Chirida gllttala (01.) 

Melriona bie%r (F.) 

Number 

120 

200 

Year 

1971 

1971 

Source 

Ontario 

Ontario 

Release 



Bindweed competes with crop plants for nutrients and water, and thus lowers yields. It 

twines around plants, smothering them and interfering with harvesting, and is a haven 

for crop pests (Rosenthal 1980}. It is considered to be the 12th most important weed in 

the world and the 14th most important weed in the United States (Rosenthal 1980). It is a 

serious weed in Ontario and Quebec but a lesser problem in the western provinces. It is 

mainly a weed in cultivated fields and so not a good candidate for biological control. 

A large number of insects are associated with bindweed in North America. but only 

sporadically in localized areas is appreciable damage done to the plant (Maw unpublished 

data). Also, it appears that most insect damage occurs when bindweed is 

supported by other plants or fences, rather than in the prostrate growth in fields. 

Attempts to move Chirida gllliala, Melriona bicolor and M. purpurala, and Che/ymorpha 

cassidea into new areas were unsuccessful. This may indicate that these species 

have reached their geographic limits. 

Rosenthal & Buckingham (1982) found a number of European organisms that may 

be useful as control agents of bindweed in North America. Of these. the arthropods 

Ga/eruca rufa, Spermophagus sericeus, and Eriophyes sp. probably have the most 

potential (Rosenthal 1980) and several other species may also be useful (Rosenthal &

Blank Page 

158

Pest Status 

Table 39 

Chapter 35 

Euphorbia esula-virgata complex, Leafy 

Spurge and E. cyparissias L., Cypress 

Spurge (Euphorbiaceae) 

P. HARRIS 

Leafy and cypress spurge. Euphorbia esu/a'I'irgala complex and E. cypar/ss/as 

L.. are herbaceous perennials of European origin that have become problem species in 

parts of North America. Leafy spurge is particularly serious on the Canadian prairies 

and the north central United States. while cypress spurge is most prevalent in Ontario 

and Quebec. Both spurges are unpalatable to most grazing animals except sheep and 

displace other herbaceous vegetation. In two leafy spurge stands investigated in Sas· 

katchewan in 1981. there was 65-72% less grass within the stand than just outside it. 

Cypress spurge on a thin limestone soil at Braeside. Ontario. comprised 56% of the 

herbaceous vegetation in a dry year and 26% in a wet year (Table 39). Cypress spurge is 

Density of Hy/es euphorbiae (L.) larvae, dry weight of E. cyparissias L. and total 

herbaceous vegetation at Braeside. Ontario. 

Year No. H. euphorbiae Dry weight of Dry weight of all 

larvae/m 1 E. cyparissias glml vegetationlm l 

1968 

6.8 x 10-) 

1969 1.75 x 10- 1 

56.6 216.0 

1970 0.4 44.7 79.2 

1971 1.0 73.1 147.1 

1972 0.3 91.9 213.1 

1974 0.6 

1975 2.3 

1976 0.4 

also of concern as extremely small amounts of its latex are intensely irritating to the 

eyes. The provincial and most municipal governments of the Canadian prairies have an 

active programme for the control of leafy spurge. For example in the early 1950s, 

Saskatchewan spent around $100 OOO/year against persistent perennial weeds and by 1979 

the amount had risen to $150 OOO/year, with leafy spurge being the main target. The sum 

covers the cost of treatment on provincial and municipal lands and roadsides but only 

the cost of the chemical on private lands. Thus the actual cost of controlling leafy spurge 

was considerably higher. In Manitoba in 1981. $38649 was spent on leafy spurge control 

by the provincial government of which $32 890 represented the cost of the chemical (E. 

Johnson. 1982. personal communication). In Saskatchewan in 1982, the full cost was 

$640Iha of spurge treated as the infestations are scattered or on rough terrain. 

In the first twenty years of the control programme in Saskatchewan the chemicals 

used were soil stcrilants such as sodium chlorate and various borates either alone or in 

combination with other herbicides. These were both expensive and ecologically un- 

159

160 P. Harris 

Background 

desirable. In 1971, the treatment of 65 ha with borascu (disodium tetraborate and 5 

bromo-3-sec-butyl-6-methylurate) cost $15 727 while the treatment of 86 ha with 

picloram (4-amino-3,5,6-trichlorpiclinic acid) cost $12 073 (SaskatchewllO Production 

and Marketing Branch 1972). Not only was picloram cheaper but the grass cover 

remaining was greatly preferable to the bare patches following treatment with soil 

sterilants. Thus in the past ten years picloram has been used almost exclusively on 

uncultivated stands except in Manitoba where its use is more restricted. 

The effectiveness of the chemical control programme is not impressive. Eleven 

Saskatchewan municipalities were resurveyed for leafy spurge llfter approximately 30 

years of chemical control. The weed has disappeared on cereal land with normal cultivation 

and application of 2.4-D, while on uncultivated land the area infested with spurge has 

more than doubled. These two trends almost cllOcelled eaeh other in the municipalities 

sampled. 

In Manitoba. where little picloram has been used, the increase has been large: from 

3236 ha in 1952 (Craik 1953) to an area estimated by Johnson (1982, personal communication) 

to be 46 693 ha in 1981. The difference in spurge increase between Saskatchewan 

and Manitoba is attributed entirely to the use of picloram; but against the 

benefits of the herbicide is the hazard that large scale continued use will contaminate the 

ground runoff water since the herbicide is subject to little microbial breakdown. 

The largest cypress spurge infestation in Ontario is on thin uncultivated limestone 

soils at Braeside. The species appears to have been introduced in 1870 and by 1981 had 

spread, initially with highway construction. to about 14000 ha on two limestone ridges. 

The main cause for concern is that the present infestation is only 15 km away from the 

360 000 ha Smith Falls Limestone Plain. 

The discussion of the biological control of leafy spurge by Harris et al. (in press) lists 

many insects and pathogens that are restricted to the genus Euphorbia. The difficulty is 

finding species that will survive on North American leafy spurge which seems to be a 

species complex. Specialized E. esula insects such as the aphid Acyrthosipholl neerlandicum 

HRL and the clear-winged moth. Chamaesphecia tentilrediniformis. do not survive on the 

common North American leafy spurge. To find insects that will accept the spurge. it has 

been necessary to seek those that can survive on several Euphorbia spp. Conversely. 

there are several spurges that should not be damaged in North America: E. antisyphilitica 

(a source of high quality wax in Mexico), E. pu/cherrima (the ornamental poinsettia). E. 

lathyris (a plant suggested as a source of hydrocarbon (Calvin 1978» and native North 

American spurges in general. Hence the biological control of leafy spurge is not without 

its difficulties even though the presence of large dense stands that arc almost unutilized by 

phytophagous organisms suggests that it is an extremely amenable target for biological 

control. 

About three quarters of the insects attacking Euphorbia in Europe are restricted to the 

genus. This is a higher proportion than for most other herbaceous plants. For example. at 

least three quarters of the insects that feed on the genus Solidago attack other plant 

genera (Harris et al .• in press). It appears that the degree of specialization in the insect 

guild on spurge is determined by the presence of enzymes and toxins that make it difficult 

for utilization by unspecialized insects and this extends to individual spurge species. For 

example. Ellis & Lennox (1941) reported the proteolytic enzyme euphorbain from E. 

lathyris but that E. peplus contained little or none of it. That some of the compounds are 

extremely toxic has been long known. For example the Geoponika (6th or 7th century) 

records that tithymalus (possibly E. cyparissias) mixed in a bait could be used to control 

mice by making them blind. I can confirm that minute amounts of E. cyparissias latex in


HyJes euphorbiae 

(L.) (Lepidoptera: 

Sphinguidae) (a) Ecology 

Euphorbia esula-I'irgata complex. 161 

the eye are extremely painful. In the 12th century. Ibn Al Awan (Clemont-Mullet 1864) 

described the use of a spurge extract for repelling and killing insects. Portier & Busnel 

(1951) found that E. cyparissias latex contained a substance that produced violent muscle 

tetany in most insects although the specialized spurge hawkmoth larvae. Hyles euphorbiae 

(L.). recovered without ill effects. Geilser (1955) reported that the effects of the 

substance were similar to those of acetylcholine in that atropine was antagonistic to it. 

Such differences presumably account for the specialization of some of the Chamaesphecia 

spp. moths to a single Euphorbia sp. For biological control purposes. this makes the 

precise identification of the target leafy spurges of North America an urgent matter. As 

this has so far proved difficult on morphological grounds perhaps a chemical or isozyme 

classification should be attempted. 

H. euphorbiae. the spurge hawkmoth. is a large defoliator of Euphorbia species in the 

subgenus esula in south and central Europe. northern India. and central Asia. The pupae 

can survive cold winters (Harris & Alex 1971) and its northern distribution seems to be 

limited by a requirement for high summer temperatures as the larvae feed little and 

eventually die if kept below 14°C. Also for unknown reasons the moth is uncommon south 

of the Mediterranean. H. euphorbiae has three generations a year in the south of its range 

and one in the north. 

The moth was selected a a biological control agent as it appeared to have the capability 

of defoliating spurge stands over large areas. Indeed it was a major pest of commercially 

grown E.lathyrisin the USSR (Malyuta 1934). The moth was approved for release in 1965 

and subsequently attempts were made to establish it in both Canada and the United 

States. 

(b) Releases 

Large numbers of H. euplrorbiae were bred in the laboratory and released. mostly as 

larvae. in spurge stands across Canada (Table 40). The stock used was from scattered 

collecting in Switzerland. France, and Germany on E. cyparissias and E. seguierana. 

Other larvae presumably from these hosts were purchased from collectors in East Germany. 

Initial establishment was disappointing and the first evidence of breeding was 68 widely 

scattered nearly mature larvae recovered at one of four release sites at Braeside, Ontario 

in 1968. These were collected and two generations bred from them over winter in the 

laboratory with the result that over 5000 of their progeny were released at Braeside in the 

spring of 1969. The only other site where a few field bred larvae were collected was at 

Sidney. Ontario, but this colony has not been visited since 1972. 

Most of the releases of H. euplrorbiae larvae made in 1966 and 1967 suffered a 

mortality of over 95% during the subsequent two weeks. The exception was a series of 

releases made in September at Sidney. Ontario. and one release at Braeside. Ontario. 

where 23% of the larvae survived this period. The development of the larvae released 

late in the season was so slow that many of them failed to pupate and died. Forwood 

(1977) with a release of 51 larvae on leafy spurge in Nebraska found that they had all 

disappeared within seven days. The reason for the larval mortality was predation by

162 P. Harris 

Table 40 

Table 41 

Open releases and recoveries of Hyles euphorbiae (L.) against Euphorbia spp. in Canada. 


Year Euphorbia sp. Location No. and Stage Recovery 

1965 Cypress spurge Sidney. Ontario 206 larvae 

1966 Leafy spurge Jameson, Saskatchewan 1200 larvae 

Wilmer, British Columbia 300 larvae 

Miami. Manitoba 195 larvae 

14 pupae 

Hartney. Manitoba 186 larvae 

Cypress spurge Sidney. Ontario 3606 larvae 

Jones Falls. Ontario 550 larvae 

1967 Leafy spurge Wilmer. British Columbia 1900 larvae 

Kamloops, British Columbia 3000 larvae 

Moose Jaw Creek. Saskatchewan 979 larvae 

Balgonie, Saskatchewan 361 larvae 

Nr. Balgonie, Saskatchewan 3000 larvae 

Milestone, Saskatchewan 901 larvae 

Miami, Manitoba 1100 larvae 

Picton, Ontario 825 larvae 

1967 Cypress spurge Braeside, Ontario 13680 larvae 1968 

1968 Cypress spurge Sidney, Ontario 1565 larvae 

Braeside, Ontario 2801 larvae 

1969 Cypress spurge Braeside, Ontario 5210 larvae 

1973 Cypress spurge Hornings Mills, Ontario 600 larvae 1982 

1973 Leafy spurge Guelph, Ontario 200 larvae no recovery 

1974 Leafy spurge Regina Beach, Saskatchewan 37 larvae 

600 pupae 

1978 Leafy spurge Cardston, Alberta 229 larvae 

ants, mice, carabids, wasps, pentatomids, and spiders (Harris & Alex 1971). At three 

sites in Ontario the percentage survival of larvae after four days decreased almost 

directly with the average number of ants caught in a standard series of pitfall traps 

during the period (Table 41). 

The 68 larvae found in 1968 and the 179 found in 1979 that had not been released that 

summer were expressed on a m l basis as if all the larvae were confined to a hectare. In 

most of the subsequent years the survey was restricted to 100 m l samples taken in early 

August at paced intervals from a hectare within the release field but in 1975 the samples 

were taken from the adjacent roadside which usually supported a higher density of 

larvae. 

Relationship between the number of ants in pitfall traps and the survival of H. euphorbiae 

(L.) larvae in a four day period 

Place 

Braeside 

Sidney 

Picton 

No. ants/trap 

5.4 

35.9 

58.7 

% H. euphorbiae 

larvae recovered 

34.5 

20.5 

11.8

166 P. Harris 

Table 43 

in East Austria with 3-5 larvae per plant. Some field mortality was noted: at one site on 

E. cyparissias, 31 % ofthe eggs failed to hatch although they developed embryos and 9% 

of the larvae died in the early instars. The population in part seems to be controlled by 

oviposition behaviour as multiple oviposition into a stem is rare and when it does occur 

only one larva survives to enter the root. In choice tests O. erythrocephala attacked 

Canadian leafy spurge more often than E. esula, but there was no indication that 

association with a particular spurge species in the field had formed a host race. 

(b) Releases 

Authority to release O. erythroceplwla was obtained in October 1979. The stock was 

field collected as beetles in Switzerland on E. segllierana and E. cyparissias, and in 

Austria on E. cyparissias and E. eSllla (Table 43). The sexes were separated on 

collection and then released together at the release site in Canada later. 

Open releases and recoveries of Oberea erythrocephala (Schr.) on E. esula-virgala complex 

in Canada. 

Release Date No. and Stage Source Release Site Recovery 

15 Oct 79 30 larvae Switzerland Caronport, Saskatchewan 1 of 12 alive 

May 80 

27 Jun 80 70 males Switzerland Caronport, Saskatchewan 15 larvae Sep 80 

60 females 31 larvae Sep 81 

3 Jul80 70 males Switzerland Cardston. Alberta 17 larvae Sep 80 

53 females o larvae Aug 81 

14 Jul 80 49 males Switzerland Jameson, Saskatchewan 1 larva Sep 80 

57 females o larvae Aug 81 

26 Jun 81 55 males Switzerland Weyburn, Saskatchewan 14 larvae Aug 81 

(8 on plants 

attacked in lab) 

30 Jun 81 59 males Switzerland Lauder, Manitoba 12 larvae Aug 81 

36 females 

10 Jul 81 90 adults Switzerland Manitou Lake, Saskatchewan 13 larvae Aug 81 

& Austria 

5 Aug 81 17 larvae Austria Caronport, Saskatchewan 

In 1979,30 leafy spurge plants that had been attacked in the laboratory were transplanted 

in mid-October to a spurge stand in Saskatchewan (Table 43) to check on 

the ability of the larvae to survive the winter. The plants did not have time to establish 

themselves before winter and some were killed. In the following May one larva was 

found in 12 crowns examined and subsequently some oviposition girdling was found at 

the site but no eggs or larvae. 

Field collected beetles were released on three spurge stands in 1980 (Table 43) and 

during the summer, stems with oviposition scars were tagged and then harvested in 

September to determine the number of larvae that had tunnelled into the roots before 

winter (Table 44). 

The Cardston site was extremely fertile and the spurge so tall and dense that many 

stems with oviposition scars were certainly missed but it had by far the best ratio of 

oviposition scars to larvae. Unfortunately the site was burnt just before winter and in the 

following June the spurge was sprayed with pic\oram. Thus it was hardly surprising that 

no sign of the beetle was found in August 1981. In contrast at Caronport winter survival

Table 44 


Euphorbia esula-virgata complex. 167 

Oviposition attempts and success by o. erythrocephala (Schr.) at three sites 

No. stems with No. larvae in No. larvae in 

Site oviposition scars roots by September stems in Septcmber 

Jameson. Saskatchcwan 25 1 3 

Caronport. Saskatchewan 93 15 2 

Cardston. Alberta 29 17 2 

was good in spite of a poor snow cover as live larvae were found in three out of four 

plants examined in May. About twice as many larvae were found at the end of the 

summer as in the previous year including two plants (untagged the year before) with 

larvae developing over a two year period. The colony had a radius of about 25 m in the 

fall of 1981. No progeny were found at the Jameson release site. 

In 1981, beetles were released at three widely separated sites but as in the previous 

year breeding success was poor (Table 43). The table indicates that the date of release had 

little influence on breeding success so the problem does not appear to be related to the 

synchrony of the plant and larval development. 

The larvae developed readily in the stems of spurge plants from the Jameson area 

grown in pots but these plants tended to have larger stems than most of those in the field. 

The colony at Caronport was still present in 1982 and for the first time one adult was 

found (a fertilized female). A search made in mid-September produced one larva which 

was still in the stem only a few centimeters from the oviposition point. As most of the 

spurge stems were dead by October it had little prospect of survival. The problem is 

apparently not cool summer temperatures as the Cardston site had fewer heat units than 

the other release sites. The stem diameter at Caronport was, however, considerably less 

than at Cardston (the soil is sand and too light to be cultivated) so it appears that the 

beetle is only likely to thrive on spurge plants growing on fertile soils. 

The biological control of spurge in Canada has so far been a failure. The one insect 

established on cypress spurge has had little impact and the possible impact of O. 

erythrocephala on leafy spurge will not be apparent until its population has reached its 

plateau. Other insects tested have failed to survive on Canadian leafy spurge although 

some like C. tenthrediniformis appear to have a major impact on E. esula in Europe. The 

initial difficulty arose from equating the E. esula of Europe with the plant called E. esula 

in North America. Some difficulties still remain as it is not possible to search Europe 

for the Canadian spp. of leafy spurge for possible agents since the precise origin and 

identity of this spurge is not clear. Indeed, some of it may have arisen in North America 

through hybridization. Thus agents have to be found by testing the acceptability of North 

American leafy spurge to organisms found attacking closely related European spurges 

(those in the section Esu/a). A number of these are already known and can be subjected to 

the usual screening tests to establish their specificity. A few species have already been 

screened and effort should be made to establish them as widely as possible. 

The difference in the density of spurge in European and North American stands 

appears to be related to the cropping pressure by a complex of insects and pathogens in 

Europe, although it would be nice to demonstrate this by removing the insects from a 

European stand. One possible explanation for the richness of the complex in Europe is

168 P. Harris 


that like R. euphorbiae in Ontario each insect species is only able to utilize a small 

proportion of the total resource. The establishment of a complex of insects in North 

America large enough to reduce spurge density seems to be largely a matter of time and 

effort. Meantime any insect that can be established in reasonable numbers should be 

regarded as a success as it contributes to the cropping pressure on the weed in North 

America. 

The priorities in the biological control of leafy and cypress spurge for the immediate 

future are recognized as follows: 

(1) To complete host specificity studies on additional biological control agents in 

order to obtain approval for their release in North America. A reasonable target is the 

establishment of 10 agents in Canada since several species of spurge are probably 

involved. 

The root feeding beetles in the genus Aphthona (Chrysomelidae) are of particular 

interest as they are widespread and common on Euphorbia spp. in Europe. Investigations 

by Maw (1981) showed that A. cyparissiae Koch, A. {lava Guill., and A. 

czwalinae Weise would accept Canadian leafy spurge although the first two species are 

most common on E. cyparissias and the latter on E. esula. A. cyparissiae is likely to be 

the most useful for the Canadian prairies: it has the broadest ecological range of the three 

species, but prefers dry open sites with dense spurge and the larvae are reasonably cold 

tolerant. A. czwalinae will probably be restricted to moist sites such as along streams 

and in well wooded areas. A. f1ava prefers dry open sites but is less cold tolerant than A. 

cyparissias and so may be most applicable for southern Ontario or the United States. 

The following insects have been bred on Canadian leafy spurge in the laboratory and 

warrant further investigation as biological control agents. The leaf-tying moth Lobesia 

euphorbiana (Ferr.) (Tortricidae), the defoliating moths Minoa murinata Scop. and 

Bistonfiducarius Anker (Geometridae): both the former two moths in feeding tests were 

restricted to a few species of Euphorbia and they appear suitable for use as biological 

control agents. The gall midges Bayeria capitigena Bremi, Dasineura capsulae Kiett., 

and D. loewi Mik. (Cecidomyiidae); the aphids Acyrthosiphum cyparissiae Koch and 

Aphis euphorbiae Kltb. (Aphididae) are also worthy of testing. 

(2) The root-feeding moth, Chamaesphecia empiformis Esp. (Sesiidae), can almost 

certainly be established on the tetraploid E. cyparissias in Ontario and Quebec. 

Renewed efforts should be made to do this. 

(3) Chamaesphecia tenthrediniformis (D. & S.) should be established on E. esula s. 

str. if this spurge is a problem anywhere in North America. It is the most effective agent 

on E. esula in Austria. 

(4) The poor survival of Oberea erythrocephala (Cerambycidae) on the Canadian 

prairies may be related to the low fertility of most of the release sites. Releases 

should be tried again at Cardston, Alberta, and on cypress spurge in Ontario. Possibly 

the colony at Caronport can be made to flourish and hence be a source for distribution if 

the site is fertilized with nitrogen. 

(5) The populations of the spurge hawkmoth, Ryles euphorbiae (L.) (Sphingidae), 

established on cypress spurge near Mulmur, Ontario, suggest that the species may have 

value in other places in Ontario and Quebec. The strain imported from Europe appears 

to have a strong ovipositional preference for cypress spurge over leafy spurge. Stock 

from the colony established on leafy spurge in Montana should be tried again on leafy 

spurge in western Canada. As summer temperature may be limiting on much of the 

Canadian prairies, the releases should be made first in the regions receiving the greatest 

number of Corn Heat Units such as around Medicine Hat, Alberta, Estevan, Saskatchewan, 

and southcentral Manitoba.

Blank Page 

170

Pest Status 

Background 


Hypericum perforatum L., St. John's-wort 

(Hypericaceae) 

P. HARRIS and M. MAW 

In the early 1950s, St. John's-wort was forming large stands on the grasslands in the 

interior of British Columbia where it became the dominant herbaceous species. A number 

of biological control agents were introduced (McLeod 1962, Harris & Peschken 1971) and in 

most areas the weed has been reduced to scattered plants or patches up to 2 m in diameter 

and usually 100 to 200 m apart. The use of herbicides against the weed on public and private 

lands practically ceased. The main agent responsible for this reduction has been the beetle 

Chrysofina quadrigemina (Suffr.). In the few areas, such as the eutric brunisols on fluvial 

glacial gravel and morainal deposits near Cranbrook, British Columbia, where the beetle 

popUlation has been patchy, the weed has continued to spread. In this area, dense stands of 

St. John's-wort occur on about 30 km! of lightly grazed Douglas fir, Pseudotsuga menziesii, 

forest. At present, the weed is causing little monetary loss, but if it continues to spread, 

extensive wildlife and cattle grazing areas in the east Kootenays are threatened. 

In Ontario, St. John's-wort continues to be a common weed on poor quality grasslands, 

on thin dry soils, on gravel, limestone, or rock; but it was removed from the noxious weed 

list when the Weed Control Act was amended in 1976. If the availability of an effective 

biological control agent contributed to its removal from the list, biological control can be 

considered to have been a success. The weed is localized in New Brunswick and Nova 

Scotia, but it is capable of forming dense stands and appears to be spreading. 

The background to the biological control of St. John's-wort in Canada was described by 

McLeod (1962) (Harris & Peschken 1971). In these accounts, the beetle C. quadrigemina 

was most effective in the semiarid to dry subhumid regions (Harris el af. 1969) as they had 

an obligatory aestival diapause which they could not enter under continuously wet conditions 

(Huffaker 1967). The smaller beetle, C. hyperici, was most effective in the moist 

subhumid to humid regions. This assessment must now be revised with the spread of C. 

quadrigemina onto the moist coastal plain at Agassiz, British Columbia. In the years 

immediately following the release of the beetles, eggs and larvae were only found on the 

procumbent foliage from September to May. In 1981 in a moist region of British Columbia, 

eggs and first instar larvae were found on 23 June on the upright stems just prior to bloom 

while in the drier regions the beetle was in the adult pre-aestival feeding stage. 

The colour forms of C. quadrigemina vary markedly between release sites in British 

Columbia. Pesch ken (1972) found that the prevalence of the bronze forms was correlated 

with the mildness of the winter. He also found several behavioural adaptations between 

beetles in British Columbia and those in California which were the source of the British 

Columbia stock.

172 P. Harris and M. Maw 


Agrllus hyperici 

(Crotch) (Coleoptera: 

Buprestidae) 

Analtis plag/aIB (L.) 

(Lepidoptera: 

Geometridae) 

Aphis chloris (Koch) 

(Homoptera: 

Aphididae) 

Renewed attempts to establish the root boring beetle A. hyperici in the Cranbrook, British 

Columbia, area (Table 45) were not successful. This beetle is established at Mt. Shasta. 

California, and the climate of southern British Columbia is within the range of the species in 

Europe. The problem seems to be related to shipping stress in the newly emerged beetles, 

two shipments arrived dead at Cranbrook airport and no eggs or larvae were found from the 

release of live beetles. If further attempts are made to establish this insect, it is suggested 

that it should be done by transferring newly hatched larvae to plants growing at the release 

site. 

Two releases of A. plagiala were made in the Cranbrook British Columbia area and one 

in New Brunswick. No establishment has been reported from New Brunswick. In 

British Columbia, two moths were caught in September 1980, about 3 km from the 

release site and on 23 June 1981, when the first flowers had opened, an egg, a first instar 

larva, and several moths were seen. The moth was also found in 1981 near Grandforks, 

an area where it had been released in 1967 and not previously recovered. The moths 

were flying actively between the widely scattered clumps of the weed and had survived 

in spite of strong populations of C. quadrigemina. Many larvae were found at Grandforks in 

late July and a few near Cranbrook in late July and early October (K. Williams 1981 

personal communication). The colony at Agassiz, British Columbia, in 1981 caused 

browning and defoliation of H. perforalum in patches (L. Sigurgeirson 1981 personal 

communication). 

The A. plagiala larvae released in 1977 at North Tay Creek, New Brunswick, may have 

been killed by insecticide drift from aerial spray of the adjacent forest for spruce 

budworm (D. Finnamore 1981 personal communication). 

(a)Ecology 

The sexual generation of the aphid A. chloris appears in the fall (October in Cranbrook) 

in response to lower temperatures and shortened day length. During this period and in 

early November. an average of four (maximum of eight spread over a month) yellow 

eggs, which tum shiny black, are laid per female at the base of the flowering stems or on 

the procumbent foliage. Hatching occurs in April or May giving rise to a generation of 

apterous females. These mature in about a month and several generations of apterous 

viviparous females are produced. During midsummer, when colonies become crowded. 

alate viviparous females develop and disperse to found new colonies. 

A. chloris has a wide geographic range. It is found in Sweden near the northern limit of 

St. John's-wort (Johansson 1962). in Poland (Czechowskii 1975), in Israel (Neser. 1973, 

personal communication), in Britian in cool and damp conditions, and in the arid south 

of France, from sea level to 1500 m in the mountains (Wilson 1943). 

In the south of France and at Cranbrook, the aphids in summer are found near the tip 

of the shoots or beneath the flowers. In contrast, in England, northern France. and in the 

Alps, they are normally found at the base of the stems. Wilson (1943) suggested that the 

feeding site depends on conditions of heat and moisture. If so, the ability of the aphid to

Chrysolina hypericJ 

(Forester) 

(Coleoptera: 


Ilypericum perfOrUlIlm L.. 173 

adjust in this manner bodes well for its survival in the varied conditions at Cranbrook. 

British Columbia. 

In France, A. chloris can be heavily parasitized by Ap/,idius cardui Marsh. (Braconidae) 

and Aphidencyrtus aphidiverus Mayr. (Encyrtidae), but its reproductive capacity is 

such that it remains a common species (Wilson 1943). The stocks of A. chloris received 

from the Rhine Valley and Alsace contained Lysiphlebus faborum (Marsh.) (Braconidae). 

This is an aggressive parasitoid and if left unchecked can destroy a laboratory colony. 

Although A. chloris will attack various species of Hypericum, the damage done to the 

plant or its acceptance by the aphid varies with the species. For example, at the end of 5 

days the number of offspring from two mature apterous females on H. perforatum. H. 

rhodopaeum, H. calyeinum, and H. densiflorum were 37, 10, 7, and 0, respectively. 

Large colonies of A. chloris consistently killed vigorous plants of H. perforatum in 

about a month, while H. rhodopaeum lived for over seven months and put on new 

growth in spite of a heavy aphid population. 

(b) Releases 

Two releases of A. chloris were made in the Cranbrook, British Columbia, area (Table 

45). Infested H. perforalum plants were transplanted into the field. In 1979 this was done 

during a period of drought: the transplanted plants died and most of the surrounding H. 

perforatum had lost their foliage. No evidence of aphid survival was found. In 1980 

infested plants were transplanted earlier in the spring and the aphids moved readily onto 

the surrounding plants. By early November all of the rosettes sampled in a 20 m radius at 

the two release sites had a few fundatrigeniae and/or eggs. By late June 1981 following a 

wet and cool spring, scattered plants within a radius of 50 m of the release point had 

small colonies of A. chloris near the flower buds. By far the strongest colony of the aphid 

was on the site least favoured by C. quadrigemina. 

British Columbia was used as a source for obtaining stock for release in Ontario, Nova 

Scotia, and New Brunswick (Table 45). 

In Ontario, C. hyperici became established at the release site near Picton. Overwintering 

survival was 63% for adults and 31% for eggs compared to 19% and 6% 

respectively, for C. quadrigemina (Harris & Peschken 1974). Nevertheless C. quadrigemina 

rapidly became the most common species, although both species were still 

present in 1979 (13 ddand4 22 C. quadrigemina:4 ddand 322 C. hypericiin the sample 

collected). 

The releases in Nova Scotia contained a few individuals of C. quadrigemina collected 

with the C. hyperici from Fruitvale, British Columbia. Both species became established 

but by 1979 C. hyperici had become numerous enough at one site in the Annapolis Valley 

to generate one query about the identity of the beetles sitting on the side of a house (H. 

Specht, 1979, personal communication). This was about 30 km from the release site. 

According to M. Neary (1979, personal communication), the original release site has 

been cleared of the weed and it has been substantially reduced in the Kingston-Auburn 

area. C. hyperici is also established in the Dundurn and Fenwick regions. At Dundurn 

between 1970-72 the number of flowering stems declined from 5.8 to 3.4/m2. This is a 

more gradual decline than has been usual with C. quadrigemina in British Columbia. 

C. hyperici released at Tay Creek, New Brunswick, were well established in 1977, but 

were not numerous enough to control the weed. A problem with the release made in 1975 

is that all the individuals examined were female. Apparently the females continued their

174 P. Harris and M. Maw 

Table 45 Open releases and recoveries of insects against Hypericum per/oralum L. 


Release site Year Origin Number Recovery 

Chrysolina hyperici 

Pictou Co., Nova Scotia 1969 British Columbia 2 100 adults 1970 

Prince Edward Co., Ontario 1969 British Columbia 70 adults 1970 

Annapolis Co., Nova Scotia 1969 British Columbia 1320 adults 1979 


Tay Creek, New Brunswick 1971 British Columbia 1 150 adults 1972 

Lime Kiln, New Brunswick 1971 British Columbia 1 150 adults 

Tay Creek, New Brunswick 1975 British Columbia 496 adults 

Chrysolina quadrigemina 


Sidney Twp., Ontario 1971 British Columbia 15 adults 

1971 California 139 adults 

Tay Creek, New Brunswick 1975 British Columbia 128 adUlts} Not found 

Tay Creek, New Brunswick 1977 British Columbia 55 adults in 1981 

Guelph, Ontario 1979 Ontario 40 adults· 7000 collected 

in 1981 

4 sites near Guelph, Ontario 1979 Ontario 560 adults No recovery 

34 sites in and around 

Guelph, Ontario 1981 Ontario 7000 adults 

Agrilus hyperici 

Elko, British Columbia 1977 California 56 adults No recovery 

up to 1981 

Aphis chloris 

Elko, British Columbia 1979 Germany 300 plus Did not 

survive 

Elko, British Columbia 1980 Germany 150000 1981 

Anailis plagiata 

Grandforks, British Columbia1967 Europe 875 larvae 1981 

Westbridge, British Columbia 1967 Europe 500 larvae 

Tay Creek, New Brunswick 1977 Switzerland 715 adults Not found 

in 1978 

Elko, British Columbia 1977 Switzerland 3648larvae 

Agassiz, British Columbia 1977 Switzerland 476 larvae 1981 

Elko, British Columbia 1980 France 169 larvae 1981** 

• Sample examined contained 17 C. quadrigemina: 7 C. hyperici 

.. In view of the small population in 1981, it is assumed that establishment occurred 

from the 1980 releases. 

pre-aestival feeding on the flowering plants for longer than the males, so that mass 

collecting produced a badly distorted sex ratio. It is not known whether other releases 

were adversely affected in this manner. The release site at North Tay Creek, New 

Brunswick, has been subject to insecticide drift from aerial treatments of the forest 

against spruce budworm. In 1978, 1979, and 1980, a buffer strip of two miles was left 

between the treated forest and the release field and beetle density increased noticeably

176 P. Hnrris nnd M. MlIw 


beetle, C. hyperici, was needed to control the weed in moist sites. C. quadrigemina has now 

become numerous at the moist sites of Fruitvale and Agassiz, British Columbia, although 

C. hyperici has persisted and spread to other sites in the province (K. Williams 1981 

personal communication). However, in spite of the release of pioneer moist-adapted 

individuals of C. qlladrigemina with C. hyperici in the maritimes, the latter species has 

become dominant and C. quadrigemina was not present in the samples examined. C. hyperici 

is only slightly smaller than C. quadrigemina and the two species feed in a similar manner on 

H. perforattun, so it is surprising that they coexist in the same habitats. It is not known what 

occurred to allow C. quadrigemina to colonize moist habitats and invade the thriving colony 

of C. hyperici at Fruitvale. The adaption has not extended to the maritimes and again the 

reasons are unknown. From a purely pragmatic purpose of controlling H. perforatum the 

important thing is that one species or another will reduce the weed to a low density in most 

places in Canada. For example, at the release site in Ontario, the weed declined to only 0.2% 

of its former density. 

A strong colony of C. quadrigemina with some C. hyperici was established near 

Guelph, Ontario, with stock from the Picton, Ontario, colony. A total of 7000 beetles 

collected from the Guelph colony before its destruction in 1981 was distributed to 34 

other sites in and around the city. By 1983 there should be massive populations of the 

beetle in the Guelph area. These could be collected at little cost and released at other H. 

perforatum sites throughout Ontario. Some of the releases would fail (two out of five 

release sites of 1979 at Guelph were destroyed) but the beetle would distribute itself 

from the survivors. The pilot studies at Picton, Ontario as well as those in British 

Columbia indicate that the prevalence of H. perforatum would be greatly decreased by 

such a programme with a corresponding increase in forage for livestock or wildlife. 

The apparently few sites where Chrysolina spp. have been ineffective are on nutrientpoor 

soils and in insecticide-drift areas. No insects are likely to be effective for biological 

control if they receive an insecticide spray while they are exposed on their host 

plant. It might be possible to find a root-boring insect that was inside the plant during the 

spruce budworm spraying season; however, in view of the public outcry, the spray 

programme is likely to become increasingly circumspect, so the problem for C. hyperici 

should diminish. 

More investigations are needed to determine whether the effectiveness of the Chryso 

Iina spp. can be increased on nutrient-poor soils; however, as the moth A. plagiata is 

increasing on some of the areas not favored by the beetle, we already may have part of 

the solution. Aphis chloris was chosen as a biological control agent as the presence of 

symbionts in aphids often enables them to survive on plants that lack one or more 

essential amino acids or B vitamins. However, its effectiveness as a biological control 

agent for H. perforattun remains to be seen. 

(1) C. quadrigemina and/or C. hyperici have shown that they are able to reduce H. 

perforatum to well below the economic threshold in most regions of Canada. Any 

province with H. perforaltun on their noxious weed list should distribute the beetles or, 

if the importance of the weed does not justify this small effort, remove the weed from the 

list. 

(2) Provinces where the weed is being satisfactorily controlled should remove H. 

perforalum from their noxious weed list as mowing or spraying operations against the 

weed are a waste and not likely to assist its biological control. 

(3) Further study is required to determine the role of Anaitis plagiata and/or Aphis 

chloris. 

(4) If further attempts are made to establish Agrilus hyperici, these should be done 

by transferring the young larvae to plants in the field.

Blank Page 

178

Pest Status 

90 

80 

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-u 

ctI 

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"t:I 

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Chapter 37 

Linaria vulgaris Miller, Yellow Toadflax 

and L. dalmatica (L.) Mill., Broad-leaved 

Toadflax (Seroph ulariaeeae ) 

P. HARRIS 

The importance of Linaria vulgaris Mill. in western Canada has declined since the early 

1950s so that now, as in eastern Canada, it is a conspicuous but relatively unimportant 

weed. In a study in the Peace River area of Alberta, Darwent et al. (1975) found that in 

• • 

54 56 58 60 62 64 66 68 70 72 74 76 78 

Year 

Fig. R. Cumulative number of abstracts on the control of toadnax with hcrbidcs in the Research Report of the Expert 

CommiUec on Weeds (Canada Western Section) 

179

180 P. Harris 

Background 

Table 47 

most areas it was less abundant in the early 1970s than it had been in 1956 and that 

toadflax was not a serious problem in cereal crops. In creeping red fescue, 180 toadflax 

stems/m 2 reduced the yield by a third; but in most areas there were 20 or less stems/m 2 

with no measurable effect on yield. Most of the dense stands of the weed were on sites 

that had been cleared and abandoned or were cropped infrequently. 

In Saskatchewan, the weed is still dense on uncultivated sandy soils from North 

Battleford west to Alberta. In other regions of the province it has disappeared or greatly 

declined since the 1950s. 

The decrease in the importance of the weed is reflected by the decline in the number of 

abstracts relating to its chemical control in the Research Report of the Expert Committee on 

Weeds (Canada Western Section) (Fig. 8). The decrease of the weed has not however 

changed its status under noxious weed legislation. For example in Saskatchewan provincial 

subsidies are still paid to municipalities for its control. 

L. dalmatica (L.) is considerably more persistent that L. vulgaris, and it appears to 

exclude most other herbaceous species from the stand. Stands are local and the total 

area occupied does not appear to be large. Thus in the absence of documented evidence 

it does not appear to offer a serious threat. 

A more detailed history of the biological control of toadflax is given by Harris & 

Carder (1971). The decline of the weed in western Canada coincided with the appearance 

of the flower-feeding beetle Brachypterolus pulicarius (L.). This European 

beetle was present in eastern Canada and spread to the west. In addition the seedfeeding 

weevil Gymnaetron antirrhinii (Payk.), another European insect present in the 

east, was released in western Canada in 1957. Both insects are now present in regions of 

western Canada where toadflax is common. 

In 1962, a European defoliating moth, Calophasia lunula (Hfn.), was first released in 

Canada, and it became established on the railway right-of-way at Belleville, Ontario in 

1966. The moth has two overlapping generations and lays single well distributed eggs. 

The first two larval instars are inconspicuous and frequently feed inside the flowers, but 

the third to fifth instars feed externally on the foliage and are easily seen. Samples taken 

along the railway right-of-way (Table 47) indicate that larvae were present from late May 

to early September, usually at a density of 2-6 larvae/100 stems regardless of the 

toadflax density. The density of the toadflax increased greatly following soil disturbance 

in the previous year. The overall level of damage was not impressive with less than 20"10 

of the stems being defoliated. 

Density of C. lunula and toadflax, L. vulgaris Mill. and L. dalmatica (L.) Mill .• along 

the railway at Belleville. Ontario. 

No. 3rd-5th instar 

Date No. samples· No. Toadflax stemsfm Z C. lunula larvae/m 2 

2 Jun 1968 26 85.7 2.0 

8 Aug 1968 19 89.1 3.8 

3 Sep 1969 158 6.6 0.05 

18 Jun 1970 52 7.2 0.31 

13 Aug 1970 205 0.98 

15 Aug 1971 31 7.7 0.13 

• (0.25 m 2 ) samples taken at 5 pace intervals

Table 48 



Linaria \·ulgaris Miller. 181 

The area has not been surveyed since 1972, but the moth has continued to spread; it 

was recovered from light traps at Ottawa, Ontario in 1977, a distance of over 300 km 

from the release site (E. Monroe, 1978, personal communication). Thus C. lunula is now 

probably present in most of southern Ontario. According to I. Jones (1978, personal 

communication), larvae were scarce in the Ottawa area in 1980: less than half a dozen 

were seen in several organized and many casual searches. In 1981, there was a large 

increase in the population, larvae were seen from early June to mid-October and along 

the railway track 47 to 57 larvae could be collected in an hour. Defoliated stems were 

evident, and some small stands were completely defoliated. Both the larvae and defoliation 

were associated with stunted toadflax plants and they rarely occurred in adjacent 

lush stands. 

Op'en releases and recoveries of Calophasia [wUlla against L. vulgari.v Mill. and L. 

dalmatica (L.) Mill. 


Weed Species Province Year Origin Number Recovery 

L. vulgaris New Brunswick 1971 Ontario 1565 larvae 

& 136 pupae 

L. vulgaris Saskatchewan 1973 Ontario 2725 larvae 

L. dalmatica British Columbia 1969 Ontario 200 pupae 

L. dalmatica British Columbia 1971 Ontario 1180 larvae 

Four attempts were made to establish Calophasia lunula in regions of Canada outside 

Ontario and all were unsuccessful (Table 48). The release site in Saskatchewan was 

flooded in the year following the release. The larvae released on Dalmation toadflax in 

British Columbia disappeared within days, apparently from ant predation. Survival 

was not followed closely in New Brunswick but no evidence of establishment was 

found in the following year. 

The moth, C. lunula, is obviously well established in Ontario and it should be possible 

to establish it in the rest of Canada. C. lunula has not defoliated enough L. vulgaris to 

control the weed on its own, but it has added to the stress inflicted by the now 

ubiquitous beetles, G. antirrhinii and B. pulicarius. The possibility that it may 

sometimes inflict more damage is indicated by the populations in Ottawa in 1981 which 

seem to be about ten times the density at Belleville prior to 1972. 

C. lunula favors the stunted toadflax stands that are found on dry soils. It is these 

stands that are persistent as edaphic conditions that permit the formation of tall lush 

stands also lead to the displacement of toadflax by grass and other vegetation. Thus C. 

lunula concentrates its attack where the weed is most persistent. 

The combination of the three toadflax insects can control L. vulgaris at below the 

economic threshold in most parts of Canada. Indeed in most regions this has been 

achieved by the two beetles alone. An exception is North Battleford, Saskatchewan,

182 P. Harris 




where there are extensive dense stands of toad flax. Based on the results from Ontario, 

it is doubtful whether the establishment of C. lunula in the area would solve the 

problem. Whether it is worth screening and establishing a fourth agent for the control 

of toadflax around North Battleford needs to be determined by a cost-benefit study as 

opinions vary about the importance of toadflax to the region. 

Surveys for the biological control agents of toadflax and their host specificity testing 

should not be done by Canada unless it can be shown that the potential benefits are 

large enough to justify the costs of biological control. However, the costs to Canada 

for biological control would be minimal if the tests were done by other countries. In 

this event the control agent should be imported as there would be benefits to individual 

land holders from the biological control of Dalmation and common toadflax. The moth 

C. lunula can almost certainly be established outside Ontario. 

I am grateful to Mr Ian Jones for the observations on C. lunula in the Ottawa area in 

1980 and 1981. 

Darwent, A.L.; Labay, W.; Yarish, W.; Harris, P. (1975) Distribution and importance in northwestern Alberta of loadflax and its insect 

enemies. Catuldian Journal 01 Piant Science 55, 157-162. 

Harris, P.; Carder. A.C. (1971) Linaria vulgaris Mill .• yellow loadfiax and L. dalmaJica (L.) Mill .• broad-leaved toadflax (Scrophulariaccae). In: 

Biological control programmes against insects and weeds in Canada 1959-1968. Commonwealth 

inslilute 01 Biological Control Technical Communication 4. 94-97.

Chapter 38 

Opuntia polyacantha Haworth, Plains 

Prickly-pear Cactus (Cactaceae) 

M.G. MAW 

There are three species of cacti on the Canadian Prairies: the prickly-pears, Opuntia 

polyacantha Haw. and O. tragi/is (Nutt.) Haw., and the pincushion or ball cactus, 

Mammillaria vivipara (Nutt.) Haw. Mammillaria is not considered to be a problem. 

In the western provinces cacti are found on dry hillsides and flatlands throughout the 

more arid parts of the brown soils zone. These areas have some grazing capacity, but 

have limitations that make improvement and cultivation impractical. For example, 

when the surface is disturbed the soils are likely to erode and blow easily. 

Periodically, especially during droughts, prickly-pear becomes a concern. Ranchers 

then worry that it will displace valuable grass, use scarce moisture, and cause injury to 

stock. It is generally thought that overgrazing increases cactus growth and spread. 

Certainly, severely overgrazed grasslands greatly facilitate the spread of cacti for when 

soils have been denuded, cactus pads broken from clumps come into contact with bare 

soil, root, and establish new clumps. On the other hand, Bement's (1968) study of heavy, 

moderate, and light pasture use showed that while populations of cactus doubled in area 

in 28 years, it never exceeded 2.4% of land area. Removal of cactus did not increase 

forage production significantly but did make it more available for grazing. In lightly 

grazed pastures, grasses tended to mask cactus while under heavy grazing, cactus was 

more conspicuous. Farmers in the Avonlea area of Saskatchewan maintain that cactus 

has not changed much in the past 20 years and where it has increased, it was through 

careless efforts to break up the clumps with harrows (personal interviews). 

The value of cactus in the North American ecosystem is not always appreciated. 

During drought and under heavy grazing, cactus reduces soil erosion. Clumps of cactus 

conserve moisture by holding snow, and after summer showers the soil within the 

clumps remains moist for several hours longer than soil outside them. Clumps also 

protect desirable plants from grazing so that seeds can be produced to repopulate the 

range after drought or heavy grazing (Houston 1963). 

Prickly-pear is a food for at least 44 species of birds and mammals. For example, seeds 

may account for 65% of the diet of the Harris ground squirrel and up to 5.0% of the 

browse of deer and antelope (Martin et al. 1961). 

The earliest record of an insect attacking cactus dates back several hundred years, 

and there is indication that cultivation of the cochineal, Dactylopius coccus Costa, was 

conducted in Mexico and Central America for many centuries before the voyage of 

Columbus (Mann 1969). 

The first comprehensive study of insects of Cactaceae in the United States was done 

by Hunter et al. (1912). This work described the life history and habits of various 

species, summarized previous information. and provided an extensive and useful bibliography. 

Surveys for insects associated with O. polyacantha and O. /ragilis in Saskatchewan 

and Alberta were made from 1974 to 1979 (Maw & Molloy 1980). Although only 20 

species were found. three, Chelinidea vittiger Uhler, Dacty/opius con/usus (Ckll.), and 

Melitara dentata (Grote), were numerous enough to exert considerable pressure on the 

cactus. D. con/usus and M. dentala can be very destructive and each year destroy about 

10% of the pads (Maw & Molloy 1980) 

Two species of Lepidoptera. Cactob/aslis doddi Heinrich and C. bucyrus Dyar. were 

183

184 M. G. Maw 

Discussion 



obtained from the high altitude valleys of Jujuy province in Northern Argentina for 

screening at Regina. The two species fed on local prickly-pear, but it was necessary to 

injure the pads before the larvae would enter to feed. Once inside, the larvae completely 

hollowed the pads, but then would not leave them to attack new ones. Either the local 

cactus was unsuitable or the insects were diseased for both species became weak and the 

colonies died out after a few generations in the laboratory. 

No introductions of cactus insects are considered, for any harm or inconvenience 

caused by our prairie cactus is balanced by benefits from it. The native biotic agents 

exert considerable pressure on the cactus and our native grasses, when not overgrazed 

are well able to compete. 

Any release of biological control agents to control prickly-pear would be vigorously 

opposed by both the United States and Mexico, because Opuntia spp. are used as 

emergency fodder for cattle and as human food. In addition, at least one species of 

Opuntia is listed as endangered and 12 as threatened and still others are valued as 

ornamentals throughout the American southwest. 

(I) Introduction of biological control agents for Opuntia spp. in Canada should not 

be pursued. 

(2) Any control of cactus in Canada should be approached as a range management 

problem. 

Bement, R.E. (1968) Plains prickly-pear; relation to grazing intensity and blue grama yield on Central Great Plains. Journal of Range 

Matulgement 19, 83-86. 

Houston, W.R. (1963) Plains prickly-pear, weather, and grazing in the Northern Great Plains. Ecology 44, 569-574. 

Hunter, W.O.; Pratt, F.C.; Mitchell, J.D. (1912) The principle cactus insects of the United States. USDA Bureau of Entomology 113. 1-71. 

Mann, J. (1969) Cactus-feeding insects and mites. Smithsonian Institute Bulletin 256, 158 pp. 

Martin, A.C.; Zim, H.S.; Nelson, A.L. (1961) American wildlife and plants. A Guide to wildlife food habits. New York, Dover Publications 

Inc., 500 pp. 

Maw, M.O.; Molloy, M.M. (1980) Prickly-pear cactus on the Canadian prairies. Blue Jay 38, 208-211.

Pest Status 

Chapter 39 

Rhamnus cathartica L., Common or 

European Buckthorn (Rhamnaceae) 

M.G. MAW 

Common or European buckthorn, Rhamnw calhartica L., is the alternate host of crown 

rust or leaf rust of oats, Puccinia coronala Cda. f. sp. avenae Eriks. 

Considerable amounts of urediospore inoculum of crown rust is blown northwards 

every year from the United States and has nothing to do with the presence of buckthorn 

in Canada. Moreover, in some years, crown rust is so widespread and severe, such as in 

1980, that the presence or absence of buckthorn is probably not important (R. V. Clark, 

1980, personal communication) (Hanson & Grau 1979, Peturson 1954). Nevertheless, 

buckthorn is responsible for virtually all of the early infection by crown rust in the 

northern United States and in Canada (Hanson & Grau 1979), infecting oats from two 

weeks (Harder & McKenzie 1974) to a month (Harder 1975) before the arrival of the 

urediospores from the south. 

Buckthorn leaves are the site of spermagonial and the aecial stages of crown rust of 

oats. This is a potential source of new pathogenic variation because hybridization and 

recombination occur in the pathogen on buckthorn (Simons el al. 1979). The greater 

diversity of rare races in the east, as opposed to the west, may be attributed to the 

presence of buckthorn (Fleischmann el al. 1963). Although there are a number of species 

of Rhamnw, both native and introduced, in North America, of those susceptible to P. 

coronala f. sp. avenae, only R. cathartica occurs in any significant numbers in 

Canada (Peturson 1954). 

It is difficult to assess overall losses due to crown rust of oats. Unless there is a general 

epidemic of the rust, the infection is generally extremely variable. In Ontario, in 1977, 

infections ranged from a trace in some fields to nearly complete destruction of the oat 

crop in others (Harder 1978). Yield reductions are negligible if crown rust development 

does not precede heading, especially in relatively dry seasons. A late attack can, 

however, cause losses of 763-1029 kg per ha if the season is delayed by cool and wet 

weather (Fleischmann 1968). When there are few late fields of oats, severe infections of 

30-90% may cause little damage (Fleischmann 1963). 

In Manitoba, estimates of combined crown and stem rust damage in 1970 indicated a 

loss in excess of 154 000 tonnes but less than half of it was attributed to crown rust 

(Martens 1971). In 1969, in Manitoba, losses to crown rust were estimated at 108 ()()() 

tonnes and losses in individual fields ranged from 5-30% (Fleischmann 1969). 

It is only when there is a minimal urediospore shower that the losses due to crown rust 

associated with buckthorn can be determined. Buckthorn is responsible for local and 

persistent infestations of the rust wherever buckthorn and oats are in close proximity 

and a single large buckthorn is sufficient to generate a moderately severe infection in an 

adjacent field (Harder 1975, 1978). The distribution of crown rust in Ontario in 1977 

indicates that buckthorn was responsible in that year for most of the rust infection of 

oats. The very light infection occurring in the absence of buckthorn suggests there was 

little influx of spores from elsewhere (Harder 1978). 

Crown rust adversely affects yield, quality, weight, and protein content of oat seed. 

Light infections cause minor reductions, but infections of 68-80% cause yield 

reductions of 19.2 - 27 .8%, kernal weight of 12.3 -16.1 % , and a grade reduction of about 

one grade (Peturson 1952). 

185

186 M.G. Maw 

Background R. cathartica was introduced into North America as a hedge and shelterbelt shrub or as 

an ornamental in parks and gardens. It varies considerably in size, ranging upwards of 10 

m high under favourable conditions but is more usually less than half that height. It is 

very bushy, often many stemmed, and the shoots and branches terminate in a sharp 

spine. The leaves are alternate, smooth, and elliptical with toothed margins. The flowers 

are in the axils of the leaves, small, greenish, and dioecious. The mature fruit is a bluish 

to nearly black drupe, bitter to the taste, and about 8 mm in diameter. The seed is 3-4 

grooved. 

Reproduction is entirely by seeds which germinate 90-100% when the fruit is just 

ripe. The plant regenerates quickly from cut stems and after burning and grazing 

(Montgomery 1956, Mulligan 1952, Rydberg 1932). 

(a) Habitat 

In eastern Canada, buckthorn is found along fence rows, along roadsides, in open 

woods, and along the gently sloping banks of lakes, rivers, and streams, it is often seen in 

solid masses along every fence row in many locations, but apparently is not found to any 

extent in pastures. Plants of about 2.5 m can be found in wood openings with many 

smaller plants and seedlings in the more shaded locations. Where the trees are removed, 

these smaller plants grow rapidly forming a forest of buckthorn. It tends to be more 

commonly on soils of high moisture content than on light, dry soils (Mulligan 1952). 

In Manitoba, there are relatively few areas outside of the larger towns and cities where 

buckthorn is found (Peturson 1954). It is concentrated in Winnipeg, Brandon, and near 

Macdonald, generally as park and hedgerow plantings (Bassett 1958), and in a sheltered 

ravine near Morden (Harder 1975). 

In England, it is found chiefly on alkaline peat and limestone soils (Godwin 1943). 

(b) Geographic range 

In England, it is found in the midland, southern and eastern counties, but is absent 

from Cornwall, North Devon, Northumberland, and western counties of Wales. 

In Ireland, it is present in a wide belt across the central Irish plain, but absent from the 

southern counties and absent or rare in the northern. 

It is doubtfully native in Scotland, except possibly in Dumfries. 

Its range extends through the greater part of Europe to 60" 48' in Norway and 61 0 41' in 

Sweden, in southern Finland, Esthonia, and across Russia into western Asia, Afghanistan, 

and Turkestan. 

It is present in southern Europe to middle and eastern Spain and Macedonia, and 

sparingly at high altitudes in Morocco and Algeria, but absent in the Balearics, Corsica, 

and Sardinia, also from western Siberia, Transcaucasia to Altai (Godwin 1943). 

In North America, R. cathartica is found in the New England states, Virginia, 

westward to Illinois, Missouri, Wisconsin, Minnesota (Fernald 1950), Quebec, Ontario 

Manitoba, and to a limited extent in Saskatchewan, Alberta, and the Maritimes. 

(c) Uses 

R. cathartica is a useful hedge and shelterbelt shrub and as such has been extensively 

planted in Ontario and Quc!bec and to a lesser extent in other provinces. It is also used as 

an ornamental in gardens and parks.

Discussion 

Rhamnus cathartica L.. 187 

The fruit is eaten by birds but usually only as a last resort. For example. robins will 

take them sparingly when no other food is available in the early spring. It is claimed that 

emodin in the green fruits prevents premature predation by birds (Trial & Dimond 1979). 

Perhaps late retention of fruit well into the spring attests to this. 

Several species of birds are cited as feeding on the fruit in Germany and England. and 

mice have been seen to eat the seed from dried fallen fruit. 

(d) Control 

Buckthorn is so prevalent in Ontario. especially in the eastern counties. and the bush is 

of such a large size that it is an almost impossible task to eradicate it by spraying. cutting, 

or bulldozing. So very little, if anything, is being done to control it. 

Herbicides give unsatisfactory results and 2,4,S-T which was recommended as a 

treatment of freshly cut stumps is now outlawed in many states and provinces (Hanson 

& Grau 1979). In any event, combinations of 2,4,-D and 2,4,S-T had little permanent 

effect and treated bushes regrew from the base and many of the test buckthorn leafed out 

one year after treatment (Switzer 1961). Ammate-X (ammonium sulfamate, duPont) is 

recommended as either a foliar spray or a stump treatment in Wisconsin (Hanson & 

Grau 1979) but early tests in Ontario showed that Ammate-X and fenuron (3-phenyl-l, 1dimethylurea) 

had little effect in that most of the test plants over four feet high continued 

to grow (Switzer et al. 1960, Switzer 1961). 

Cutting buckthorn gives at best temporary control because the stumps send up 

vigorous shoots in a relatively short time. However, cutting of individual bushes can 

reduce the incidence of crown rust in nearby fields. 

(e) Biological control 

Because chemical control of buckthorn is at best temporary, biological control is an 

attractive alternative and so at the request of Canada a survey for biological control 

agents was made by tbe Commonwealth Institute of Biological Control in 1964 

(Malicky et al. 1970). It was found that practically all the phytophagous insects specific 

to or closely associated with Rhamnaceae are in the orders Lepidoptera and 

Hemiptera. Many Coleoptera were found on Rhamnaceae but none was specific 

(Malicky el al. 1970), 

Investigations. particularly starvation tests suggest that the geometrids SCOlosia 

vetulata Schiff., Triphosa dubitata L., and the Iycaenid Thecla spini L. may be 

possible species for the biological control of R. cathartica in Canada. The geometrids 

combine a high degree of host specificity with a potential to defoliate their host, 

however. T. dubitata overwinters as an adult which may prove difficult in Canadian 

situations. T. spin; may have too wide a host range to be an acceptable agent, but 

there is some doubt as to the correctness of the host records (Malicky el al. 1970). 

R. calharlica is only one of several species of Rhamnaceae capable of being an 

alternate host to crown rust of oats (Dietz 1926). It is, however, the only one occurring 

in any significant numbers in Canada (Peturson 19S4) .. Eradication of buckthorn would 

not erase the problems of crown rust but would remove the site of the aecial or sexual 

spores of the rust and thus the source of pathogenic variation through hybridization 

and recombination of genetic material (Simons el al. 1979). Hybridization and recom-

188 M. G. Maw 



bination, however, may not be as important as once thought. New races appear first in the 

main north-south rust population, and only later become established in populations 

cycling on buckthorn. (Simmons M.D. personal communication 1983). 

Infections of rust due to buckthorn are usually very local but can result in complete 

loss of the crop near buckthorn. Infection levels usually decline linearly with distance 

from the buckthorn (Harder 1975) and a few hundred meters from the source is 

sufficient to make a significant difference in infection incidence. Growers must either 

avoid planting oats near buckthorn or eradicate it from their farms. Buckthorn is so 

widespread and persistent that complete eradication is not feasible. 

Biological control of buckthorn appears to be the only course to lessen the impact 

of crown rust on oat production. It is not expected that introduced bi;:'logical agents 

will eradicate buckthorn, but they might add to the stress of climate and soil type to 

slow the spread of the shrub. Also, it is expected that any reduction in leaf surface will 

aid in diminishing rust inoculum early in the season when the greatest injury is caused 

to the oat crop. Not many insects find buckthorn an attractive food source because of 

the feeding deterrent chemical, emodin (Trial & Dimond 1979). The original sources of 

the North American populations of buckthorn are not known and there could be 

different biotypes containing varying amounts of emodin. This may make selection of 

effective biological control agents difficult. 

Surveys for phytophagous insects in Europe found no species specific to R. 

eathartiea, although the Lepidoptera Seotosia vetulata and Thecla spini exhibit a 

degree of specificity to Rhamnaceae. 

Thus when attempting to control buckthorn biologically, one has to consider that 

species other than R. eathartiea will be attacked. The degree to which these other 

species will be damaged must be determined in the screening tests, and decisions made 

as to whether damage and possible loss of other species of Rhamnaceae can be 

tolerated. 

Even though R. eathartiea is the source of early infection of oats by crown rust and is the 

site of the aecial stage of the rust, its complete eradication would at best result in only a 

reduced incidence of the disease and the appearance of new rust races. Therefore. it is 

recommended that biological control work on R. cathartiea be discontinued. 

Bassett. 1.1. (1958) A sUlVey of the European buckthorn and common barberry in southern Manitoba. Science Service, Division of Botany 

and Plant Pathology, Canadian Department of Agriculture Ottawa, 22 pp. 

Dietz, S.M. (1926) The alternate hosts of crown rust, PucciniD corofUlta Corda. Jounuzl 0/ Agricultural Research 33, 953-970. 

Fernald. M.L. (1950) Gray's manual of botany. American Book Corp., New York, 1632 pp. 

fleischmann. G. (1963) Crown rust of oats in Canada in 1963. ConodiDn Plant Disease Survey 43,168-172. 

fleischmann, G. (1968) Crown rust of oats in Canada in 1968. CatuldiDn Plant Disease Survey 48,99·101. 

fleischmann, G. (1969) Crown rust of oats in Canada in 1969. Canadian Plant Disease Survey 49,91-94. 

fleischmann. G.; Samborski, D.l.; Peturson, B. (1963) The distribution and frequency of occurrence of physiologic races of Puccinia 

coronata Corda. f. sp. avenae Erikas. in Canada. CanaditJn Journal of Botany 41, 481-487. 

Godwin, H. (1943) Rhamnaceae. Journal of Ecology 31, 66-92. 

Hanson, E.W.; Gmu, G.R. (1979) The buckthorn menace to oal production. University of Wisconsin Extension Bulletin A 2860,2 pp. 

Harder, D.E. (1975) Crown rust of oats in Canada in 1974. Canaditln Plant Disease Survey 55, 63-65. 

Harder, D.E. (1978) Crown rust of oats in Canada in 19n. CafUldian Plant Disease Survey 58, 39-43. 

Harder, D.E.; McKenzie, R.l.H. (1974) Crown rust of oats in Canada in 1973. CafUldian Plant Disease Survey 54, 16-20. 

Malicky, H.; Sobhian, R.; Zwolfer, H. (1970) Investigations on the possibilities of a biological control of Rhamnus cathartica L. in 

Canada. Host mnges, feeding sites, and phenology of insects associated with European Rhamnaceae. 

Zriuchri/t fUr angewantlte Entomologie 6S, n -97.

Blank Page 

190

Pest Status 

Background 

Chapter 40 

Salsola pestiter A. Nels., Russian 

Thistle (Chenopodiaceae) 

P. HARRIS 

Russian thistle, Salsola peslifer A. Nels. (= S. iberica Sennen & Pau; = S. kali var. 

lenuifolia Tausch.) is an annual, native to southern Russia and western Siberia. It was 

introduced as a flax seed contaminant into South Dakota in 1873 (Robbins el al. 1951), 

but it was probably also present in the many introductions of Turkestan alfalfa imported 

into Canada and the United States. The reason for suspecting this source was that Wilcox 

& Stevenson (1909) found it in 51 out of 201 samples of alfalfa seed in Nebraska. In 

Canada, it became particularly prevalent in the 19305: Moynan (1939) reported Russian 

thistle constantly invading new territory in Manitoba, and that between 1935-38 it 

became established on illustration stations at Roblin, Gilbert Plains, and Ste. Rose. It is 

now present in all provinces except Newfoundland, although in eastern Canada it is 

almost exclusively a railway and roadside weed (Frankton & Mulligan 1970). It is, 

however, abundant in the drier parts of the prairies and British Columbia on both 

cultivated land and over-grazed or disturbed pasture. In Saskatchewan, Russian thistle 

varied between the fifth to the seventh most abundant weed on cultivated land and in the 

southwest of the province it was present in 64% to 100% of the 0.25 ml samples surveyed 

(Thomas 1976,1977,1978, 1979). In winter the plants become tumble weeds that collect 

on fences and other obstructions. 

In western United States, Russian thistle is the favored alternate host of the beet 

leafhopper, Circulifer lenellus (Baker), which is the vector of the curly top virus of sugar 

beet and other crops (Severin 1933). The losses caused by this disease have been a major 

impetus for the biological control ofthe weed in the United States, however, the disease 

does not occur in the sugar beet areas of either Manitoba (Robertson 1968) or Alberta 

(R.J. Howard, 1981, personal communication). 

The insect guild on Russian thistle in North America is typical of an introduced weed. 

Goeden & Ricker (1968) found 91 species of insects feeding on it, but none of them did 

appreciable damage and all but two were polyphagous. In contrast, in the palaearctic the 

plant is attacked by a number of specialized insects (Hawkes 1969, Goeden 1973). Two 

of these have been cleared by workers in the United States. The Canadian programme 

against Russian thistle has been based on this work. 

The stem boring moth, Coleophora parthenica Meyr., was released in the United 

States in 1973 following host specificity studies by Hawkes & Mayfield (1976). The 

species has a high temperature threshold: a minimum of IS.5°C is required for development 

and about 500 degree-days above this temperature for maturation; however, about 

twice this number of degree-days are required for a population increase (Hawkes, 1976, 

personal communication). The moth is well established and has attained high population 

densities at many places in southwestern United States where it normally has three 

generations a year (Hawkes & Mayfield 1978b). At Indio, California, Goeden & Ricker 

(1979) found an average of one larva per 7.4 cm of stem. This level of attack had no 

effect on plant size, mortality. or seed production so the moth will have to be supplemented 

with other biological control agents to achieve beneficial results. 

The case bearer. Coleophora klimeschiella Toll., was released in California in 1977 

191

192 P. Harris 


Table 49 


following screening studies by Hawkes & Mayfield (19780). The biology of this insect 

is reported by Khan & Baloch (1976): the first two instars are leafminers; in the last 

three, the larva lives outside the leaf in a case of hollowed leaves, and feeds by 

protruding its head and forelegs through a hole in the leaf so that it continues to feed 

inside the leaf. The insect overwinters as a larva inside the case attached to SaJsoJa 

stems or stones. There are one to three generations a year in Pakistan, depending on 

elevation. C. klimeschiella is established in California (Julien 1982). 

The releases of both C. parthenica and C. klimeschielJa are listed in Table 49. 

C. parthenica was released on a number of occasions in July and August in stands of 

Russian thistle at the Regina and Swift Current Research Stations. The moths remained 

on the plants where they were released for several days, but no eggs or larvae were 

found in the vicinity. Larvae in the stems of potted plants that were placed outside failed 

to complete development. The problem was presumed to be the cool summer temperatures 

of the Canadian prairies. At Regina in July and August, the minimum temperature 

was below the threshold for development for 50 days in July and August, and on 16 

August, the temperature fell to 1.3°C. At all sites on the Canadian prairies, there is 

normally less than the 500 degree-days required by the insect. 

C. klimeschielJa was released in June at the Regina Research Station and bred in the 

summer of release and the following summer. The population was less than one larva per 

Russian thistle plant and they did no appreciable damage. In the spring of 1979, the 

release site was flooded for several weeks in the spring and the colony was destroyed. 

Open releases and recoveries against SaJsola pestifer A. Nels. 

Year No. of moths released Source Release site 

Coleophora parthenica 

1975 273 

1975 66 

1975 33 

Coleophora klimeschiella 

1977 91 

California 

California 

Pakistan 

Swift Current. Saskatchewan 

Regina. Saskatchewan 

Regina. Saskatchewan 

California Regina, Saskatchewan 

ex Pakistan 

Recovery 

bred in 1977 

and 1978 but 

not in 1979 

Summer temperatures on the Canadian prairies are too low for C. parthenica, and there 

is no purpose in making additional releases unless a strain with a low temperature 

threshold can be found. Even if such a strain can be established in Canada, on the basis of 

results in the United States, the density of Russian thistle is unlikely to be affected. 

C. klimeschiella can survive in Saskatchewan and hence presumably elsewhere in 

southern Canada. Insects released for the biological control of a weed often require 

several years for the selection of a strain adapted to the region, so the lack of a rapid 

increase in the population should not be the sole reason for discontinuing further




Sa/.m/a pestilL'r A. Nels.. 193 

attempts. More discouraging is the absence of any data on the losses caused by this 

extremely common weed on the prairies and the present general lack of interest in a 

biological control solution for Russian thistle. 

Biological control of S. pestifer should be discontinued until its use can be justified in 

economic terms. 

I am grateful to R.B. Hawkes for reviewing the manuscript. 

Frankton. C.: Mulligan. G.A. (1970) Weeds of Canada. Canadian Department of Agriculture. 217 pp. 

Goeden. R.D. (1973) Phytophagous insects found on Salsola in Turkey during exploration for biological weed control agents for California. 

Entomophaga 18. 439-448. 

Goeden. R.D.; Ricker. D.W. (1968) The phytophagous insect fauna of Russian thistle (Salsola kali var. tenuifolia) in southern California. 

Annals of the Entomological Society of America 61. 67-72. 

Goeden. R.D.; Ricker. D.W. (1979) Field analysis of Coleophora parthenica (Lcp.: Coleophoridae) as an imported natural enemy of 

Russian thistle. Salsola iberica. in the Coachella valley of southern California. Environmental 


Hawkes. R.B. (1969) Insects recorded from Salsola spp. and Halogeton spp. Report of the Entomology Research Division. USDA. ARS. 

Albany. California. 55 pp. 

Hawkcs. R.B.; Mayfield. A. (1976) Host specificity and biological studies of Coleophora parthenica Meyrick. an insect for the biological 

control of Russian thistle. Commemorative Volume in Entomology. Department of Entomology. 

University of Idaho. 37-43. 

Hawkes. R.B.; Mayfield. A. (19780) Coleophora klimeschitlla. biological control agent for Russian thistle: host specificity testing. 

Environmental Entomology 7. 257 - 261. 

Hawkes. R.B.; Mayfield. A. (l978b) Coleophora spp. as biological control agents against Russian thistle. Proceedings of the 4th Inter. 

national Symposium on Biological Control of Weeds. 113-116. 

Julien. M.H. (1982) Biological control of weeds: a world catalogue of agents and their Iarget weeds. Commonwealth Institute of Biological 

Control. lOS pp. 

Khan. A.G.; Baloch. G.M. (1976) Coleophora klimeschiella (Lcp: Coleophoridae) a promising biocontrol agent for Russian thistles. 

Salsola spp. Entomophaga 21. 425-428. 

Moynan. J.e. (1939) Di\ision of illustration stations. Progress report 1934 to 1938. Part II. Department of Agriculture. Canada. 130 pp. 

Robertson. H. (1968) Sugar farmers of Manitoba. The Manitoba Beet Growers Association. 176 pp. 

Robbins. W.W.; Bellue. M.K.; Ball. W.S. (1951) Weeds of California. Sacramento; California State Printing Office. 547 pp. 

Severin. H.H.P. (1933) Field observations on the beet leafhopper. EUlellix ttnnt'llus. in California. Hilgardia 7. 281-360. 

Thomas. A.G. (1976) Weed survey of cultivated land in Saskatchewan. First annual report. Agricultural Canada. 93 pp. 

Thomas. A.G. (1977) Weed survey of cultivated land in Saskatchewan. Second annual report. Agriculture Canada. 103 pp. 

Thomas. A.G. (1978) Weed survey of cultivated land in Saskatchewan. Third annual report. Agriculture Canada. 113 pp. 

Thomas. A.G. (1979) Weed survey of cultivated land in Saskatchewan. Fourth annual report. Agriculture Canada. 141 pp. 

Wilcox. E.M.; Stevenson. N. (1909) Report of the Nebraska seed laboratory. Bulletin of the Agric-u1tural Experiment Station, Nebraska 110. 

29pp.

Blank Page 

194

Pest Status 

Background 

Chapter 41 

Senecio jacobaea L., Tansy Ragwort 

(Compositae) 

P. HARRIS, A.T.S. WILKINSON and J.H. MYERS 

The status of tansy ragwort, Senecio jacobaea L., in Canada was described by Harris el 

al. (1971). Since that time the distribution has changed slightly. A small stand of the 

weed that had existed at Guelph, Ontario, for many years recently started to spread (J. 

Alex, 1981, personal communication). A small infestation in the Gaspe Peninsula, 

Quebec, recorded prior to 1900 could not be found by Watson & Muirhead (1979). The 

weed has continued to spread in the lower Fraser Valley in British Columbia, and it 

remains a serious socio-economic problem in the maritimes where there are many small 

mixed farms with a few cattle. The small field size and lack of specialized equipment 

makes chemical and mechanical control difficult and expensive. On the other hand, the 

death of one or two cattle from ragwort poisoning is a serious loss to the family food and 

income. There are no provincially compiled statistics of cattle deaths from ragwort as 

diagnosis is difficult and many cattle are sent for early slaughter if ragwort poisoning is 

suspected. However, in 1981, in Prince Edward Island the Montague Veterinary Clinic 

reported 12-20 ragwort-related cattle deaths; the Kensington Clinic had 20 but many 

more were suspected; the Provincial Veterinary Pathology Laboratory reported 10-12 

but suspected more (L. Thompson, 1981, personal communication). Thus the total 

cattle mortality from ragwort is similar to the 40-65 deaths estimated to have occurred 

in 1968 (Harris et al. 1971). 

The cinnabar moth, Tyria jacobaeae (L.), was established in the Canadian maritimes in 

1964 and in British Columbia in 1965 for the biological control of tansy ragwort. Despite 

difficulties in getting the moth established (Harris et al. 1975), it is now present throughout 

the ragwort infested regions of Canada, including Newfoundland where no releases 

were made (Larson & Jackson 1980). 

The effect of the moth on the weed has varied widely. At Prince Charles, Prince 

Edward Island, and Durham, Nova Scotia, the weed has practically disappeared from 

the release sites although it has persisted in the disturbed ground along the roadsides 

(Harris el al. 1978). At Durham it was largely replaced by goldenrod Solidago sp. At 

Sussex, New Brunswick, the ragwort stand collapsed after defoliation by cinnabar 

larvae while the Canada thistle, Cirsium arvense (L.) Scop., increased. Tansy ragwort 

has since returned to the site and the density of cinnabar reached circa three larvae/stem 

in 1980 with scattered but numerous larvae in 1981 (D. Finnamore, 1981, personal 

communication). Near Nanaimo, British Columbia, over the past ten years an average 

of 38% of the ragwort was defoliated with another 18% partially defoliated. This has had 

little effect on the density of the flowering plants but they are smaller. In California, 

Hawkes & Johnson (1978) found that, with cinnabar moth attack, the number and size 

of the ragwort flowering stems decreased and the number of rosettes increased. Not all 

the declines were the result of the cinnabar moth as Myers (1980) found that two of five 

stands in Nova Scotia declined even though the cinnabar population was not large 

enough to cause extensive defoliation. 

Many papers have been written in Canada and elsewhere on the causes of the diverse 

effects of the cinnabar moth on tansy ragwort. Harris et al. (1978a) related the collapse 

195

196 P. Harris. A. T. S. Wilkinson and J. H. Myers 

of some maritime stands of the weed following cinnabar defoliation to the frost sensitivity 

of the regenerating plants. Several studies (Green 1974, Campbell 1975, Myers 1976, 

Myers & Campbell 1976a, 1976b) have investigated the importance of ragwort spacing 

on cinnabar egg distribution and the success of larval transfer between plants. They 

showed that one requirement for explosive increases of the moth was dense stands of the 

weed. Dempster (1971) reported a higher mortality of cinnabar eggs and larvae on 

ragwort rosettes than on flowering stems and Myers (1980) found that cinnabar populations 

in areas with a high density of closely spaced rosettes tended to be less stable than 

on those with low rosette density. A high nitrogen content in the plant increased both 

moth fecundity and egg mass size in the following generation. Myers & Post (1981) 

argued that this would tend to destabilize the cinnabar population by over-exploitation 

of the food resource. In a study by Lakhani & Dempster (1981), the number of eggs had 

a rather small effect on the subsequent moth numbers because high egg density was 

often associated with larval starvation. In a dune habitat, Meijden (1979) described the 

cinnabar population as "walking on ice floes" because small stands of ragwort became 

extinct one or two years after attack by the moth and then reappeared after the moth 

emigrated to other stands. Predators were important in some instances (Wilkinson 1965, 

Myers & Campbell 1976c, Meijden 1979). In 1980 at Nanaimo, British Columbia, most of 

the pupae were destroyed resulting in a low population in 1981 in which only 3% of the 

plants were attacked. 

Philogene (1975) found that the day length and temperature during larval development 

did not affect the obligatory pupal diapause. However, the moth has adapted its temperature 

threshold for emergence in the spring so that in the various regions of North 

America larval feeding remains synchronized with ragwort flowering (Myers 1979). 

Richards & Myers (1980) found that maternal moth size and temperature requirements 

for moth emergence were heritable and Myers (1978) found that the present populations 

of the moth have regional differences in their enzyme systems that are irrespective of 

their origin. Thus in a few years since release, the moth has adapted to its new habitat 

with the result that its behaviour now is not necessarily the same as that of the stock 

released. 

A model by Lakhani & Dempster (1981) showed that for both Nanaimo, British 

Columbia, and Weeting Heath in Britain, the changes in the density of the weed closely 

conformed to the amount of spring and early summer rainfall. The model showed that at 

these sites the cinnabar population merely tracked the changes in the density of the 

weed. Myers (1980) also concluded that population fluctuations after an initial reduction 

of plant size by introduced cinnabar moths have a large environmental component. One 

indication that different factors are important in different sites is that the model did not 

fit the results from a more moist site in Oregon. In a more generalized model Roff & 

Myers (unpublished) found that depending on the degree of larval dispersal, the cinnabar 

population could be cyclic, stable, or chaotic. The gamut of these conditions 

occurs in nature. There are several ragwort habitats that are not utilized by the moth: the 

weed tends to be avoided when growing in partial shade; the cinnabar pupae are not able 

to overwinter in wet sites (Dempster 1971) so the moth tends to be absent in Europe from 

pastures on river flood plains, which often have dense ragwort stands; the moth is rare in 

the Swiss Jura on the widely separated plants or small clumps of plants. It is a weak flier 

and has dispersed less rapidly in California than the beetle Longitarsus jacobaeae 

(Waterhouse). 

In many habitats the cinnabar moth has not reduced the density of tansy ragwort, but 

plants defoliated annually tend to be smaller so there has been some reduction in ragwort 

biomass. Also for about two months in the summer there is little ragwort foliage in the 

pastures or hay fields so that availability of the toxic foliage to cattle is reduced. The 

level of control is not satisfactory as a high density of the weed remains on many sites for 

much of the year, so the cinnabar moth needs to be supplemented by additional agents.


HyJemya senecieJJa 

Meade (Diptera: 

Muscidae) 

Tyriajacobaeae (L.) 

(Lepidoptera: 

Arctiidae) 

(a) Ecology 

Senecio j(lcoh(l('(l L. . 197 

H. senecie/la larvae reduce seed production by feeding in ragwort flower heads. The 

biology was described by Miller (1970). and an unsuccessful attempt to establish it in 

British Columbia and Prince Edward Island in 1968 was reported by Harris el 01. (1971). 

The fly has been established in New Zealand where it infested up to 77% of the heads at 

peak flowering but the effect of the reduced seed production on ragwort density was not 

determined. The fly was established in California and probably in Oregon and 

Washington (Frick 19690) but the California site was subsequently destroyed (Julien 

1981). 

(b) Releases 

A summary of releases in the current review period is shown in Table 50; none of them 

became established. At least part of the problem was poor synchrony between emergence 

of the flies and ragwort flowering: in 1970 the H. seneciella were received in May 

and placed outside in a field cage in Prince Edward Island. The flies emerged between 8 

and 17 June but the host plant did not flower until August. In 1971 emergence was 

delayed until the second half of July but still did not result in establishment (L. 

Thompson. 1981. personal communication). The results from British Columbia were 

similar. 

Establishment in the United States was obtained with much larger releases of circa 

2000 flies. As egg viability was circa 25% (Frick 1969b) a larger release than that used in 

Canada is necessary. The problem with the synchronism of fly emergence can probably 

be overcome by releasing the mature larvae at the end of the summer; this could be done 

with the Oregon or Washington stock providing that it is free of parasites. The value of 

establishing the fly is less clear since most ragwort reproduction in pastures is by vegetative 

propagation from existing plants. It is unlikely that the fly would survive in stands 

defoliated by cinnabar larvae which consume the flowers preferentially. 

Releases 

Field collected larvae from Nova Scotia were released at two sites in New Brunswick in 

1970 and at seven sites in Ontario in 1979 and 1981 (Table 50). These were the only 

releases since those reported by Harris el 01. (1971). Establishment occurred at both 

sites in New Brunswick resulting in widespread defoliation of tansy ragwort but on a 

long-term basis this is a less than desirable level of control. The insect did not become 

established in Ontario, possibly because of predation by ants (Alex, 1981, personal 

communication). About 20% of the Ontario shipment died in transit indicating that the 

popUlation was heavily stressed and probably diseased.


Table 50 

Senecio jacobaI'll L. , 199 

L. jacobaeae was recovered at the two Prince Edward Island sites in 1982 and 1983 

although numbers were low (L.S. Thompson personal communication 1983). Also the 

possibility of some root damage from larval feeding was noted in New Brunswick (D. 

Finnamore personal communication 1981). Prince Edward Island has a more even 

distribution of summer rain than occurs on the south west coast of British Columbia, so 

possibly the summers are too moist for the biotype released. Frick & Johnson (1972) 

found that the life cycle of the Swiss biotype adapted in the laboratory by a decrease in the 

length of the egg diapause. With the beetle's rapid adaptability and the probable wide 

genetic variation of the British Columbia population (stock from three sources has been 

released there), it should be possible to select an adapted biotype in a field cage and 

increase the survivors in the laboratory if the field population falls critically low. The 

other alternative is to import beetles from a climate with a similar summer rainfall to 

Prince Edward Island, but even so some adaptation would probably be necessary. 

(1) The cinnabar moth has reduced the seriousness of tansy ragwort in many areas; 

however additional species of biological control agents are needed if a fully satisfactory 

level of ragwort control is to be achieved. 

(2) The most obvious candidate as a second biological control agent is the beetle 

Longilarsils jacobaeae. A biotype of this beetle is now adapted to the southwest coast of 

British Columbia and should be distributed to ragwort infestations in the region. Estab- 

Open releases and recoveries against Senecio jacobaea L. 

Species and release site Year Origin No. Recovered 

Long;tarsus jacobaeae (Waterhouse) 

British Ollumbia 

Vancouver 1971 California ex Italy 100 adults 1974 

Vancouver 1973 Switzerland 38 adults 

Abbotsford 1971 California ex Italy 400 adults 

1972 Lab reared ex California 

and England 400 adults 

1972 California and England 250 adults 

1974 UBC site ex Switzerland 200 adults 1975 

Nanaimo 1974 England 92 adults 1976 

1976 Oregon ex Italy 1000 adults 

Chilliwack 1978 Abbotsford 500 adults 1979 

Prince Edward Island 

Mt. Herbert 1978 British Columbia 300 adults 1982 

Charlottetown 1981 British Columbia ISS adults 1982 

New Brunswick 

Fredericton 1981 British Columbia 180 adults 

Tyrill jacobaeat (L.) 

New Brunswick 

Sussex 1970 Nova Scotia 1000 larvae 1971 

Bathurst 1970 Nova Scotia 1000 larvae 1971 

Ontario 

Guelph 1979 Nova Scotia 4500 larvae Not recovered 

Guelph 1981 Nova Scotia 4500 larvae Not recovered 

H)'lemya sm«iella (Meade) 

British Ollumbia 

Abbotsford 1970 Switzerland 6S adults 

453 puparia Not recovered 


Charlottetown 1970 Switzerland liS adults Not recovered 

Charlottetown 1971 United States liO adults Not recovered

Sellecio jacoba('(/ 201 

Myers, 1.H. (1980) Is the insect or the plant the driving force in the cinnabar moth-tansy ragwort system? Oecologia 47.16-21. 

Myers. J.H.: Campbell. B.l. (19700) Indirect measures of larval dispersal in the cinnabar moth. Tyriajacobal'al' (Lepidoptera: Arctiidae). 

Canadian Entomologi5/ lOB. 967-972. 

Myers. 1.H.: Campbell. B.l. (1976b) Distribution and dispersal in populations capable of resource depletion. A field study on cinnabar 

moths. Oecologia 24. 7-20. 

Myers, J.H.: Campbell, B.l. (1976c) Predation by carpenter ants: a deterrent to the spread of cinnabar moth. Journal of the Entomological 

Society of British Columbia 73. 7-9. 

Myers, I.H.: Post. B.I. (1981) Plant nitrogen and fluctuations of inM:ct populations: a test with the cinnabar moth-tansy ragwon system. 

Oemlogia 48, 151-156. 

Newton. H.C.F. (1933) On the biology of some species of Longi;ar.sus living on ragwon. Bulletin of Entomological Research 24. 511-520. 

Philogene. B.J.R. (1975) Responses of the cinnabar moth, Hypocrita jacobaeae to various temperature/photoperiod regimes. Journal of 

Insect Physiology 21. 1415-1417. 

Richards. L.J.: Myers, 1.H. (1980) Maternal influences on size and emergence time of the cinnabar moth. Canadian Journal of Zoology 58. 

1452-1457. 

Roff, D.; Myers. J.H. Simulating the dynamics of the cinnabar moth populations: a study of complexity in a deterministic world 

(unpublished manuscript). 

Shute, S.L. (1975) Longitarsw jacobaeae Waterhouse (Col.. Chrysomelidac): identity and distribution. Entomologists' Monthly 

Magazine. 111 (1328-13300). 33-39. 

Watson, A.K.; Muirhead. L. (1979) Exploration of the Gaspe region of Quebec for tansy ragwon. p. 41 I. In: Research repon. Expen 

Committee on Weeds (Eastern Canada). 412 pp. 

Wilkinson. A.T.S. (19(5) Releases of cinnabar moth. Hypocrita jacobaeae (L.) (Lepidoptera: Arctiidae) on tansy ragwon in British 

Columbia. Proceedings of the Entomological Society of British Columbia 62. 10-13.

Blank Page 

202

Pest Status 

Background 

Chapter 42 

Silene cucubalus Wibel, Bladder Campion 

(Caryophyllaceae) 

M.O. MAW 

Silene cucubalus Wibel is a deep rooted perennial of Eurasian origin. It is spread by seed 

(as many as 20 000 per plant) as well as vegetatively by parts of the root crown severed 

by implements. It is resistant to the common herbicides 2,4-D (2,4-dichlorophenoxyacetic 

acid) and MCPA (4-chloro-2-methylphenoxyacetic acid) at rates which can be 

safely used in grain crops. The weed grows in waste places, roadsides, and railyards, 

and although it is an infrequent weed in cultivated ground (Boivin 1968), it can be 

troublesome in well drained pastures, cereal crops, and hay. It is found in the northeastern 

and central United States and in every province of Canada to latitude 54°N 

(Scoggan 1978) and is more common in the eastern than in the western parts of its range 

(Frankton et al. 1970). 

Although the weed is generally not a great problem throughout its Canadian range, 

there are localized areas where it causes concern. For example, in the Ethelbert district 

of Manitoba, a survey of weeds in cultivated fields (Thomas 1978) showed it to be 

present in 25% of the samples in 50% of the fields surveyed with a mean density of 5.9 

plants per square meter. In contrast, the weed was reported in only one of the remaining 

38 Manitoba districts surveyed. and there it was found only in 0.4% of the samples in 

8.3% of the fields at a density of 0.6 plants per square meter. 

Although it would seem that there has been little change in the status of the weed on 

cultivated lands since the 1966 survey (Alex 1966), agricultural practices have altered 

the situation in areas such as in southeastern Manitoba. Here a shift has been away from 

annual tillage to establishment of pastures and forage crops and forage seed production. 

Where bladder campion was not a problem as recently as three years ago, it now is a 

concern in over 4200 hectares and only limited control is being provided by herbicides 

and cultural methods. 

Surveys of the European insect fauna on species of Silene and Melandriwn were made 

by the Commonwealth Institute of Biological Control (Miotk 1973). Sixty-six percent of 

the phytophagous insects on the two genera were oligophagous and the supposedly 

stenophagous species were either weevils or noctuids. 

The chrysomelid, Cassida azuna Fab. (mistakenly identified as Cassida hemisplwerica 

Hbst.) (Maw & Steinhausen 19800. 1980b), was collected in Switzerland and screened in 

Canada (Maw 1976). The Cassidinae are generally specialized in their feeding habits and 

species in a subfamily are usually restricted to a limited group of plants. This was found 

to be so with C. azurea. 

First instar larvae fed on all the plants in the tribes Sileneae and Alsineae tested but 

they developed only on S. cucubalus. S. cserei. S. glauca. S. noctiflora. S. maritima, S. 

alba, S. acau/is, Gypsophila repens, Dianthus chinensis .. and D. plumarius. Damage by 

young larvae is confined to the epidermis of the leaf. while older larvae and adults eat 

large holes in the leaf blade. Flowers of Silene are eaten by both larvae and adults. 

203

2M M. G. Maw 

Discussion 



Although starvation tests give the impression that C. azurea has a wide host range, only 

plants in the family Caryophyllaceae supported development and in most instances only 

the younger tender leaves were eaten. Older and harder leaves and those with waxy 

coatings resist attack from young larvae and older larvae fare little better. It is expected 

that under field conditions, C. azurea would direct its attack to S. cucubalus. Other 

Silene would at best be marginal hosts. Dianthus spp. might be eaten when Silene spp. 

are unavailable. This would, however, be very restricted because the hard texture and 

waxy coating of the leaves make sustained feeding difficult for older larvae and adults 

and almost impossible for young larvae. 

With the main concern being the spread of S. cucubalus into forage, hay, and forage 

seed production fields, leaf feeding biological control agents may not be too successful. 

They will however be useful in situations where bladder campion is not cut, such as in 

waste areas. Root feeders should be of more use and so should be actively sought for 

biological control of S. cucubalus in hay and forage crops. 

(1) A biological control programme for S. cucubalus be continued. 

(2) C. azurea be reconsidered as a control agent. 

(3) Root feeders such as Hadena luteago Schiff. and H. andalusica Stgr. be 

studied and their potential as control agents be assessed. 

Alex, J .F. (1966) Survey of weeds of cultivated land in the prairie provinces. Regina, Saskatchewan; Canada Agriculture, Research Branch, 

68 pp. 

Boivin, B. (1968) Flora of the prairie provinces. Pan 2. Provancherea 3. Herbier Louis-Marie. Quebec; Universite Laval. 185 pp. 

Frankton. C.; Mulligan. G.A.; Wright, W.H.; Steins. I. (1970) Weeds of Canada. Ottawa; Canadian Depanment of Agriculture. 217 pp. 

Maw. M.G. (1976) Biology of the tonoise beetle Cossilill hemisphaerica (Coleoptera: Chrysomelidae), a possible biological control agent 

for bladder campion. Silene cucuba/us (Caryophyllaceac), in Canada. Canadian Entomologist 108. 

945-954. 

Maw. M.G.; Steinhausen. W.R. (19800) Corrigendum for "Biology of the tonoise beetle Cassilill hemisphaerica (Coleoptera: Chrysomelidae), 

a possible biological control agent for bladder campion Silene cucubalus (Caryophyllaceae). in Canada. 

Canadian Entomologist 112. 639. 

Maw. M.G.; Steinhausen, W.R. (1980b) Cassida azurta (Coleoptera: Chrysomelidae) - not C. hemisphaerica - as a possible biological 

control agent of bladder campion. Silene cucubalus (Caryopbyllaceae) in Canada. Ztitschri{t fur 

ange",andte Entomologie 90.420-422. 

Miotk. P. (1973) Phytophagous insects associated with weeds in central Europe. Pan 11. Wced Projects for Canada. Progress Repon 32. 

Commonwealth Institute of Biological Control. Delc!mont. Switzerland, 29 pp. 

Scoggan, H.J. (1978) The flora of Canada. Pan 3. Ottawa; National Museum of Natural Sciences. pp. 547-1115. 

Thomas. A.G. (1978) The 1978 weed survey of cultivatcd land in Manitoba. Regina; Agriculture Canada Research Station, 109 pp.

Pest Status 

Chapter 43 

Sonchus arvensis L., Perennial Sowthistle, 

S. oleraceus L., Annual Sowthistle 

and S. asper (L.) Hill, Spiny Annual 

Sow-thistle (Compositae) 

D.P. PESCH KEN 

Four species in the genus Sonchlls have been introduced into North America from 

Europe and Asia. Three of them are weeds. Perennial sow-thistle. Sonchus arvensis L.. 

is a common weed in all provinces of Canada but it is particularly abundant in Ontario. 

Manitoba. and the northern agricultural areas of Quebec. Ontario. and the Prairie Provinces 

(Frankton & Mulligan 1970). It includes the varieties S. arvensis L. s. str. and S. 

arvensis var. glabrescens Guenth .• Grab & Wimm. (Boulos 1961). It reproduces by 

seed and an extensive underground root system. About 9750 achenes are produced per 

flowering shoot (Stevens 1932) and 59500 per m 1 (Stevens 1924). The seeds are dispersed 

by means of a pappus. Stevens (1924) noted that most seeds are not carried far 

and that there is a difference in the persistence of the pappus in different lots. In our 

experiments only one of 26 seeds which were released into the air at wind speeds 

averaging 7 km per hour and gusting to 22 km per hour became detached from its pappus. 

Eighteen out of 20 seeds flew out of sight at average windspeeds of 15 km per hour and 

gusting to 38. The pappus of one seed became entangled on vegetation and fluttered in 

the wind for 15 minutes. but did not separate from the seed (Peschken, unpublished). 

Seedlings establish more readily where there is litter. and the moisture in low habitats 

may help seedling establishment in pond and ditch margins (Stevens 1926). This is the 

reason why S. arvensis is particularly serious in the irrigated area around Outlook, 

Saskatchewan (W.J. King. 1980, personal communication). Perennial sow-thistle 

thrives on low heavy soils and on lighter soils with a good moisture supply (Stevens 

1924). 

Fifty-nine shoots per m l reduced the yield of oats by 25% (Friesen & Shebeski 1960). 

Shaskov el al. (1977) report reduction in wheat yield by 4.5% to 27% in Kazakh SSR. at 

3-15 plants per mI. In Saskatchewan five shoots per ml reduced the yield of rapeseed by 

12% and 10 shoots by 18'Yo (Peschken unpublished). 

Control of perennial sow-thistle growing in grain is possible with herbicides, but 

difficult in broad-leaved crops. Cultivation has to be repeated every three to four weeks 

for at least one year to deplete root reserves (Derscheid & Parker 1972). 

The annual sow-thistle. S. oleraceus L.. an annual or rarely biennial weed, reproduces 

by seeds and has a strong tap root which may reach to a depth of 1 m and may 

spread to 1.29 m (Kutschera 1960). It grows up to 2 m tall and it produces about 6000 

seeds per plant (Salisbury 1961). It is a weed of cultivated fields, lawns, gardens. grainfields, 

vineyards and occurs in all provinces of Canada. In Canada, it may harbor virus 

diseases such as tobacco streak, alfalfa mosaic, cucumber mosaic. and the mycoplasma 

disease. aster yellows (Gayed 1978. Holm el al. 1917. Smith 1972). The spiny annual 

sow-thistle. S. asper (L.) Hill. is an erect annual or sometimes biennial weed up to 2 m 

tall, with a strong taproot reaching down to 2 m (Kutschera 1960). Salisbury (1961) 

estimates seed production to be about 18 000 per plant. 

205

206 D. P. Pes( 

Background 

Tephrltis dHscerata 

Lw. (Diptera: 

Tepbritidae) 

Cystiphora sonchl 

(Bremi) (Diptera: 

Cecidomyiidae) 

Both annual sow-thistles occur throughout Canada, but are more abundant in Ontario, 

Quebec, and British Columbia than in other provinces (Frankton & Mulligan 1970). S. 

lenerrimus is only reported from California (Shetler & Skog 1978). 

No biological control of sow-thistles has been reported from other parts of the world. In 

Canada, only one as yet unidentified Lepidoptera larva has been found feeding on the 

flower heads or destroying seeds, and no monophagous insects have been reported 

feeding on any other part of the perennial sow-thistle (M. Maw, 1982, personal communication). 

Conners (1967) lists three disease organisms specialized on S. arvensis: 

Marssonina sonchi Dearn. & Bisby, Seploria sonchi-arvensis Deam. & Bisby, and S. 

sonchifolia Cke. However, these do not control their host. The survey in eastern Austria 

and the Swiss Jura, and of the literature by Schroder (1974), and in Iran, Pakistan, and 

Japan by Zwolfer (1973) on Sonchus spp. produced only six insect species which appeared 

to be sufficiently host specific to warrant further study. Five of these are 

endophytic in the flower heads and one is a leaf gall fly. Two of these, Tephriris dilDcerata 

Loew and Cysliphora sonchi (Bremi) have been studied in detail and will be discussed 

below. In addition, the moth Celypha rosaceana (Schlager) is reported from Sonchus 

spp. and Taraxacum officinale Weber only and should be studied further (Bradley el al. 

1979). 

Ecology 

The fly deposits clutches of six to seven eggs into flower buds and in the laboratory the 

oviposition period may last up to ten weeks (Berube 1978a,1978b). The larvae transform 

the flower bud into a gall in which they pupate when mature. The adult fly enters 

diapause when exposed to a short day or cool temperatures or both and it overwinters as 

an adult. There is one generation per year (Berube 1978a). T. dilacerata is widely distributed 

in the palaearctic covering about three quarters of the range of S. arvensis (Berube 

1978a). 

Ecology 

C. sonchi is recorded from Sweden (Sylven 1975) and Denmark in the north (Henriksen 

1944) to Italy and Romania (Skuhrav6 el al. 1972) in the south, and from France (Kieffer 

1899) in the west to the European part of the USSR in the east (Peschken, in press). 

C. sonchi females lay their eggs on the underside of leaves. Galls are produced and 

become about 5 mm in diameter when mature. The larvae pupate in the gall or in the 

ground. The adults live up to 16 hours in the laboratory. Up to 721 galls were produced 

on one perennial sow-thistle rosette by six females. There are three generations per year 

in the field (Skuhrav6 & Skuhravy 1973). 

The fly is host specific to Sone/lus spp. (Peschken in press).


Table 51 

Scmc/lus an'ens;s L.. 207 

T. dilacerata has been released on a total offive sites in Saskatchewan in 1979. 1980. and 

1981. and one site each in Alberta. Quebec. and Prince Edward Island (Table 51). 

Breeding occurred in 1979 when the flies were released in large field cages (180 cm high. 

180 x 180 cm). At Estevan three galls were found in August and 250 at Regina. From the 

latter an estimated 1150 flies emerged in the cage at Regina. Many of these were allowed 

to escape so that they could search for overwintering sites but no survivors were found 

in 1980. In 1981. only three galls were found in Outlook and 22 at Wishart. Saskatchewen. 

However. 98% of the flies were released for overwintering in the fall of 1980 and 97% in 

1981. All fall releases were made with flies that emerged from galls collected in Austria. 

In 1980. the flies emerged in the quarantine laboratory in a 16 hour day except for 1000. 

which had emerged in an eight hour day at 14°C and were released into a large field cage 

at Regina. Saskatchewan in September 1980. A log pile covered loosely with straw was 

provided as a possible overwintering site. The cage was removed in late fall to allow 

additional insulation by snow and replaced on 15 April 1981. No flies emerged. 

Subsequently it was learned that flies emerging at room temperature in a 16 hour day 

do not enter diapause. Releases made in the fall of 1981 were all made with flies conditioned 

for overwintering. 

C. sonciJi was released on four sites in Saskatchewan in 1981. where it survived the 

first winter on two sites and produced two generations in 1982 (Table 51). The colony in 

Alberta produced galls in 1981 but did not survive the winter. No galls were found from 

the 1982 release in Alberta nor from the 1981 and 1982 releases in Manitoba and Quebec. 

Open releases and recoveries against Sonchus arvensis L. 

Species and Province 

Tephritis dilacerala Lw. * 

Saskatchewan 

Alberta 

Quebec 


Cysliphora sonchi (Bremi)* 

Saskatchewan 

Alberta 

Manitoba 

Quebec 

Total 

Total 

Year Number 

1979 810 

1980 11486 

1981 1093 

1981 2000 

1981 1947 

1981 2000 

19336 

1981 21900 

1981 5000 

1982 4500 

1982 2000 

1981 5000 

1982 2100 

40500 

Year of Recovery 

1979 

1982 

1981 

* All insects were originally collected in Austria. All C. sonchi and 6% of the T. dilacerala 

releases were made with laboratory reared stock. and the remaining T. dilacerala releases 

were made with flies that emerged from pupae collected in the field in Austria.

208 D. P. Pesch ken 




So far no T. dilaeerata overwintered in Saskatchewan. Saskatchewan, with its thin or 

often non-existent snow-cover, constitutes a harsh climate for overwintering. Also 

suitable food for the adult flies may be scarce in spring and fall on the prairies. 

(1) Releases of CystipllOra sonehi and T. dilaeerata should be made and monitored in 

areas where S. arvensis is frequent, i.e. in Ontario and Manitoba, and the northerly areas 

of Ontario, Quebec. and the Prairie Provinces, and in irrigated areas where S. arvensis is a 

problem. 

(2) A study of the overwintering habits of T. dilaeerata should be made. 

(3) The role of seeds of S. arvensis in the propagation of existing stands and the 

establishment of new stands should be investigated to determine whether the establishment 

of seed-destroying biological control agents should be pursued. 

(4) The moth Celypha rosaeeana (Schlager) (Lepidoptera: Tortricidae) and the seedhead 

fly Contarinia sellleclllendaliana Rubs. (= soneh; Kieffer) appear to have a narrow 

host range and warrant screening as biological control agents. 

(5) The survey for S. arvensis insects should be resumed and concentrated in the 

northern agricultural areas of Europe, such as Sweden, Finland. and the northern areas 

of European and Asian USSR, where S. arvensis is frequent. 

Berube. D.E. (1978a) Larval descriptions and biology of Tephritis dilacerata (Dipt.: Tephritidae) a candidate for biocontrol of Sonchus 

arvensis in Canada. Entomophaga 23. 69-82. 

Berube. D.E. (1978b) The basis of host plant specificity in Tephritis dilacerata and T. formosa (Dipt.: Tephritidae). Entomophaga 23. 

331-337. 

Boulos. L. (1961) Cytotaxonomic studies in the genus Sonchus. 3. On the cytotaxonomy and distribution of Sonchus arvensis L. Botaniska 

Notiser 114(1). 57-64. 

Bradley. J. D.; Tremewan. W.G.; Smith. A. (1979) British tortricoid moths. Tortricidae: Olethreutinae. Vol. II. London; The Ray Society and 

British Museum. 320 pp. 

Conners. I.L. (1967) An annotated index of plant diseases in Canada. and fungi recorded on plants in Alaska. Canada and Greenland. 

Canadian Department of Agriculture Publication 1251.381 pp. 

Derscheid. L.A.; Parker. R. (1972) Thistles. Canada thistle. perennial sow-thistle. South Dakota State University Extension Fact Sheet 450. 

4 pp. 

Frankton. D.; Mulligan. G.A. (1970) Weeds of Canada. Canadian Department of Agriculture Publication 948. 217 pp. 

Friesen. G.; Shebeski. L.H. (1960) Economic losses caused by weed competition in Manitoba grain fields. I. Weed species. their relative 

abundance and their eUeet on crop yields. Canadian Journal of Plant Science 40. 457-467. 

Gayed. S.K. (1978) Tobacco diseases. Canadian Department of Agriculture Publication 1641, 57 pp. 

Henriksen. K.L. (1944) Fortegne1se over de danske galler (zoodeccidier). Spolia Zoologica Musei Hauniensis VI. 1-212. 

Holm. L.G.; Plucknett. D.L.; Pancho. J. V.; Herbcrger.J.P.(1977) Thc world's worst weeds. Honolulu; University Press of Hawaii. 609 pp. 

Kieffer. J.J. (1899) Enumeration des eecidies recueillies aux Petites-Dalles (Seine-Inferieure) avec description de deux Cccidomyies 

nouvelles. Bulletin de la Sociltl des Amis des Sciences Naturelles de Rouen. 89-105. 

Kutschera. L. (1960) Wurzelatlas mitteleuropiiischer Ackerunkriiuter und Kulturpllanzen. Frankfurt; DLG. 574 pp. 

Pesehken. D.P. (in press) Host specificity and biology of Cystiphora sonchi (Loew) (Diptera: Cecidomyiidac). a candidate for the 

biological control of Sonchus species. Enromophaga. 

Salisbury. E. (1976) Weeds and aliens. London; Collins. 384 pp. 

SchrOder. D. (1974) The phytophagous insects attacking Sonchus spp. (Compositae) in Europe. Proceedings of the 3rd International 

Symposium on Biological Control of Weeds. Montpellier. France. Commonwealth Institute of Biological 

Control Miscellaneous Publication 8. 89-96. 

Shaskov. V.P.; Kokmakov. P.P.; Volkov. E.E.; Trifanova. L.F. (1977) The influence of rhizomatous weeds in spring wheat crops on the 

utilization of nitrogen. phosphoros and potassium. Agrokhimiya 14(3).57-59. 

Shetler. S.G.; Skog. L.E. (1978) A provisional checklist of species for Rora North America (Revised). Rora North America Report 84. 

Missouri Botanical Garden. 199 pp. 

Skuhrava • M.; Skuhravj. V. (1973) Gallmiicken and ihre Gallen auf Wildpllanzen. Wittenberg Lutherstadt; Ziemsen. 118 pp.

Sone/Ills arvensis L., 209 

Skuhravd , M.; Skuhravy, v.: Neacsu, P. (1972) Verbreitung der Gallmiicken in Rumlinien. Deutsche entomologische Zeitschrift 19, 

375-392. 

Smith, K.M. (1972) A textbook or plant virus diseases. 3rd ed., New York; Academic Press, 684 pp. 

Stevens, O.A. (1924) Perennial sow-thistle, growth and reproduction. North Dakota Agricultural Experiment Station Bulletin 181,44 pp. 

Stevens, O.A. (1926) The sow thistle. NOTlII Dakota Experiment Station Circular 32, 16 pp. 

Stevens, O.A. (1932) The number and weight or seeds produced by weeds. Ameriam loumal of Botany 19. 784-794. 

Sylven, E. (1975) Study on relationships between habits and external structures in Oligotrophidi larvae. (Diptera. Cecidomyiidae). 

ZoologiCD Scripta 4, 55-92. 

Zwiilrer, H. (1973) A survey ror weed insects in Japan. Iran and Pakistan. Weed projects for Canada. Commonwealth Institute of 

Biological Control Progress Report 3D, 27 pp.

Blank Page 

210

Pest Status 

Biological Control Studies 

Discussion 

Chapter 44 

Verbascum thapsus L., Common Mullein 

(Scrophulariaceae) 

M.O.MAW 

Verbascum thapsus L. is a biennial or, rarely, an annual of Eurasian origin. It was 

probably introduced into North America several times as a medicinal herb (Gross & 

Werner 1978). It is found over most of the United States and southern Canada, but is rare 

on the Canadian prairies, North Dakota, and Montana (Gross & Werner 1978. Maw 

1980). It is most vigorous on well drained gravelly or stony soils in rough pastures, 

fence rows, roadsides, railway yards, and waste places. It is not a major weed, not 

allergenic, not poisonous to humans, and not a problem on cultivated land. It does, 

however, harbor insects that may be vectors of diseases of economic plants. For example, 

the mullein leaf bug, Campy/omma verbasci Meyer, whose normal plant food is mullein, 

may cause damage to apple or pear fruit and potato leaves (Pickett 1939) and may also be 

a vector of fire blight, Bacillus amy/ovorus (Burr.) Trev. (Leonard 1965). 

The most effective control agents of mullein in Europe appear to be a weevil, Gymnaetron 

letrum F .• and the mullein shark moth, CucuJ/ia verbasci L. (Noctuidae) (Miotk 1973). 

The weevil is already well established in Ontario, British Columbia. and the United 

States from New England to Arkansas and the Pacific states (Blatchley & Leng 1916, 

Hatch 1971). The adults eat mullein leaves, and the larvae and adults destroy up to 50% 

of the seeds (Gross & Werner 1978). 

C. verbasci was screened (Maw 1980) and although there was some feeding on all 

Scrophulariaceae tested, and there was some nibbling on tomato, Nicoliana sp. and 

Brass;ca napus, sustained feeding and development occurred only on Verbascum spp. 

V. thapsus is an early colonizer on abandoned agricultural fields with the tall flowering 

stocks usually appearing the second year after abandonment. Populations are usually 

scattered but locally abundant, and the weed may cover entire fields where the ground 

has been left undisturbed. This situation is, however, relatively short-lived. In a study 

by Gross & Werner (1978) it was found that in a barley field that had been abandoned for 

three years, the density of V. thapsus was 1.0 plants per mI. In an adjacent field that had 

been abandoned for 12 years, the density of V. thapsus had declined to O.17/m l • Since 

seeds can be dormant but viable for 35 years, the typical pattern seems to be one of 

ephemeral adult populations and long-lived seed pools (Gross & Werner 1978). 

Although the mullein leaf bug. Campy/omma verbasci, may damage apple and pear 

fruit, the bug is only partially phytophagous. It cannot complete its life cycle without 

insect prey and feeds on several species of mites and insects that attack the fruit crop 

(Gross & Werner 1978). 

211

212 M. G. Maw 



The mullein moth, Cucullia verbasci, is considered to be a safe biological control 

agent to release. However, the inherent risk in releasing any organism into newenvironmental 

conditions remains and until the economic value in controlling the weed is 

determined, no release should be made. 

Until the loss caused by mullein has been determined, no releases of biological control 

agents should be made. 

Blatchley, W.S.; Leng, C.W. (1916) Rbynchophora or weevils of North Eastern America. Indianapolis; Nature Publishing Co., 682 pp. 

Gross, K.L.; Werner, P.A. (1978) The biology of Canadian weeds. 28. Verboscum thopsus L. and V. blal/aria L. Canadian Journal of 

Plant Science 58, 401-413. 

Hatch, M.H. (1971) The Beetles of the Pacific Northwest. Part V. University of Washington Press, 662 pp. 

Leonard, D.E. (1965) Atractotomus mali and Campylomma verbosci (Heteroptera: Miridae) on apples in Connecticut. Journal of 

Economic Entomology 58(5),1031. 

Maw, M.G. (1980) Cucullia verbose;, lin agent for the biological control of common mullein (Verboscum thapsus). Weed Science 28, 

27-30. 

Miotic, P. (1973) Phytophagous insects associated with weeds in central Europe. Part II. Weed Projects for Canada. Commonwealth 

Institute of Biological Control Progress Report 32, 29 pp. 

Pickett, A.D. (1939) The mullein (eafbug, Campylomma verbose; Meyer, as a pest of apples in Nova Scotia. Entomological Society of Ontario 

Annual Report 69, 105-106.

PART III 

BIOLOGICAL CONTROL OF FOREST 

INSECT PESTS IN CANADA 1969-80

Blank Page 

214

216 M. A. Hulme and G. W. Green 

Selection of Biological Control Agents 

pusilla (Lep.), both of which feed on birch; the gypsy moth, Lymamria dispar (L.); the 

balsam fir sawfly, Neodiprion abietis (Harr.), which, in the first review, was only examined 

using surplus parasitoid stock; Bruce spanworm, Operophtera bruceata (Hulst); two 

tussock moths, Orgyia leucostigma (J .E. Smith) and Orgyia pseudotsugata (McDunnough); 

and the mountain-ash sawfly, Pristiphora geniculata (Htg.). Effort was almost equally 

divided between treatments with entomopathogens and releases of predators or parasitoids. 

The current review thus contains evaluations of control attempts against 21 insect 

pests, although in some cases this simply entails updating assessments of control 

attempts made during the previous review period. 

Despite the increased number of pests covered in the current review, total effort 

devoted to biological control of forest pests declined as the Canadian Forestry Service 

went through a period of austerity. Work with predators and parasitoids suffered 

particularly severe reductions of resources; and certain aspects of all programmes, such 

as the population dynamics of the pest and of the control agent, were almost totally 

neglected. These cutbacks are reflected in the lack of depth with which many of our 

investigations were undertaken and inevitably reduced our chances of finding successful 

controls. Despite these difficulties significant progress has been made, as detailed 

later. 

The definition of biological control of forest insect pests used in this review follows 

that of the previous review - it is confined to the regulation of pest populations by the 

introduction of parasitoids, predators, or entomopathogens. Population regulation is 

considered acceptable if damage is controlled at tolerable levels in economic andlor 

·0 social terms. The methods of introduction of the control agent cover all strategies from 

inoculative releases of an organism, which then spreads through the pest population, to 

augmenting agents already present in the pest popUlation, or to inundation of the pest's 

environment with a control agent that mayor may not already be present (Knipling 

1979). 

The chapters that follow this overview are organized in alphabetical generic sequence, 

and each chapter is written by the scientists responsible for conducting or assessing the 

control attempts. An outline is given of the present status of the pest, background is 

given where needed on reasons for the choice of control agents, and the authors' 

evaluation is given of each attempt. Each chapter concludes with specific suggestions 

for future work. 

In describing the pest status, and in many of the assessments of control effectiveness 

reference is made to the Forest Insect and Disease Survey (FIDS), an organization 

within the Canadian Forestry Service that carries out major surveys of pest populations 

and pest damage across the country. In earlier times surveys included routine rearings to 

measure parasitoid levels in pest populations, but due to staff cutbacks such measurements 

are rarely performed now and surveys by FIDS are generally confined to measurements 

of pest numbers and pest damage. This in turn has seriously impeded the 

effectiveness of the biological control research applied to forest pests. 

For taxonomic and other reasons, many changes in the names of insects or the spelling 

of insect names have taken place during the current review period. In order to standardize 

sQme of these changes, forestry contributions follow the nomenclat.ure of insect pests 

given in the "Common names of insects and related organisms" published by the 

Entomological Society of America in 1980. 

Inoculative releases of parasitoids and predators 

When planning this strategy of biological control it has become customary to first 

establish whether the target pest is a native or an introduced species. Of the 21 pests

Biological control of forest insect pests 217 

included in this review, 9 are considered native: C. fum;ferana, spruce budworm; C. 

occidentalis, western spruce budworm; M. disslria, forest tent caterpillar; N. abielis. 

balsam fir sawfly; N. lecontei, redheaded pine sawfly; N. swainei, Swaine jack pine 

sawfly; Operophtera bruceala. Bruce spanworm; Orgyia lellcostigma. whitemarked 

tussock moth; and O. pselldot.mgata. Douglas-fir tussock moth. There is disagreement on 

whether P. erichsonii. larch sawfly, is native or introduced. although most favour the 

latter view (A. Giroux' 1981. personal communication; Pschorn-Walcher 1977). Following 

this division into introduced and native species it has been customary to concentrate 

on introduced pests as being promising candidates for biological control by inoculative 

introduction of predators or parasitoids obtained from the pest's native habitat. Thus. in 

the present review. all but two such control attempts are against introduced pests: the 

exceptions are attempts against C. fumiferatla. where mostly limited and unpromising 

cage studies were formed with parasitoids. and attempts against N. swainei. where trials 

were made to introduce Formica spp. of ants as predators. The former attempts are best 

described as preliminary investigations rather than control attempts. and the latter trials 

as introductions of polyphagous predators aimed at control of several forest pests rather 

than just the sawfly. In general. the number of parasitoids or predators released in each 

control attempt depended on numbers obtained from field collections. Because of 

limited resources of both people and material. little rearing was carried out to increase 

insect numbers and few of the female parasitoids were deliberately mated before 

release. Reeks & Cameron (1971) feel that a minimum of 500 mated females should be 

released but this was rarely achieved in the work reported here. Indeed. Beirne (1975) 

regards releasing inadequate numbers and other faulty procedures as important reasons 

for failure in control attempts. 

The question of whether to release one or several species of parasitoids or predators 

continues to evoke controversy (e.g. DeBach el al. 1976). Both release strategies were 

practised during the current review period without either showing obvious superiority in 

terms of control success. In co-operation with CIBC Delemont and other shipping 

stations, precautions were taken to screen out unwanted parasitoids, such as c1eptoparasitoids 

and hyperparasitoids. before releases were attempted. A further difficult question 

is whether to release monophagous or polyphagous parasitoids. In the case-studies 

reported here both types shared in the control successes. In all, 31 species of parasitoids 

and predators were released against 11 target pests and a further 3 species of parasitoids 

were tested in laboratory and field cage studies against C. fumiferana. Well over half of 

the introductions were from Europe, three were from Japan. and one from Argentina; 

the remainder were relocations within Canada. All but three of the species belonged to 

the order of Hymenoptera; the three exceptions. all Diptera. were a laboratory culture of 

Agria house; Shewell tested unsuccessfully against C. fumiferana, Lypha dubia 

Fallen, released against R. buoliana but not known to be established, and 

Cyzenis albicans (Fall.) successfully established and helping to control O. brumala. 

Approximately half of the released parasitoids and predators are known to be established 

and the list may be extended as more time is allowed for establishment to become evident. 

A summary of all free field releases is shown in Table 52. Three parasitoids tested only in 

cages are also included to complete the list of those examined during the review period. 

Application of entomopathogens 

Entomopathogens were used for attempted control against all the native insect pests 

covered in this review. and similar controls were explored against the introduced pests 

N. serlifer and L. dispar. The main entomopathogens used here were the bacterium B.I. 

and a number of baculoviruses. 

, Biosystematics Research Institute, Ottawa


Table 52 Free field releases of parasitoids and predators against forest insect pests between 1969 

and 1980 

Host 

Chorisloneura fumiferana 

Coleophora laricella 

Coleophora serralella 

Fenusa pusilla 

Lymantria dispar 

Neodiprion seTlifer 

Neodiprion swainei 

Operophlera brumala 

Prisliphora erichsonii 

Prisliphora geniculala 

Rhyacionia buoliana 

• Laboratory culture . 

•• Cage release only. 

Parasitoidslpredators 

Agria housei 

Cephaloglypla laricis 

Cephaloglypla murinanae 

Lissonola sp. 

Trichogramma sp. 

Agalhis pumila 

Chrysocharis laricinellae 

Diadegma laricinellum 

Dicladocerus japonicus 

Apanteles coleophorae 

Apanleles mesoxanthus 

Apanteles corvin us 

Campoplex borealis 

Campoplex sp. 

GrypocentTUS albipes 

Lalhrolesles nigricollis 

Anaslaws dis paris 

Ooencyrlus kuvanae 

Dipriocampe diprioni 

Exenterus abruplorius 

Lophyropleclus IUlealor 

Pleolophus basizonus 

Formica lugubris 

Formica obscuripes 

Agrypon flaveolawm 

Cyzenis albicans 

Mesoleius lenthredinis 

Olesicampe benefaclor 

Olesicampe geniculalae 

Rhorus sp. 

Lypha dubia 

Orgilus obscuralor 

Parasierola nigrifemus 

Agathis binominala 

I 

Total 

number 

released 

2800 • 

•• 

•• 

59 

20000·· 

2633 

530 

101 

292 

337 

1480 

1 753 

4994 

1404 

25000 

1 189 

4072 

2389 

1032 

1000 000 

5000000 

820 

1238 

467 

8588 

912 

63 

496 

560 

595 

85 

B.I. has been tried against a variety of pests, all belonging to the Lepidoptera, because 

the pathogenic effects of many strains of the bacterium are promoted by the alkaline 

digestive conditions typical of this order of insects. Much of the pioneering work on the 

bacterium was carried out by the Canadian Forestry Senice and work on the mode of 

action of the entomopathogen is continuing. B.I. is now used operationally by forest 

managers: the control agent is fully registered as a pesticide in Canada and is commercially 

produced in a number of different formulations for use against C. fumiferana, L. dispar, 

and several other lepidopterous defoliators. Methods of applying the bacterium have 

varied. In a few cases the bacterium was applied from ground sprays on localized areas

Biological control offorest insect pests 219 

of pest outbreaks (examples are treatments to control M. disstria and L. dispar) , 

whereas in most other cases the bacterium was applied with aerial sprays (examples 

here include attempted control of C. fumiferana, C. occidentalis, and O. 

pseudotsugata). Most development of aerial spraying of B.t. was conducted with C. 

fumiferana. Both water-based and oil-based formulations were used and the spray 

aircraft included fixed-wing aircraft equipped with from one to four engines, and 

various sizes of helicopters. Areas treated ranged as high as 90 000 ha, and in all cases 

results to a large extent depended on the application techniques that were employed. 

The time period during which B.t. can be applied during the insects' development is 

shorter than that permissible with chemical insecticides because the bacterium must be 

ingested to be effective whereas the standard chemical insecticides are neurotoxins and 

exhibit contact toxicity. An interesting international aspect of this work involved cooperative 

trials between Canada and the United States under the 6-year CAN USA 

Spruce Budworms Research Programme that started in 1977. The two countries also cooperated 

in one trial using B.t. against O. pseudotsugala in British Columbia. 

The use of viruses, particularly baculoviruses, for control of forest insect pests has 

progressed rapidly since the last review, and Morris (1980) provides a convenient 

tabulaton of all field tests where either ground or aerial applications of virus were used. 

Most attention has been focused on the neodiprionid sawflies because NPVs that attack 

these sawflies were found to be particularly virulent. Many sawflies also feed colonially, 

which facilitates cross infection, and some of the viruses spread from the point of 

infection, thus allowing spot introductions of virus to be used rather than complete 

coverage of the infected areas. Predacious and scavenging insects are thought to be the 

main disseminators of the viruses. In some cases strips of the infected area were 

sprayed, and in the case of N. swainei spot introductions of laboratory-infected pupae 

were used. Other viruses, again mainly NPVs, with good virulence against a number of 

Lepidoptera, have also been evaluated. Examples are tests against the tussock moths, 

O. leucostigma, and O. pseudotsugata. Some less virulent viruses were also applied 

aerially against, for example, C. fumiferana and C. occidenlalis; others were applied by 

ground sprays. for example. those against M. disstria and L. dispar. 

The remaining entomopathogens covered in this review are essentially at the laboratory 

stage of development. Fungi are well known to cause epizootics, such as the one 

believed to have helped collapse a recent outbreak of hemlock looper, Lambdina 

fiscellaria fiscellaria (Guenee), in Newfoundland (Otvos 1973). Other North American 

forest pests in which fungal epizootics have been recorded include spruce budworm C. 

fumiferana, black headed budworm, Acleris variana (Fern), and forest tent caterpillar, 

M. disslria. Entomophthora spp. of fungi are generally responsible and these are the 

fungi on which the Canadian Forestry Service concentrates its effort. Much of the 

biology of these fungi is now elucidated; before direct applications are attempted, efforts 

continue to devise techniques for mass production of resting spores, to devise practical 

application systems, and to induce spore germination, particularly under field conditions. 

One study, not reported elsewhere in this review, is an examination of control possibilities 

of mountain pine beetle, Dendroctonus ponderosae Hopkins, with Beauveria bassiana 

Vuillemin. This work can be summarized by stating that although the fungus is lethal to 

the insect in laboratory trials, no satisfactory way has yet been found to infect insects in 

the field (S. Whitney2 1981, personal communication). 

Work with protozoa roughly parallels that with fungi and emphasis is now on epizooticlogical 

studies. Protozoa are dominant entomopathogens of insects such as spruce 

budworm, C. fumiferana, but their effects are to debilitate rather than to kill the insects, 

by affecting larval and pupal vigour and by reducing adult longevity and fecundity. 

Because these entomopathogens are ubiquitous. work continues to elucidate their 

interaction with other control agents. 

2 Pacific Forest Research Centre, Victoria. British Columbia.



Table 53 

Virtually no work has been carried out with nematodes during the review period, 

although recent laboratory studies have shown that Heterorhabditis hefiothidis (Khan et 

al.) is lethal to C. fumiferana (G. Finney' 1981 personal communication). Work with 

rickettsia has been deliberately avoided because of potential human health problems. 

We have attempted to summarize the authors' evaluations of control success under the 

headings of predators and parasitoids, and of entomopathogens. As previous reviews in 

this series have been devoted largely to predators and parasitoids, we have also 

summarized these earlier evaluations of the major control attempts to show progress 

through the review periods. Simmonds' classification of control success has been used 

to provide continuity with the previous review (Simmonds 1969). Practical control using 

entomopathogens received relatively little attention until the current review period, 

except for work with NPVs against G. hercyniae and N. lecontei, hence few comparisons 

can be made with earlier work. Furthermore, Simmonds' classification of control 

success does not adequately describe the control strategy attempted with many entomopathogens 

and a separate rating system has thus been devised for entomopathogens that 

better reflects the behaviour of these control agents. 

The summary of control attempts given in Tables 53 and 54 shows that two-thirds of 

the forest insect pests covered in this review were considered to be successfully 

Evaluation of biological control attempts against forest insect pests using predators and 

parasitoids 

Degree of success· 

Pest 1910-58 1958-68 1969-80 

Adelges piceae promising 

Coleophora laricella good ++++ ++++ 

Coleophora se"atella 

Fenusa pusilla + 

Gilpinia hercyniae good ++++*. ++++** 

Leucoma salicis good +++ +++ 

Lymantria dispar 

Neodiprion sertifer ++ ++ 

Operophtera brumata ++++ ++++ 

Pristiphora erichsonii promising ++ +++ 

Pristiphora geniculata ++ 

Rhyacionia buoliana + +++ 

• Based on McGugan & Coppel's assessment up to 1958, and on Reeks & Cameron's 

evaluation for 1959-68. Simmonds' (1969) classification of control success is used 

in the final two columns, viz. 

No control. 

+ Slight pest reduction or too early for evaluation of control. 

+ + Local control; distribution restricted or not fully investigated. 

+ + + Control widespread but local damage occurs. 

+ + + + Control complete 

** Acting in conjunction with a virus. 

) Memorial University of Newfoundland, St. Johns, Newfoundland.

Table 54 


Evaluation of biological control attempts against forest insect pests using entomopathogens· 

Entomopathogens 

Pest Type Degree of success·· 

Chorisloneura fumiferana NPV-CPV-GV-EV·" slight 

Chorisloneura occidenraiis 

GiJpinia herr:yniae 

Lyl11lJlJJria dispar 

Maiacosoma disstria 

Neodiprion abietis 

Neodiprion Iecontei 

Neodiprion sertifer 

Neodiprion swainei 

Operophtera bruceala 

Orgyitl Jeucostigma 

Orgyitl pseudotsugata 

•• 

... 

•••• 

8.1. 

NPV 

8.1. 

NPV 

NPV 

8.1. 

NPV 

8.1. 

NPV 

NPV 

NPV 

NPV 

NPV 

NPV 

NPV 

B.t. 

good 

none 

none 

exceUent· .. • 

slight 

slight 

none 

good 

unknown 

excellent 

excellent 

good 

unknown 

good 

good 

slight 

Covering the period 1969-80, except for N. Ieconrei and G. herc:yniae where work 

was undertaken before 1969. 

The rating system is as follows: 

slight - decreased pest population but little damage prevented. 

good - decreased pest population and damage reduced to economically acceptable 

levels 

excellent - pest populations and damage reduced to almost zero. 

NPV 

CPV 

GV 

EV 

B.t. 

nuclear polyhedrosis virus 

cytoplasmic polyhedrosis virus 

granulosis virus 

entomopox virus 

Bacillus thuringiensis 

Acting in conjunction with parasitoids . 

regulated by using biological control agents and that success was equally divided 

between parasitoids and entomopathogens. A number of evaluations cannot yet be 

made due to lack of data, although in some cases, as mentioned later, prospects for 

success are promising. Brief details of control evaluations with parasitoids and predators, 

and with entomopathogens are as follows. 

Parasitoids and predators 

Many of the following chapters report work continued from the previous review period. 

Most evaluations have been directed to technical success in control and little further can 

be added to the earlier tentative economic assessments of Reeks & Cameron (1971). C.


laricella, G. hercyniae. L. salicis. O. brumata, and P. erichsonii continue to be controlled 

by introduced parasitoids (Table 53), as does R. buoliana, provided temperatures favour 

parasitoids by synchronising their development with nectar and pollen supplies. These 

supplies are provided by encouraging the growth of flowering plants such as buckwheat 

(Fagopyrum esculentum Moench), wild carrot (Daucus carota L.). and milkweed (Asclepias 

syr;aca L.). This effective and novel approach emphasizes the importance of examining 

several alternative tactics for inoculating and establishing the control agent in the pest 

population. The geographic range of control of some of the above insect pests does not yet 

cover the entire country and attempts are now being made to control, for example. C. 

laricella in western Canada by introducing a braconid, an ichneumonid and two eulophids 

similar to those that are successful in eastern Canada. 

Several new subjects were chosen for control attempts. Small introductions of braconids 

and ichneumon ids were made to control C. serratella, so far without success. 

However, prospects still seem good because these parasitoids are important regulators 

of populations in Europe. Limited introductions were made against F. pusilla and at 

least one of the parasitoids has become established, although it is too early to evaluate 

control potential. P. geniculata was chosen as a promising candidate for control because 

it is so heavily parasitized in its native Europe that once sufficient numbers of the 

ichneumonid were received from Europe good local control was obtained. underlining 

the importance of making adequate releases. Attempts against C. fumiferana are not 

evaluated here because they essentially did not progress beyond cage studies. Attempts 

against N. swaine; are also not evaluated because they involved release of a general 

predator of many forest pests. 

Entomopathogens 

Entomopathogens have been used for most of our current biological control attempts 

against native pests, mainly by attempting to inundate the environment of the pest 

insect. In general. entomopathogens must be applied early in the insect's development if 

foliage is to be saved in the year of application. Early application is particularly important 

when viruses are used. 

Remarkable progress has been made with B.t. during the review period. Improved 

strains of B.t. (Dulmage 1970) followed by improvements in formulation and application 

technology have now reached the point where many forest managers find B.I. can be as 

effective as chemical insecticides against C. fumiferana (e.g. Dorais el al. 1980); costs 

are three to five times higher. It is. of course, essential that the material be applied at the 

correct time, in adequate dosage, and with good application techniques that include 

suitable formulation of the spray ingredients. Many of these developments with B.I. 

sprays have not yet been adequately tested on other Lepidoptera but there are no a 

priori reasons why success should not be similar. 

Recent success with viruses has been outstanding. Effective viruses were found 

against all the tested neodiprionid sawflies, with the possible exception of N. ab;etis, 

where sufficient data are not yet available to make an assessment. The NPV of N. 

leconlei has been particularly successful in spreading from the point of application 

(apparently via predacious and scavenging insects) and has allowed spot introductions 

to be used. Observations suggest that many applied viruses continue to exert control in 

the years following application, although it is not yet clear in many cases how this carryover 

is achieved. The virus may infect offspring transovarially, for example. or the virus 

may simply contaminate the environment by residing in cadavers. twig crotches, and 

other protected locations. Further research is required to elucidate the specific mechanisms. 

Effective viruses were also found that could control certain Lepidoptera, notably the 

NPVs for O. leucostigma and O. pseudotsugata. Success against C. fum;ferana and L. 

dispar has been only marginal because of the lower virulence of the viruses tested.

Future Considerations 


The estimated cost for virus material largely depends on production methods. Thus 

NPV from field-infected sawflies costs about $2.50Iha, whereas the tussock moth NPV 

produced in vivo in the laboratory costs about S501ha. 

There have been no control successes with either fungi or protozoa during the review 

period because, with the exception of trials to infect D. ponderosae with B. bassiana 

mentioned earlier, direct control has not been attempted. Basic questions in epizootiology 

remain to be answered first. Protozoa are, in any case, not generally envisaged as 

satisfactory control agents by themselves and emphasis is directed to control strategies 

in which they act synergistically with other agents. 

Like earlier reviews, the present reports cover many approaches to biological control. 

These case histories provide a valuable base on which to build future work, whether it be 

from the standpoint of assessing development with specific control agents or of 

examining control opportunities with specific insect pests. Each of these aspects will be 

considered separately in the following discussion. 

Predators and parasitoids as control agents 

There are two schools of thought on whether to emphasize introduced pests in inoculative 

control attempts with exotic parasitoids or predators. Although it is agreed that this 

approach has been fruitful for many introduced pests, some favour a continuation of this 

planning strategy, whereas others such as Munroe (1971) point out that this concentration 

of effort on introduced pests has no theoretical basis to support it. Indeed, Pimentel 

(1963) lists a number of successes against native pests. One interesting recent addition to 

such lists is Oxydia trychiata Gn., a native forest defoliator in Colombia that was 

controlled by Telenomus a/sophilae Vier., an egg parasitoid of A/sophila pometaria 

(Harris) imported from Virginia in the United States. Not only does this example show 

control of a native pest by a parasitoid from a host of a different genus but it also 

demonstrates a successful transfer from temperate to tropical latitudes (Bustillo & 

Drooz 1977). The example serves to underline the earlier dictum of Huffaker et al. (1971) 

that "native as well as exotic pests are suitable subjects for biological control importations". 

Indeed we hope that inoculative introductions of exotic parasitoids and predators 

against native forest pests will be given more attention than in the past. 

A further point that perhaps needs to be reconsidered is the method by which 

parasitoid species are selected. Disproportionate attention has been devoted to the 

Hymenoptera during the review period, yet among other orders the Diptera, in particular, 

contain numerous species of successful parasitoids that deserve closer examination. 

Diptera can be more difficult to rear and the adults are sometimes considered more 

difficult to identify than Hymenoptera, but these factors should not prejudice the choice 

of candidate parasitoids unless all other comparative factors are judged equal. Munroe 

(1971) pointed out that during the previous review period the establishment rate for 

introduced Diptera was actually higher than that for introduced Hymenoptera although 

it is, of course, recognized that control does not always follow establishment. 

In terms of the number of species released we concur with the views of Reeks & 

Cameron (1971) that either single or multiple species' releases are acceptable when 

supporting work shows that reasons are sound. Case histories suggest even where 

competitive displacement occurs, the resulting control may well be improved (e.g. 

Caltagirone 1981). Precautions should, of course, be taken to screen out undesirable 

parasitoids, especially hyperparasitoids and c1eptoparasitoids (e.g. Schroeder 1974). 

Desirable parasitoids should have good numerical andlor functional response to host 

population changes through attributes such as high fecundity, efficient host searching


ability, and good synchronization of reproduction with the host (Pschorn-Walcher 

1977). Inbreeding that restricts genetic variability should be limited. It is always advisable to 

try to ensure genetic variation between released individuals by collecting breeding stock 

from several locations (Bennett 1974, Mackauer 1976). 

Selection of collecting locations for exotic parasitoids and predators has rightly been 

focused on the native habitat of the pest when introduced insects are the subject of 

control attempts and this has inevitably led to a concentration of collection efforts in 

Europe. Case histories, however. show that successful control agents have also been 

found on different hosts and in different parts of the world. and to allow for this 

possibility. and thus increase the probability of success, a proportion of effort should be 

devoted to collecting from areas other than the native habitat of the pest (Pschorn 

Walcher 1977). This approach is, of course. essential where native pests are the subject 

of control attempts by inoculative releases. 

Although the above remarks are aimed principally at so-called classical biological 

control. they are not intended to preclude attention to other release strategies. Augmentative 

or inundative releases of parasitoids or predators should perhaps be considered 

in some cases. These techniques remain essentially untested in Canadian forestry 

applications despite successes claimed in Russia and China (Tropin et 01. 1980, McFadden 

et al. 1981). For example, in Russia release of Trichogromma evanescens Westw. against 

eggs of R. buoliana and Petrona resine/la (L.) reduced the number of damaged pine buds 

by over 50% (Beglyarov & Smetnik 1977); and in China Trichogrommo dendrolimi Mats. 

reduced infestation by Dendrolimus sibericus Tschetw. from 63% of trees in 1956 to 1 % 

of trees in 1970 (Hussey 1977). Attention could also be given to the use of behavioural 

chemicals such as kairomones (e.g. Gross Jr. 1981, Weseloh 1981, Vinson 1977); these 

semiochemicals should improve control by augmenting the ability of natural enemies to 

locate hosts. 

Finally, two fundamental research needs in predator and parasitoid introductions 

have been raised repeatedly in this overview. The first need covers rearing techniques to 

ensure that adequate numbers of biological control organisms (mated females) are available 

for whatever release strategy is employed. The second fundamental need is for better 

knowledge of the population dynamics of the pest insect and of the candidate predators 

or parasitoids. Many feel that neglecting this aspect in favour of an ad hoc approach 

inevitably reduces chances of obtaining successful control.It is of course recognized. as 

Pschorn-Walcher (1977) states, that "predictions derived from multivariate analysis or 

population models are no guarantee that the biological control agents selected will be 

effective." Judgement must be exercised in deciding how much background information 

is desirable before releases are attempted. As Simmonds (1972) points out. "The introduction 

... is the crucial experiment. Promising biological control agents have failed to 

live up to expectations whereas apparently unlikely species have been very successful". 

Entomopathogens as control agents 

Bacteria and viruses have dominated control successes with entomopathogens and will 

probably continue to do so in the immediate future as improved methods are found for 

producing and applying these organisms. With B.t .• for example, efficacy against C. 

fumi/erona has been widely demonstrated and future research emphasis will be on 

reducing costs. This can be approached in a number of ways. Development of more 

concentrated formulations to reduce the volume of carrier liquid will reduce both shipping 

and application costs. Development of even more potent strains of B.t. will lead to similar 

reductions in costs. Finally, development of better application methods will increase the 

probability that larvae will ingest a lethal dose from a given quantity of applied B.t. by 

optimising the distribution of B.t. on the leaf surface. These methods entail all aspects of 

application technology: generating optimum-sized droplets that contain the optimum


production of biological control agents is seen as a less attractive commercial proposition, 

and it is thus important that government organizations maintain an interest in providing 

opportunities for large-scale production of biological control agents. 

Economic aspects of various biological control strategies have been briefly mentioned 

in this chapter. These aspects need addressing in more detail to supplement the few cost 

estimates developed here by biologists. Analysis by economists could provide a more 

comprehensive picture of costs and benefits: cost figures should separate production 

from application; and benefit figures should include carry-over effects following the 

year of application. 

Target pests for control 

Judging by progress reported in this and other reviews of biological control there seems 

little reason to rule out any forest pest on a priori grounds as a suitable candidate for 

biological control. Each decision to attempt control must, of course, take into account 

the specific situation of pest and host tree(s) and the range of control options that might 

be applied. However, in considering biological control there seems good reason to give 

more attention to research opportunities with the key economic pests in Canada's 

forests, which would include C. fumiferana in eastern Canada and D. ponderosae and D. 

ru/ipennis (Kby.) in western Canada 

In the case of C. fumiferana, a good short-term option using biological control is now 

available commercially. Longer term control is desirable but biological control attempts 

have met with limited success. There is, of course, scope for further work and, although 

all attempts will be difficult, we suggest that searches for more virulent viruses and for 

exotic parasitoids be given special emphasis. Candidate viruses to date exhibit marginal 

virulence against C. fumiferana but some control has nevertheless been obtained and 

further work is warranted. Parasitoid introductions as a biological control option have 

been given little more than a cursory examination, perhaps because C. fumiferana is a 

native pest. Many of the releases were conducted in unsuitable conditions and a more 

systematic study of this control option would allow a more factual comparison of its 

potential with other control options. The most common candidate hosts in Europe that 

have been suggested for parasitoid collections, based on the similarity of their life cycles 

to C. fumiferana, are C. murinana Hb. and Epinolia nigricana L. on Abies spp., Dichelia 

histrionana Froel. on Picea spp., and Archips oporana L. on Larix spp., Pinus spp., and 

Picea spp. Several Zeiraphera spp. offer more remote possibilities. Collection activities 

should not, however, be confined to Europe. China, for example, has a Choristoneura sp. 

that attacks Picea spp. and appears to be well controlled by natural factors (Macdonald & 

Pollard 1976). 

With Dendroctonus spp. of bark beetles, particularly D. ponderosae and D. ru/ipennis 

that are major pests in western Canada perhaps the whole range of biological control 

agents needs closer examination to see which, if any, have practical potential for control. 

Certainly a wealth of information exists on related scolytids such as the southern pine 

bark beetle, D. frontalis Zimmerman (Thatcher et al. 1978), some of which could provide 

a useful starting point in considering options with other Dendroctonus spp. More field 

examinations of the natural enemy complex of Dendroctonus spp. in Canada is obviously 

required. Multiphagous parasitoids of bark beetles that attack hardwoods should not be 

overlooked, as some also parasitize bark beetles that attack softwoods. 

Other particularly destructive pests that are not included in this review are the 

hemlock looper, L. [lScellaria[lScellaria, and the western hemlock looper, L. [lScellaria 

lugubrosa (Hulst); populations are now at endemic levels and irruptions are likely within 

the next few years. For the present, however, the most logical approach is to give priority 

to biological control research, mainly in accordance with the current importance of the 

pest, as the scope of research opportunities is limited not by lack of suitable problems but 

by the resources we are able to devote to biological control. There seems little doubt that



interest in this method of pest control is growing and more resources are likely to be 

committed in the future. This increased effort should in turn lead to progress that better 

reflects the potential of biological control as a viable pest management option. 

Beglyarov. G.A.; Smetnik. A.J. (1977) Seasonal colonization of entomophages in the USSR. In: Ridgway. R.L.; Vinson. S.B. (Eels.) 

Biological control by augmentation of natural enemies. New York: Plenum. pp. 283-328. 

Beirne. B.P. (1975) Biological control attempts by introductions against pest insects in the field in Canada. Canadian Entomologist 107. 

225-236. 

Bennett. F.D. (1974) Criteria for determination of candidate hosts and for selection of biotic agents. In: Maxwell. F.G.: Harris. F.A. (Eels.) 

Proceedings of a Summer Institute on Biological Control of Plant Insects and Diseases. Jackson. 

Mississippi; University Press of Mississippi. pp. 87-96. 

Bustillo. A.E.; Drooz. A.T. (1977) Comparative establishment of a Virginia (USA) strain of Telenomus alsophilae on Oxydia try'chiata in 

Columbia. Journal of Economic Entomology 70.767-770. 

Caltagirone, L.E. (1981) Landmark examples of classical biological control. Annual Review of Entomology 26. 213-232. 

DeBach. P.; Huffaker. C.B. : MacPhee. A. W. (1976) Evaluation of the impact of natural enemies. In: Huffaker, C. B.; Messenger, P .S. (Eels.) 

TIleory and practice of biological control. London, New York; Academic Press. pp. 255-285. 

Dorais. L.; Pelletier. M.: Smirnoff. W.A. (1980) Pulvcrisations acriennes de Bacillus thuringiensis Berliner realisees au Quebec de 1971 1\ 

1979 contre la tordeusc des bourgeons de I·cpinette. Choristoneurafumiferana (Oem.). [Abstract) Rapport 

presentc au VI' Congres International de I'Aviation Agricole a Turin. Italic 22-26 Sept. 1980. unpaginated. 

Dulmage, H.T. (1970) Insectidical activity of HD-l. a new isolate of Bacillus thuringiensis val. alesti. Journal of Invertebrate Pathology 15. 

232-239. 

Gross. H. R. Jr. (1981) Employment of kairomones in the management of parasitoids. In: Norlund. D.A.: Jones. R.L.; Lewis. W.J. (Eels.) 

Semiochemicals and their role in pest control. New York; John Wiley. pp. 137-152. 

Huffaker. C.B.; Messenger. P.S.; DeBach. P. (1971) The natural enemy component in natural control and the theory of 

biological control. In: Huffakcr. C. B. (Ed. ) Biological control. New York. London; Plenum. pp. 253-293 

Hussey. N.W. (1977) Biological control techniques. In: Rishbeth. R.S. (leader). The Royal Society delegation on 

biological control to China. Aug. 15 - Sept. 3. London; Royal Society. 38 pp. 

Knipling. E.F. (1979) The basic principles of insect population. suppression. and management. US Department of Agriculture Handbook 

512.659 pp. 

Macdonald. D.R.: Pollard. D.F.W. (1976) Report on the scientific exchange in forestry with the People's Republic of China. Canadian 

Forestry Service Report Pacific Forestry Research Centre. 32 pp. 

McFadden. M.W.; Dahlsten. D.L.; Berisford. C.W.; Knight. F.B.: Metterhousc. M.W. (1981) Integrated pest management in China's 

forests. Journal of Forestry 79. 723-726. 

McGugan. B.M.; Coppel. H.C. (1962) Biological control of forest insects 1910-1958. In: A review of the biological control attempts against 

insects and weeds in Canada. Commonwealth Institute of Biological Control Technical Communication 

2.35-127. 

Mackauer. M. (1976) Genetic problems in the production of biological control agents. Annual Rel'iew of Entomology 21.369-385. 

Morris. O.N. (1980) Entomopathogenic viruses: strategies for use in for usc in forest insect pest management. Canadian Entomologist 112. 

573-584. 

Munroc. E.G. (1971) Status and potential of biological control in Canada. In: Biological control programme against insects and weeds in 

Canada. Commonwealth Institute of Biological Control Technical Communication 4. 213-255. 

Otvos. I. (1973) Biological control agents and their role in the population fluctuation of the eastern hemlock looper in 

Newfoundland.Canadian Forestry Sen'ice Information Report N-X-102. 34 pp. 

Pimentel. D. (1963) Introducing parasites and predators to control native pests. Canadian Entomologist 95.785-792. 

Poinar. G.O. Jr. (1979) Nematodes for biological control of insects. Boca Raton. Florida: Chemical Rubber Company. 220 pp. 

Pschorn-Walcher. H. (1977) Biological control of forest insects. Annual Review of Entomology 22. 1-22. 

Reeks. W .A.; Cameron. J.M. (1971) Current approaches to biological control of forest insects 1959-1968. In: Biological control programmes 

against insects and weeds in Canada. Commonwealth Institute of Biological Control Technical Communication 

4. 105-112. 

Schroeder. D. (1974) A study of the interaction between internal larval parasites of Rhyacionia buoliana. Entomophaga 19. 145-171. 

Simmonds. F.J. (1969) Brief resume of activities and rccent successes achieved. Commonwealth Institute of Biological Control Report. 

Trinidad. 16 pp. 

Simmonds. F.J. (1972) Approaches to biological control problems. EnlOmophaga 17.251-264. 

Thatcher. R.C.; Searcy. J.L.; Coster. J.E.; Hertel. G.D. (1978) The southern pine beetle. US Department of Agriculture Technical Bulletin 

1631, 266 pp. 

Tropin.I.V.; Vedernikov. N.M.: Kranguaz. R.A.; Maslov. A.D.; Zubov. P.A.: Khramtsov. N.N.;Andreeva.G.I.;Lyashenko, L.1. (1980) A 

manual on the protection of the forest against pests and diseases. Moscow: Lcanaya promyshelnnost. 500 pp. 

Vinson. S.B. (1977) Behavioural chcmicals in the augmentation of natural cnemies. In: Ridgway. R.L.: Vinson. S.B. (Eels.) Biological 

control by augmentation of natural enemies. New York; Plenum. pp. 237-265. 

Weseloh. R.M. (1981) Host location by parasitoids. In: Nordlund. D.A.; Jones. R.L.: Lewis. W.J. (Eels.) Semiochemicals and their role in 

pest control. New York: John Wiley. pp. 79-96.

Blank Page 

228

Pest Status 

Chapter 46 

Background and Evaluation of Control Attempts 

Adelges piceae (Ratz.), Balsam 

Woolly Adelgid (Homoptera: Adelgidae) 

H.O. SCHOOLEY, l.W.E. HARRIS and B. PENDREL 

The balsam woolly adelgid, AdeJges piceae (Ratz.), is a destructive pest of firs, Abies 

spp. In recent years, however, populations have been low and dispersal has been 

limited. The distribution of the adelgid remains about the same as in 1968 (Clark el al. 

1971). In eastern Canada, expansion of the infestation has been largely into those small 

areas that had been bypassed as the initial infestation developed (Schooley 1980). The 

adelgid is now present throughout most of the fir forests of the Maritime Provinces, 

Newfoundland, and the eastern tip of the Gaspe Peninsula. A total area of about 103600 

kml is affected. In western Canada there have been only minor increases in the size of 

the infestation, which now covers about 10 360 kml in southwestern British Columbia. 

The infestations in Canada extend southward into the United States on both the east and 

west coasts (Mitchell el al. 1970). Climate seems to be the main factor limiting further 

spread of this insect in Canada (Greenbank 1970). 

The balsam woolly adelgid attacks all species of firs in Canada but some are more 

resistant to injury than others. In eastern Canada, mortality of balsam fir, Abies balsamea 

(L.) Mill., has been common. In western Canada, subalpine fir, A. Jasiocarpa (Hook.) 

Nutt., growing at low elevations, is the most vulnerable species, but it rarely occurs 

within the present infestation boundaries (Harris 1968). Pacific silver or amabilis fir, A. 

amabilis (Doug!.) Forb., is the second most vulnerable western host and considerable 

mortality of this species has occurred. Grand fir, A. grandis (Doug!.) Lind!', is also 

deformed and killed by the adelgid, primarily on southern Vancouver Island. The 

adelgid is also threatening to destroy Fraser fir, A. fraseri (Pursh.) Poir., in the few 

remaining spruce-fir stands of the southern Appalachian Mountains of eastern United 

States (Johnson 1980). 

Some of the causes of variation in the response to adelgid infestation among Abies 

host species have been identified. Puritch (1973), for example, has shown that the onset 

and intensity of adelgid attack caused premature heartwood formation and a resulting 

abnormal water stress. Thus, ability to withstand this stress among fir species corresponds 

to their susceptibility to adelgid damage. It has also been observed that adelgid attack 

has little effect on European species because a layer of dead bark tissue develops during 

the wound healing process and protects the trees from further attack for several years 

(Oechssler 1962). This healing process is delayed or absent in balsam fir that is under 

continuous adelgid attack. 

Clark et al. (1971) stated that there was little scope for additional study in the control of 

this adelgid by introduced predators. Field trials in eastern Canada tested all the 

apparently suitable insects over a 35-year period and failed to find a predator or predator 

complex that would control the adelgid. Only eight species of introduced predators have 

become established, at least temporarily, but none has been effective (Table 55) in 

reducing damage to economically tolerable levels. Consequently, it was recommended 

that the importation and release of predators be discontinued. This recommendation has 

229

230 H. O. Schooley. J.W.E. Harris and B. Pendrel 

been accepted and no introductions or releases have been made since 1969. The search 

for surviving introduced predators was discontinued in 1969, 1971. and 1978 in both New 

Brunswick and Nova Scotia (D.O. Greenbank. personal communication). in Newfoundland 

(Bryant 1971). and in British Columbia (Harris & Dawson 1979). The history of 

predator releases and recoveries tabulated by Clark et al. (1971) has been updated 

Table 55 Open releases and recoveries of predators against Adelges piceae (Ratz.) 


Species and province Year Origin Number Recovery 

Adalia luteopicta Mulsant 

Newfoundland 1960 India 159 

Adalia ronina (Lewis) 

Newfoundland 1961 Japan 67 

Nova Scotia 1963 Japan 290 

New Brunswick 1960 Japan 25 1960 

1962 Japan 37 1962 

1963 Japan 585 1963 

Adalia tetraspilota (Hope) 


Aphidecta obliterata (L.) 

Newfoundland 1959 Czechoslovakia 735 

1960 Germany 934 

1962 Czechoslovakia 848 


1964 Germany 1 187 


Germany 267 


1966 Austria 1380 1966 

1967 Austria 4288 1967 

1968 Germany 1096 1968 

and Austria 

Nova Scotia 1964 Germany 1 773 1967 

1966 Austria 370 

Norway 47 

1967 Norway 422 

New Brunswick 1962 Germany 1827 1962 

1963 Germany 3157 1963 

British Columbia 1960 Germany 1050 

1961 Germany 1 141 


1963 Germany 1997 


1968 Germany 1069 


Aphidoletes thompsoni (Mohn) 

Newfoundland 1959 Czechoslovakia 3 124 

Germany 25 952 

1962 Germany 270 1961 

1963 Germany 5201

Tablc 55 continucd 

Adelges piceadRatz.), 231 

Yearof 

Species and province Year Origin Number recovery 

1965 Germany 826 1967 

1966 Germany 35119 

1968 Germany 7248 

Nova Scotia 1965 Germany 450 1965 

1966 Germany 37 110 1966-67 

New Brunswick 1959 Germany 36131 1959-61 

1965 Germany 551 1965 

1966 Germany 6300 1966 



1965 Germany 1080 1967 

1966 Germany 6845 

Balaustium sp. 

Quebec 1967 Pakistan 126 

Ballia eue/,aris Mulsant 


New Brunswick 1959 Pakistan 79 

1960 India 55 

Coccinella septempunctata L. 

New Brunswick 1959 India 28 

1960 India 22 

Cremifania nigrocel/ulata Czerney 

Newfoundland 1959 Germany 198 1971 




1966 Germany 17 1966-68 


1968 Germany 706 1969 

Exochomus lituratus Gorham 

Newfoundland 1960 Pakistan no 

Nova Scotia 1963 Pakistan 991 


Exochomus uropygialis Mulsan! 


1960 Pakistan 2839 





Harmonia breiti Mader 

Newfoundland 1960 Pakistan 88 


Laricobius erichsonii Rosenhauer 

Newfoundland 1959 Czechoslovakia 1043 1959 

Germany 2159 1960

232 H. O. Schooley. J.W.E. Harris and B. Pendrel 

Tahlc 55 continucd 



1960 Germany 8228 1961 

1961 Germany 1 118 1963 

1962 Germany 7940 1964 

1963 Germany 1869 1965 

Newfoundland 

via Europe 1984 1966 

1964 Germany 1819 1968 

Newfoundland 

via Europe 300 




1966 Germany 3497 1958-68 

British Columbia 1960 Germany 800 1962-65 

1961 Germany 1432 1978 

1963 Germany 4871 1966,74 


1968 Germany 3164 1969,71,74 

Leucopis (Leucopis) n. sp. or. 

'melanopus'Tanasijtshuk* 

Newfoundland 1959 Germany 160 1959-62 

1968 Germany 1040 




Leucopis (Neoleucopis) 

obscura Holiday 

Newfoundland 1965 Austria 24 1959-68 

Leucopis (Neolellcopis) 

alralula Ratz. 

New Brunswick 1965 Germany 385 

Pul/us impexus (Mulsant) 

Newfoundland 1959 Germany 9500 

1960 Germany 1 146 1960 

1961 Germany 131 1961 

1966 Germany 18036 

Nova Scotia 1963 Germany 1000 1965-67 

1964 Germany 2031 1965-67 

1966 Germany 4700 1965-67 


1963 Germany 397 1958-59 

1964 Germany 200 1958-59 

1966 Germany 26550 1958-59 

British Columbia 1960 Germany 1240 1961 

1963 Germany 1400 

1965 Germany 2417 

1966 Germany 18513 

1968 Germany 2079 1969,71.74.78

Table 55 

continued 

Aclelge.\· ph-elle (Ratz.). 233 



Scymnus pumilio (Weise) 

Newfoundland 1960 Australia 9687 

New Brunswick 1959 Australia 5590 

1960 Australia 7286 

British Columbia 1960 Australia 2930 

Telraphleps abdulghani Ghauri 



1963 Pakistan I 157 


1965 India 278 

Pakistan 2921 

British Columbia 1965 India 19 

Pakistan 1257 

Tetraphleps raoi Ghauri 

Nova Scotia 1965 India 59 


• Species 'M'. 

Attempts to control the adelgid with contact or systemic insecticides have been 

unsuccessful. Several insecticides tested proved suitable for ornamental and nursery 

applications where it was possible to saturate infested trees with chemical solutions. 

However, not one of the 51 insecticides used in laboratory and greenhouse experiments 

caused acceptable levels of adelgid mortality under field conditions (Nigam 1972, 1976). 

Recently, some success has been obtained in controlling adelgids on individual trees 

with insecticidal soaps (Puritch 1975). These chemicals are expected to be useful only 

for ornamental and nursery applications. 

There are no known insect parasites of the balsam woolly adelgid but several fungal 

diseases have been reported. including Fllsarium larvaTllm Forbel and Cephalosporium 

coccoTllm Petch found in the Gaspe region of Quebec (Smirnoff 1970), Cephalosporium 

sp. and Penicillium sp. found in British Columbia (Harriset al. 1966), and F. nivale (Fries) 

Cesati found on adelgids in North Carolina. USA (Fedde 1971). Greenhouse and field 

experiments with the diseases from Quebec have been unsuccessful. The potential of 

organisms from other locations as natural control agents remains unknown. 

Failure to control the balsam woolly adelgid is viewed with special concern in Atlantic 

Canada. In Nova Scotia and Prince Edward Island, balsam fir stands are usually 

damaged before reaching a marketable size. On the island of Newfoundland, spectacular 

and unprecedented mortality of balsam fir has occurred on an accelerated scale in stands 

where adelgid attack has been followed by severe spruce budworm defoliation (Schooley 

1981). In affected areas. stand conversion. i.e. the replacement of balsam fir with other 

tree species, is being conducted on a large scale. Black spruce, Picea mariana (Mill.) 

B.S.P., is the favoured alternate species but white spruce. P. glauca (Moench) Voss, 

eastern larch. Larix larici"a (Du Roi) K. Koch. and hybrid larch species are being 

considered.

234 H. O. Schooley. J. W. E. Harris and B. Pendrel 



As previously recommended by Clark et al. (1971) no further introduction of predators 

should be made into eastern Canada until new species that might effectively control 

the adelgids are identified. Suitable predators may be found attacking two closely related 

fir shoot adelgids. Adelges merkeris Eichhorn and Adelges nusslini C.B .• in Europe. The 

milder winter temperatures of coastal British Columbia could favour a species that failed 

in the east. Also. some species already tested on the west coast may have failed because 

too few individuals were released or because of unfavourable weather conditions at the 

time of release. Therefore. further introductions may be considered for western Canada. 

Any predator successfully introduced and proved to be effective in western Canada 

should be considered for testing in the mild coastal areas of eastern Canada. 

Population dynamics studies should be conducted regularly in all regions where the 

adelgid is present. These studies should include observations that will identify any 

factors that successfully control mortality. Financial support should also be made 

available for periodic reappraisal of the effect that natural insect and disease organisms 

have in controlling the balsam woolly adelgid in other countries. 

Bryant. D.G. (1971) Forest protection: balsam woolly aphid. Adelges piceae (Ratz.). Annual Report Newfoundland Forest Protection 

Associalion 1971. 43 PI'. 

Clark, R.e.; Greenbank, D.O.; Bryant. D.G.; Harris, J.W.E. (1971) Adelges piceae (Ratz.). balsam woolly aphid (Homoptera: Adclgidae). 

In: Biological control programmes against insects and weeds in Canada. Commonwealth Institute of 

Biological Control Technical Communication 4. 113-127. 

Fedde. G.F. (1971) A parasitic fungus disease of Adelges piceae (Homoptera: Phylloxeridae) in North Carolina. Annals of the Entomological 

Society of America 64, 749-750 

Greenbank, D.O. (1970) Climate and the ecology of the balsam woolly aphid. Canadian Entomologist 102. 546-578. 

Harris. J.W.E. (1968) Balsam woolly aphid in British Columbia. Canadian Department of Forestry and Rural Development Forestry 

Researcl. Forest Pest Leaflet B.C.-I, 5 PI'. 

Harris, J. W. E.; Dawson. A. F. (1979) Predator release program for balsam woolly aphid, Adelges piceae (Homoptera: Adelgidae), in British 

Columbia, 1960-1969. Journal of the Entomological Society of British Columbia 76, 21-26. 

Harris. J.W.E.; Allen. S.1.; Collis, D.G.; Harvey, E.G. (1966) Studies of the balsam woolly aphid. Adelges piceae (Ratz.), in British 

Columbia. Canadian Department of Forestry Information Report BC-X-5, 5 pp. 

Johnson, K. (1980) Fraser fir and balsam woolly aphid. Summary of information. Southern Appalachian Reserve Resources Management 

Commillee Report, 62 pp. 

Mitchell. R.G.; Amman, D.G.; Waters. W.E. (1970) Balsam woolly aphid. US Department of Agriculture Forestry Service, Forest Pest 

Leaflet 118. 10 PI'. 

Nigam. P.e. (1972) Summary of toxicity of insecticides and chemical control studies against balsam woolly aphid. Canadian Forestry Sen'ice 

Information Report CC-X-26. 7 pp. 

Nigam. P.C. (1976) Summary of chemical control studies against balsam woolly aphid in British Columbia. 1973-74.Canadian Forestry 

Service Information Report CC-X-133, 6 PI'. 

Oechssler. G. (1962) Sucking injuries to the tissue of native and exotic firs caused by central European fir aphids. Zei/Schriftfiir angl'wandte 

EnlOmologie SO, 418-459 (Canadian Department of Forestry Translation 57). 

Puritch. G.S. (1973) The effects of water stress on photosynthesis. respiration and transpiration of four Abies species. Canadian Journal of 

Forl'st Rl'search 3. 293-298. 

Puritch. G.S. (1975) The toxic effects of fatty acids and their salts on the balsam woolly aphid. Adelges piceae (RalZ.). Canadian Journal of 

Forest Resl'arch 5, 515-522. 

Schooley. H.O. (1980) The introduction. spread and occasional resurgence ofthe balsam woolly aphid in Newfoundland. Proceedings of thl' 

International Union Forest Research Organizations Conference on Dispersal of Forest Insec/S, Aug.Lrt 

27-31. 1979. Washington State University, Pullman, Washington. PI'. 116-127. 

Schooley, H.O. (1981) An evaluation of the hazard rating systcm for balsam woolly aphid damage in Newfoundland. Procel'dings of a 

Symposium on Hazard Rating Systems in Forest Insect Pest Management, July 31 - August I, 1980. 

Athens, Georgia. US Department of AgriculTUre Forestry Service General Technical Report WO-27. 

Smirnoff. W.A. (1970) Fungus diseases affecting Adelges piceae in the fir forest of the Gaspe Peninsula. Quebec. Canadian Entomologist 

102. 799-805.

Pest Status 

Chapter 47 

Choristoneura fumiferana (Clemens), 

Spruce Budworm (Lepidoptera: 

Tortricidae) 

C.A. MILLER 

The spruce budworm, CllOristoneura fumiferana (Clem.). is a native defoliator of the 

spruce, Picea spp., and balsam fir. Abies balsamea (L.) Mill., forests of North America, 

which extend from northern Alberta to the Atlantic seaboard. It is the most important 

economic pest in forests of eastern Canada because of the frequency of epidemics and 

the intensity and extent of fibre losses. Budworm populations periodically irrupt to 

epidemic proportions and cause extensive tree mortality and reduced growth in surviving 

trees. There have been three major epidemics in this century. The first occurred around 

1915 and covered most of the eastern Quebec - Atlantic Region; the second irrupted in 

Ontario - western Quebec in the late 1930s and appeared in the Atlantic Region in the 

late 1940s, but had little impact in Nova Scotia and Newfoundland; and the current 

outbreak irrupted in the late 1960s. In sequence, these three outbreaks of the 20th 

century have tended to increase in size and frequency. 

The review period of this publication, 1969-80 largely coincides with the third major 

epidemic. The prolonged second epidemic collapsed in the 1960s, except for a persistent 

infestation covering less than a million hectares in central New Brunswick. During the 4 

years 1967 - 70, spruce budworm population increases were recorded in all provinces 

from Ontario to Newfoundland, and by 1975 the epidemic reached its peak, covering 

about 54 x 10 6 ha, or about half of the land area in eastern Canada classified as productive 

forest. Much of the remainder is not occupied by spruce and fir. 

In general, the intensity of the infestation, as measured by egg-mass densities across 

eastern Canada, declined in the latter part of the 1970s but the density of feeding larvae 

relative to the decreased quality of foliage on previously attacked trees remained high 

enough to cause severe damage. Thus in 1980 the epidemic still caused moderate to 

severe defoliation over 36 x 10" ha and it is expected that extensive defoliation will 

continue into the mid-1980s. 

Maturing balsam fir trees in unprotected forests usually die after 3 or 4 successive 

years of severe spruce budworm attack. Spruce trees, particularly black spruce, Picea 

mariana (Mill.) B.S.P., are more tolerant of defoliation and may withstand up to 6 years 

of attack. In the current outbreak, tree mortality was first recorded in northeastern 

Ontario and western Quebec in 1972, about 5 years after the beginning of the epidemic. 

In Nova Scotia (Cape Breton Highlands) and Newfoundland, mortality was first recorded 

between 1975 and 1976. Throughout the whole region, the area of vulnerable forest 

containing dying and dead trees increased each year and by 1980 was estimated at about 

19 x 10" ha (Table 56). Although 'zones of heavy defoliation' and 'zones of tree mortality' 

were delineated, it has proved difficult to translate these spatial data to a volumetric 

estimate of fibre loss. Inventory data on spruce and fir before the outbreak are meagre; 

moreover, the rapid detection of dying stands of trees by remote sensing is not yet 

operational. However, some estimates of fibre loss in mortality zones are available 

(Table 56). Generally, in eastern Canada in the late 1970s there was (1) continuing loss of 

radial and height growth in severely defoliated stands; (2) tree mortality ranging from 10 

to 80% at the stand level in a mortality zone of about 19 x 10" ha; (3) a loss in fibre quality 

and volume due to secondary pest attack in dead trees that were salvaged; and (4) 

235

236 C. A. Miller 

Table 56 

Table 57 

evidence that the future marketable volume of young stands that recover from the epidemic 

may be significantly lower than the site potential (Baskerville & Maclean 1979). 

Estimates of tree mortality in eastern Canada during the spruce budworm, Clwristoneura 

fumiferana (Clem.), outbreak of the 1970s· 

Dead and dying 

trees, 1980 

Date of first Area Volume 

Province tree mortality (x 10" hal (x 10" ml) 

Ontario 1972 8.4 ? 

Quebec 1972 9.3 ? 

New Brunswick •• 0.7 30 

Nova Scotia 1976 16 

Newfoundland 1975 0.4 40 

• Data extracted from: Forest Insect and Disease Conditions in Canada 1980. Canadian 

Forestry Service, Ottawa, 1981. 

•• Persistent infestation in central New Brunswick from the mid-1950s, with some tree 

mortality. 

No comprehensive policy was developed to deal with the spruce budworm problem in 

the 1970s in eastern Canada. The main reason is that each province administers its own 

forest resource and each gave a different priority to the social, economic, and political 

problems caused by spruce budworm. For example, in New Brunswick (Table 57) where 

the forest industry is of great importance to the provincial economy and the rate of 

utilization of spruce and fir is high, the policy was to protect Crown forests and designated 

private holdings where there was risk of severe tree damage and imminent tree mortality 

(Miller & Kettela 1975). Extensive annual use of chemical insecticides was the principal 

tactic in implementing this policy. In contrast, Ontario adopted a policy limiting chemical 

Softwood utilization relative to spruce, Picea spp., and balsam fir, Abies balsamea (L.) 

Mill., supply in New Brunswick and Ontario 

Pre-outbreak 1973 

Average 

Potential annual area 

Estimated Estimated A verage softwood··· wood of 

spruce and fir annual harvest 1979 supply sprayed 

volume· 

(x 10' ml) 

growth·· 

(x 10' ml) 

Allowable 

(x 10' ml) 

Actual 

(x 10' ml) 

(D-C) forest (ha) 

1975-79 

A 

New Brunswick 348 

Ontario 1744 

B 

8.7 

44···· 

C D 

7.1 7.4 Deficit 

27.1 19.3 Excess···· 

• Statistics Canada, 1973 . 

•• Broad-scale estimate . 

••• F.L.C. Reed and Associates ltd., Canadian Forestry Congress. 1980 . 

•••• No correction for accessibility. 

2.3 x 10" 

4.0 x 10'


ChorislOIU'lIfCI fllmiferallil (Clemens). 237 

control programmes to high investment areas such as parks, nurseries, and high value 

timber stands, because in that province wood supply problems are less pressing and fir is 

a minor component of utilized softwood. In all provinces, the issue of protection kindled 

debate on the use of chemicals. Various citizen groups argued that the use of chemical 

insecticides in forest spraying created unacceptable environmental and human health 

risks; they called for biological control and other pest management options. All provincial 

administration reacted to these concerns, but in Nova Scotia and Newfoundland the 

reaction resulted in curtailment of chemical spraying in forests that, with no intervention, 

had already suffered severe defoliation and increasing mortality. 

Although there has been research into many potential spruce budworm control techniques, 

operational control tactics in the face of a widespread epidemic are largely limited to 

removal of vulnerable stands and the suppression of feeding larval populations with 

chemical insecticides or with Bacillus Ihuringiensis Berliner. The following sections 

summarize the progress made with each of the biological control methods. 

Baskerville. G.L.; MacLean. D.A. (1979) Budworm caused mortality and 20-year recovery in immature balsam fir stands. Canadian 

Foreslry Sen'ice, Marilime Foresl Research Cenlre Informalion Reporl M-X-102. 

Miller. CA.; Kettela. E.G. (1975) Aerial control operations against the spruce budwonn in New Brunswick. 1952-1973. In: Prebble M.L. 

(Ed.) Aerial control of forest insects in Canada. Ottawa. Ontario; Thorn Press. pp. 95-112.

23R W. A. Smirnoffand O. N. Morris 

Background 

A. Field Development of Bacillus thuringiensis Berliner 

in Eastern Canada, 1970-80 

W.A. SMIRNOFF and O.N. MORRIS 

Bacillus Ihuringiensis var. kurslaki, (B.I.) is a bacterium registered in Canada for control 

of agricultural and forest pests. The registered preparations, derived from cultures of the 

serotype 3a, 3b, are a mixture of dormant endospores and endotoxin crystals suspended 

in a liquid carrier. 

Forest protection agencies have found spraying to be more expensive with B.I. than 

with chemical insecticides, yet B.I. remains a desirable alternative because its toxicity is 

confined to lepidopterous larvae and its use rarely arouses public antagonism. The 

Canadian experience of B.I. aerially applied against spruce budworm, Chorisloneura 

fumiferana (Clem.) is that its efficacy is variable. Field trials have indicated differences 

among commercial products, varying efficacies among field formulations, uncertainties 

over dosages, technical difficulties in spraying methods, weaknesses in means of measuring 

deposits, and inadequacies in techniques of assessing the agent's effectiveness in reducing 

larval populations and protecting foliage. 

Research into these problems was conducted in the 1970s, in two main areas, by two 

laboratories of the Canadian Forestry Service (C.F.S.): (a) in Quebec, where the 

Laurentian Forest Research Centre collaborated with the Quebec Department of Lands 

and Forests, and (b) in Ontario and the Atlantic Provinces, where the Forest Pest 

Management Institute participated in provincial-federal field trials. This paper collates 

the results from both laboratories. 

Mode of action 

B. Ihuringiensis serotype 3a, 3b is a bacterium that is pathogenic to lepidopterous 

larvae. On spruce budworm and other tortricids the commercial formulations cause 

enterotoxicosis by the action of the crystal-like parasporal inclusions (= delta endotoxin), 

followed by septicaemia from the action of their spores (Smirnoff & Valero 1979, Fast 

1981). The mode of action of the crystal toxin is described by Cooksey (1971). 

The pathogenic action of 8.1. on spruce budworm depends on the dose ingested. the 

age and physiological state of the larvae, the temperature, and possibly on the presence 

of natural infections by microsporidia. The optimal temperature for this action is 

20-22°C (Smirnoff 1967). Young larvae are more susceptible to B.I. than fifth- and sixthinstar 

larvae (Morris 1973). 

Formulations 

Initially B.I. was tested against spruce budworm in New Brunswick in 1960. The 

material used was Thuricide® SO-75 (Bioferm Corp.), based on the Berliner serotype. 

Next, a small-scale aerial application of Thuricide® 90T was made in 1969, using both 

suspensions in water and water-in-oil emulsion (Morris el al. 1975). Assessment of 

population density reduction and foliage protection was inconclusive owing to clogging 

of the spray nozzles and poor distribution of the active ingredient. 

Improved commercial preparations of B.I. became available for testing between 1970 

and 1980, namely Thuricide® 24B, Thuricide® 32B, Dipel® 36B (Abbot Ltd.), and 

Novabac® 32B (Cyanamid Canada) or Novabac® wettable powder titrating 80 000

A. Field development of Bacillus Ihurillgiellsis 239 

I. U .Img. These concentrates included various additives designed to improve deposit 

efficiency and adherence to foliage (rain fastness), and to prolong residual activity of the 

biological agent. 

Three field formulations were developed at the Laurentian Forest Research Centre, 

and have been used experimentally in Quebec. The first formulation, based on an 

aqueous solution of sodium dihydrogen phosphate (NaH 2P04), and the second, based 

on an aqueous solution of sorbitol, incorporate chitinase and Chevron® sticker (Chevron 

Chemical (Canada) Ltd.), and have been used since 1973 in low-volume sprays 

(4.7 l/ha). Sorbitol is a humectant, whereas sodium dihydrogen phosphate is added to 

increase the specific gravity of the liquid B.t. formulation. The third formulation, named 

Futura by the Laurentian Forest Research Centre, also uses sorbitol, chitinase, and 

sticker but incorporates less aqueous carrier and has been used for reduced-volume 

sprays (2.5 Jlha) since 1978 (Smirnoff 1980a, 1981a). Formulations used in Ontario and 

the Atlantic Provinces were similar, but did not include chitinase, sorbitol, or sodium 

dihydrogen phosphate (Morris 1980). 

Smirnoff (1973, 1977) concluded after several years of experiments that the addition of 

minute quantities of chitinase increases the efficacy of B.t. against spruce budworm; in 

his view, it enhances penetration of ingested ingredients through the gut lining, and 

rapidly potentiates symptoms of infection (lethargy, weight loss) even at low temperatures. 

Some other additives have been tested for compatibility. Smirnoff (1981b) found that 

either mineral oil in large quantities or various dyes inhibited spore development. 

During 1970-79, Thuricide® 16B (Sandoz. Inc.) was the only product fully registered 

for spruce budworm control under the Canadian Pest Control Products Act; around 1980 

Dipel® 88 and Novabac® (Cyanamid Canada) have been fully registered. 

Spray delivery systems and measurement of deposit 

Sprays were applied by various aircraft ranging from four-engined freight planes to 

single-engined biplanes and helicopters. They included the Lockheed Constellation L- 

749, Douglas DC-6B, Canadair CL-215, Grumman Avenger TBM, Grumman Ag-cat, 

Boeing Stearman, Piper Pawnee, Cessna Agtruck, and the Sikorsky S55-T helicopter. 

Several kinds of spray emission hardware were tried, including Beecomist® (Beeco 

Products Co., USA), Micronair® (Micronair (Aerial) Ltd., U.K.) boom and flat fan 

Teejet® nozzles, and boom and open nozzles. Spray aircraft were calibrated to ensure 

appropriate emission rates for prescribed swath widths. Swath width varied from 305 m 

for a Constellation to 38 m for an Ag-cat (Smirnoff 1979a, Smirnoff & Juneau 1982). 

There is no general agreement on the optimal droplet size or optimal foliage coverage. 

Spray coverage is measured as the number of droplets per square centimetre on Kromekote® 

cards, or as the number of colonies per square centimetre collected on agar plates 

or MiIlipore® filters, placed at ground level in forest clearings. The number of spores 

deposited per unit area on glass plates at ground level has also been measured (Morris 

1980). In 1979, Smirnoff & Valero proposed a new method whereby a given volume of 

peptonized water was exposed to the spray, so that the number of spores deposited per 

unit area could be calculated. For B.t. treatments, this value is more important than the 

total volume of liquid deposited (Smirnoff 1980a). Field tests have shown the necessity 

for calibration of the spray system: assessment based on the viable spore count deposited 

per unit area provides an adequate calibration. 

The concentration of B.t. within the proprietary product, the properties of the 

adjuvants added at the airstrip mixing plant, and the composition of the tank concentrate 

all affect the rate of deposition and the success of operations (Smirnoff 1980b). 

Operators used various kinds of spray hardware designed for chemical insecticides. 

Beecomist® spray heads were satisfactory on the Sikorsky helicopter. However, a

240 W. A. Smirnoff and O. N. Morris 

Field Trials 

boom and nozzle spray system composed of Teejet® 8004 flat fan nozzles gave better 

results with a Grumman Ag-cat fixed-wing aircraft (Smirnoff 1979a). A larger aircraft 

such as the DC-6B is used with open type nozzles, provided that the pumping system is 

able to produce a 413 kPa to 482 kPa pressure in the booms. 

In summary, a variety of means was used in the development of B.I. application 

technology: field trials using new formulations; improved hardware and nozzle systems; 

atomization and distribution of B.I.; knowledge of meteorological parameters; swath 

paths; improved deposit analysis; dosage rates; application timing and frequency; 

methods of measuring treatment effectiveness; and knowledge of the spruce budworm 

population densities most amenable to effective control (Morris 1980, Morris el al. 1981, 

Smirnoff 1979a, 1979b, 1980a, Auger el al. 1981). 

Assessment of efficacy 

The assessment of efficacy continues to be a major problem because both criteria - 

foliage saved and number of larvae killed - present sampling difficulties. The estimate 

of foliage saved by treatment is derived from comparisons of foliage persisting in 

untreated check plots with foliage retained in the sprayed plot. An important element of 

the comparison is the production of new buds as a measure of foliage potential in the 

year following treatment. Quantification of foliage saved is based on counts of shoots, 

but the method lacks sensitivity because all shoots do not develop consistently. Since 1978 

an improved method has been developed at the Laurentian Forest Research Centre based 

on weight of new foliage produced and retained; it compares the weight of foliage 

produced by a defoliated tree with the expected weight of foliage produced by a healthy 

tree of similar branch area. 

The estimation of larval population reduction has usually been based on a comparison 

of the survival rate in the treated plot with that in an untreated check plot, using Abbott's 

formula to isolate the effect of the spray. Most workers recognize that this technique 

has major problems of sensitivity owing to the variability encountered in sampling. 

Non-lethal residual effects from B.I. have been observed by Morris (1973), Smirnoff 

(1978), and Morris el al. (1981); the influence of these effects on the dynamics oftreated 

budworm populations cannot yet be assessed, but should not be ignored. Smirnoff 

detected changes in the "vitality" of survivors in treated populations, calculated by 

measurements of pupal weight, total lipids, calcium, and various enzymes. In a comparison 

of pupal populations in stands treated with the chemical insecticide fenitrothion, 

stands treated with B.I., and untreated stands, the survivors exposed to B.t. had the 

lowest vitality assessed by these biochemical criteria (Smimoff 1979c). 

Province of Quebec 

The field trials (Table 58) had various objectives, but were especially designed to test 

formulations and to measure deposits, larval mortality, and foliage protection under 

operational and experimental circumstances. The first trials in 1971 and 1972 encouraged 

the expectation that spruce budworm mortality and defoliation control could be achieved 

by adequate deposits of B.t. (Smimoff el al. 1973a, 1973b). Small trials in 1973 showed 

that B.t. sprays might be ineffective where spruce budworm populations were very high 

and stands were already weakened (Smirnoff el al. 1974). In 1974 and 1975, four-engined 

aircraft were used on a large scale for the first time, but the results were inconclusive 

because of improper calibration of the spray system (Smirnoff el al. 1976, Smirnoff &

244 W. A. Smirnoffand O. N. Morris 

Table 61 

Table 62 

Tests of Bacillus Ihuringiensis Berliner aerially applied against the spruce budworm, 

Clrorisloneura fumiferana (Oem.), on red spruce Picea rubens Sarg., in Nova Scotia and 

New Brunswick 1979-80" 

Ground 

Dosage deposit Pre·spray larval Percentage 

applied rate density per Percentage deroliation roliage 

Formulation"" Year (LU. x I0 9 iba) (drops/em l ) 45-cm branch Expected Actual saved 

Nova Scotia 

Thuricidcs 168 1979 I x 20 38-56 22 60 14 46 

Thuricidcs 168 1979 I x 20 51 14 38 9 28 

Thuricidc s 168 1979 2 x 20 27-31 12 36 14 22 

Thuricide!l 168 1900 I x 20 24 7 25 0.2 25 

Thuricidc:s 168 1900 1 x 20 30 7 25 14 II 

Thuricide!': 168 1900 I x 20 19 6 25 12 J3 

New Brunswick 

Dipell'l88 1979 1 x oW 20 17 46 23 23 

Thuricides 168 1979 I x 20 12-33 19 50 28 22 

" Includes only tests reporting pre-spray larval densities. 

"" Includes only formulations without chemical additives, e.g. chemical pesticides and 

enzymes. 

Extent of acceptable protection with Bacillus Ilruringiensis Berliner in eastern Canada 

1979-80· 

Mean no. of Percentage of 

Area droplets/em 2 area acceptably 

Province trea ted (ha) (range) protected"" 

Ontario 4846 22 (11-30) 74 

- FPMI (1980 only) 320 34 (24-40) 100 

New Brunswick (1979 only) 360 23 (2-53) 100 

Nova Scotia 30188 51 (9-111) 92 

Newfoundland 15699 9 (5-16) 48 

and Labrador 

Quebec 33 174 43 (10-87) 89 

"" 


Based on efficacy data provided by provincial departments or agencies. 

Acceptable protection is less than 50% defoliation of current year's growth. 

protected, ranged from 74 to 100% except for Newfoundland and Labrador, where the 

success rate was only 48%. The poor efficacy in Newfoundland was apparently due to 

inadequate spray deposits. 

The encouraging results with B.I. up to 1978 prompted the C.F.S. to formulate technical 

guidelines for the use of this product against the spruce budworm. A preliminary C.F.S. 

policy statement recommended "the operational testing of B.I. in environmentally 

sensitive areas or in sensitive areas where the forest manager either chooses not to use


A. Field development of Bilcilllls IllIlringiensis 245 

or is forbidden to use conventional chemical insecticides for the control of the spruce 

budworm". The main technical recommendations were as follows: 

Objective - primarily to limit the average annual defoliation to less than 50% and 

secondarily to reduce the numbers of spruce budworm by 75-85%. 

Formulation - Thuricide® 16B. water (not chlorinated). Chevron® sticker (0.1 %). 

Optional for experimental trials: Thuricide lt 32B. sorbitol. Chevron® sticker. chitinase 

(9880 nephelometric units per hectare). water. and Erio Acid Red (experimental tracer). 

Note that dyes may inhibit B.I. efficacy. 

Dosage - 20 x 10" I.U. of B.I. in a minimum of 4.7 I/ha. In mixed spruce·fir stands. two 

applications of 10-20 x 10" I. U .Iha each. 

Operational constraints - pre·spray population density of 25-30 larvae per 45·cm branch 

tip. Application should start at shoot flare and continue no later than the date when 30% of 

the spruee budworm have developed to the fifth instar. 

Deposit specifications - agar plates or Millipore® filters should be used to collect ground 

level deposits. aiming for a density of 25 droplets/cm l or more. 

In an attempt to reduce the inconsistencies of results in previous years, the 8.t. 

applications using these guidelines were co-ordinated in 1979 and 1980 (Morris 1980, 

1981). In general, the guidelines were followed unless extenuating circumstances were 

encountered. Clearly, B.I. is an effective alternative to the use of chemical pesticides for 

the protection of foliage. An analysis of the results of these applications (Morris 1980) 

showed that successful treatments had the following common characteristics: 

1. Pre-spray densities were usually less than 28 larvae per 45-cm branch tip 

2. Larval development at spray time was around fourth instar 

3. Bud flushing was 80-100% complete (except on red spruce) 

4. LV. applied per hectare were 20-40 x 10" in single or double applications 

5. Ground level droplet density was greater than 25/cm 1 

6. Spray time relative humidity was mostly higher than 65% 

7. Good weather followed spraying. 

These conditions are now generally accepted by researchers as desirable for 8.1. 

application in the forest. 

Smirnoff (1980c) advocates further conditions for reducing costs and increasing success; 

a) The required 8.1. dosage should be emitted in a formulation dispensible at 

2.5-3.0 l/ha; or (in the case or Thuricide® 32B with sorbitol in water) at 4.711ba; 

b) formulations should include Chevron® sticker at 1:1600; and chitinase at 10 000 

nephelometric units per hectare; 

c) spore viability in the concentrate drum should be checked; 

d) large capacity aircraft equipped with boom and nozzle are more cost-effective 

than small aircraft. Spray output must be calibrated and checked by counts of viable 

spores at ground level; the ground deposit should attain at least 60% of the emission 

rate; 

e) B.t. treatments should be carried out when most ofthe larvae are third instar, and 

buds are flushing (Smirnoff 1980c. Auger el 01. 1981). 

Improvements in commercial formulations and application technology during the past 

decade have brought B.I. to a point where it is now considered a clear alternative to 

chemical insecticides for use against spruce budworm. especially in environmentally 

sensitive areas. It is almost as effective for tree protection as the available chemical 

pesticides. Success or failure cannot yet be totally explained or predicted because 

relationships between foliage protection and dosage per volume emitted are not firmly 

established. Moreover, estimates of ground deposits have borne little practical relationship 

to deposits on foliage. The technical guidelines prepared in 1978 (see earlier)

246 W. A. Smirnoff and O. N. Morris 


continue to be valid, but require updating. B.t. spray operations are expensive 

compared with the use of chemical insecticides (2.5-5 times higher around 1980). As 

much of the cost is in material transport, more concentrated proprietary products should 

be devised to lower the shipping and application costs. 

Technical development of formulations, spray applications, and efficacy assessment 

should be continued: the search for more efficaceous formulations, droplet spectra, and 

timings should be continued; field dosage and volume/response relationships should be 

established, to provide the pest manager with costlbenefit options; and a quantitative 

method of measuring deposits at the feeding site is needed, to relate deposit rate of the 

active ingredient to its effectiveness. 

Auger. M.; Chabot. M.; Pelletier. M.; Bordeleau. C. (1981) Ellpertises entomologiques relices aux pulvl!risations al!riennes contre la 

tordeuse des bourgcons de I'!!pinette au QuI!bec en 1980. Qucbec; Ministl!re de I'Energie et des Ressources, 

107 pp. 

Cooksey, K.E. (1971) The protein erystaltollin of Bacillus thuringiensis: biochemistry and mode ofaction.ln: Burges. H.D.; Hussey. N.W. 

(Eds.) Microbial control of insects and mites. New York; Academic Press, pp. 247-274. 

Dorais, L.; Pelletier, M.; Smirnoff, W.A. (1980) Pulvl!risations acriennes de Bacillus thuringiensis Berliner realisees au Qucbec de 1971 a 

1979 contre In tordeuse des bourgeons de I'cpinette, Choristoneura fumiferana (Clem.). Rappon presente 

au VI' Congres International de l'Aviation Agricole a Turin. Italie, Septembre 1980. 

Fast. P.G. (1981) The crystal toxin of Bacillusthuringiensis.ln: Burges, H.D. (Ed.). Microbial control of pests and plant diseases 1970-1980. 

New York; Academic Press, pp. 223-248. 

Morris, O.N. (1973) Dosage·monality studies with commercial Bacillus thuringiensis sprayed in a modified Potler's Tower against some 

forest insects. Journal of Invertebrate Pathology 22,108-114. 

Morris, O.N. (1980) Repon of the 1979 CAN USA Cooperative Bacillus thuringiensis (B.t.) spray trials. Canadian Forestry Service 

Information Report FPM-X-40, 160 pp. 

Morris, O.N. (1981) Repon on the 1980 Cooperative Bacillus thuringiensis (B.t.) spray trials. Canadian Forestry Service Information Report 

FMP-X-48, 80 pp. 

Morris, O.N.; Moore. A. (1975) Studies on the protection of insect pathogens from sunlight protection. II. Preliminary field trials. Canadian 

Forestry Service Information Report CC-X-113. 

Morris, O.N.; Angus, T.A.;Smirnoff, W. (1975) In: Prebble, M.L. (Ed.). Aerial control offorest insects in Canada. Ottawa; Thorn Press, pp. 

129-133. 

Morris, O. N.; Hildebrand, M.J.; Moore, A. (1981) Comparative effectiveness of three commercial formulations of Bacillus thuringiensis for 

control of the spruce budworm, Choristoneura fumiferana (Oem.). Canadian Forestry Service 

Information Report FMP-X-47. 31 pp. 

Smirnoff, W.A. (1967) Innuence of temperature on the rate of development of sill varieties of Bacillus cereus group. Insect pathology and 

microbial control. Amsterdam; Nonh-Holland, pp. 125-130. 

Smimoff, W.A. (1973) Results of tests with Bacillus thuringiensis and chitinase on larvae of the spruce budworm. Journal of Invertebrate 

Pathology 21,116-118. 

Smirnoff, W.A. (1977) Confirmations ellperimentales du potential du complelle Bacillus thuringiensis et chitinase pour la rl!pression de la 

tordeuse des bourgeons de I'cpinette Choristoneura fumiferana (Lepidoptera: Tortricidae). Canadian 

Entomologist 109.351-358. 

Smimoff, W.A. (1978) Impact des traitemcnts bacteriologiques et des traitcmcnts chimiqucs sur une I!pidemie de la tordeuse des bourgeons 

de I'cpinette. Resumc des communications, 46' congres ACFAS. p. 68. 

Smirnoff, W.A. (1979a) Results of spraying Bacillus thuringiensis two consecutive years over balsam fir stands damaged by spruce 

budworm. Canadian Journal of Forest Research 9,509-513. 

Smirnoff, W.A. (1979b) Result of a 3-phase research program related to the biological control of the spruce budworm in 1979. LFRC, Repon 

to the Candian Forest Pest Control Forum, Nov. 27-28, 1979, Ottawa, Ontario. 

Smirnoff. W.A. (1979c) Changes in metabolites in insects during starvation, infections or poisoning. Abstracts of papers, 9th International 

Congress of Plant Protection and 71st Annual Meeting of the American Phytopathological Society, 

Washington, D.C., No. 928. 

Smirnoff, W.A. (19800) Deposit asscssment of Bacillus thuringiensis formulations applied from an aircraft. CalUJdian Journal of 

Microbiology 26,1364-1366. 

Smimoff, W.A. (1980b) Calibration tests with various Bacillus thuringiensis preparations. Canadian Forestry Service Bi-monthly Research 

Notes 36,30-31. 

Smirnoff, W.A. (198Oc) Technological requirements for a successful Bacillus thuringiensis application against spruce budworm. Canadian 

Forestry Service Bi-monthly Research Notes 36.29-30. 

Smirnoff, W.A. (19810) Developpement d'une preparation compacte et economique de Bacillus thuringiensis pour la rl!pression de la 

tordeuse des bourgeons de I'cpinetle Choristoneura fumiferana. Annales de I'ACFAS 48.203.

248 J. C. Cunningham and G. M. Howse 

Background 

Field Trials 

B. Viruses: Application and Assessment 

J.C. CUNNINGHAM and G.M. HOWSE 

Five different types of viruses have been found to infect larvae of the spruce budworm, 

Chorisloneura fumiferana (Clem.). Four of them share one feature in common, that is, 

virus particles are contained within proteinaceous inclusion bodies. These infectious 

particles are released when the inclusion bodies are ingested by larvae and the inclusion 

body protein dissolves in their alkaline gut juices. The four viruses comprise a nuclear 

polyhedrosis virus (NPV), a granulosis virus (GV), a cytoplasmic polyhedrosis virus 

(CPV), and an entomopoxvirus (EPV). Between 1971 and 1980, all four viruses have 

been field tested either alone or in various combinations. The fifth virus, which has been 

found to infect spruce budworm, is cricket paralysis virus. It has no inclusion body, has 

a very wide host range, has little potential as a biological control agent, and will not be 

discussed further. Collapse of a spruce budworm population due to a naturally occurring 

virus epizootic has never been observed. Both NPV and CPV are occasionally detected 

in eastern spruce budworm populations in Ontario. but generally less than 1 % of larvae 

are infected. 

The first field trials of spruce budworm viruses were conducted in 1959 and 1960 by 

applying NPV and GV on single small trees (Stairs & Bird 1962). In 1969, different 

dosages of NPV were applied on single trees at 2- to 3-day intervals throughout the larval 

period (Bird & McPhee 1970). In 1970, an EPV was found in 2-year cycle spruce 

budworm, C. biennis Freeman (Bird el al. 1971). In the laboratory very low dosages of 

this EPV (in comparison to other viruses) caused high larval mortality and, although it 

was slow acting, there was high hope that it would prove to be an effective biological 

control agent. By 1970, the use of artificial diet had greatly improved methods of rearing 

spruce bud worm (McMorran 1965), and sufficient larvae could be reared in order to 

produce viruses for aerial spray trials (Grisdale 1970). 

The first aerial spray trial was conducted in 1971 and trials have been carried out each 

season since then. Sixty plots were treated with viruses or combinations of chemical and 

viral insecticides in Ontario between 1971 and 1980. Such factors as dosage, timing of 

application, tank mixtures, spray equipment, impact on different species of host trees, 

and persistence of viruses from one year to the next have been evaluated. The following 

viruses and combinations of viruses were tested during this period: NPV, EPV, GV, 

EPV plus NPV plus CPV, and NPV plus CPV. In addition, NPV and EPV plus NPV have 

been applied following chemical insecticide sprays. 

Assessment of the impact of treatments 

The same methods used to evaluate chemical insecticide treatments in Ontario were 

used to assess virus spray trials. In addition to carrying out larval population studies 

and defoliation estimates, attempts were made to determine the levels of infection in 

the spruce bud worm population, to assess the effect on successful pupal emergence and, 

on some plots. to continue these studies for one or more years after the initial application.


Estimating current year's defoliation 

The percentage of the current year's defoliation was obtained by detailed examination of 

the 46-cm branch tips collected for the post-spray sample from the treated and check 

plots. These samples were collected after all surviving larvae had pupated and feeding 

had ceased. In the tables, the percentage of foliage saved was calculated using Abbott's 

formula. 

Follow-up studies 

Many plots were re-examined the following year and some plots were studied for several 

years because carry-over of viruses from one year to the next and the impact on the spruce 

budworm population in the years following the year of treatment are considered important 

factors in evaluating these biological control agents. The same observations were recorded 

as in the year of treatment. 

Tank mixes for virus applications 

Several tank mixes have been used for spruce budworm virus applications and are described in 

the tables. The viral product in all tests was a finely ground lyophilized preparation of 

virus-infected larvae. A few plots were treated with this product in water alone, but 

without a tracer dye no deposit assessment could be made. In many of the tests IMC 90- 

001 (International Minerals Corp.) UV protectant was added. It is a water-soluble wood 

byproduct that has a dark colour; it can also be used as a tracer dye. This material was 

renamed Shade® (Sandoz Inc.), but its production was discontinued in 1979. 

Molasses has been used in most of the tank mixes. It is an anti-evaporant that enhances 

deposit of aqueous sprays, may give some UV protection, and may be a feeding attractant 

to spruce budworm larvae. The results from single-tree ground spray tests indicated that 

molasses in the mix had a marked beneficial effect. A commercial molasses preparation, 

Sandoz adjuvant V® (Sandoz Inc.), was used in 1975. 

Many wetting and sticking agents have been tested in combination with Shade®, with 

or without molasses. These agents include Biofilm® (Colloidal Products Corp.), Chevron® 

spray sticker (Chevron Chemical Co.), Triton® X-lOO and Triton® B-1956 (Rohm and 

Haas Co. of Canada Ltd.). All passed a laboratory test to determine their compatibility 

with virus at a concentration of 1 %. 

Two other preparations tested were:Sandoz San 285® wettable powder, which is a 

feeding attractant for the virus of cotton bollworm, Heliothis zea (Boddie), incorporated 

in a polymer-bound carbon formulation prepared by the Southwest Research Institute, 

San Antonio, Texas; and an emulsifiable oil, Sunspray® 11E (Sunoco Inc.). The process 

used to produce the polymer-bound carbon formulation inactivated most of the virus 

and the feeding attractant did not enhance virus infection levels in spruce bud worm 

(Cunningham et al. 1978). The emulsifiable oil used at 66% had no adverse effect on the 

virus and its use would be beneficial if sprays were applied when the humidity was low. 

Entomopoxvirus plus nuclear polyhedrosis virus plus cytoplasmic polyhedrosis virus 

In 1971 a helicopter was used to treat six 1.07-ha plots with EPV (Table 63). When 

smears of larvae from treated plots were examined microscopically it was discovered 

that the EPV preparation was contaminated with both NPV and CPV. All three viruses 

gave consistently higher levels of infection in larvae on white spruce, Picea glauca 

(Moench) Voss, hosts than on balsam fir, Abies balsamea (L.) Mill., hosts (Bird et al. 

1972, Howse et al. 1973).

Table 63 

Table 64 

B. Viruses: Application Clnd assessment 251 

Application of EPV contaminated with NPV and CPV on six 1.07-ha plots using a helicopter 

fitted with boom and nozzle equipment and calibrated to deliver 28.2 Ilha* 

Population 

Pre·dominant Deposit Highest virus infection (01.,) reduction due Current 

Dosage. instar at card, to treatment year's foliage 

PIB/ha time of droplets! EPV NPV CPV (%} saved ('Yo} 

Plot (x 10") application cm 2 bF·· wS bF wS bF wS bF wS bF wS 

1 750 2 10 9 38 10 0 7 0 40 R 15 

2 75 2 9 3 16 0 12 1 4 0 61 3 0 

3 7.5 2 9 1 12 0 2 II II 0 25 0 0 

4 750 3&4 29 6 5 4 7 1 4 30 79 1 0 

5 75 3&4 31 2 2 0 1 II II 48 57 0 0 

6 7.5 3&4 NO··· 4 6 0 0 0 0 II 59 1 0 

* Aqueous tank mix contained 2.5% IMC 90-001 sunlight protectant. 

** bF = balsam fir, Abies balsamea (L.) Mill.; wS = white spruce, Picea glauca 

(Moench) Voss. 

••• ND = Not determined . 

Follow-up studies were undertaken between 1972 and 1975 on the two plots treated 

with the highest dosage (Table 64). It can be seen that, although there was little foliage 

protection in 1971 (Table 63), there was significant foliage protection in the subsequent 3 

years. Also, the NPV, which was a minor contaminant in the EPV preparation, was 

considerably more prevalent in the following years than the EPV (Cunningham el al. 

1975a). 

Follow-up studies on two I?lots treated with EPV contaminated with NPV and CPV at a 

dosage of 750 x to" inclUSIon bodieslha in 1971· 

Population Current 

Highest virus infection (%) reduction due "ear's 

to virus oliage 

EPV NPV CPV {%l saved {%} 

Plot Year bF** wS bF wS bF wS bF wS bF wS 

1972 0 5 7 19 2 5 64 82 72 59 

1973 2 5 3 13 0 0 3 60 27 22 

1974 1 2 1 4 0 0 0 5 29 49 

1975 1 6 5 16 1 1 0 78 22 2 

4 1972 0 0 17 20 to 4 16 68 44 49 

1973 0 1 4 16 2 0 15 83 26 22 

1974 0 1 3 11 1 0 0 48 25 40 

1975 0 1 17 11 0 0 47 26 1 1 

* See Table 63 for details and results in 1971 

.* bF = balsam fir, Abies balsamea (L.) Mill.; wS 

(Moench) Voss. 

Entomopoxvirus 

white spruce, Picea glauca 

In 1972, pure EPV was tested and three plots with a total area of512 ha were treated. The 

timing of the application was on second- and third-instar larvae, but an unseasonably 

late snow fall destroyed most of the spruce budworm larvae and killed the new growth 

on the trees. Population studies and defoliation estimates were abandoned and only

Table 67 

B. Viruses: Application and assessment 253 

levels of CPV as well as of NPV infection were recorded (Table 66) (Bird el al. 1972, 

Howse el al. 1973). Follow-up studies were undertaken on these plots between 1972 and 

1977 (Table 67). The incidence of NPV was higher than CPV during this period. Although 

not spectacular, some saving of foliage was recorded between 1972 and 1975 (Cunningham 

el al. 1975a). 

Follow-up studies on two white spruce, Picea glauca (Moench) Voss, plantations treated 

with NPV plus CPV (400:1) in 1971- 

Highest virus 

infection % 

Population 

reduction 

due to virus Current year's 

Plot Year NPV CPV carry-over ('Yo) foliage saved ('Yo) 

G 1972 28 8 20 0 

1973 17 5 82 22 

1974 6 I 56 27 

1975 21 0 74 0 

1976 8 0 NO-- NO 

1977 3 0 NO NO 

H 1972 

1973 

1974 

1975 

1976 

1977 

24 

14 

6 

9 

0 

2 

3 

0 

0 

0 

0 

0 

65 

68 

62 

48 

NO 

NO 

63 

20 

44 

0 

ND 

NO 

- See Table 66 for details and results in 1971. 

-. ND = not determined. 

Rigorous quality control facilitated production of pure NPV between 1972 and 1978, but 

in 1979 a CPV contaminant was again found and aUempts to eliminate it were unsuccessful 

both that year and in 1980. In 1979, the ratio of NPV:CPV was 178:1, and in 1980 the 

same preparation and one with an NPV:CPV ratio of 300: I were applied (W.J. Kaupp 

1980, personal communication) (Table 66). In 1979, the viruses were applied either as 

second-instar larvae emerged from hibemacula or on later instars following budflush. 

Following the early application, high levels of virus infection and acceptable foliage 

protection were recorded. On the remaining plots reasonable levels of virus infection 

and population reduction but little or no foliage protection were recorded. In 1980, an 

attempt was made to repeat the early applications made in 1979. However, when the 

spray was applied about 90% of the larvae had mined into needles and buds. Infection 

levels were lower than in 1979, although moderate levels of both popUlation reduction 

and foliage protection were recorded. 

Nuclear polyhedrosis virus 

Tests were conducted with pure NPV in 1972 (Cunningham & McPhee 1973), in 1973 

(Cunningham el al. 1974) in 1974 (Cunningham el al. 1975b), in 1975 (Cunningham etal. 

1975c), in 1976 (Kaupp el al. 1978), in 1977 (Cunningham el al. 1978), and in 1978 (Cunningham 

el af. 1979). During that 6-year period, 33 plots with a total area of 1741 ha were treated 

(Table 68). In 1972 the trials were a failure because of the same late snow fall that 

affected the EPV trials that year. In subsequent years, tests were made with lower 

dosages than those used in the original 1971 test, a variety of tank mixes containing



use will probably be restricted to high value stands and environmentally sensitive areas. If it 

can be demonstrated conclusively that treatment with a virus gives foliage protection for 

several years following the year of application, then the high initial cost of the treatment 

becomes more acceptable. 

The application of contaminated virus preparations in 1971 was accidental. The 

presence of a CPV contaminant in the NPV used in 1979 and 1980 was known. but the 

material was still applied on the basis of the 1971 results. The minute amounts of CPV 

gave dramatic infection levels in the spruce budworm population that were often higher 

than the levels of NPV. This was surprising because the ratios of NPV:CPV were 400: 1. 

300: 1. and 178: 1. It appears that there is a synergistic effect between NPV and CPV. but 

this would require detailed laboratory investigations to prove conclusively. 

Foliage protection in the year of application was demonstrated in 1979 following treatment 

with NPV plus CPV on second-instar larvae as they emerged from hibernacula. Treatment 

of second-instar larvae has many benefits. although timing is extremely critical and 

it would only be practical to treat small. carefully monitored areas. Second-instar larvae 

are much more susceptible to infection with NPV than later instars and the LD50 in terms 

of numbers of PIB has been calculated for different instars as follows: second. 25; third. 

204; fourth. 462; fifth, 2514; and sixth, 3 643 (F.T. Bird 1978, unpublished data). At the 

time of emergence from hibernacula. leaves on the hardwood overstorey. frequently 

found in spruce-fir stands, have not flushed and a good aerial spray deposit can be 

obtained on the target species. 

To date, the tank mix considered most suitable for spruce budworm virus applications 

was an aqueous suspension containing 25% molasses, 6% Shade® and 1 % Chevron® 

sticker. It has been widely used with the NPVs of both Douglas-fir tussock moth. Orgyia 

pseudotsugata (McDunnough), and gypsy moth, Lyman/ria dispar (L.). Since Shade® is 

no longer commercially available, it will be necessary to find a new screening agent 

against ultra-violet light or a totally new formulation. 

Safety tests on spruce budworm NPV conducted at Ontario Veterinary College 

showed that this virus presents no hazard to birds and mammals (Valli et al. 1976). Fish 

tests, although indicating no hazard. were inconclusive and should be repeated (Savan 

et al. 1979). There are only limited safety testing data available for EPV (Buckner & 

Cunningham 1972). and no CPV and GV safety testing data are available. These would 

be required before any of these three .. iruses could be registered by Canadian authorities. 

The use of any of the four viruses with inclusion bodies that infect spruce budworm is still at 

the experimental stage. In the near future only treatment of small areas can be considered. 

Applications of NPV or NPV plus CPV on second-instar larvae as they emerge from 

hibemacula should be retested in an effort to find if. under closely monitored conditions. 

this is a feasible and effective strategy. 

An improved tank mix that will keep the virus in a viable state on the foliage for more than 

a week would greatly increase the effectiveness of treatments and possibly allow lower 

dosages. Research on formulations is being conducted by both commercial and government 

agencies in the United States and formulations developed for other pathogens. such as 

bacteria and fungi. will probably have the characteristics suitable for use with viruses. 

The search for new viruses or strains of viruses that infect spruce budworm should be 

continued. There are several isolates of NPV • GV, and EPV from different Choristoneura 

species, but none has been found that is more virulent than the strains used in field trials. 

The search for larger. easily reared host larva for spruce budworm virus production has also 

proved unsuccessful. but should be continued. 

A long-term goal in the use of viruses for the regulation of spruce budworm population is 

to study the nucleic acid of spruce budworm NPV with a view to constructing a genetic


B. Viruscs: Applicmion and assessmcnt 259 

map. Once this is accomplished, techniques of genetic manipulation can be used in an 

attempt either to increase the virulence of spruce budwonn NPV or to modify some highly 

virulent, easily produced insect virus in such a way as to render it capable of infecting 

spruce budwonn. 

Abbott. W.S. (1925) A method of computing the effectiveness of an insecticide. Journal of Economic Entomology 18.265-267. 

Arif. B.M.; Sohi. S.S.; Krywienczyk. J. (1976) Replication of alkali-released NPV in a cell line of ChorislOneurafumiferana. Proceedings of 

the 1st International Colloquium on Im'mebrate Pathology Kingston, Ontario, pp. 108-110. 

Bird. F.T.; McPhee. J. R. (1970) Susceptibility of spruce budworm to pure nuclear polyhedrosis virus (NPV) sprays. Canadian Department 

of Fisheries and Forestry Bi·monthly Research Notes 26.35. 

Bird, F.T.; Sanders. C.J.; Burke. J.M. (1971) A newly discovered virus disease ofthe spruce budworm. Choristoneura biennis (Lepidoptera: 

Tortricidae). Journal of Invertebrate Pathology 18.159-161. 

Bird. F.T.; Cunningham. J.e.; Howse. G.M. (1972) Possible use of viruses in the control of spruce budworm. Proceedings of the 

Entomological Society of Ontario 103,69-75. 

Buckner. C.H.; Cunningham. J.C. (1972) The effect of the poxvirus of the spruce budworm. Choristoneura fumiferana (Lepidoptera: 

Tortricidae). on mammals and birds. Canadian Entomologist 104.1333-1342. 

Cunningham. J.e.; McPhee. J.R. (1973) Aerial application of entomopoxvirus and nuclear polyhcdrosis virus against spruce budworm at 

Chapleau. Ontario, 1972. Canadian Forestry Service, Sault Ste. Marie, Information Report IP-X-3. 27 pp. 

Cunningham, J.C.; McPhee, J.R.; Howse. G.M.; Harnden, A.A. (1974) Aerial application of a nuclear polyhedrosis virus against spruce 

budworm near Massey and Aubrey Falls, Ontario in 1973 and a survey of the impact of the virus in 1974. 

Canadian Forestry Service, Sault Ste. Marie, Information Report IP-X-4, 45 pp. 

Cunningham, I.C.; Howse, G.M.; Kaupp, W.J.; McPhee, J.R.; Hamden, A.A.; White, M.B.E. (1975a) The persistence of nuclear 

polyhedrosis virus in populations of spruce budworm. Canadian Forestry Service, Sault Ste. Marie, 

Information Report IP-X-lO, 32 pp. 

Cunningham. J.C.; Kaupp. W.J.; McPhee, I.R.; Howse, G.M.; Harnden, A.A. (1975b) Aerial application of nuclear polyhedrosis virus 

against spruce budworm on Manitoulin Island, Ontario in 1974 and a survey of the impact of the virus in 

1975. Canadian Forestry Service, Sault Ste. Marie, Information Report IP-X·8, 30 pp. 

Cunningham. I.C.; Kaupp. W.I.; McPhee, J.R.; Howse, G.M.; Harnden, A.A. (1975c) Aerial application of nuclear polyhcdrosis virus on 

spruce budworm on Manitoulin Island, Ontario in 1975. Canadian Forestry Service, Sault Ste. Marie, 

Information Report IP-X-9, 35 pp. 

Cunningham. J.c.; Kaupp. W.J.; Howse. G .M. ; McPhee. J. R.; de Groot. P. (1978) Aerial application of spruce budworm baculovirus: tests 

of virus strains. dosages and formulations in 1977. Canadian Forestry Service. Sault Ste. Marie. 

Information Report FPM-X-3. 37 pp. 

Cunningham. I.C.; Howsc. G.M.; McPhee. J.R.; de Groot. P.; White. M.B.E. (1979) Aerial application of spruce budworm baculovirus: 

replicated tests with an aqueous formulation and a trial using an oil formulation in 1978. Canadian 

Forestry Service, Sault Ste. Marie, Information Report FPM-X-21. 19 pp. 

Grisdale. D. (1970) An improved method for rearing large numbers of spruce budworm. Chonstoneura fumiferana (Lepidoptera: Tonricidae). 

Canadian Entomologist 102.1111-1117. 

Howse. G.M.; Sanders. C.J.; Harnden. A.A.; Cunningham, J.e.; Bird, F.T.; McPhee. J.R. (1973) Aerial application of viruses against 

spruce budworm. 1971. Pan A. Impact in the year of application (1971). Pan B. Impact in the year 

following application (1972). Canadian Forest,)' Service, Sault Ste. Marie. Information Report O-X·I89. 

62pp. 

Kaupp. W.J. Cunningham,; J.C.; Howse. G.M.; McPhee. J.R.; de Groot. P. (1978) Aerial application ofspruce budworm baculovirus: tests 

on sccond instar larvae in 1976. Canadian Forestry Service. Sault Ste. Marie. Information Report FPM 

X-2. 20 pp. 

McMorran. A. (1965) A synthetic diet for the spruce budworm. Chonstoneura fumiferana (Clem.) (Lepidoptera: Tonricidae). Canadian 

Entomologist 97,58-62. 

Morris. O.N.; Armstrong. J.A.; Hildebrand. M.J.; Howse. G.M.; Cunningham, J.C.; McPhee. J.R. (1972) Aerial applications or virusinsccticide 

combinations against spruce budworm Chonstontura fumifl'rana (Clem.) (Tonricidae: 

Lepidoptera) at Rankin. Ontario, 1972. Canadian Forestry Servicl', Ollawa, Information Report CC-X- 

37,65 pp. 

Morris. O.N.; Armstrong, J.A.; Howse. G.M.; Cunningham, J.e. (1974) A 2-year study of virus-chemical insecticide combination in the 

integrated control or the spruce budworrn. Choristoneura fumiferana (Tortrieidae: Lepidoptera). 


Savan. M.; Budd. J.; Reno, P.W.; Darley, S. (1979) A study of two species of fish inoculated with spruce budworm nuclear 

polyhedrosis virus. Journal of Wildlife Disl'ases 15,331-334. 

Stairs, G.R.; Bird. F.T. (1962) Dissemination of viruses against the spruce budworm. Choristoneura fumiferana (Clemens). Canadian 

Entomologi.ft 94,966-969. 

Valli, V.E.; Cunningham, J.C.; Arir, B.M. (1976) Tests demonstrating the safety or a baculovirus of the spruce budworm to mammals and 

birds. Proceedings of the 1st International Colloquium on Invertebrate Patllology, Kingston, Ontario, pp. 

445-446. 

Wilson, G.G. (1981) Nosema fumiferanae, a natural pathogen of a forest pest: potential ror pest management. In: Burges. H.D. (Ed.) 

Microbial control of pests and plant diseases 1970-1980. London; Academic Press. pp. 595-601.

C. AppliclItion of microsporidia and fungi. 261 

The natural levels of microsporidian infection in spruce budworm populations tend to 

increase with the age of the infestation. Examination of spruce budworm larvae collected in 

the Uxbridge forest of southern Ontario over a 6-year period indicated that the infection 

rate from N.fllmiferanae increased from 36% in 1973 to 69% in 1978 (Wilson 1977b). The 

Uxbridge forest was in fact an old infestation; severe defoliation was recorded in 1952 

and has persisted at fluctuating levels ever since. 

Fungi 

Steady progress was made during the 1970s in documenting the effects of fungi in natural 

epizootics and developing various species for use in biological control, with the result 

that Hirslllelia thompsoni Fisher, the first fungus to be registered for mite control in 

North America, is now available under the trade name Mycar® (Abbott Laboratories) 

and is also used against citrus rust mites. 

The occurrence of entomophthoraceous fungi on spruce budworm has been documented 

throughout much of the insect's range in the last 10 years. Outbreaks of fungal disease 

occurred in 1974 and 1979 in northern Ontario; in the former year the outbreak was of 

Zoophlhora radicans (Brefeld) A. Bakto (= Entomophthora sphaerosperma Frasenius) 

(Harvey & Burke 1974), in the latter it was of the same fungus together with E. egressa 

MacLeod (Tyrrell, unpublished). In Newfoundland, the same two fungi were first 

recorded from the spruce budworm in 1972. The disease was widespread in western 

Newfoundland in 1973, and subsequently spread to the whole of the Island (Otvos & 

Moody 1978). Mortality varied from 10-40%, depending on weather conditions, and 

occasionally reached much higher values in localized areas. Both fungal species, together 

with an unidentified Conidiobo/w species, were responsible for spuce budworm mortality 

in northern Maine, where disease prevalence varied between 4 and 7% during 1975-77 

(Vandenberg & Soper 1978). 

In northern Ontario, mortality was higher in white spruce than in balsam fir in 1974, 

when fungal incidence was high (Harvey & Burke 1974), but no difference was observed 

between tree species in 1980, when fungal incidence was much lower (TyrreU, unpublished). In 

Maine, fungal prevalence was found to be both density-dependent and significantly 

higher in the lower crown area of the tree, and appeared to be enhanced by periods of 

cool, wet weather (Vandenberg & Soper 1978). The link between moist conditions and 

• increased incidence of fungus has also been observed in Newfoundland (Otvos & 

Moody 1978). 

Fungal infection occurs in the later stages of larval development. Incidence of Z. 

radicans peaked between the fifth and sixth instars, E. egressa between the sixth instar 

and pre-pupa, and Conidiobolus sp. between the pre-pupal and pupal stages, respectively, 

in Maine (Vandenberg & Soper 1978); while in northern Ontario peak fungal infection 

coincided with the peak development of sixth-instar larvae (Tyrrell unpublished). 

Earlier instars however, are not resistant to the disease, and can readily be infected with 

Z. radicans under laboratory conditions (Kenneth 1978, Perry unpublished). 

Both Z. radicans and E. egressa can be isolated and grown in pure culture, and a 

number of different isolates of both species are now available. Z. radicans grows readily 

on a variety of solid and liquid media, and the mycelial stage can also be grown in small 

fermentors. E. egressa grows slowly on complex media such as coagulated egg yolk, but 

can be grown as a protoplast in osmotically stabilized media. 

Z. radicans can sporulate on artificial media to give both conidia and resting spores. 

The effects of environmental conditions, including temperature, photophase, and nutrient, 

on conidial germination have been determined (van Roermund, personal communication). 

Maturation of laboratory-produced resting spores under controlled conditions has been 

shown to be a key factor in potentiating their subsequent germination (Perry & Tyrrell 

in press), and the effects of environmental conditions on their germination are currently

264 G. G. Wilson, D. Tyrrell and T. J. Ennis 


schubergi spores resulted in infection rates of 64.8% for white spruce and 96.3% for 

balsam fir 19 days after spraying. There was no infection in larvae from the check area 

and no carry-over of the microsporidium to the following year. All samples showed 

higher levels of infection in spruce budworm taken from balsam fir. 

Based on laboratory results there is a relationship between levels of infection and 

mortality. As an example, spore concentrations of 10" spores/ml fed to second-instar 

larvae resulted in 100% mortality in up to 24 days, with 50% mortality occurring about 14 

days after infection (balsam fir buds were dipped in the spore suspension). As a 

comparison, spore concentration of 100/ml resulted in 61 % mortality over a period of 

6-28 days. For fifth-instar larvae Hr spores/ml gave 75% mortality over 8-33 days, 

and 10" sporeslml resulted in only 5.6% mortality, which was similar to the controls. 

Fungi 

E. egressa does not sporulate well on artificial media and conidia are normally obtained 

from infected insect cadavers. These are easily produced by injection of insect larvae 

with protoplasts, which have been shown to be part of the natural life cycle of this fungus 

(Tyrrell 1977). Transmission of E. egressa from laboratory-infected to natural populations 

of spruce budworm under field conditions using conidia produced in this manner has 

been demonstrated (Lim el al. unpublished). 

Genetic manipulation 

Topical application of thiotepa or 250-300 Sv of Co'" irradiation induced complete 

sterility in male spruce budworm (Retnakaran 1970, 1971). Males sterilized with thiotepa 

remained fully competitive and could suppress fertility of caged laboratory populations 

by up to 90% (Ennis unpublished data). However, release of chemosterilized males into 

caged field populations produced no detectable reduction in popUlation, mainly because 

of adverse effects on adult male mating behaviour. High level irradiation of male pupae 

or adults reduces fitness and mating competitiveness, militating against their effective 

use. However, at 20-50 Sv, induced chromosome aberrations have a heritable effect on 

fertility of subsequent generations, with depression of fertility persisting for up to three 

generations in the laboratory (Ennis 19790). The potential of inherited semi-sterility has 

not yet been tested in field populations. Dispersal and behaviour of irradiated males 

have also been studied using pheromone re-trapping techniques (Ennis 1979b). 

Few microsporidian parasites have been investigated as possible control agents of pest 

insects. If we take the amount of research on Bacillus Ihuringiensis Berliner (B.I.) 

before it was accepted as an insecticide as being representative in the development of a 

biological control agent, then it is obvious that we have barely begun the task with 

microsporidia. However, there are indications that many microsporidia do have good 

potential as biological control agents that, given appropriate research and development, 

may one day be realized. There is still much research needed on the development of 

microsporidia in a control plan for the spruce budworm. Thorough studies are required 

on the host-parasite relationships and the incidence and effects of the microsporidia in 

their natural setting. Although these parasites can be introduced into a population of the 

spruce budworm, their effect on insect numbers has not been quantified. The use of 

these parasites in integrated control should be investigated, not only in conjunction with 

chemicals, but also with other spruce budworm pathogens.


C. Application ofmicrospnridia and fungi. 265 

The level of research effort on fungi for control of spruce budworm has been low 

compared to the effort on such biological agents as the viruses and B.t., but the results 

obtained to date suggest that fungi playa significant role in the regulation of spruce 

budworm populations, and the recent demonstration that infectious diseases can in 

theory drive population cycles (Anderson & May 1980) will provide further impetus for 

studies designed to delineate the role of fungi in the spruce budworm ecosystem. To this 

end, extensive epizootiological investigations on the biotic and abiotic factors affecting 

the fungus-budworm interaction should be carried out. These, coupled with continuing 

laboratory studies on the production of fungal material suitable for field dissemination. 

and on the selection and mode of action ofthe most virulent strains of fungi. will. in the 

long term. determine how and under what circumstances fungi may be used in the 

manipulation of spruce budworm populations. 

At present it is difficult to draw definite conclusions on the potential of microsporidia 

and fungi in the management of the spruce budworm. However. because of their 

potential in a control programme. any comprehensive model of spruce budworm population-dynamics 

must embrace a thorough understanding of these pathogens. 

Research into the genetic manipulation of the spruce budworm to date has supplied 

the basic level of information required for further testing: methods for mass sterilization. 

effects on fertility of caged population, and dispersal and detection of released insects. 

However, the large numbers of insects and extensive areas of forest affected by epidemics 

of this pest suggest caution in trying to develop genetic manipulation for control of 

outbreak populations. The logistics of application, in terms of numbers and area. and the 

uncertainty of success indicate that its greatest potential lies in controlling endemic 

population levels, where the released insects' ability to detect and mate with females 

even when they are relatively rare provides one of the greatest advantages of the genetic 

approach. Future research should be aimed at such low level populations, and should be 

conducted with the objective of reducing reproduction potential to a level below that 

necessary to support a transition from endemic to epidemic levels. 

Anderson. R.M.; May. R.M. (1980) Infectious diseases and population cycles of forest insects. Science 210.658-661. 

Burges. H.D. (Ed.) (1981) Microbial control of pests and plant diseases, 1970-1980. London; Academic Press, 949 pp. 

Ennis. TJ. (1979a) Detection and isolation of induced chromosome aberrations in Lepidoptera. Experientia 35.1153-1154. 

Ennis, T.J. (1979b) A release·recapture experiment with normal and irradiated spruce budworrn males. Cana4ian Forestry Service Bi· 

monthly Research Notes 35.9-10. 

Harvey. G.T.; Burke. J.M. (1974) Monality of the spruce budworrn on white spruce caused by Entomophthora sphaerosperma. Canadian 

Forestry Service Bi·monthly Research Notes 30.23-24. 

Kenneth. R.G. (1978) Entomophthora sphoerosperma as an insect pathogen for spruce budworrn control. Abstracts of the Acadian 

Entomological Society's 38th AnnWlI Meeting. pp. 35-36. 

Lachana:. LE. (1979) Genetic strategies affecting the swx:css and economy of the sterile insect release method. In: Hoy. M.A.; McKelvey. J.J. 

(Eds.) Genetics in relation to insect management. Rockefeller Foundation. USA. 

Otvos.I.S.; Moody. B.H. (1978) The spruce budworm in Newfoundland: history. status and control. Canadian Foresty Sen·ice. Newfoundland 

Forest Research Centre, Information Report N·X-150. 

Outram. J. (1969) Potential use of the sterility principle for spruce budworm control in eastern Canada. Canadian Department of Fisheries and 

Fort'stry' InteTllal Report M-45. Fredericton. N.B. 

Perry. D.; Tyrrell. D. (in prcss) Resting spore germination in ZoophtllOra radicans. Mycologia. 

Rctnakaran. A. (1970) Preliminary results of radiation induced sterility of the male spruce budworm. Canadian Department of Fisherit's and 

Forestry' Bi·monthly Research Notes 26.13-14. 

Retnakaran. A. (1971) Thiotepa as an effective agent for mass sterilizing the spruce budworrn. Choristoneura fumiferana (Lepidoptera: 

Tortricidae). Canadian Entomologist \03.1753-1756. 

Thomson. H.M. (1958) The effect of a microsporidian parasite on the development. reproduction and mortality of the spruce budworrn. 

Choristoneura fumiferana (Clem.). Canadian Journal of Zoology 36.499-51 J. 

Tyrrell. D. (1977) Occurrence of protoplasts in the natural life cycle of Entomophthora egressa. Experimental Mycology 1.259-263. 

Vandenberg. J.D.; Soper. R.S. (1978) Prevalence of entomophthorales mycoses in populations of the spruce budworm. Choristoneura 

fumiferana. Environmental Entomology 7.847-853.

266 G. G. Wilson. D. Tyrrrell and T. J. Ennis 

Vandenberg, J.D.; Soper, R.S. (1979) A bioassay technique for Entomophthora sphaerosperma on the spruce budworm, Choristoneura 

fumiferana. Journal of Invertebrate Pathology 33,148-154. 

Wilson, G.G. (l977a) The effects of feeding microsporidian (Nosema fumiferanae) spores to naturally infected spruce budworm (Choristoneura 

fumiferana). Canadian Journal of Zoology 55,249-250. 

Wilson. G.G. (l977b) OhselVations on the incidence rates of Nosema fiuniferOlUle(microsporidia) in a spruce budwonn. ChoristoTU!ura fumiferana. 

(Lepidoptem: Tortricidae) population. Proceedings of Iile Entomological Sociely of Ontario 108,144-145. 

Wilson, G.G. (1980) Persistence of microsporidia in populations ofthe spruce budworm and forest tent caterpillar. Canadian Forestry Service, 

Sault Ste. Marie, Information Report FPM-X-39. 

Wilson, G.G. (1981) The potential of Pleistophora schubergi in microbial control afforest insects. Canadian Forestry Service, Sault Ste. Marie, 

Information Report FPM-X-49.

Background 

Table 73 

D. Testing of Parasitoids 

I.W. VARTY 

D. Testing of parasitoids 267 

The two strategies for biological control of the spruce budwonn, CJwristoneura fwniferatUl 

(Clem.), by parasitoids are the introduction of exotic species and the manipulation of 

native ones. Most entomologists agree that the best prospects for introduction are those 

species that parasitize Choristoneura spp. (or near relatives) in spruce (Picea spp.) and fir 

(Abies spp.) forests in similar climatic zones abroad. The problem is to be ready for 

opportunities in those few years when pest outbreaks overseas permit sizeable collections 

of candidate parasitoids. The manipulation of native parasitoids offers two other avenues 

for action: inundative release of laboratory-reared stock, and management of forest 

habitats to favour the dynamics of parasitoid response to available hosts. 

Efforts to establish exotic parasitoids in spruce budworm populations of eastern 

Canada have not succeeded. In 1944-53, large numbers of four species (two tachinids, 

one sarcophagid, and one ichneumonoid) from unidentified western spruce budworms 

(British Columbia) were released at various sites from Manitoba to Newfoundland. In 

1948-56, 12 ichneumonoid species from European hosts, especially Choristoneura 

murinana (Hb.) (France, Germany, Czechoslovakia), were released in small numbers 

in northwestern Ontario and Quebec. No evidence of the establishment of any introduced 

species has been produced (McGugan & CoppeI1962), and there were no explanations 

of the causes of failure. Interest in further introductions was inhibited by these failures 

and by lack of sources of parasitoids abroad. However, during the 1960s unsuccessful 

efforts were made to obtain three ichneumonoids specific to C. murinana (Miller & 

Angus 1971). 

Interest was renewed when an outbreak of Choristoneura diversana (Hb.) on Japanese 

(todo) fir (Abies firma Sieb & Zucc.) in Hokkaido, Japan, occurred in the late 1960s. 

Collaboration among four institutes (Hokkaido Forest Experimental Station, Maritimes 

Forest Research Centre, Commonwealth Institute of Biological Control, and the Agriculture 

Canada Research Station at Belleville, Ontario) resulted in the shipment of 

parasitoids by air from Japan to New Brunswick in 1970-75 (Tables 73 and 74). Further, 

a small collection of parasitoids from C. murinana in Czechoslovakia was shipped to New 

Brunswick in 1972. These introductions are detailed below. 

In the early 1970s, the theory that spruce budworm epidemics may start in isolated 

local epicentres led to interest in methods of quelling incipient outbreaks over small 

areas. At the Laurentian Forest Research Centre this interest developed into a research 

study of the native egg parasitoid, Trichogramma minutum Ril., as a candidate for 

inundative release, now briefly reported. As pressure to find a biological alternative to 

Open releases and recoveries of parasitoids against Choristoneura fumiferana (Clem.) 



Agria housei Shewell 1971 Ontario (laboratory 2800 1971 

New Brunswick culture) (14 adults) 

Nil in 1972-73 

Lissonota sp. 1973 Japan 59 Nil in 1974 

New Brunswick

CephaJogl)pta 

murinanae Bauer 

(Hymenoptera: 

Ichneumonidae) 


success varying from 17 to 60% as indicated by dissection of samples. Substantial host 

larval mortality during early diapause was attributed partly to ovipositional wounding. A 

problem was to optimize survival of parasitized hosts by exposing candidate larvae long 

enough to achieve a high percentage of attacked hosts. but short enough to avoid a high 

percentage of superparasitism and fatal wounding. The exposure patterns usually resulted 

in a single egg per host; the egg hatched within a few weeks and the parasitoid overwintered 

as a first-instar larva. 

In rearing thousands of prospectively parasitized spruce budworrn larvae, only 70 C. 

laritis pre-pupae emerged from their hosts. Of these, 27 successfully pupated in a 

cocoon, a few adults emerged, and only one female oviposited. Efforts to rear its 

progeny were unsuccessful. Between autumn and late spring in all years, the percentage 

parasitism of sampled host stock declined sharply, almost to zero. Hypotheses to 

account for the decline included ovipositional injury to hosts, lack of cold hardiness in 

the parasitoid, host diet unfavourable to the parasitoid, encapsulation reaction, and 

other biochemical defence mechanisms. 

Mortality of hosts in hibernacula was 20-62%, higher than the usual 9-22% recorded 

from populations in their natural environment. Some of the additional mortality was 

attributed to ovipositional wounding, as C. laricis has a large ovipositor compared with its 

native homologue, Glypla fumiferanae (Vier.). However, mortality of hosts was not an 

important factor in reduction of percentage parasitism. It is unlikely that low winter 

temperature discriminated against parasitoids within their spruce budworm hosts. In a 

test for cold hardiness, overwintering larvae of C. fumiferana, G. fumiferanae, and C. 

larieis were rapidly supercooled down to -60°C. All three species showed ice-crystal 

formation in the -40 to -43°C range, which is below the coldest natural environment in 

New Brunswick. Thus the parasitoid stock of Hokkaido provenance appeared to be as 

hardy as the native stocks of parasitoids and hosts, just as one would expect from a 

comparison of the monthly mean temperatures of the two regions. 

When a stock of second-instar spruce budworrn larvae was held in storage from 

October to May at a constant temperature of 7°C, the rate of decline of parasitism was 

unusually rapid compared with stock held out-of-doors at much lower temperatures. 

Evidently the "cold room" was a selectively hostile environment to the parasitoid, but 

not to the host. This suggested that the decline in parasitism was temperature-related 

rather than time-related. 

Most of the loss of parasitism occurred in post-diapause stocks; however, no evidence 

implicating host diet appeared, as rearings with either artificial diet or with natural 

foliage produced healthy hosts and moribund or vanished parasitoids. Dissections 

revealed very few encapsulated parasitoid larvae, not enough to indicate a mechanism 

for decline in percentage parasitism. The expected parasitoids seemed to disappear 

without trace, but occasionally parasitoid head capsules, faintly yellowed and very 

membranous, were discovered within the body cavity of healthy maturing hosts. Thus 

the most plausible hypothesis is that the spruce budworrn is able to kill and absorb larvae 

of C. larieis, leaving the host unimpaired. 

A small shipment (Table 74) of pupae was air-freighted from Czechoslovakia to New 

Brunswick in July 1972. Some 1300 spruce budworrn larvae in hibemacula were exposed, 

and females oviposited vigorously with behaviour similar to C. larieis. A January 

sample of hosts wintered out-of-doors indicated 25% parasitism of survivors and 18% 

host mortality. Overwintered hosts were successfully reared in May on artificial diet, or 

on diet followed by foliage, but only four parasitoid pre-pupae matured, two dying 

within pupal hosts and two emerging from larval hosts but failing to pupate. The 

disappearance of the expected population of parasitoids is unexplained, but circumstances 

were similar to those of C. larieis.

270 1. W. Varty 

Lissonola sp. 

(Hymenoptera: 


Trichogramma 

minutum Riley 

(Hymenoptera: 

Chalcidoidea) 

The biology of this ichneumonid species from C. diversana hosts on todo fir in Japan has 

been reported by Zw61fer (1972, personal communication). Shipments were air-freighted 

from Hokkaido to New Brunswick in 1972, 1973, and 1975 (Tables 73 and 74). Females 

mated soon after emergence from the cocoon, and were maintained on a diet of sugar, 

honey, and water for up to a month in insectary cages. No responses were observed to 

the presence of free-moving first-instar or spun-up second-instar spruce budworm. 

However, large samples dissected in winter revealed parasitism rates of 7% in 1972 and 

1% in 1973. No more than one egg shell was dissected from anyone host, although 

heavy superparasitism is the rule in C. diversana hosts. Although many thousands of 

spruce budworm hosts were exposed, only one parasitoid emerged as a pre-pupa, and 

it failed to pupate. Three more mature larvae were dissected frot:T\ dead hosts, but no 

evidence of encapsulation or of tissue absorption of the parasitoids was found. Thus 

Lissonola sp. appears to be incompatible with spruce budworm because of low ovipositional 

stimulus to the parasitoid and some innate resistance by the host. 

The object ofthis study in Quebec in 1970-75 (F.W. Quednau 1974, personal communication, 

unpublished work reported to the Annual Review of Spruce Budworm Research, 

Canadian Forestry Service) was to explore the potential of this egg parasitoid for 

inundative release against rising spruce budworm populations in local epicentres. This 

native chalcidoid wasp is already present in all eastern North American forests, attacking 

eggs of scores of species, and typically contributing 5-25% parasitism of spruce budworm 

eggs. Apparently, scarcity of alternate hosts prevents the numerical response that T. 

m;nulUm might otherwise make to rising budworm density. Quednau believed that about 

2.5 x 10" female parasitoids per hectare would be needed for effective release in epicentres. 

The research problems facing the Laurentian Forest Research Centre were: (l)the 

maintenance of year-round research cultures of the parasitoids and suitable hosts; 

(2)comparison of commercial strains and arboreal ecotypes, and the selection of a 

type most responsive to laboratory rearing and the spruce budworm forest habitat; 

(3)determination of the parasitoid female's functional response to host density; 

(4)refinement of a mass-culture method, and (5)development of techniques for 

inundative release and assessment of efficacy. 

From 1970 to 1975 considerable biological knowledge and research experience was 

gained in the first three problems. Methods of air-freighting stock from the United States 

and Mexico were established, and techniques for small-scale rearing and storage of 

parasitoids and host eggs were developed (Table 74). However, the application of 

American commercial techniques of mass-rearing was thwarted by quarantine regulations, 

which prevented the utilization of the angoumois grain moth, Silotroga cerea/ella 

(Olivier), the most suitable host for Trichogramma cultures. Moreover, there were 

worker health problems (allergies) associated with mass-rearing. 

Progress was made in the selection of a Canadian ecotype well adapted to the forest 

environment and with superior host-finding potential. However, T. m;nulum was shown 

to have only a weak functional response to density of spruce budworm egg-masses; that 

is, in caged-tree experiments with varying parasitoid densities and host densities, the 

number of attacked host eggs per individual parasitoid was greater when egg-mass 

density was increased. However, increased density of parasitoids tended to lower 

success in finding hosts, perhaps because of mutual interference and increased superparasitism. 

Parasitism greater than 50% was not attained in cage experiments. Thus the 

prospects for useful impact on spruce budworm dynamics appear low, because only a 

drastic change in egg parasitism could have any significant effect on generation survival 

in spruce budworm outbreak densities (Morris 1963). 

The research was terminated in 1975 without definitive assessment of the feasibility of 

application to spruce budworm control.

Agria housei Shewell 

(Diptera: Sareophagidae) 

Native parasitoids of 

spruce budwonn larvae 



The native sarcophagid fly, Agria housei, has long been recorded as a pre-pupal and pupal 

parasitoid of spruce budworm and western spruce budworm, usually at low percentage 

parasitism. However, it merits consideration for inundative release because it is one of 

the few budworm parasitoids that can be laboratory-produced in large quantities at 

acceptable costs; it can be reared directly on pork liver without an intermediate insect 

host. It has other characteristics that enhance its prospective application to the spruce 

budworm problem. However, the laboratory stock available for experimentation had 

been reared for many generations under artificial conditions, causing loss of cold hardiness 

and diapause induction (House 1967). Therefore there were doubts about the responsiveness 

of this stock to spruce budworm hosts and about its capacity to revert to univoltine 

reproduction. 

Field and laboratory tests were conducted in 1971 to gain experience in handling the 

species and to test its response to larval and pupal spruce budworm hosts (Tables 73 and 

74). The fly stock was provided by the Agriculture Canada Research Institute, Belleville, 

Ontario. Laboratory cage experiments designed to test hostlparasitoid densities failed 

to elicit any apparent interaction, and no parasitoid progeny issued. However, some 2800 

adult flies (34% female) were freely released into a balsam fir, Abies balsamea (L.) Mill., 

stand highly infested with spruce budworm pupae, at Fundy National Park. From a 

sample of 1114 pupae collected within 10 days of release and within 7S m of release point, 

14 A. housei puparia were recovered. Based on estimates of the density of available 

hosts, this rate of recovery indicated an excellent response by the introduced stock. No 

further specimens were recovered from samples of host pupae in 1972 and 1973, but 

given the poor cold hardiness inheritance of the stock and the dispersal characteristics of 

the species, detectable persistence at the release point was not expected. The potential 

for applied biological control under appropriate pre-outbreak conditions remains unassessed. 

The Canadian Forestry Service has maintained a sporadic surveillance of the effectiveness 

of native parasitoids attacking spruce budworm, especially G. fumiferanae and 

Apanteles fumiferanae Vier., which parasitize overwintering larvae. A study at the 

Maritimes Forest Research Centre was conducted from 1977 to 1980 on the premise that 

an understanding of the factors limiting parasitoid effectiveness might lead to methods 

of managing the forest habitat to stimulate parasitoid regulation of spruce budworm. The 

study was directed to the behavioural biology of adults of these two species (feeding 

habits, flight periodicity, distribution in the canopy), but did not reveal any clear avenue 

for practical application (R.S. Forbes 1980, unpublished work, Canadian Forestry 

Service). 

It is recommended that the Canadian Forestry Service (a) maintain contacts with 

CIBC concerning collection opportunities abroad; (b) investigate the compatibilities 

of a range of non-indigenous parasitoids with spruce budworm hosts; (c) develop 

rearing, release, and assessment skills and facilities; and (d) assess opportunities for 

incorporating parasitoid manipulation in integrated pest management programmes based 

on spruce budworm population dynamics.

272 I. W. Varty 


House, H.L. (1967) The decreasing occurrcnce of diapause in the fly Puudosarcophaga a!finis through laboratory-reared generations. 

Canadian Journal of Zoology 45,149-153. 

McGugan, B.M.; Coppel, H.C. (1962) Biological control of forest insects 1910-1958. In: A review of the biological control attempts against 


2,35-127. 

Miller, C.A.; Angus, T.A. (1971) Choristoneurafumiferana (Clemens), spruce budworm (lcpidoptera: Tortricidae). In: Biological control 

programmes against insects and weeds in Canada 1959- 1968. Commonwealth Institute of Biological 

Control Technical Communication 4,127-130. 

Minot, M.C.; Leonard, D.E. (1976) Host preference and development of the parasitoid Brachymeria intermedia in Lymantria dispar L.. 

Galleria mellonella and Choristoneura fumiferana. Environmental Entomology 5.527-532. 

Morris, R.F. (1963) The analysis of generation survival in relation to age-interval survivals in the unspmyed areas. In: Morris, R.F. (Ed.) 

The dynamics of epidemic spruce bud worm populations. Memoirs of the Entomological Society of Canada 

31,32-37.


experimental biological insecticides with weak dispersion and self-sustenance in subsequent 

years. The Canadian Forestry Service (CFS) has undertaken fundamental and 

innovative research for more than 30 years, yet a cost-effective operational treatment for 

spruce budworm has not been achieved so far. In the 1970s, the emphasis was on 

isolation. mass-propagation, formulation, and spray-testing of baculoviruses. The economic 

problem was the high cost of virus propagation on diet-reared spruce budworm larvae, 

currently about $250 per sprayed hectare, or 30-40 times the cost of chemical treatment. 

The technical problem was the low rate of foliage protection, even when high larval 

mortality was attained. 

The probability of large-scale operational application in the 1980s is low. The future of 

virus sprays may depend on development of a cheap culture method. Prospects for a selfspreading 

low-density inoculation method are poor. As no natural epizootic has been 

recorded, it appears that spruce budworm viruses have low natural infectiveness. Spray 

efficacy will probably demand high dosage and high density coverage of the target forest. 

Bacteria 

The commercial production of Bacillus thuringiensis Berliner (B.t.) and its Canadian 

registration for forest use have already been achieved. B.t. is widely used and effective 

for North American field crops, but has been generally less successful against forest 

pests in experimental trials. Its toxicology, formulation, aerial delivery techniques, and 

field assessment methods have been developed for use against spruce budworm. B.t. is 

essentially a biological insecticide, and is not designed to meet the self-regulating, selfdistributing, 

density-dependent criteria of c1assicial biological control. Canadian laboratory 

studies in the 1970s addressed the mode of action of the crystal, its structure, and assays 

of potency of field preparations; field research was designed to develop formulations, 

test aerial delivery techniques, and assess efficacy for population reduction and foliage 

protection. Even so, B.t. application is 4-5 times more costly and somewhat less 

reliable than corresponding treatments with the chemical insecticide fenitrothion. B.t. 

technology is still short of its full potential: potential future developments include 

selection of more potent strains, preparation of synthetic mimics of the crystal toxin, 

improvements in formulation, and more effective aerial delivery systems. 

Fungi 

The study of mycoses caused by entomogenous fungi holds a modest posItIon in 

research and development of biological methods for agricultural pests (Ferron 1978). 

International interest has focused mainly on the role of fungal epizootics in pest 

population regulation. but in practice few commercial products exist and experimentation 

in forestry, for example in the USSR, has been limited. The object of field application is 

to initiate an epizootic by artificial dissemination of inoculum, and research has been on 

the nature of infectiveness, methods of mass propagation, and methods offield distribution. 

Canadian research in this field, conducted mostly at the Forest Pest Management 

Institute and at Memorial University of Newfoundland, was exploratory in the 1970s and 

was on methods of culture of inoculum and the mode of spore formation and germination. 

Until 1980 no field spray experimentation for spruce budworm control had been attempted. 

Fungi are valuable agents for biological control because of their high specificity and high 

infective ness in the laboratory. However, their natural incidence in spruce bud worm 

populations is low, so the prospects for stimulating large-scale epizootics are correspondingly 

weak. Development of an operational cost-competitive treatment apears to be remote.

Protozoa 

E. Review of biological control opportunities 275 

Protozoan parasitism of agricultural pests is commonplace and is reported to reduce 

population vigour. Many species occur in forest defoliator insects, including two species 

of microsporidia in spruce budworm. However, in pest control history the applied use of 

protozoa has been rare, because they are costly to propagate in quantity, and exhibit low 

infectiveness after artificial distribution. 

Canadian research on microsporidian parasites of spruce budworm was restricted to 

the Forest Pest Management Institute in the 1970s, which documented their natural 

incidence and parasitic role. Spray experiments on single trees demonstrated that 

parasitism rates can be artificially raised, but left the problem of mass production 

unsolved. Operational application is not yet practicable. 

Parasitoids 

Canada has enjoyed some success in the importation of exotic parasitoids to control 

introduced pest insects in both agriculture and forestry, but the record of releases to 

control native forest pests has been discouraging (Munroe 1971). However, it is not 

known whether the low success rate in the control of native hosts is associated with the 

separate evolutions of host and parasitoid, or stems from imperfect testing techniques. 

In agriculture, inundative release of a few species of natural enemies is routine practice, 

but experimentation against forest pests has been fragmentary and unsustained (Pschom 

Walcher 1977). 

Canadian research on manipulation of spruce budworm parasitism was scant in the 

1970s, but was on a sounder base than the hit-and-miss releases of the 1940s and 1950s. 

Research was on field-cage studies of host and site compatibility with exotic parasitoids 

and studies of the numerical response of native parasitoids, with the inundative release 

method in mind. 

The case for increasing the Canadian effort with respect to spruce budworm parasitism 

is not strong if the probability of establishing additional natural enemies decreases with 

increasing diversity of the natural enemy complement. There is a need for better 

theoretical guidelines in order to achieve maximum success. The empirical approach - 

to collect homologous parasitoids abroad, then release and monitor their distribution 

and persistence - is unpredictable and does not increase understanding of the processes 

unless accompanied by studies of host-parasitoid compatibility. 

Predators 

In world agriculture, some striking successes have been achieved by inoculative release 

of exotic predaceous arthropods, but in Canadian forestry few such releases have been 

attempted (Munroe 1971). In general, the release of an exotic broad-spectrum predator 

gives rise to more concern about ecological integrity than the introduction of hostspecific 

parasitoids. In Canada, the only releases of non-native arthropod predators of 

forest pests in 1969-80 were the successful introductions of two red wood ant species 

from Italy and Manitoba to Quebec (Finnegan 1978); the experiments show encouraging 

results in the control of spruce budworm populations in young stands. However, in 

general. the technical and economic feasibilities of predator releases against spruce 

budworm have not been assessed. 

Genetic approaches 

Pest insect genetics is an important means of biological control, because it leads to 

autocidal methods for manipulating popUlations. The technique of releasing sterile


Further research 


males to interfere with the transmission of genes is best exemplified by the successful 

screwworm and fruit fly mntrol operations by the United States Department of Agriculture. 

During the 1970s many agencies around the world attempted pest control based on this 

principle (Whitten & Foster 1975). 

Exploratory research on spruce budworm genetics was conducted by CFS in the 

late 1970s, the only research agency with a declared interest. Such work is essentially 

long-term, demanding of innovation and risky as an investment; it includes investigations of 

induced sterility, gene-damaging methods, and procedures for attaining population 

control. It may offer opportunities for diminishing the budworm's reproductive success, 

but has potential mainly for small areas in the early stages of population increase. 

Prospects for early operational application are dim. 

Clearly none of the biological methods of control is ready to displace chemical spraying 

in a significant percentage of the area needing protection from spruce budworm. 

However, B.I. is efficacious and acceptable financially for small areas, especially in high 

value stands and in zones where chemicals are prohibited. The technical research, as 

recommended by Smirnoff & Morris in this chapter, should be strongly supported, 

because B.I. is close to being cost-competitive. It is the only non-chemical method able 

to replace the registered chemicals in the event of further restrictions, and it has 

considerable international research interest. 

For other entomopathogens, the main barrier to progress is the lack of methods for 

mass-propagation of agents at acceptable cost. Research agencies should re-examine 

the feasibility of hastening such capability, consulting with the many international 

agencies interested in similar, but problem-specific, developmental research. Because 

the search for new species or virulent strains of known entomopathogens has shown 

little promise, the prospects for induced genetic alteration should be monitored by close 

contact with scientific advances in agriculture. Meanwhile it is desirable to maintain the 

current steady progress reported already in this chapter. 

Research on parasitoids and predators is at low ebb. More basic research on hostparasitoid 

compatibility and on release and dispersion methods should be conducted. 

Research on genetic methods of autocidal control have been exploratory, but results 

have been sufficiently encouraging to justify further work. 

The contributors to each section of this chapter have recommended further long-term 

research. The potential for effective alternatives to chemical control is real, even if slight 

in most cases. Except for 8.1., none of these alternatives is likely to have a significant 

role in forest protection operations in the 1980s. However, because the spruce budworm 

is a long-term problem, and spruce-fir forest is a long-term resource, the need for an 

array of protection techniques for both remedial and preventive intervention is likely to 

persist. 

Beirne. B.P. (1975) Biological control attempts by introductions against pest insects in the field in Canada. Canadian Entomologist 

107.225-236. 

Ferron. P. (1978) Biological control of insect pests by entomogenous fungi. Annual Review of Entomology 23.409-442. 

Finnegan. R.J. (1978) Predation by Formica lugubris (Hymenoptera: Formicidae) on Choristoneura fumiferana (Lepidoptera: Tonricidae). 

Canadian Forestry Service Bi-monthly Research Notes. 34(1).3-4. 

Miller. C.A.; Vanyo I.W. (1975) Biological methods of spruce budworm control. Forestry Chronicle 51.16-19. 

Munroe. E.G. (1971) Status and potential of biological control in Canada. In: Biological control programmes against insects and weeds in 

Canada. 1959·68. Commonwealth Institule of Biological Control Technical Communication 4.213-255. 

Pschorn-Walchcr. H. (1977) Biological control of forest insects. Annual Review of Entomology 22.1-22. 

TInsley. T.W. (1979) The potential of insect pathogenic viruses as pesticidal agents. Annual Review of Entomology 24.63-87. 

Whitten. M.J.; Foster. G.G. (1975) Genetic methods of pest control. Annual Review of Entomology 20.461-476.

Pest Status 

Background 

Field Trials 

Chapter 48 

Choristoneura occidentalis Freeman, 

Western Spruce Budworm (Lepidoptera: 

Tortricidae) 

R.F. SHEPHERD and J.e. CUNNINGHAM 

Two outbreaks of the western spruce budworm, Choristoneura occidentalis Freeman, 

on Douglas fir, PseudolSuga menziesii (Mirb.) Franco, in British Columbia have been 

well documented and evidence of three more outbreaks during this century has been 

found by examination of tree radial sections. The current outbreak began in 1970 and 

still persists in 1980. It is more extensive and has continued longer than the previous 

outbreak, which lasted from 1954 to 1958. 

These outbreaks all occurred in the Frazer and Lillooet River valleys, which form an 

inter-zone between the moist coastal and dry interior zones of British Columbia. In the 

western and southern portions of these valleys, defoliation occurred in a mid·slope band 

but not in the valley bottoms. With time, populations have decreased in the western 

extremities of the infestation and increased toward the northeast, but during the current 

outbreak populations have decreased and then increased regionally more than once. 

Typical damage to trees includes reduction in height and radial growth, dieback, and 

deformity. Complete tree mortality has occurred in a few small patches but more 

commonly occurs in the understorey below larger heavily defoliated trees. 

The same viruses that infect C. occidentalis also infect spruce budworm, C. fumiferana 

(Clem.), and laboratory tests indicate that the former is more susceptible to a nuclear 

polyhedrosis virus (NPV) and a granulosis virus (GV) (Cunningham unpublished). In 

addition, populations of western spruce budworm are virtually free of the microsporidian 

parasites that are found at very high levels in older infestations of spruce budworm; it is 

possible that infection with microsporidia may be antagonistic to subsequent infection 

with viruses but this has to be verified. 

The first aerial spray trial using NPV on western spruce budworm was conducted in 1976 

on a 20.5·ha plot, using a fixed.wing aircraft fitted with boom and nozzle spray equipment. 

The dosage was 250 x 10" polyhedral inclusion bodies (PIB) per hectare; the aqueous 

formulation contained 25% molasses, 6% IMC 90-001 (International Minerals Corp.) 

UV protectant, and 1% Chevron® sticker; the emission rate was 9.4 I/ha and larvae 

were in the fourth, fifth, and sixth instars. Population reduction as a result of treatment, 

calculated by Abbott's formula (Abbott 1925), was 36%; the incidence of NPV in larvae, 

determined microscopically, was 6.8% in the treated plot and 1.6% in the check plot 

respectively. In 1977 the incidence of virus in the treated plot fell to 1.3% (Shepherd & 

Cunningham unpublished). This poor result was probably due to too Iowa dosage of 

virus. applied too late. 

In 1978 the same equipment and emission rate were used to treat three 20-ha plots with 

NPV at a dosage of 750 x 10" PIBlha just after budflush when larvae were at the peak of 

the fifth instar, with third, fourth. and sixth instars also present. The aqueous formulation 

277

27R R. F. Shcphcrd and J. C. Cunningham 



contained 25% molasses, 3% Shade® (Sandoz Inc.) (the same product as IMC 90-001), 

and 0.05% Triton® B-1956 (Rohm and Haas Co. of Canada Ltd.) sticker. Fifteen days 

after spraying, NPV infection levels, detemined microscopically, were 55, 87, and 25%; 

and population reductions due to treatment were 0, 26, and 48% respectively. Successful 

adult emergence was lower in treated than in check plots,and the male:female ratio 

was 2: 1 in the treated plots compared to 1:1 in the check plots (Hodgkinson et al. 1979). 

In 1979 and 1980, follow-up studies were conducted on two of the three virus-treated 

plots, the third being abandoned because of a local population decline. In these two 

plots, NPV infection rates were recorded as 18 and 54% in 1979, and 7 and 17% in 1980. 

In 1979, population declines of 51 and 62% in the virus treated plots were recorded 

compared to increases of 46 and 201 % in the corresponding check plots. However, this 

trend was reversed in 1980; populations more than doubled in the virus-treated plots 

compared to 1979 levels and substantial population declines were noted in the check 

plots (Shepherd el al. 1982). 

Bacillus Ihuringiensis Berliner 

In 1978, four 4O-ha plots were treated with Thuricide® 16B (Sandoz Inc.), a commercial 

preparation of Bacillus Ihuringiensis Berliner (B.t.). The emission rate was 9.4 Vha and 

the dosage 20 x ur I. U ./ha. Fifteen days after spraying, populations were reduced by 32, 

66, 79, and 91% (Hodgkinson el al. 1979). 

In the plots treated with B.t., western spruce budworm populations increased in 1979 

in two of the four plots; in the third plot the population increased at a lesser rate and in 

the fourth it showed a small, but significant, decrease compared to corresponding check 

plots. In 1980 this trend was reversed, with untreated populations decreasing and B.t.treated 

populations increasing dramatically (Shepherd el al. 1982). 

Applications of NPV and B.I., in 1978 did not provide adequate control in that year, but 

NPV and possibly B.I. did provide some carry-over effect and continued to cause a 

population regulating effect a year later. This carry-over effect might have continued 

longer, but the plots treated in these trials were small and results were probably masked 

by immigration of moths. If either NPV or B.t. can regulate populations for a number of 

years after a single application, their use may be justified economically. 

The same constraints that apply to the viruses on C. fumiferana also apply to C. 

occidentalis. However, the western species is virtually free from microsporidian 

parasites; preliminary laboratory tests have also shown that it is more susceptible to 

both NPV and av than microsporidia-free, laboratory-reared spruce budworm larvae. 

It therefore appears that western spruce budworm is a better candidate for population 

regulation with viruses. 

More field trials should be conducted to compare the efficacy of NPV and av. 

A test involving an isolated population, where moth immigration would be negligible, 

should be conducted in order to evaluate the long-term effects of these biological 

control agents.


CflOris(rmcllra occidelllalis Freeman. 279 

Abbott, W.S. (1925) A method of computing the erfeetiveness of an insecticide. Journal of Ecotromic Entomology 18.265-267. 

Hodgkinson, R.S.; Finnis. M.; Shepherd, R.F.; Cunningham, J.C. (1979) Aerial applications of nuclear polyhedrosis virus and Bacillus 

tllUTitlgietlsis against western spruce budworm. British Columbia Ministry of Forests/Canadian Forestry 

Service Joim Report 10. 19 pp. 

Shepherd, R.F.; Gray, T.G.; Cunningham, J.C. (1982) Effects of nuclear polyhedrosis virus nnd Dacilllts tllUritlgietlSis on western spruce 

budworm one nnd two xenrs after aerial application. Canarlian Entomologist 114,281-282.

Blank Page 

280

Pest Status 

Background 


AgaIhis pumila (Ratz.) 

(Hymenoptera: 

Braconidae) 

Chapter 49 

Coleophora laricella (Hiibner), Larch 

Casebearer (Lepidoptera: Coleophoridae) 

I.S. OTVOS and F. W. QUEDNAU 

The larch casebearer. Coleophora laricella (Hubner). was accidentally introduced from 

Europe, probably on nursery stock. It was first recorded in North America in 1886 at 

Northampton, Massachusetts (Herrick 1912), and in Ottawa in 1905 (Retcher 1906). 

The casebearer spread rapidly and by 1947 infested most tamarack, Larix laricina (Du 

Roi) K. Koch, in Newfoundland. the Maritimes. and Ontario. spreading west as far as 

Thunder Bay (McGugan & Coppel 1962). By 1970 it was present in southeastern 

Manitoba. It was first found on western larch. Larix occidentalis Nutt .• around St. 

Maries, Idaho, in 1957 (Denton 1958). and in British Columbia in 1966 (Molnar et al. 

1966). The larch casebearer moved rapidly along major larch stands in the valleys, and 

became established throughout the range of western larch in southeastern British 

Columbia in varying degrees of infestation. Successive years of severe defoliation cause 

growth reduction. crown dieback. and subsequent tree mortality (McGugan & Coppel 

1962. Turnock et al. 1969). 

Successful control of the larch casebearer in eastern and central Canada (Webb & 

Quednau 1971) by the introduction of parasitoids and by similar biological control work 

in the northwestern United States (Denton 1972. Ryan & Denton 1973) led to a resumption 

of the use of parasitoids in 1974 to combat the larch case bearer in British Columbia. 

An intensive survey of larch casebearer parasitoids conducted in British Columbia in 

1973 yielded 32 species of Hymenoptera (Miller & Finlayson 1974). In Quebec, studies 

on Diadegma laricinellum (Strobl) were continued after 1968, but the project was 

terminated in 1974 because of low priority. 

Four species of parasitoids. Agathis pumila (Ratz.), Chrysocharis laricinellae (Ratz.). 

Diadegma laricinellum (Strobl). and Dicladocerus japonicus Yshm. have been released 

in southeastern British Columbia. and a few D. laricinellum were also liberated in 

Quebec. The details of these releases are summarized in Table 75. 

This species was first introduced into British Columbia in 1969 when parasitized larch 

casebearers. collected in Montana (USA) were placed in larch casebearer infested 

stands at Arrow Creek and Fruitvale. The species was recovered in 1972 at both sites. 

Between 1974 and 1977 more adults of A. pumila, this time from Europe. were released 

at other locations in the southeastern part of the province. In addition, larch casebearer 

larvae parasitized by A. pumila in the laboratory were placed in infested larch stands. 

and parasitoids from an old larch case bearer infestation in British Columbia were also 

relocated. 

2XI

282 I. S. Otvos and F. W. Quednau 

Chrys«haris 

buidneHae (Ratz.) 

(Hymenoptera: 

EuJophidae) 

Table 75 

The establishment of the parasitoids was monitored by rearing last-instar larch casebearer 

larvae and pupae collected at the release sites. These rearings showed that A. 

pumila became established, but its numbers seem to be declining as another parasitoid, 

C. laricinellae, is increasing over the years. Quednau (1970) has shown that the 

multivoltine C. laricinellae increased at the expense of A. pumila in Quebec. 

Summad' of parasitoid releases and relocations in British Columbia and Quebec between 

1969 an 1980 

No. and sex of 

Species and locality Lat. Long. Origin parasitoids released Year 

Agathis pumiJa (Ratz.) 

Fruitvale 49.06"N 117.33o"V Montana 100 M & F 1969 

Arrow Creek 49.07"N 116.26"W Montana 100> M & F 1969 

Nelway 49.02"N 117.1nV Austria 87M+89F 1974 

Blewett 49.28"N 117.2SW France 15 M + 15 F 1974 

Creston 49.06"N 116.31o"V Italy 10 M + 24 F 1975 

East Arrow 49.09"N 116.26o"V Italy 2OM+32F 1975 

Thrums 49.23"N 1l7.33"W Italy 9M+32F 1975 

Pass Creek 49.25"N 117.36o"V Italy 17 M + 31 F 1975 

Blewett 49.28"N 117.25"W Italy 14 M + 31 F 1975 

North Salmo 49.13"N 1l7.l4"W 400 (parasitized larvae) 1976 

Christina Lake 49.02"N 118.10"w Austria 25M+30F 1976 

Ross Spur 49.11"N 117.28"W Austria 24M+28F 1976 

Rossland 49.04"N 1l7.47"W Italy & Austria 16 M + 36F 1977 

Cherryville SO.13"N 118.34"W (relocation from l00M& F 1978 

Arrow Creek) 

Chrysocharis laricinellae (Ratz.) 

Thrums 49.23"N 1l7.33"W Switzerland 6 M + 12 F 1974 

Shuttleworth Creek 49.1ffl 119.32"W (relocation from 512 M & F 1980 

B.C.) 

Diadegma laricinellum (Strobl) 

South Slocan 49.23"N 1l7.33"W Austria IOM+5F 1974 

Thrums 49.23 c N 1l7.33"W Austria 7 M + 5 F 1974 

East Arrow 49.09"N 116.26"W Italy 9M + SF 1975 

Thrums 49.23°N 1l7.33"W Italy 9M + SF 1975 

North Creston 49. 12°N 116.34"W Italy 12 M + 28 F + 25 1976 

parasitized larvae 

Joliette' 46.02"N 73.27"W own rearings 12 F (mated) 1972 

Dicladocerus japonicus Yshm. 

Blewett 49.28"N 1l7.25°W Japan 52 M + 215 F 1974 

Thrums 49.23°N 1l7.33"W Japan 5M+20F 1974 

• Located in Quebec; all others are in British Columbia . 

C. laricinellae was apparently introduced in the Pacific Northwest with its host or it was 

released inadvertently with the early introductions of A. pumila (Ryan et al. 1974). In 

1974 a small number of imported C. laricinellae were released in British Columbia; in 

1980 greater numbers of the parasitoid were relocated from older infestations in the 

province.

Dladegma I8ricineIJum 

(Strobl), formerly 

known as D. nBnB 

(Grav.), (Hymenoptera: 

Ichneumonldae) 

DlclBdocerus 

jBponlcus Yshrn. 

(Hymenoptera: 

Eulophidae) 



Co/eop//Ora laricella (Hubner), 283 

Adults of this parasitoid were liberated in small numbers in British Columbia from 1974 

to 1976, but none of the species has been recovered. In Quebec, 12 mated females from 

laboratory rearings were released in 1972, but recoveries could not be made because the 

project was terminated. Quebec received small quantities of D. laricinellum from 

Austria between 1968 and 1973. Because the biology of D. laricinellum was incompletely 

known, laboratory studies on competition between it and A. pumila were conducted 

before it was released in the field. These studies have shown that host larvae attacked by 

A. pumila are normally avoided by D. laricinellum except at high densities of A. pumila, 

which are rare in nature. D. laricinellum proved to be intrinsically inferior and died from 

the presence of A. pumila when both parasitoid species occurred in the same host larva 

(Quednau, unpublished). Synchronous attacks on larch casebearer larvae by both 

parasitoid species are unlikely to occur in nature, because A. pumila attacks smaller 

needle-mining stages than D. laricinellum. Factors adversely affecting the sex ratio of 

the progeny of this parasitoid were discussed by Ryan (1980). These factors comprise 

continuous supply with hosts, overmating, too-early contact with hosts, superparasitism 

and lack of sufficient time between attacks to encourage the fertilization of parasitoid 

eggs. Because some of these factors were not used to provide optimum conditions for 

the proper sex ratio during the laboratory rearings of D. laricinellum in Quebec, too 

few female parasitoids were obtained for field liberations (Quednau unpublished). 

This species was released in 1974 at Blewett, British Columbia, in relatively small 

numbers and has not been recovered to date. 

It is too early to evaluate the effect of the parasitoids on the larch casebearer in British 

Columbia. Data obtained so far indicate that both A. pumila and C. laricinellae have 

become established. The latter is now fairly common in this province (Otvos unpublished) 

and may have contributed to the reduction of the larch case bearer and hence of tree 

mortality. 

Further searches should be made for D. laricinellum; because of the failure to recover it, 

the role of this parasitoid in Canadian larch casebearer populations remains to be 

evaluated. Its presence in the ecosystem can be only beneficial because it also may serve 

as a host for C. laricinellae. The introduction of A. pumila has probably facilitated the 

distribution of C. laricinellae in British Columbia. Although no studies have been made 

on this subject, winter mortality of the parasitoids should be considerably less in British 

Columbia than in the eastern part of Canada, and the impact of C. laricinellae on larch 

case bearer populations should be stronger because of the more favourable climate in the 

west. Life-table studies, although time consuming, are essential to the understanding of 

host-parasitoid population regulation mechanisms.

2M.. I. S. OtV()S and F. W. Quednau 


Denton. R.E. (1958) The larch c3scbearer in Idaho - a new defoliator for western forest. US Department of Agriculture Forest Service 

Research Note 51. Intermountain Forest and Range Experiment Station, Ogden, Utah, 6 pp. 

Denton. R.E. (1972) Establishment of Agathis pumila (Ratz.) for control oflarch casebearer. and notes on native parasitism and predation in 

Idaho. US Department of Agriculture Forest Service Research Note INT·I64. 6 pp. 

Retcher. J. (1906) Insects injurous to Ontario crops in 1905. Forest and shade trees. Entomological Society of Ontario Report 36.89-90. 

Herrick. G.W. (1912) The larch cascbearer. Blllletin of the Cornell Agricultural Experiment Station No. 322. 

McGugan. B.M.; Coppel, H.C. (1962) Biological control of forest insects, 1910·1958. In: A review of biological control attempts against 

insects and weeds in Canada. Commonwealth Institute of Bioiogicill Contwl Technical Communication 

2.35-216. 

Miller. G.E.; Finlayson, T. (1974) Native parasitoids of the larch cascbearer, Coleophora laricella (Lepidoptera: Coleophoridae), in the west 

Kootenay area of British Columbia. Journal of the Entomological Society of British Columbia 74.14 - 21. 

Molnar, A.C.; Harris. J.W.E.; Ross, D.A. (1966) British Columbia Region. Annual Report of the Forestln.rect and Disease Survey, Ottawa 

1967. PI'. 108-123. 

Quednau. F. W. (1970) Competition and cooperation between Chrysoclwris laricinellae and Agathis pumila on larch casebearer in Quebec. 


Ryan. R.B. (1980) Rearing methods and biological notes for seven species of European and Japanese parasitoids of the larch casebearer 

(Lepidoptera: Coleophoridae). Canadian Entomologist 112.1239-1248. 

Ryan. R.B.; Denton, R.E. (1973) Initial releases of Chrysocharis laricinella and Dic/adocerus westwoodii for biological control of the larch 

casebearcr in the western United States. US Department of Agriculture Forest Sen-ice Research Note 

PNW·200. Pacific Northwest Forest and Range Experiment Station. Portland, Oregon. 4 pp. 

Ryan. R.B.; Bousfield, W.E.; Miller. G.E.; Finlayson, T. (1974) Presence of Chrysocharis Ia,icinellae. a parasite of the larch casebearer. in 

the Pacific Northwest. Journal of Economic Entomology 67.805. 

Tunnock, S.; Denton, R. E.; Carlson, C.E.; Janssen. W. W. (1969) Larch casebearer and other factors involved with deterioration of western 

larch stands in northern Idaho. US Department of Agriculture Forest Service Research Paper, INT-68. 

Intermountain Forest and Range Experiment Sation, Ogden, Utah. 10 pp. 

Webb. F.E.; Quednau, F.W. (1971) Coleophora laricella (Hiibner), larch casebearer (Lepidoptera: Colcophoridae) In: Biological control 

programme against insects and weeds in Canada, 1959·1968. Commonwealth Institute of Biological 

Contwl Technical Communication 4,131-143.

Pest status 

Chapter 50 

Coleophora serratelfa (L.), Birch Casebearer 

(Lepidoptera: Coleophoridae) 

A.G. RASKE 

The birch casebearer, Co/eophora semlIe/JQ (L.)I, is native to Europe; Salman (1929) 

postulated that the insect was accidentally introduced into northeastern North America 

about 1920. There it has become the most important defoliator of white birch, Betula 

papyri/era Marsh. It was discovered in Maine in 1927 (Salman 1929) and had spread to 

New Brunswick by 1933, to Nova Scotia by 1937 (Reeks 1951), to Ontario by 1944 

(Raizenne 1952), to Prince Edward Island by 1951, to Quebec by 1956, and to Manitoba 

by 1969 (Cochran 1974). It was discovered in western Newfoundland in 1953 and had 

spread throughout the island by 1971 (Raske 1974a). It was discovered in Victoria, 

British Columbia, in 1962 (probably from a separate introduction) and was causing 

severe defoliation of ornamental trees in about 100 ha of the city by 1980 (van Sickle 

personal communication). The pest has also been collected in Alberta (B. Wright 1981, 

personal communication). This casebearer thus appears to occur throughout Canada 

(Fig. 11) but the exact distribution in central and western Canada is largely unknown. 

Identification records for Ontario were recently revised. Thus C. serratella has never 

been positively identified in Ontario but a thorough search has not been undertaken. 

The most common form of damage to trees is the browning and reduction of foliage 

caused by the feeding of late instar larvae in early summer (Bryant & Raske 1975). The 

larva feeds like a leafminer. It attaches its case to a leaf and mines as far as it can reach 

without leaving the case, creating somewhat rectangular mined patches. After a larva 

has eaten all the food within reach, it moves to another part of the leaf and repeats the 

process. The mined portion turns brown and this causes the scorched appearance of 

severely damaged trees. The damage tends to become masked later in the summer by the 

continuous production of new foliage. 

The more severe form of damage occurs in early spring when large numbers of earlyinstar 

larvae destroy the flushing buds, causing twig, branch, and sometimes tree 

mortality (Bryant & Raske 1975); many insects starve. 

Outbreaks of the birch casebearer have been reported from Victoria, British Columbia, 

and from Quebec to Newfoundland. The insect probably reached St. John's, Newfoundland, 

in the late 1960s. It was extremely rare in Newfoundland in 1971 (Raske 19740) but 

had reached outbreak proportions by 1980. In a newly invaded area, populations tend to 

increase to a super-saturation level. After 1 or 2 years populations decline but continue 

to cause a high level of chronic defoliation of 20-50%. However, the post-outbreak 

population levels vary in both location and time. 

The life history and habits of the birch case bearer in the northeastern United States 

were reported by Salman (1929) and by Gillespie (1932). Guevremont & Juillet (1974) 

and Raske (1976) described aspects of the life history in Canada. Cosh an (1974) and 

Gepp (1975a) have summarized life history studies in Europe. The life cycle ofthe insect 

spans two calendar years. In Canada, eggs are laid in July on the underside of leaves. 

Larvae hatch in August and mine the leaf until early September. After moulting they 

cut a case from the leaf epidermis, crawl to a different area of the leaf, and feed until fall. 

I J.C. Bradley (In: Kloet, G.S.; Hinks, W.D. (Ells.) 1972 - Handbook for the identification 

of British insects, Vol. 2, Part 2. Lepidoptera. Royal Entomological Society, 

London) cites C. fuscedinella Zell. as a synonym of C. serralella (L.). 

285

Background 


Coleophora serralella (L.). 287 

Just before leaf drop they crawl to branch crotches or to the base of leaf buds to 

overwinter. In the following spring, after moulting, they feed on developing leaves. 

When fully grown, by early summer, they pupate and adults emerge in July. 

Species of alder (Alnus spp.) are the main hosts in continental Europe (Gepp 1975a), 

but in the British Isles several species of birch are the most severely attacked trees 

(Coshan 1974). In North America (Guevremont & Juillet 1974, Bryant & Raske 1975) 

white birch is the most severely damaged species, although grey birch, Betula populi/olio 

Marsh., may also sustain continuous severe damage. The casebearer may complete its 

life cycle on several species of hardwood trees and shrubs, but in North America it is 

known to build up high population levels only on white and grey birch (Guevremont & 

Juillet 1974, Bryant & Raske 1975). 

In North America, the extent of mortality of various life stages has been determined in 

Quebec (Guevremont & Juillet 1974) and in Newfoundland (Raske unpublished). Life 

tables for the two regions differ substantially. In Quebec, mortality of first- and secondinstar 

larvae and pupal parasitism seem to be the most important mortality factors. In 

Newfoundland, highly variable egg mortality, from unknown causes, seems to regulate 

the population at a chronic high level. This egg mortality (Raske 1974b) has not been 

reported on mainland Canada. In fall, early instar larval mortality in Newfoundland is 

about 20%. Surviving larvae that overwinter suffer mortality of about 60% annually. In 

spring, larval mortality among those remaining is about 80% and pupal mortality is 25%. 

Total losses from parasitism of all stages is about 10%. 

The parasitoid complex of this casebearer has been studied both in Europe and in 

North America where biological control of this pest has been attempted. In its native 

Europe, parasitoids are more important in regulating the population of the birch 

casebearer (Pschom-Walcher 1969 to 1975, Gepp 1975b, 1975c, Coshan 1974) than in 

North America (Guevremont & Juillet 1975, Raske 1978). However, the parasitoid 

complexes on the two continents resemble one another. Many genera are native to both 

regions: Scambus, ltoplectis, Gelis, Orgilus, Agathis, Habrocytus, Cirrospilus, and 

Chrysocharis. The species on each continent differ, except for Habrocytus semotus 

(Walker). Apanteles spp. and Campoplex spp. are dominant parasitoids of this casebearer 

in Europe, but are virtually absent on it in North America. The main difference between 

Quebec and Newfoundland is that Agathis cincta was common in Quebec and absent in 

Newfoundland. 

Most parasitoid species in North America are parasitic on many lepidopterous insects 

and are best considered incidental parasitoids that have adapted to this host. 

In 1968 the Canadian Forestry Service, in co-operation with the aBC, initiated a 

biological control programme against the birch casebearer in Newfoundland; introductions 

of European parasitoids began in 1971 and terminated in 1975 (Raske 1977). Two 

species complexes of parasitoids were released: Campoplex (= Porizon) spp. (Hymenoptera: 

Ichneumonidae) and Apanteles spp. (Hymenoptera: Braoonidae) (Table 76). The Campoplex 

spp. consisted of C. borealis (Zett.) and an undescribed species. The Apanteles complex 

included three species: predominantly A. coleophorae (Wilk.) and a few each of A. 

mesoxanthus Ruschka and A. corvinus Reinh. Living individuals of neither complex

Blank Page 

290

Pest Status 

Background 

Chapter 51 

Fenusa pusilla (Lepeletier), Birch Leafminer 

(Hymenoptera: Tenthredinidae) 

F.W. QUEDNAU 

Fenusa pusilla (Lepeletier) is an important endemic pest on ornamental birches, Betula 

spp., in Canada. This insect was accidentally introduced from Europe into the State of 

Connecticut, USA, in 1923 (Friend 1933). The tree species attacked are Betula papyri/era 

Marsh., B. populi/olia Marsh .• B. lema L.. and the European B. verrucosa Ehrh. and its 

varieties. The present distribution of the sawfly in Canada is mainly from Newfoundland 

to Thunder Bay in northwest Ontario. but it has recently been recorded from the Prairie 

Provinces (Fig 12). The infestation level of F. pusilla in Canada is usually high and 

remains relatively constant from one year to another. The insect, by its oviposition and 

the ensuing feeding of larvae in leaf mines, causes discolouration of the foliage by the 

destruction of parenchyma cells. The affected trees have an unsightly brownish discolouration 

of the leaves. which drop prematurely. Repeated infestations of the sawfly 

weaken a tree and make it prone to attack by other insects or diseases. There are about 

three overlapping generations of F. pusilla in a year. The biology of this insect in Quebec 

has been described by Cheng & leRoux (1965) and Guevremont (1975). 

A preliminary study of biological control agents affecting F. pusilla in Europe was 

undertaken by the Commonwealth Institute of Biological Control (CIBC) at Delemont. 

Switzerland (Pschorn-Walcher & Eichhorn 1968). The observation that F. pusilla is 

much less abundant in Central Europe than in Canada led to the decision by the 

Canadian Forestry Service to introduce parasitoids. In 1972 the Newfoundland Forest 

Research Centre initiated a programme at Pasadena, Newfoundland. In 1974 the project 

was transferred for technical reasons to the Laurentian Forest Research Centre at Ste 

Foy, Quebec. The aim of this biological control programme was the implantation of the 

two hymenopterous parasitoid species, Latlrrolestes nigricol/is Thoms. and Grypocentrus 

albipes Ruthe. For information on the techniques employed for the releases and recoveries 

the reader is referred to reports by Guevremont & Quednau (1976, 1978). 

Releases and Recoveries The numbers of parasitoids released in Canada are listed in Table 77. 

LaIhroIestes nigrirolJis 

Thoms. (syn. 

Priopoda nigricollis 

(Thoms.» 

(Hymenoptera: 

(chneumonidae) 

This is a multivoltine solitary endoparasitoid of semi-mature and mature larvae of the 

leafminer. Its biology in Europe was described by Eichhorn & Pschorn-Walcher 

(1973). Additional observations on its mating and oviposition behaviour were made by 

Quednau & Guevremont (1975). It is the most important natural enemy of F. pusilla 

in Central Europe. It is probably monophagous and well synchronized with successively 

overlapping stages of the host in the field. In captivity the female parasitoids are easily 

mated. Partial encapsulation of parasitoid eggs in the host larva, the incidence of 

superparasitism. multiple parasitism by other parasitoid species. and entry in diapause 

291

Pest Status 

Chapter 52 

Gilpinia hercyniae (Hartig), European 

Spruce Sawfly (Hymenoptera: Diprionidae) 

L.P. MAGASI and P.O. SYME 

The European spruce sawfly, Gilpinia hercyniae (Hartig), a major pest of spruce (Picea 

spp.) in eastern Canada during the 1930s and early 19405, has lost its economic 

importance with the collapse of outbreaks in the Gaspe Peninsula and in northern New 

Brunswick (Neilson er aI. 1971). Populations have remained generally low since the 

early 1940s. The insect, and specifically its biological control by parasitoids and 

pathogens, has thus received very little attention since the last review in 1969. Consequently, 

the information presented here is meagre. It deals mainly with major population 

changes and changes in distribution of the insect during the past decade. No research 

has been conducted on the biological control of the spruce sawfly in Canada since 1969 

and few references are available. Distribution of the pest is summarized in Fig. 13. 

Newfoundland 

Populations were generally low, with occasional minor increases. Larval numbers in 

western Newfoundland increased from l.4/tree in 1970 to 18.0/tree in 1971 and to 

24.OItree in 1972. However, by 1974 the population decreased to 1.0 larva/tree throughout 

the province and has remained at that level. 

The nuclear polyhedrosis virus (NPV) Borrelinavirus hercyniae, introduced in 1943, 

is assumed to be a principal factor in controlling outbreaks but the introduction of 

invertebrate parasitoids and perhaps even the masked shrew, Sorex cinereus cinereus 

Kerr, have doubtless improved the biological control of this insect. 

Maritimes 

Population levels were generally low in the region throughout the decade. The highest 

number recorded was in Pictou County, Nova Scotia, where 17 larvae were found on 

four white spruce trees, Picea glauca (Moench) Voss, in 1978. The NPV B. hercyniae 

was last found in larvae in 1975. The dipterous parasitoid Drino bohemica (Mesn.) and 

the hymenopterous parasitoid Exenterus veIlicatus Cush. were last reared in 1977, but it 

should be added that, apart from these rearings, no efforts have been made to identify 

these control agents. 

Neilson et aI. (1971) in an earlier edition of this book described an increase in the 

sawfly population after the cessation of chemical insecticide spraying to control spruce 

budworm, Choristoneurafumiferana (Clem.). This situation occurred again in the early 

1970s when the monitoring plot was sprayed for 2 years. Sawfly levels increased 

immediately afterwards and remained high for a number of generations until, presumably, 

the host and its control agents re-established their balance. 

Quebec 

The insect was present in low numbers throughout its known range, with minor 

fluctuations. Laboratory rearings showed the presence of the NPV B. hercyniae in 1971, 

1973, 1974, and 1975, and the virus is considered a major factor in controlling the 

population. 

295

Ontario 

Gilpitlia Ill'rcylliae (Hartig), 297 

The insect has been sporadically reported, and occurs throughout the province within 

its known range but usually in very low numbers. In 1977, light defoliation of white 

spruce occurred in parts of southwestern Ontario. 

The Forest Insect and Disease Survey participated in a parasitoid identification 

project with CIBC in 1973. Of 160 sawfly cocoons, 7 adults of E. vellicatus emerged 

(4.4% parasitism); the parasitoids were mostly male. 

Manitoba 



The insect was first reported in Manitoba in 1969, when it was found in low 

populations on 5200 km! adjacent to the Ontario border. In 1970, populations were 

reported on a further 2600 kml, as far north as Otter Falls and Meditation Lake in the 

Whiteshell Provincial Park, and as far west as the Agassiz and the Sandilands Provincial 

Forests. It has not extended its range since then and population levels have remained 

low. 

The European spruce sawfly appears to be controlled, largely by biological agents. 

However, there may be differences in areas that are regularly subjected to chemical 

sprays. Neilson et al. (1971) stated that when spraying stopped, there was a sharp 

increase in sawfly populations - at least until the balance between host and control 

agent was re-established. This phenomenon was observed again in the 19705. In each 

case, the spray period lasted only 2-4 years. It is not known what is happening in areas 

of sustained chemical insecticide application: the European spruce sawfly, obviously, 

is kept at low populations but possibly not by biological control agents. Nor is it known 

what the status of these agents is or if they would rapidly re-establish the balance 

necessary for control once chemical insecticide spraying ceased. High-value spruce 

plantations, which were practically non-existent in the 1930s and 194Os, are now 

plentiful and provide a bountiful food supply for the sawfly. 

Neilson, M.M.; Martinez. R.; Rose, A.H. (1971) Diprion hercyniae (Hartig), European spruce sawfly. In: Biological control programmes 

against insects and weeds in Canada. 1959-1968. Commonweahh /outilUle of Biological Control Technical 

Communication 4,136-143.

Blank Page 

298

-(I) 

C 

c::: 

o 

'';:; 

::::l 

.c 

';: 

300 L. P. Magasi and O. A. Van Sickle

Leucoma salids (L.), 301 

was recorded at Upper Ferry and light damage occurred on willow in the Stephenville 

area. In 1980 the outbreak spread from St. Andrews to Fischell's River, mostly along the 

major rivers where natural stands of balsam poplar occur. 

Maritimes 

In 1969, over 3200 ha of woodland trees, trembling aspen, Populus tremuloides Michx., 

and largetooth aspen, Populus grandidentata Michx., sustained moderate to severe 

defoliation in southeastern New Brunswick. The outbreak began in 1967, persisted for 3 

years, and collapsed in 1970. The collapse was partly due to biological control agents. At 

Elgin, New Brunswick, cocoons of A. solitarius were numerous on tree trunks in the 

winter of 1969-70 and counts of up to 732 cocoonslm l of bark surface were made. A 

cytoplasmic polyhedrosis virus, known in the maritimes since 1954, infected up to 67% 

of field-collected laboratory-reared larvae in 1968 near Anagance, within the same area 

as the L. salids infestation. 

Small outbreaks occurred in natural stands in 1974 in south-central New Brunswick, 

in 1976 in the central and in 1979 in the east-central parts of the province. All these 

outbreaks affected trembling aspen, but in 1974 largetooth aspen was also affected. 

None of the outbreaks lasted most than a single season. 

The insect was found on ornamental silver and Carolina poplars Populus alba L. and 

P. canadensis Moench, and willow, during 1969-80 at locations scattered throughout 

the region, resulting in varying degrees of defoliation. 

The parasitoids reared from satin moth in 1969-70 and their frequency are listed as 

follows: 

Apanteles solitarius (Ratz.) 

Compsilura concinnata (Mg.) 

12 locations; mean parasitism 51% 

(range 16-100%) 

6 locations; mean parasitism 15% 

(range 5-55%) 

Exorista sp. 1 location; percentage parasitism unknown 

The mean parasitism from all rearings was 28% for A. solitarius and 4% for C. 

concinnata. No rearings or insect analyses have been done since 1970. 

Quebec 

The general distribution of satin moth has increased considerably during the past decade 

and now includes all eastern Quebec and both sides of the St. Lawrence River. Infestations, 

causing defoliation that varied from trace to severe, were localized and were reported 

every year with the exception of 1970. No examinations of parasitism were made from 

1969-80. 

Ontario 

The insect was first reported in Ontario in 1972 from Cornwall and Lancaster Township, 

where it caused severe defoliation of individual silver poplar trees. By 1976 it had spread 

to near Ottawa. By 1980 it had reached west of Brockville and the severity of attack was 

reported on the increase. There are no records of parasitoids from the province. but 

again no check was made.

302 L. P. Magasi and G. A. Van Sickle 

Evaluation or Control Attempts 



The general distribution has not changed appreciably during the reporting period but 

satin moth infestations were recorded in three new areas; at Revelstoke in 1972, at Avola 

in the North Thompson Valley in 1975, and at Rossland in 1976. Whether these represent 

a true range extension or are only outlying areas cannot be stated with certainty because 

of the discontinuous nature of the tree-host and insufficient collections of insects. 

Infestations usually occurred on small groups of a few shade trees. However, starting in 

1973 a few severe outbreaks on trembling aspen and black cottonwood, Populus 

trichocarpa Torr. & Gray, were observed near Merritt, and by 1976 almost 1500 ha of 

natural stands were severely defoliated between Aspen Grove and Kamloops. Another 

outbreak, near Rossland, occurred in 1977 on over 140 ha of trembling aspen and small 

patches of trees were again defoliated in both these areas in 1978. 

In contrast to 67 rearing records during 1959-68, there were only two during 1969-80: in 

1972, 3 larvae reared from Revelstoke yielded one native parasitoid, Exorisla mella 

(Walker), and in 1976, 24 larvae, collected near Victoria, were reared: 6 were parasitized 

and 11 Apanteles melanoscellus (Ratt.) were recovered. 

Field observations recorded, but apparently unsubstantiated by collections, include: 

(l)in 1969, larvae were heavily parasitized in Lewis Park, Courtenay, where some 

trembling aspen was 80% defoliated; (2)in 1969, cocoons of Apanleies spp. were 

numerous on the trunks of severely defoliated black cottonwood at Slocan City; (3)in 

1975, A. solilarius was present in the second and last year of defoliation of black 

cottonwood over 1 ha along Birkenhead Lake. 

In a collection of more than 50 larvae from Lillooet in 1975, 6 were infected with a 

Beauveria sp. of fungus. 

The information presented here deals mainly with major population changes and changes in 

distribution of the host insect during the past decade; there are few instances where 

reference to biological control is made. No research has been conducted on the biological 

control of satin moth in Canada during the review period and none is recommended, 

given the minor economic importance of the pest. We have no information to alter the 

assessment given in the previous review, that parasitoids must recieve major credit for 

helping to shorten periods of pest outbreak and thus for reducing damage (Forbes & Ross 

1971). 

Forbes, R.S.; Ross, D.A. (1971) Stilnoptio salicis (L.). satin moth. In: Biological control programmes against insects and weeds in Canada, 

1959-1968. Commonwtalth lnslilutt of Biological Control Technical CommUllication 4,205-212.

Pest Status 

Background 

Chapter 54 

Lymantria dispar (L.), Gypsy Moth 

(Lepidoptera: Lymantriidae) 

K.J. GRIFFITHS and F.W. QUEDNAU 

The natural distribution of the gypsy moth, Lymantrio dispar (L.), extends across the 

whole of Europe, including Norway and Sweden up to about 58"N and all the temperate 

areas of North Africa and Asia, including Japan. Outbreaks occur periodicaUy throughout 

most of this range (Leonard 1974). The gypsy moth was accidentally introduced into 

North America at Medford. Massachusetts, in 1869, and within 20 years had become a 

serious local pest that required control (Burgess 1914). This pest has continued to cause 

serious periodic damage in spite of almost continuous work to control it. It is now found 

in the United States throughout the New England States, New York, New Jersey, and 

Pennsylvania, and has also been recorded in Delaware, Maryland, Virginia, and West 

Virginia. Isolated infestations have been reported in Washington, Oregon, California, 

Michigan, Wisconsin, Illinois, and Ohio (Forest Pest Survey Report, Virginia Division 

of Forestry, Sept.-Dec., 1980, unpublished report). 

The gypsy moth was first recorded in Canada in 1924 in Stanstead and St-Jean 

Counties, Quebec (McLaine 1925). A second invasion occurred in New Brunswick in 

1936 (McLaine 1938). Both these invasions apparently died out (Brown 1968) but a third, 

into Quebec south of Montreal in 1959 (Brown 1968), did not disappear and the gypsy 

moth has continued to spread in all directions from that area. The first invasion into 

Ontario occurred on Wolfe Island, just south of Kingston in 1969 (Sippell et 01. 1970), 

and it was reported on nearby Howe Island and the mainland near Kingston in 1970 

(Sippell et al. 1971). The Plant Quarantine Division of Agriculture Canada reports that 

the 1979 distribution of gypsy moth extends from approximately 60 km west of Quebec 

City to Morrisburg, Ontario, and north to Ottawa, and from near Brockville, Ontario, to 

25 km west of Belleville, with a northward extension of approximately 70 km. There is 

also a population in Greater Toronto and in Oakville, Ontario (Fig. 15). A small 

infestation was detected over a two-block area in Vancouver, British Columbia, in the 

summer of 1978, and a control operation was undertaken in 1979. There were no male 

adult recoveries in pheromone traps set out in the area in the fall of 1979 and the 

infestation is believed to have been averted. On the east coast there seems to be an 

annual influx of male moths from Maine. In Nova Scotia and New Brunswick males 

have been recovered in pheromone traps every year since 1971, with a marked increase 

in both provinces in the past 4 years. There were no male recoveries on Prince Edward 

Island in the first 6 years oftrapping, but in 1979 nearly 47% and in 1980,19% of the traps 

produced males. However. egg masses have never been recovered in the maritimes in 

this period (Magasi 1981). 

Since its arrival in North America, the gypsy moth has acquired a large complex of 

native insect parasites, and predators. Griffiths (1976) lists 22 species of insect parasites 

and Sabrosky & Reardon (1976) added 4 more to this list. In addition there are 17 species 

of insect predators, 4 species of mammalian predators (Griffiths 1976), and 46 species of 

303

Lymcltllria dispar (L.). 305 

avian predators (McAtee 1911) recorded from the United States. A major programme of 

importation and liberation of exotic insect parasites and predators was carried on in the 

United States from 1905 to 1933 (Dowden 1962) in which 44 species of insect parasites 

and 9 species of predators were released. Thirteen insect parasites and one predator 

became established. As pointed out by Ticehurst et 01. (1978) these natural enemies have 

not prevented the dispersal ofthe gypsy moth in North America, but their influence may 

be responsible for initiating population collapses and for maintaining relatively stable 

infestations in many areas following a collapse. The introduction programme was 

revived in the early 1970s and is continuing. Eight species of insect parasite and one 

species of nematode have been released. Four of the insect species were released 

unsuccessfully in earlier work (Griffiths 1976). None of these nine species is known to be 

established. 

Fourteen of the 26 species of native parasitoids that attack the gypsy moth in the United 

States have been recovered from other hosts in areas of Ontario and Quebec adjacent to 

the American infestation. Also 11 of the 17 insect predators, all of the four mammalian 

predators and 43 of the 46 species of avian predators are known to be in this area of 

Canada (Griffiths 1976). In addition, four exotic parasitoids established in the United 

States were present in southern Ontario and Quebec before the gypsy moth was recorded. 

Three of these species, Compsilura concinnata (Meigen), Apanteles lacteicolor Vier., and 

Meteor/IS versicolor (Wesm.) had been introduced against the browntail moth, Euproctis 

chrysorrhoea L., and the satin moth, Leucoma salicis L.. and one, Exorista larvarum (L.). 

apparently dispersed naturally from the United States. 

Several studies have been carried out recently to determine which parasitoid species 

are attacking the gypsy moth in Canada. The first of these investigations, in 1974 and 

1975, involved the collection and rearing of gypsy moth larvae from four woodlots near 

Kingston and three woodlots near Cornwall, Ontario. From these rearings, one native 

and three introduced parasitoid species were recovered (Table 79) (Griffiths 1977). The 

second study was carried out in 1977 and 1978 near Havelock, south of Montreal. and 

Mt-St-Hilaire, east of Montreal, Quebec. Larvae and pupae were collected and reared, 

and one more native and four more exotic species recovered (Table 79) (Madrid & 

Stewart 1980). A third study, carried out in 1978-80, used Malaise traps to capture 

adults at Mt-St-Hilaire and Mt-St-Bruno. east of Montreal. In this survey five additional 

native species were found (Table 79). The final study, carried out in 1979 and 1980, was a 

repetition of the work done by Griffiths (1977); two new native species and one exotic 

species, Ooencyrtus kuvanae (How.). were recovered (Table 79). 

Howard & Fiske (1911) noted that naturally occurring pathogens were playing a role 

in gypsy moth population regulation in the United States shortly after the introduction of 

the insect there. Much work has been done on pathogens since then. Bacterial and 

fungal pathogens are a minor influence (Doane 1971, Podgwaite & Campbell 1972, 

Majchrowicz & Yendol 1973), but viral pathogens, especially the nuclear polyhedrosis 

virus (NPV) Borrelinavirus reprimens Holmes, are known to be a major factor in 

reducing outbreaks (Doane 1970, Campbell & Podgwaite 1971). The gypsy moth NPV 

was registered for use in the United States in 1978, and quantities of it have since been 

produced and marketed as Gypcheki!!) (US Department of Agriculture) (Doane & McManus 

1981). 

An NPV was recorded from gypsy moth larvae in southeastern Ontario during studies 

of gypsy moth parasites carried out in 1974. 1975. 1979, and 1980 (Griffiths 1977. 

Griffiths & Wallace in press). It was also recorded in southwestern Quebec by Cardinal 

& Smirnoff (1973). Smirnoff has pointed out that for the last 3 years NPV has lowered 

gypsy moth numbers in Quebec (W.A. Smirnoff 1981 personal communication).

306 K. J. Griffiths and F. W. Qucdnau 

Table 79 


Anastatus dis paris 

Rusdaka (Hymenoptera: 

Eupelmldae) 

Parasitoids recovered from the gypsy moth, Lymantria dispar (L.), in Canada 1974-80 

Madrid & Quednau Griffiths 

Griffiths Stewan 1978-80 1979-80 

1977 1980 (unpublishcd) (unpublishcd) 

Diptera 

Sarcophagidae 

Sarcophaga aldrichi (Park.) xx xx 

Tachinidae 

Blepharipa pralensis (Mg.)' xx xx xx 

Compsilura concinnala (Mg.)' xx xx xx xx 

Exorisla larvarum (L.)' xx xx 

Exorisla mella (Wlk.) xx 

Paraseligena silvestris (R-D)' xx xx xx xx 

Hymenoptera 

Braconidae 

COlesia melanosceills (Ratz.)· xx xx xx xx 

Chalcididae 

Brachymeria intermedia (Nees)' xx xx 

Encyrtidae 

Ooencyrtus kllvanae (How.)" xx 

Eupelmidae 

AnaslalllS disparis Ruschka" xx 

Ichneumonidae 

ExochllS sp. xx 

Iloplectis conquislilor (Say) xx xx 

Phobocampe disparis (Vier.)· xx xx xx 

Pimpla pedalis (Cress.) xx xx xx xx 

77reronia llIilfattJae fulvescens (Cress.) xx 

Theronia hilaris (Say) xx 

Scelionidae 

TelonomllS sp. xx 

• Exotic parasitoids established in the United States . 

This parasitoid is a European species, successfully established in the United States by 

Howard & Fiske (1911)_ Natural dispersal is slow because female adults cannot fly and the 

species was subsequently distributed by further releases throughout the gypsy moth's 

American range (Dowden 1962). 

Adults of this species emerge from the previous year's gypsy moth eggs at about the 

time female moths are ovipositing. Female parasitoids attack the eggs and the parasitic 

larvae can develop in all embryonic stages of the gypsy moth. However, the proportion 

of gypsy moth females produced and the fecundity and longevity of the ovipositing 

female is reduced only if older eggs are attacked. There is usually only one generation 

per year and the parasitoid overwinters as a mature larva within the host egg. Preliminary 

work on the overwintering ability of mature larvae of the parasitoid indicated that A. 

dis paris apparently could survive over the same geographic area in Canada as the 

gypsy moth (Sullivan el 01. 1977). Because parasitism up to 28% had been recorded by 

Burgess & Crossman (1929), introduction of this species into Canada was undertaken

Table 80 

Table 81 

Ooenc)'rtus kuvsnse 

(How.) (Hymenoptera: 

Encyrtidae) 

Lymantria clispur (L.). 307 

following preliminary field cage and insectary studies (Table 80). The first releases were 

made near St-Mathias, Rouville County, Quebec. in 1979. with further releases near 

Acton Vale and Drummondville, Bagot and Drummond Counties respectively, in 1980 

(Table 81). Establishment of A. disparis occurred in all areas where releases were 

made. The initial occurrence of parasitism was 20-30% when batches of 25 female 

parasitoids were implanted in small ventilated cages, but only 2% when open releases of 

batches of 200-400 females were made. Successful hibernation of A. disparis at St 

Mathias was observed in 1980. A third release ofthis parasitoid was made in August 1980 

near Kilburnie, Ontario, but there have been no recoveries from this release as yet 

(Table 81). 

Laboratory and field cage studies of parasitoids against the gypsy moth, Lymanrria 

dis par (L.) in Quebec 

Species Year 

AnUSlalUS disparis Ruschka 1979 

• Field cage studies. 

•• Laboratory and insectary studies. 

1980 

Origin 

Hungary 

Austria 

Romania 

Hungary 

Austria 

Romania 

Hungary 

Number 

845* 

2505** 

234" 

Open releases and recoveries of parasitoids against the gypsy moth, Lymanlria dispar (L.) 



Anuslalus disparis Ruschka 

Quebec 1980 USA 

Hungary 

5600 1980 

Ontario 

Ooencyrtus kuvanae (How.) 

1980 Hungary 1020 

Ontario 1976 USA 25000 1978 

This Japanese egg parasitoid was introduced into New England in 1909. Its establishment 

was immediate and its natural dispersal was augmented by additional large releases 

throughout the infested area (Burgess & Crossman 1929). 

In the United States O. kuvanae can have three generations per year on gypsy moth. 

The first generation cycle takes approximately 6 weeks but the subsequent ones only 3 

weeks. Early studies showed that attack by this species was weak. Britton (1935) 

recorded that in southeastern Massachusetts and in Rhode Island egg parasitism was not 

more than 10% per year. However, higher attack levels have been recorded in more

308 K. J. Griffiths and F. W. Qucdnau 

Borrelinsyirus 

reprlmens Holmes 

Bad11us tburingiemis 

Berliner (B.t.) 


recent work. Dowden (1962) found attacks of 40-45% in Massachusetts and Connecticut. 

Weseloh (1972) gives a total summer attack of 29-42% in Connecticut. Thus its 

introduction into Canada was justified and preliminary investigations of the ability of the 

overwintering mated female adult to withstand low temperatures were undertaken 

(Griffiths & Sullivan 1978). It was found that adults were unable to survive continuous 

exposure to O°C for 30 days, and it was concluded that this species would be incapable of 

surviving in the current range of the gypsy moth in Canada. To test this hypothesis, 

approximately 25 000 adults supplied by the New Jersey Department of Agriculture 

were released on Wolfe Island, Ontario, on 24 September 1976 (Table 81). Gypsy moth 

egg masses have been collected in the release area in late August or early September 

each year since the release. There were no recoveries of O. kuvanae until 1978, when 28 

adults were recovered from two egg masses. A single adult was obtained from the 

release area in 1980. In addition, 45 adults of O. kuvanae were recovered from two egg 

masses collected near Glen Norman, Glengarry County, Ontario, in September 1980. 

Because this recovery site is approximately 180 km from the Wolfe Island release site, it 

is unlikely that there is any relation between the two; the parasitoids must have dispersed 

there naturally. 

Two experimental techniques for the application of NPV were tested by Cardinal & 

Smirnoff (1973) in Missisquoi and St-Jean Counties, Quebec, in 1972. They handapplied 

an aqueous solution of NPV at 40 x 10' polyhedral inclusion bodies (PI B) per 

millilitre to egg masses in early May and recorded nearly 100% mortality in the larvae 

emerging from them. They also sprayed foliage by mist blower with an aqueous solution 

at 4 x 10' PIBlml when larvae were in the second or third instar, resulting in higher 

mortality than was seen in larvae on unsprayed foliage. 

Jobin & Caron (1982) made aerial applications of B.I., using the commercial product 

Thuricide® 32B (Sandoz Inc.) in Chambly and Rouville Counties, Quebec, in 1979. 

There were two applications in each area at dosages of 19.6 and 39.52 x W"I.U.fha. All 

applications included a sticker and chitinase and the B.I. was applied at a rate of 9.36 

Vha. Spraying was carried out in late May when 60-70% of larvae were in the second 

instar. Mortality of larvae in the treated areas 20 days after treatment was 100%, 

compared to a decrease of 70-76% in control areas over the same time period. 

The establishment of exotic insect parasites on the gypsy moth in Canada is proceeding 

well, largely through natural dispersal. We now know that 8 of the 13 established exotic 

species are attacking gypsy moth in the infested zone in Canada and we are confident 

that a 9th species, Anaslalus disparis Ruschka, will become established. Two of the 

remaining four species are already present in Canada on other hosts. They are Apanleles 

klcteicolor Viereck, essentially a parasitoid of the browntail moth, which was established 

against that species in the maritimes and Quebec in 1915 (Tothill 1916); and M. versicolor, 

introduced against browntail moth and satin moth in Canada (TothillI916) and recovered 

in Ontario from Rlleumaplera lIaslala L. by Forest Insect and Disease Survey staff. M. 

versicolor is infrequently recovered from the gypsy moth in the United States. The 

other two exotic species are Eupleromalus hemiplerus (Walker) and Monodonlomerus 

aereus Walker. The former species is a common parasitoid of the satin moth in the 

United States but is rarely obtained from the gypsy moth there (Burgess & Crossman



Lymantria dispar (L.). 3()9 

1929, Proper 1931). nle latter species is a secondary parasitoid as frequently as it is a 

primary one (Howard & Fiske 1911). 

It is too soon to state that the release of egg parasitoids in Canada has resulted in the 

permanent establishment of these insects. We do know that seven other species of 

exotic parasitoids previously established in the United States are now attacking gypsy 

moth in Canada, but, in the absence of careful population studies of the gypsy moth we 

cannot say what impact any of them is having. 

A combination of applications of carbaryl on some areas and of "insecticide soap" on 

other areas in 1979 in Vancouver apparently resulted in elimination of the population 

there. It should be pointed out, however, that very few of the isolated infestations 

recorded in the history of the gypsy moth in the United States have ever been completely 

eradicated. Spraying with either an NPV or B.I. has been effective in small scale trials 

but the cost of application is many times higher than the cost of applying chemicals. 

It is evident that, aside from continuing to release and sample for the two egg parasitoids, O. 

kuvanae and A. dis paris , there is little more to be done in the introduction of biological 

agents because there are no more known suitable candidates. The one successfully 

established exotic predator, Calosoma sycophanla L., was introduced unsuccessfully 

into Canada at a number of locations (McGugan & Coppe11962) and it is questionable 

whether further work on this species is justified. 

Cardinal & Smimoff (1973) were able to produce gypsy moth NPV by rearing 

contaminated larvae in cages in the field. Smimoff (personal communication) recommends 

that the NPV so produced be used to inoculate incipient outbreaks by application on 

either egg masses or foliage to prevent buildup of gypsy moth to outbreak levels. 

In view of the above and of the relatively innocuous levels of gypsy moth populations 

in Canada in 1980, we feel there is no urgent need for further classical biological control 

work on this species. However, we strongly recommend that careful surveillance of the 

dispersal of the gypsy moth be continued by staff of the Plant Protection Division of 

Agriculture Canada. Continued monitoring in the Vancouver area is especially important. 

Brillon. W.E. (1935) The gypsy moth. Connecticut Agricultural Experiment SUllion Bulletin 375,623-647. 

Brown, G.S. (1968) The gypsy moth, Porthetria dispar L., a threat to Ontario honicullure and forestry. Proceedings of the Entomological 

Society of Ontario 98,12-15. 

Burgess, A. F. (1914) The gypsy moth and the brown· tail moth. with suggestions for their control. US Department of Agriculture Farm Bulletin 

564,24 pp. 

Burgess, A.F.; Crossman. S.S. (1929) Imponed insect enemies of the gypsy moth and the brown-tail moth. US Departnunt of Agriculture 

Technical Bulletin 86, 147 pp. 

Campbell, R.W.; Podgwaite. J.D. (1971) The disease complex of the gypsy moth. I. Major components. Journal of In"ertebrate Pathology 

18(1).101-107. 

Cardinal. J .A.; Smimoff. W.A. (1973) Introduction ex¢rimentale de la polyCdrie nucleairc de Portherria di.fpar L. (Upidoptcres: Lymantriidae) 

en foret. Phytoprotection 54(1).48-50. 

Doane. C.C. (1970) Primary pathogens and their role in the development of an epizootic in the gypsy moth. Journal of Invertehrate Pathology 

15(1),21-23. 

Doane. c.c. (1971) Field application of a Streptococcus causing brachyosis in larvae of Porthetria dis par. Journal of In"enehrate Pathology 

17(3),303-307. 

Doane. c.c.; McManus. M.L. (Eds.) (1981) The gypsy moth: research toward integrated pest management. US Department of Agriculture 

Science Education Agency APHIS Technical Bulletin 1584,757 pp. 

Dowden. P.B. (1962) Parasites and predators of forest insects liberated in the United States through 1960. US Department of Agriculture Forest 

Se",ice Handbook 226. 70 pp. 

Griffiths. K.J. (1976) The parasites and predators of the gypsy moth: a review of the world literature with special application to Canada. 

Canadian Forestry Se",ice Sault Ste. Marie. Ontario Report O-X·243. 92 pp.

Pest Status 

Background 

Chapter 55 

Malacosoma disstria Hubner, Forest Tent 

Caterpillar (Lepidoptera: Lasiocampidae) 

W.G.H.IVES 

The forest tent caterpillar, Malacosoma disstria HUbner, has had a long history of 

periodic outbreaks in Canada (Baird 1917, Hodson 1941, Hildahl & Reeks 1960, Sippell 

1962, Witter et al. 1975). The insect attacks a wide variety of tree species (Prentice 

1963), although the preferred host in most areas is trembling aspen, Populus tremu/oides 

Michx. Host trees are often completely stripped of foliage during outbreaks, but because 

the outbreaks usually last for only 3-6 years at anyone location (Sippell 1962, Witter et 

al. 1975), and even severely defoliated trees usually refoliate within a few weeks, there is 

usually very little tree mortality directly attributable to defoliation (Kulman 1971). However, 

severe mortality has occasionally been reported (Hodson 1941, G.N. Sti111980 

personal communication). Observations by the author suggest that such mortality is 

attributable primarily to the effects of severe drought fonowing several years of moderate to 

severe defoliation. 

Between 1969 and 1980 records compiled by the Forest Insect and Disease Survey 

(Anon. 1970-79) show that outbreaks of the forest tent caterpillar have occurred in all 

provinces except Newfoundland (Fig. 16). In New Brunswick, about 9 000 ha of trembling 

aspen were severely defoliated in 1969, and the infestation was expected to enlarge in 

1970. However, a combination of unseasonably wann weather in early May 1970, fonowed by 

several frosts, apparently resulted in the starvation of many young larvae. The area of 

infestation therefore decreased, and the expected outbreak did Dot materialize. In Nova 

Scotia, about 50 km 2 of aspen were defoliated in 1972, and in Prince Edward Island about 

28 000 ha in 1974. In Quebec, several small areas totalling less than 100 km 2 were 

defoliated between 1973 and 1976. In Ontario, remnants of earlier outbreaks persisted 

into the survey period and new outbreaks began developing soon afterwards. A total 

of over 100 000 km 2 east of the Lakehead was defoliated between 1975 and 1977, while 

the outbreak in northwestern Ontario alone covered about 160 000 km 2 in 1978. In 

Manitoba, an incipient outbreak was detected in 1971 and by 1977 most of the southern 

part of the province was affected. The outbreak collapsed in 1978, except for an area 

west of Lake Winnipegosis where it collapsed in 1979. In Saskatchewan, the outbreak 

was slower in developing and did not reach its peak until 1980, when about 128 000 km 2 

were subjected to moderate or severe defoliation. In Alberta, an outbreak in the Wabamun 

Lake area has persisted throughout the survey period, but the greatest damage occurred 

in 1980, when about 75000 km 2 were defoliated. In British Columbia, over 70 000 ha 

were defoliated in the central part of the province in 1973, but the outbreak collapsed in 

1974. 

Populations of forest tent caterpillar are influenced by a variety of environmental factors 

including weather, competition, predation, parasitism, and diseases. Ives (1973) believed that 

unusually favourable spring weather 2-4 years before any noticeable defoliation was 

responsible for triggering outbreaks, and a number of workers report that unfavourable 

spring weather appears to be a major factor in population collapse (Tothilll918, Sweetman 

311

Malacosoma disstria J-Hibner. 3/3 

1940, Blais et al. 1955, Witter et al. 1972, Hodson 1977). Unusually cold winter weather 

is also sometimes responsible for population decline (Witter et al. 1975). Hodson (1941, 

1977) found that starvation, often coupled with high pupal parasitism by Sarcophaga 

aldrichi Parker, was a major contributor to population collapse. A large variety of insect 

parasites attacks the forest tent caterpillar (Witter & Kulman 1972), but the most prevalent is 

usually S. aldrichi, which often attacks over 90% of the pupae in the declining phases of 

an outbreak (Hodson 1941, 1977). Predation by various birds (McAtee 1926, Hodson 

1941, Witter & Kulman 1972) and invertebrate predators such as ants (Tot hill 1918, 

Green & Sullivan 1950, Ayre & Hitchon 1968) has been observed on a number of occasions, 

but it is usually unimportant. 

Bacteria, fungi, microsporidia, and viruses all cause diseases in forest tent caterpillar 

larvae and pupae (Bird 1971). The bacteria isolated from M. disstria larvae include 

Bacillus cereus Frankland & Frankland, Clostridium brevifaciens Butcher, a Pseudomonas 

species, and Serratia marcescens Bizio, but all were rare (Smimoff 1968). The 

forest tent caterpillar is also susceptible to Bacillus thuringiensis Berliner (B.t.), although 

this organism is not usually found under natural conditions. Several fungi have been 

isolated from forest tent caterpillar larvae and pupae, but according to Stairs (1972) only 

Beauveria bassiana (Balsamo) Vuillemin and Entomophthora sp. were of any importance, 

and then only under humid conditions. A microsporidium, Nosema disstriae Thompson, 

has killed up to 90% of early-instar larvae in some areas (Smirnoff 1968). It also causes a 

reduction in the size of the insects and may affect their vigour, so that the full significance of 

infection is hard to assess (Bird 1971). 

Infection with a nuclear polyhedrosis virus (NPV) is often thought to be one of the 

most important factors in terminating forest tent caterpillar outbreaks. For example, 

Stairs (1966) stated that "Epizootics of nuclear polyhedrosis virus disease are known to 

be associated with the rapid decline of tent caterpillar popUlations, Malacosoma spp." 

Although this statement may be true for the tent-forming species, the evidence is 

equivocal for the forest tent caterpillar. Of the references cited by Stairs (1966), the 

following three deal with M. disstria. Bergold (1951) obtained high mortality among 

larvae in cages when they were sprayed with the virus under experimental conditions. 

Sippell (1952) demonstrated that a large percentage of egg bands collected in late fall 

were infected with virus. Neither experiment attempted to show that the virus had an 

effect on population trends. The third paper (Chapman & Glaser 1915) states: "Though 

wilt disease was also reported to have occurred in many places in the forest tent 

caterpillar, neither of us have seen more than a few typical cases from the field. Many 

caterpillars were sent in by field men but only a few of them proved to have typical wilt." 

Smimoff (1968) conducted a long-term study of M. disstria diseases in Quebec, and 

found NPV to be unimportant. Similarly, population studies by Hodson (1941) showed 

that the virus was responsible for less than 1 % mortality in Itasca State Park in 1936, and 

Witter el al. (1972), on the basis of intensive sampling, considered the virus to be 

unimportant in northern Minnesota during 1967-69. 

Although NPV appears to be unimportant as a control agent under natural conditions, 

it is possible that artificial dissemination of the virus into field populations might 

increase the amount of virus infection, thus increasing its effectiveness. Stairs (1964) 

used a small backpack mist blower to apply various dosages of virus to different larval 

instars of the forest tent caterpillar in 1963. A concentration of 10' polyhedral inclusion 

bodies (PIB) per millilitre applied to second- and third-instar larvae caused 92% mortality, 

most of the larvae dying within 10 days of the application. Stairs (1965) found virusinfected 

larvae in 1964 in both of the areas that had been sprayed in 1963, but not in an 

unsprayed area. The virus also occurred at considerable distances from the sprayed 

areas, and Stairs believed that he had been successful in artificially initiating an epizootic.

314 W. O. H. Ives 


Bacillus tburingJensis 

Berliner 

Biological control attempts against the forest tent caterpillar during the past decade have 

involved the bacterium B. Ihuringiensis, the microsporidium N. disslriae, and an NPV. 

Because some formulations of B. Ihuringiensis have been registered for control of the 

forest tent caterpillar, and have therefore been used commercially it is difficult to provide 

an accurate record of either the amounts used or the effectiveness of the applications. The 

following is a summary of the more readily available information. 

The most comprehensive trials of B.I. against the forest tent caterpillar were conducted 

in Ontario in 1975,1977, and 1978 (G.M. Howse 1981 personal communication). In 1975, 

small-scale aerial spray trials with Thuricide® 168 (Sandoz Inc.) on trembling aspen 

stands in southern Ontario showed that the preparation had promise. One application at a 

rate of 10 x 10 9 1. U .lha reduced larval populations by 71 %; two applications at the same 

rate caused 92% mortality. The treatment was applied too late in the season to save any 

foliage. In 1977, evaluations were made of the effectiveness of two applications of 

Thuricide® 16B (10 x 10' I. U .lha at each application) in controlling forest tent caterpillar 

populations over a total of about 850 ha of trembling aspen and sugar maple, Acer 

saccharum Marsh., in three provincial parks in southern Ontario. Resultant population 

reduction on trembling aspen ranged from 30 to 79%, and defoliation in the treated areas 

ranged from 5 to 46% compared to 82 to 100% in untreated areas. Similar results were 

obtained for infestations on sugar maple, where population reductions due to treatment 

ranged from 38 to 69%, and defoliation in sprayed areas was about 15%, compared to 

100% in an unsprayed area. A further 940 ha were sprayed with Thuricide® 16B in 1977, 

but no assessment of its effectiveness was made. In 1978, either one or two applications of 

Thuricide® 168, mostly at the rate of7.5 x 10' I. U .lha for each application, were made on 

a total of about 515 ha of forest tent caterpillar infestations on trembling aspen, sugar 

maple, and red oak, Quercus rubra L., in southern Ontario. Insect populations were 

lower than in 1977, so the comparison of defoliation was not a practical way of showing 

effectiveness. However, population reduction due to treatment ranged from 79 to 100% 

on trembling aspen, from 71 to 100% on red oak, and was 100% in both treated 

infestations on sugar maple. In addition, 250 ha of sugar maple were sprayed with one 

application of Dipel® WP (Abbott Ltd.) (6.0 x 10' I.U.lha) in late May. Population 

reduction due to treatments was 98%. 

Data for western Canada are more fragmentary. In Alberta, a hydraulic sprayer was 

used in 1974 to treat two 0.2-ha plots of trembling aspen with Dipel® WP (9 x 10' 

I.U.lha) and a further two 0.2-ha plots with Thuricide® HPC (Sandoz Inc.) (5 x ur 

I.U.lha) (Drouin & Kusch 1975). Control was estimated at 75 and 70% respectively. In 

1976, two O.4-ha plots of trembling aspen were treated with Dipel® WP (9 x 10' 

I.U./ha). Control was estimated at 75 and 85%, based on the reduction in amount of 

defoliation (Drouin & Kusch 1977). In addition, several applications were made by 

private operators under contract to various agencies. 

In Saskatchewan, Dipel® WP was used to control forest tent caterpillar outbreaks in 

Prince Albert and Saskatoon. In Prince Albert, about 325 ha within the city limits were 

treated in 1980 when the larvae were in the third and fourth instars, with good results (P. 

Kabatoff 1981 personal communication). The chemical insecticide malathion had been 

used earlier, when the larvae were in the first and second instars, because it was felt that 

there was insufficient foliage at that time for Dipel® WP to be effective. In Saskatoon, 

about 800 ha of city parks and about 40 000 avenue trees were treated with Dipel® WP in 

1980 (D. Scott 1981 personal communication). About 340 kg of Dipel® WP were used, 

and results were generally satisfactory.

Malam.mma disstria Hiibner, 319 

Stairs, O.R. (1964) Dissemination of nuclear polyhedrosis virus agaimt the forest tent caterpi11ar, MoJorosomo disstrio (Hiibner) (Lepidoptera: 

Lasiocampidae). Canadian EntomologisI96,1017-1020. 

Stairs, O.R. (196S) Artificial initiation of virus epizootics in forest tent caterpillar populations. Canadian Entomologist 97,10S9-1062. 

Stairs, O.R. (1966) Transmission of virus in tent caterpillar populations. Canadian Entomologist 98,1100-1104. 

Stairs, O.R. (1972) Pathogenic microorganisms in the regulation of forest insect populations. AnnUQI Review of Entomology 17,3SS-372. 

Sweetman, H. L. (1940) The value of the hand control for the tent caterpillars, Malacosoma americana Fabr. and Malacosoma di.s.stria Hbn. 

(Lepidoptera: Lasiocampidae). Canadian Enlomologis/72.24S-250. 

Tothill. J.D. (1918) The meaning of natural contro\. Proceedings of the Entomological Society 4,10-14. 

Wilson. G.O. (1977) Effects of the microsporidia Nosema disstriae and Pleistophora schubergi on the survival of the forest tent caterpillar, 

Malacosoma difstria (Lepidoptera: Lasiocampidae). Canadian Entomologisl 109,1021-1022. 

Wilson, 0.0. (1979) Effects of Nosema disstriae (Microsporidia) on the forest tent caterpillar, Malacosomo disstrio (Lepidoptera: Lasiocampidae). 

Proceedings of Ihe Entomological Socitty of Ontario 110.97-99. 

Wilson. G.O.; Kaupp. W.J. (1977) Application of Nosema disstriat and Pleistophora schubergi (Microsporida) against the forest tent 

caterpillar in Ontario. 1977. Canadian Forestry Service, Sault 511'. Marie, Information Report FPM-X-4. 

Willer. I.A.: Kulman. H.M. (1972) A rcview of the parasites and predators of tent caterpillars (Malacosoma spp.) in North America. 

University of Minnesola Agricultural Experiment Stalion Technical Bulletin 289. 

Witter, J .A.; Kulman, H .M.; Hodson, A.C. (1972) Life tables for the forest tent caterpillar. Annals of the EntomologiCilI Society of America 

6S.25-3t. 

Willer, J .A.; Mattson, W.J .• Kulman. H .M. (197S) Numerical analysis of a forest tent caterpillar (Lepidoptera: Lasiocampidae) outbreak in 

northern Minnesota. Canadian Entomologist 107,837-854.

Blank Page 

320

Pest Status 

Background 

Field Trial 


Neodiprion abietis (Harris), Balsam Fir 

Sawfly (Hymenoptera: Diprionidae) 

J.e. CUNNINGHAM 

The balsam fir sawfly, Neodiprion abietis (Harr.) complex, occurs from New England to 

the Great Lakes and south to Missouri in the USA, from coast to coast in southern 

Canada (Baker 1972), and also in Newfoundland. In Canada, periodic outbreaks, usually of 

short duration, are common on balsam fir, Abies balsamea (L.) Mill., and spruce, Picea 

spp., from Saskatchewan eastwards. Tree mortality is rare and is usually reported in 

conjunction with other pests such as spruce budworm, Choristoneura fumiferana 

(Clem.), eastern blackheaded budworm, Ac/eris variana (Fern.), and balsam woolly 

adelgid, Adelges piceae (Ratz.) (Rose & Lindquist 1977). 

Balsam fir sawfly overwinters as eggs in diapause and spring hatching is fairly 

uniform. Larvae are gregarious and feed on old needles, but eat only parts ofthem, thus 

damaging many more needles than they consume. In the later instars, the colonies 

disperse and the larvae become solitary. There are five larval instars, but males do not 

feed during their last instar (D.R. Wallace & c.R. Sullivan 1980 personal communication). 

In 1980, traces of defoliation caused by this insect were found in western and central 

Newfoundland and light to moderate defoliation was observed in the northern, eastern, 

and Algonquin regions of Ontario (Sterner & Davidson 1981). 

A nuclear polyhedrosis virus (NPV) was first reported in balsam fir sawfly by Steinhaus 

(1949). This disease has subsequently been reported in balsam fir sawfly populations in 

several Canadian provinces including Saskatchewan (Brown 1951), Alberta and Manitoba 

(Cumming 1954), and Quebec (Martineau & Lavallee 1971). 

Ground spray trials on single trees were conducted in Ontario in 1972 to test NPV on 

balsam fir sawfly (Olofsson 1973). Aqueous suspensions of lOT, 1()6, lOS, 10', and to) 

polyhedral inclusion bodies (PIB) per millilitre plus 2.5% IMC 90-001 (International 

Minerals Corporation) UV protectant were tested at two application times, 8 days 

apart, on first- and third-instar larvae. A backpack mist blower was used and a 360-ml 

suspension was applied to each 2.5-m tall balsam fir tree, five trees being treated with 

each dosage on each date. There were 5-10 sawfly colonies per tree. 

The percentage of infected larvae following the applications is shown in Table 83. 

Infection is directly related to mortality with this NPV.

322 J. C. Cunningham 

Table 83 



Infection and defoliation following application of NPV on first- and third-instar balsam fir 

sawfly, Neodiprion abietis (Harr.), larvae in a ground spray trial (from Olofsson 1973) 

Percentage virus infection Defoliation· 

Dosage I instar III instar I instar III instar 

PIBlml treated treated treated treated 

10' Q 

100 100 1 3 

10' 

HY 

100 

96 

88 

60 

2 

3 

4 

5 

10' 

10} 

72 

60 

24 

4 

4 

4 

5 

5 

Check 0 0 5 5 

• Defoliation was rated on a scale of 1 to 5 where 1 was very light and 5 severe. 

The limited ground spray trials conducted in 1972 demonstrated that this NPV is a 

potentially useful biological control agent for balsam fir sawfly. However, as this 

species feeds mainly near the tops and mid-crowns of mature trees, an aerial spray 

application would be required for complete coverage. Further testing has not been 

conducted and aerial spray trials are required before definitive conclusions can be made 

and recommendations formulated. 

Olofsson (1973) showed that timing of the application is critical and he recommended 

applying the NPVon late first-instar larvae. By the time they develop to the third instar, 

feeding damage is severe and the larvae require a much higher dosage of virus. For 

ground spray applications, Olofsson recommended a dosage of 1W PIB/ml and he 

calculated that one fully grown, NPV-infected larva produced 1 I of spray of this 

concentration. However, this dosage would have to be increased for an aerial application. If 

the economic importance of balsam fir sawfly justifies the development of non-chemical 

pesticide control strategies, this NPV merits further research. 

Baker, W.J. (1972) Eastern forest insects. US Depanment of Agriculture Miscellaneous Publication 1175. US Government Printing OCfice, 

642 pp. 

Brown, C.E. (1951) Forest insect survey nOles. Canadian Depanment of Agriculture Bi·monthly Progress Report 7(2).2. 

Cumming. M. (1954) Diseases of insects. Canadian Depanment of Agriculture Bi·monthly Progress Report 10(3),3. 

Martineau, R.; Lavallc!e, A. (1971) Quc!bec region. Canadian Forestry Service, Annual Report of the Forest Insect and Disease Survey, 

pp.34-53. 

OloCsson, E. (1973) Evaluation of a nuclear polyhedrosis virus as an agent for the control of balsam fir sawfly, Neodiprion abietis (Harr.). 

Canadian Forestry Service, Sault Ste. Marie, Information ReportIP·X·2, 30 pp. 

Rose, A.H.; Lindquist, O.H. (19n) Insects of eastern spruces, fir and hemlock. Canadian Forestry Service, Forestry TechniCDI Report 

23, 159 pp. 

Steinhaus, E.A. (1949) Principles of insect pathology. New York; McGraw· Hill, 757 pp. 

Sterner, T.E.; Davidson, A.G. (comp.) (1981) Forest insect and disease conditions in Canada 1980. Canadian Forestry Service, Forest 

Insect and Disease Survey, 43 pp.

Pest Status 

Background 

Field Trials 

Chapter 57 

Neodiprion lecontei (Fitch), Redheaded 

Pine Sawfly (Hymenoptera: Diprionidae) 

J.C. CUNNINGHAM and P. DE GROOT 

The redheaded pine sawfly, Neodiprion lecontei (Fitch), is a serious defoliator of young 

hard pine, Pinus spp., plantations in Ontario, Quebec, and, to a lesser extent, New 

Brunswick. It is the most serious pest of red pine, Pinus resinosa Ait., in these regions 

due to the increase in the number of plantations over the last 20 years. Red pine is the 

principal species attacked, but jack pine, P. banbiana Lamb., and Scots pine, P. 

syfveslris L., are also attacked. Damage can be severe, especially when trees are less 

than 2-3 years old; one sawfly colony can totally defoliate and kill several trees 

(Benjamin 1955). Heavy defoliation results in reduced height growth, branch mortality, 

and defonnity if the leader is killed (Schaffner 1951, Benjamin 1955, MacAloney & 

Wilson 1964). 

This sawfly has only one generation per year in Canada, whereas in the southern parts 

of its range it may have as many as five (Benjamin 1955). In Canada, adult sawflies 

emerge, from mid-June to early July, from overwintered cocoons in the duff layer of the 

soil. The number of eggs laid by females varies considerably, but it is not unusual to have 

a complement of 80-140 eggs. Egg development varies with the ambient temperature 

and. as temperatures increase, the incubation period shortens. An incubation period of 

3-4 weeks is typical in southern Ontario and Quebec. The sawfly larvae are gregarious 

and feed on foliage of all ages, although they show a preference for the previous year's 

foliage. Larvae are fully grown in 25-30 days from time of hatching, and are about 25 

mm long. Populations of sawflies are not evenly distributed throughout plantations but 

occur in "hot spots", often along a hardwood perimeter or on knolls. 

In the past, most attempts at control have been by applying chemical insecticides from 

the ground. In many cases, enough larvae escaped treatment to produce a population the 

following year large enough to require further treatment. This "insecticide treadmill" 

requires considerable man-power and may have to be continued for several years until 

the trees have grown enough to be out of danger or until the insect population has been 

regulated by natural control factors such as egg parasitoids (Benjamin 1955, Griffiths 

1956, Rauf el af. 1979). 

In 1950, a nuclear polyhedrosis virus (NPV) disease of the redheaded pine sawfly was 

found in Ontario (Bird 1961). In a series of laboratory and ground spray trials. Bird 

demonstrated that this virus was highly infectious to sawfly larvae, that virus can be 

introduced into the population and initiate an epizootic, and that it can be transmitted 

from one generation to the next (Bird 1961, 1971). 

Virus for field trials is produced in vivo. Because there are no known synthetic diets for 

sawflies reared in the laboratory, it is necessary to use fresh foliage, which is labour 

intensive and expensive. Hence to produce virus, a plantation with a high insect 

population, which has already been severely damaged in previous years, is selected. 

When larvae reach the fourth instar, trees are sprayed with a mist blower using a 

323

324 J. C Cunningham and P. Dc Groot 

Table 84 

suspension of 10" polyhedral inclusion bodies (PIS) per millilitre at an application rate of 

about 20 Ilha. Seven or 8 days after spraying, the first diseased and dead larvae are 

found, and colonies of moribund larvae are clipped from the trees and taken to the 

laboratory where they are picked off the foliage and frozen. Collections are made every 

day until all colonies have died or pupated, which can take up to 30 days. The frozen 

larvae are lyophilized, ground to a fine powder, and the number of PISs per gramme 

measured. This material is stored at 2°C until required and is then suspended in water. 

Recent experiments have shown that suspension in an emulsifiable oil may be preferable, 

but such preparations have not yet been field tested. 

Spraying of an entomopathogen must be shown to be efficacious and safe before it is 

approved for operational use by the Canadian federal government. Extensive safety 

testing of redheaded pine sawfly NPV has been undertaken at Ontario Veterinary 

College, University of Guelph, where this virus was found to present no hazard to 

mammals (Forsberg, ValIi & Dwyer unpublished), birds (Valli & Oaxton, unpublished), 

and fish and Daphnia pulex (Hicks et al. 1981). The impact of the virus on non-target 

organisms was monitored in conjunction with the 1977 aerial spray trials in Ontario. In 

addition, beehives were placed in the treated plantations. No deleterious effects were 

noted (Kingsbury et al. 1978). 

A petition for the registration of this virus will be submitted to Canadian authorities in 

March 1981 for approval. If accepted this will be the first \irus registered for regulation 

of insect populations in Canada. 

Field trials during the review period started with a smalI ground spray trial with NPV, 

conducted in Quebec in 1970. In 1976, an intensive research programme was initiated to 

establish an operational method of applying this virus to control redheaded pine sawfly. 

Aerial spray trials were conducted every year in Ontario from 1976 to 1980, and in 

Quebec in 1978 and 1979. Ground applications were also made during this period; the 

number of plantations and areas treated are summarized in Table 84. Details of these 

trials are given below. 

Summary of field trials conducted with NPV of redheaded pine sawfly, Neodiprion 

lecontei (Fitch), between 1976 and 1980 

Ontario 

No. of No. of 

Area planta- plantatreated 

tions tions 

Year (ha) from air from 

ground 

1976 43 3 

1977 52 3 

1978 26 2 

1979 34 4 

1980 540 8 88 

Ground spray trials in Quebec in 1970 

Area 

treated 

(ha) 

700 

330 

21 

Quebec 

No. of 

plantations 

from air 

36 

42 

No. of 

plantations 

from 

ground 

Purified NPV at a concentration of 1.3 x 10" PIBII and lyophilized NPV-infected larvae 

(with an undetermined PIB content) at 30, 60, 130, and 260 mgll were sprayed on thirdinstar 

larvae using a backpack mist blower. First mortality was observed 14 days after 

spraying and by 48 days 100% mortality was observed in the area treated with the 

lyophilized NPV-infected larval material, and 94.9 and 97.4% mortality in two areas 

treated with the purified virus (Anon. 1970). 

1 

1 

12

Aerial spray trials in Ontario in 1976 

Neodiprioll lecollId (Fitch). 325 

Three red pine plantations with a total area of 43.2 ha were sprayed with three different 

dosages of virus, 1.25 x Hr, 3.75 x 10", and 6.75 x to' PIBlha, at 9.4 Uha, using a fixedwing 

aircraft with boom and nozzle equipment, when most larvae were in the second 

instar. The formulation contained 60 gil !MC 9Q.OO1 (International Minerals Corporation) 

sunlight protectant. Pre-spray colony counts for the three plots were 59, 138, and 173 

colonies/50 trees, respectively, and 119 colonies/50 trees in an untreated check area. 

Seventeen days after spraying, the percentage of larvae infected with virus in the treated 

plots was 92, 96, and 98%, respectively, and 4 % in the check area. When the last colony 

count was made at 22 days, 7,46, and 1 colony/50 trees were recorded in the treated plots 

and 115/50 trees in the check plot. There was a good level of foliage protection in the 

treated areas (Kaupp & Cunningham 1977). 


Two red pine and one jack pine plantation with a combined area of 48 ha were treated at a 

dosage of 5.5 x 10" PlBlha at 9.4 Uha. A fixed-wing aircraft with boom and nozzle 

equipment was used to spray second- and third-instar larvae on red pine, and a fixedwing 

aircraft with Micronair (Micronair4'i (Aerial) Ltd. U. K.) equipment to spray fourthinstar 

larvae on jack pine. The aqueous formulation contained 25% v/v molasses and 60 

gil IMC 90-001. 

In the jack pine plantation, 5 days after spraying the number of colonies/100 trees fell 

from 132 to 47 while the population in the untreated check plot remained constant. This 

rapid population decline prompted an investigation of the tank mix and it was found to 

contain 522JLglml of the chemical insecticide phosphamidon (Sundaram 1977 personal 

communication). By 26 days after spraying, the population density had fallen to 2 

colonies/100 trees. 

In the two red pine plantations, pre-spray counts of colonies/100 trees were 163 and 

54, and 217 in a check plot. Counts 26 days after spraying were 7 and 0 in the treated plots 

and 200 in the check area. The NPV also spread to an untreated plantation adjacent to 

these plantations and destroyed the redheaded pine sawfly population, but not before 

severe defoliation had occurred. Defoliation was light in all the treated areas, although it 

would have been heavy in the jack pine plantation without the unintentional contamination 

by phosphamidon in the aircraft spray tank (Kaupp et al. 1978). 


Two red pine plantations with a total area of26 ha were treated when larvae were mainly 

in the second instar. The spray was applied with a fixed-wing aircraft equipped with a 

Micronair4'i spray delivery system. The dosage was 5 x 10" PIBlha in 9.4 Uha aqueous 

formulation containing 12.5% v/v molasses and 32 gil Shade® (Sandoz Inc.) (formerly 

IMC 90-001). Over 90% of sawfly colonies were diseased or dead 16 days after spraying 

and by 23 days no healthy colonies remained. Defoliation was lighter in treated than in 

check areas (de Groot et al. 1979). 

Aerial and ground spray trials in Quebec in 1978 

A large operation was undertaken and 37 red pine plantations covering 700 ha were 

treated. Two types of aerial spray equipment were used, a fixed-wing aircraft equipped 

with Micronair® and a helicopter equipped with Beecomist (Beeco Products Co., USA). 

In addition, one plantation was treated from the ground using backpack mist blowers. 

Dosage was 5 x 10' PIB/ha for aerial applications on second-instar larvae and 10 10 PIBlha

326 J. C.Cunningham and P. Dc Groot 

on third- and fourth-instar larvae for the ground application. Volume applied in all 

treatments was 9.4 l/ha. Some NPV was formulated in 25% v/v molasses and 30 gil 

Shade® and some was applied in water alone. Two application strategies were used, with 

some plantations getting total coverage and others partial coverage using widely spaced 

spray swaths. By 29 days after spraying, plantations sprayed by fixed-wing aircraft had 

an average mortality of 97.7% with total coverage and 72.5% with partial coverage. 

Plantations treated by helicopter had an average mortality of 99.4% with total coverage 

and 90.8% with partial coverage. The plantation treated with mist blowers had 98.4% 

mortality and untreated check plots had 29.5% mortality. The saving of foliage was 

satisfactory in all treatments except for the ground spray application where the application 

volume of 9.4 I/ha was too low and insect development was too far advanced (Desaulniers & 

Cunningham unpublished). 


Red pine plantations with a total area of 33.6 ha were treated at a dosage of 5 x 10" PIBlha 

at 9.4 llha when larvae were in the first and second instars. A fixed-wing aircraft with 

Micronair® equipment was used. A comparic:on was made between a suspension of 

lyophilized, NPV-infected larvae with Rhodamine B dye as a tracer and the same virus 

suspension formulated in 25% v/v molasses and 60 g.1 Shade®. There was no difference 

in the efficacy of the two treatments and it was concluded that it is unnecessary to add 

adjuvants to this virus. Both treatments gave 100% mortality, none of the larvae 

developed past the third instar and defoliation was minimal (Cunningham & de Groot 

unpublished). 

Aerial and ground spray trials in Quebec in 1979 

Forty-three red pine plantations with a total area of 330 ha were treated; 323 ha were 

sprayed from the air and 7 ha from the ground. Two helicopters were used for the aerial 

spray, one equipped with Beecomist411 units and one with boom and nozzle. From the air, 

application rate was 9.4 l/ha and dosage was 5 x 10" PIBlha. Backpack mist blowers 

were used for the ground spray application; volume sprayed was 18.8 l/ha and dosage 

was 10 10 PIBlha. Spraying was carried out when 80-90% of the eggs were hatched. The 

pre-spray population densities were 63 colonies/50 trees in the area treated with Beecomist®, 

110/50 trees in the area treated with boom and nozzle, 110/50 trees in the area treated 

with mist blowers and 22150 trees in the check area. At 35 days after spraying, mortality 

in these areas was 87, 98, 94 and 7%, respectively. Defoliation in the treated plantations 

was practically nil and only light defoliation was recorded in the check plots because of 

the low sawfly population density (Bordeleau unpublished). 

Aerial and ground spray trials in Ontario in 1980 

Red pine plantations with a total area of 539.8 ha were treated. Experimental aerial spray 

trials were conducted on four plantations with a total area of 33 ha. A fixed-wing aircraft 

with Micronair® equipment was used and dosage on all plantations was 5 x 1()O PIBlha. 

Highly purified virus at 9.4 l/ha emitted volume was compared to lyophilized, NPVinfected 

larval material at the same volume. A comparison was also made with reduced 

emitted volumes of lyophilized larval material at 4.7 and 2.4 l/ha. Applications were 

made on first- and second-instar larvae. There was no difference in effectiveness 

between the crude and purified material or between the three emitted volumes. By 31 

days after spraying, 100% mortality was achieved in all four treatments.

Table 85 

Neodipriotl {ecomei (Fitch). 327 

Semi-operational aerial spray trials were conducted on a further four plantations with 

a total area of70 ha. Lyophilized NPV-infected larval material was used at 5 x 10' PIBlha 

and the emitted volume was 9.4l1ha. Larvae were mainly in the first and second instars, 

with a few unhatched egg clusters present, at the time of application. When the final 

survey was made 28 days after spraying, mortality ranged from 82 to 99%. 

Ground spray trials were conducted by Ontario Ministry of Natural Resources staff in 

five districts, and 88 plantations with a total area of 436.8 ha were treated entirely or 

partially over a 47-day period. Insect development ranged from first and second instar in 

the early treatments to fourth and fifth instar in the later ones (Cunningham & de Groot 

unpublished). 

Ground spray trials in Quebec in 1980 

A mist blower was used to treat 12 red pine plantations when larvae were in the first and 

second instars with 90% of the eggs hatched. The dosage was 5 x 10' PIBlha and two 

application volumes were tested, 18.7 and 93.6I1ha. Better results were obtained with 

the lower volume and 100% mortality was achieved 20 days after spraying. Thirty-five 

days after spraying, 97% mortality was reached with the higher volume. Defoliation in 

the treated plantations was negligible because of comparatively low larval population 

densities (an average of 21 colonieS/25 trees on the high volume application and 8 

colonies/l00 trees on the low volume application) combined with the effectiveness of the 

treatments (Bordeleau unpublished). 

Surveys of plantations aerially sprayed in Ontario in years following the year of application 

In order to assess the durability of the virus treatments, surveys have been conducted 

annually on all the plantations aerially sprayed experimentally in Ontario, which by 1980 

numbered 15 (de Groot et al. 1979, Cunningham & de Groot unpublished). A summary 

of these surveys is shown in Table 85. Although not all these plantations remained 

Survey of plantations treated with NPV of redheaded pine sawfly, Neodiprion leeontei 

(Fitch), in years following the year of application 

Number of colonieS/l00 trees 

Pre-spray 

Year Plot estimate 1977 1978 1979 1980 1981 

1976 1 118 0 0 0 0 0 

2 176 0 0 0 0 0.75 

3 346 0 0 0 0 0 

1977 1 163 0 0 0 0.75 

2 81 0 0 1.75 0 

3 132 0 0 0 0.5 

1978 255 0.5 0 0 

2 174 2.5 1.25 2.0 

1979 1 124 0.25 0 

2 77 0 0.25 

3 5 0 0 

1980 1 52 0 

2 173 0 

3 225 0 

4 25 0

Blank Page 

330

Pest Status 

Background 

Chapter 58 

Neodiprion sertifer (Geoffroy), European 

Pine Sawfly (Hymenoptera: Diprionidae) 

K.J. GRIFFITHS, J.e. CUNNINGHAM and I.S. OTVOS 

The European pine sawfly, Neodiprion serlifer (Geoffr.), was first recorded in North 

America in New Jersey in 1925 (Schaffner 1939) and in Canada near Windsor, Ontario, 

in 1939 (Raizenne 1957). In Ontario it dispersed steadily until, by 1968, it was found 

throughout Ontario south and west of a line from Victoria Harbour to Belleville (Fig. 17). 

Transport of infested nursery stock resulted in isolated populations of N. serlifer well 

beyond this area - on Manitoulin Island, first recorded in 1966 (Sippell el al. 1966) and 

in Sault Ste. Marie and North Bay, first recorded in 1968 (Sippell el al. 1969). 

In the decade since 1968 the area occupied by N. serlifer has continued to expand, 

moving slightly to the north near Georgian Bay, but mainly to the east along the St. 

Lawrence River, until by 1978 the continuous distribution extended almost to the 

Quebec border along the St. Lawrence and as far north as Ottawa (Fig. 17) (Lindquist & 

Miller 1979). 

The isolated infestations on Manitoulin Island and at Sault Ste. Marie continued 

throughout the period 1968-78, but no N. senifer have been found in North Bay since 

1969. N. sertifer larvae were collected for the first time at several locations in Ottawa in 

1969 and by 1973 they were also found in the surrounding areas. They apparently 

remained there as Ottawa is now in an area of continuous distribution. An isolated light 

infestation was found north of Thessalon, Ontario, in 1974. The area was treated from 

the ground with nuclear polyhedrosis virus (NPV) in 1975 and 1976, and there have been 

no further recoveries of N. serliler. 

In 1970 there were several heavy infestations in southwestern Ontario, where the 

insect has been present the longest. Infestations causing moderate to severe defoliation 

continued in this area until 1972. A decrease in numbers was noted in 1973, and this 

decrease continued until by 1977 generally low populations were recorded throughout 

the area. 

In 1974 N. sertiler was recorded for the first time in Canada beyond the borders of 

Ontario. A single colony was recovered from Scots pine, Pinus sylvestris L., in Charlesbourg, 

Quebec, a few kilometres northeast of Quebec City (Martineau & Lavallee 1975), and a 

few colonies were recovered from Scots pine at Windsor Lake near St. John's, Newfoundland 

(Clark & Singh 1975). No further recoveries were made in Quebec, but N. serlifer 

has persisted and spread in Newfoundland. It was reported on ornamental pines Pinus 

spp. and in the few pine plantations within a radius of 15 km of St. lohn's by Otvos & 

Griffiths (1979). It was established by rearing some larvae that no parasitoids were 

present. The first discovery of N. serlifer in Nova Scotia was made in 1980, when it was 

obtained from ornamental pines at Little Harbour, Pictou County, and Truro, Colchester 

County (Magasi 1981). 

Studies of the population dynamics of N. sertifer carried out at the Great Lakes Forest 

Research Centre, Sault Ste. Marie, Ontario, had started in 1960 and were continued until 

1972. An overview of this work is given in Lyons el al. (1971) and Lyons (1977a). In 

brief, outbreaks in southern Ontario typically occur in young plantations where few 

natural control agents are present. Density peaks in 4-6 years, then declines to a low 

331

Neot!i/Jrio" satifer (Geoffroy), 333 

level and does not generally increase to outbreak levels again. Eventual decline of an 

outbreak was related to starvation of late-feeding larvae, parasitism of pre-spinning 

larvae by Exenlerus spp. and predation and parasitism of cocooned larvae. When 

outbreaks occur in stands of larger trees, they last longer and are associated with varying 

amounts of prolonged diapause (Lyons 1977a). 

Until 1958 the recorded insect parasitoid complex of N. sertifer consisted of 14 native 

primary parasitoids, 3 native hyperparasitoids, and 4 established European parasitoids. 

In the following decade another 14 indigenous parasitoids were recovered; recovery was 

made of Drino bolremica Mesn., another of the European species introduced during the 

1930s (McGugan & CoppeI1962); and one new exotic species, Lophyroplectus lutealor 

Thunb., was established (Griffiths & Lyons 1968). In the period under review only two 

species have been added to the parasitoid list. One of these, Exenterus affinis Roh., a 

native ichneumonid, was recovered from N. sertifer as early as 1964, but was not 

separated from the other species of Exenlerus attacking this host until 1977. It is 

recovered infrequently (Lyons 1977b). The second species is Exenterus abruptorius 

(Thunb.), a European parasitoid of N. sertifer, introduced in the 1930s but not recovered 

since the initial release. Lyons (1977b) recovered two specimens in a cocoon collection 

made in Dufferin County in May, 1972. Since then five more E. abruptorius from four 

other localities have been identified after examination of over 6 000 pinned specimens of 

Exenterus obtained from N. ser/ifer collections throughout southwestern Ontario since 

1952. Further discussion of this species is given in the following section. Another 

recovery of the rare exotic species D. bohemiea was recorded in 1972 from a collection 

made at Gore Bay on Manitoulin Island. 

Dispersal of L. IUleator from the releases made in 1962 and 1964 (Griffiths & Lyons 

1968) has been followed closely. By 1969,7 years afterthe 1962 release in Grey County, 

recoveries had been made up to 19.3 km east of the release point. However, by 1971, 7 

years after the 1964 Norfolk County release, the greatest dispersal was only 3.4 km 

(Griffiths 1973). Rose (1976) reported that by 1975 L.luteatorhad spread throughout the 

whole of the N. sertifer distribution area east and north of the Grey County release 

point. It is possible, however, that the northern dispersal into the Bruce Peninsula was 

the result of a release made near Hepworth, Ontario, in 1970 (Griffiths & Lyons 1980). 

Rose noted that L. luteator had spread 305 km in an easterly direction in the 13 years 

since its release. There had been little or no movement south or west from the 1962 

release point and little further dispersal from the 1964 release in Norfolk County. 

Investigations on the biology of the principal parasitoids of N. sertifer and the 

interactions between them have continued during the last decade. It was found that 

females of Pleolophus basizonus (Grav.), which oviposit in cocooned pre-pupae, show 

a strong rejection of hosts containing larvae or pupae of its own species, although they 

do not discriminate between unattacked hosts and those containing eggs of its own 

species (Griffiths 1972). Also, it was found that P. basizonus females show a strong 

avoidance of cocoons in which there are eggs, larvae, or pre-pupae of the larval 

parasitoid L. lutealor (Griffiths 1976) and avoid cocoons containing developing E. 

abruptorius and Dahlbominus fuscipennis (Zelt.). On the other hand, D. fuscipennis 

does not avoid hosts containing P. basizonus or E. abruptorius and is usually successful 

in competition with them. Exenterus abruptorius, E. nigrifrons (formerly E. canadensis 

Prov.) and E. amielorius (Panz.) all superparasitize and none avoids attacking hosts 

containing eggs of either of the other two species. Neither E. abruptorius nor E. 

nigrifrons has an advantage over the other when competing on the host, but E. amictorius 

is usually successful when competing with the other species. This information on 

Exenterus spp .• plus data on the three species obtained in insectary experiments over 6 

years, was incorporated into a simulation model to investigate the interactions of the 

three parasitoids and their host. More recently a more sophisticated simulation model of 

N. sertifer and the living and non-living factors that influence it has been developed. It

Table 86 

Open releases and recoveries 

Neodiprion sertiler (Geoffr.) 

Neodipriol/ satirer (Geoffroy). 335 

of parasitoids against the European pine sawfly, 

Number Year of 

Species and province Year Origin released recovery 

Dipriocampe diprioni Ferriere 

Ontario 1972 Austria 78 

1974 Germany 183 1975 

1978 Italy 

{ 

33 

Italy 


and Austria 

272 

Exenterus abruptorius Thnb. 


1973 Austria 1021 


1979 Italy 1035 

1980 Finland 235 


Newfoundland 1980 Finland 75 

Lophyroplectus lWeator (Thnb.) 

Ontario 1970 Ontario 80 1970 

1972 Ontario 2263 1972 

Newfoundland 1978 Ontario 306 

1979 Ontario 38 

1980 Ontario 467 



Pleolophus basizonus (Grav.) 

Newfoundland 1977 Ontario 1007 1977 

1978 Ontario 2104 

1979 Ontario 1007 


infested with N. sertiler near Williamsford, Ontario. Eggs of N. sertiler were collected 

in the release area and examined in the spring of 1962 and spring egg collections were 

made annually until 1968 in a population study plot 0.8 km away. No recoveries of the 

parasitoid were obtained. 

Because the egg stage of N. seniler in Canada was essentially an untapped resource 

for biological control. it was decided that more study on European egg parasitoids was 

justified in spite of earlier failures. The work was carried out by CIBC European 

Laboratory scientists. As a result of this work (Pschorn-Walcher & Eichhorn 1971, 

1973) it was found that D. diprioni had a univoltine strain adapted to N. seniler and a 

morphologically similar bivoltine strain which occurs rarely in N. sertiler. Earlier 

failures may have been the result of using the wrong strain and further work on 

introduction. using the univoltine strain, was justified. This work started in 1971 with a 

preliminary test which indicated that D. diprioni had attacked Canadian N. sertiler and 

had overwintered successfully outdoors near Chatsworth, Ontario. 

A release of 32 male and 46 female adults was made in Dufferin County Forest, 5 

September 1972 (Table 86). but this area was sprayed inadvertently with a chemical

336 K. J. Griffiths. J. C. Cunningham and I. S. Dtvos 

Table 87 

Exenterus abruptDrius 

(Thunb.) 

(Hymenoptera: 


insecticide in the summer of 1973 and the N. sertiter population there was destroyed. 

Another release was made, in Grey Country, 6 September 1974, of 29 males and 154 

females (Table 86). There was 1.3% parasitism in 87 egg clusters collected at the release 

site in the spring of 1975. Parasitoids were obtained, but in decreasing numbers in both 

1976 and 1977; none was obtained in the following 3 years (Table 87). 

Releases of D. diprioni have been made at two other localities, one in Simcoe County, 

consisting of 11 male and 22 female adults, on 16 September 1978, and the other, of 90 

male and 182 female adults, in Peterborough County, 28 August and 30 September 1979 

(Table 86). There have been no recoveries from either release (Table 87). 

Laboratory rearings of D. diprioni were started in 1974 using adults obtained from 

Switzerland and Germany. Work continued until 1977 using the offspring of the original 

stock augmented with adults from field collections of N. sertifer eggs and further 

shipments from Europe (Table 88) but it was not possible to maintain stock beyond the 

third generation. 

Recovery of Dipriocampe diprioni Ferriere 

Number of Number of 

clusters Number of egg clusters Number of Sex ratio 

Year collected eggs examined with attack eggs attacked (% females) 

Grey County, Ontario 

1975 87 6052 7 80 (1.3%) 53 

1976 57 3094 2 34 (1.1%) 50 

1977 86 3819 1 7 (0.2%) 71 

1978 6 430 0 0 

1979 144 ? 0 0 

1980 28 ? 0 0 

Simcoe County, Ontario 

1979 52 ? 0 0 

1980 48 ? 0 0 

Peterborough County, Ontario 

1980 47 ? 0 0 

Since the recovery of a small number of adults of this species in southwestern Ontario in 

the spring of 1972, noted earlier, there has been renewed interest in trying to establish it 

at higher densities and in determining why it has remained so rare since its introduction 

in the period from 1936 to 1949 (McGugan & Coppel 1962). A number of well-timed 

releases have been made in Ontario (Table 86) but because N. sertiter popUlations are 

generally low, releases could only be made in areas of low host density. At these 

population levels large cocoon collections would have been necessary to determine if 

establishment had occurred, and the cost made sampling unpractical. 

A release of 43 male and 32 female adults obtained from Finland was made in SI. 

John's, Newfoundland, in July 1980 (Table 86). 

Studies on the biology of this species were started with insectary experiments in 1969 

and 1970 and continued with laboratory experiments from 1978 to 1980, using E. 

abruptorius adults from various European locations (Table 88). Although analysis of 

results is not complete it is already clear that no single physical factor has been limiting 

the numbers of this species in Ontario.

PfeoIopbus ba9zonus 

(Grav.) 

(Hymenoptera: 


Pathogens 

Table 88 

Neotiipriol/ .f(°r/iler (Geoffroy), 337 

Laboratory and field cane studies of parasitoids against the European pine sawfly 

Neodiprion seniler (Geo r.) 

Species and province Year Origin Number 

Dipriocampe diprioni Ferriere 





1976 Switzerland 136 

1977 Switzerland 72 

£Xenlerus abruplorius Thnb. 1969 Austria 579 



1978 

1978 

Germany 

Germany { Austria 

64 

75 

1978 Italy 211 


As stated earlier, shipments of parasitoids to Newfoundland were started soon after it 

was known that N. senifer was established there. The first species to be shipped was P. 

basizonus, a multivoltine parasitoid of cocooned pre-pupae successfully introduced from 

Europe in the 19305 (McGugan & Coppell962). N. seniler cocoons containing developing P. 

basizonus were shipped to Newfoundland in the summer of 1977. They were obtained 

from a rearing programme conducted in Sault Ste. Marie, Ontario, during the winter 

preceding shipment, and were reared in St. John's. Emerging parasitoids were released 

twice weekly between 21 July and 15 August at Windsor Lake, 9.7 km from St. John's. A 

total of 631 males and 376 females was released in an infested plantation of mixed jack 

pine and Scots pine (Otvos & Griffiths 1979) (Table 86). Approximately 130 adult P. 

basizonus were recovered from 600 N. seniler cocoons "planted" in the release area in 

the summer of 1977, indicating that the released adults had attacked successfully in 

the field (Otvos & Griffiths 1979). Further releases of large numbers of this parasitoid 

obtained from rearings in Sault Ste. Marie were made in 1978 and 1979. A small number 

of adults from Finland was also released in 1980 (Table 86). There have been no further 

recoveries of adults of this species from field-collected cocoons to date. Monitoring of 

this release is continuing. 

In Ontario, European pine sawfly NPV was extensively used in the 19505 and 1960s by 

Christmas tree growers and provincial government forestry officials. 

There are several methods of producing this virus in host insect larvae, the simplest 

and cheapest being to do so in the field. Plantations with a suitable insect population 

density are found and fourth-instar larvae are sprayed using a mist blower to disseminate 

NPV at a concentration of 10" PIB/ml. The first dead larvae are found about 7 days after 

spraying and colonies of dead and dying larvae are collected daily until about 14 days 

after spraying. Larvae are removed from the foliage, frozen, lyophilized, ground to a 

fine powder, and the concentration of PIB per gramme determined. About lOS PIB are 

obtained from one dead larva, so, using a dosage of 5 x 10" PIBlha. about 50 virus-killed 

larvae are required. A virus treatment is therefore very economical. Between 1970 and 

1975 a considerable quantity of this virus was produced by Ontario Ministry of Natural


Neocliprioll sertifer (Geoffroy). 339 

There is no doubt that European pine sawfly NPV is a highly efficacious biological 

control agent when applied on early instar larvae, and treatments continue to give control 

in the years following application. The longevity of this control depends on such factors as 

the initial population density of the host and the size of the trees, but infectious PIBs 

remain in the environment for at least 3 years following a virus epizootic (Kaupp 1981). 

Given this respite from defoliation, trees grow considerably and are much less susceptible 

to damage if further European pine sawfly outbreaks occur. 

To date, there are no viruses registered for operational use in Canada. In the USA, a 

petition has been prepared for registration of European pine sawfly virus under the name 

"Neochek-S". Extensive animal safety testing has been conducted by the Americans, but 

it is not known if these data will be acceptable to Canadian authorities. With the limited 

areas of European pine sawfly infestation currently reported, registration of its NPV in 

Canada is not of high priority in comparison to viruses of certain other insect pests. Even 

if European pine sawfly NPV is eventually registered in Canada, there is little commercial 

incentive for production and marketing owing to its limited and specialized use. Virus 

production and distribution, therefore, will almost certainly remain in the hands of 

federal and provincial governments. 

In view of the successful establishment of L. lutealor in five areas of Ontario, all following 

a single release, the failure to establish this species in Newfoundland following three 

releases in 3 successive years suggests a fundamental difference between the situations in 

Ontario and Newfoundland. We recommend that no more releases be made there after 

the 1981 release until further study reveals success or the reasons for failure. 

It was pointed out by Griffithsetal. (1971) that there are 62 species of native parasitoids 

known to attack other pine-feeding diprionids in Ontario that had not been recovered 

from N. serlifer. We have not recovered any of them in the limited sampling in the last 

decade in southern Ontario. It is possible that some of them are now attacking N. serlifer 

in northern Ontario and we recommend that sampling be done to determine if this is so. 

No more releases of D. diprioni or E. abruptorills should be made. However, sampling 

to determine whether the former species has become established can be continued with 

little cost for several years. Collections to determine the presence of E. abruplorius 

should only be undertaken when they can provide adequate numbers of hosts in order to 

justify the work that the processing of collections requires. 

As stated earlier, the operational use ofNPV at Sandbanks Provincial Park in Ontario 

was considered to be an unqualified success. However, after assessing aerial applications 

of European pine sawfly NPV and evaluating reports of operations conducted outside 

Canada, two recommendations can be made. Firstly. the dosage of virus applied is about 

10 times more than required for satisfactory control. A dosage of 5 x Hf PIBlha is 

adequate. Secondly, adjuvants in the tank mix are unnecessary and virus in water alone 

will suffice. 

Although it is not within the discipline of biological control, we are concerned about the 

dispersal of the European pine sawfly beyond its present boundaries in Canada. Sullivan 

(1965) pointed out that the overwintering eggs of this species can survive a temperature of 

-26°C and that, with conditioning and selection, they may be able to withstand 

temperatures even lower. Thus the possibility of this pest spreading throughout the range 

of its widely distributed hosts, Scots pine, jack pine, and red pine, is great unless efforts 

are made to prevent it. We recommend that some attempt be made to fumigate stock 

before transport to reduce this possibility, using techniques outlined by Monro & Kirby 

(1963).

340 K. J. Griffiths, J. C. Cunningham and I. S. Otvos 


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Canadian Department of Agriculture Bi·monthly Progress Report 6.2-3. 

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1974. 

Cunningham. J.C.; Kaupp, W.J.; McPhee, J.R.; Sippell. W.L.; Barnes. C.A. (1975) Aerial application of a nuclear polyhedrosis virus to 

control European pine sawny. Canadian Forestry Service Bi·monthly Research Notes 31.39-40. 

Cunningham. J.C.; Entwistle. P.F. (1981) Control of sllwnies by baculovirus. In: Burges. D. (Ed.) Microbial control of pests and plant 

diseases. 1970-1980. London; Academic Press. 

Grirfiths, K.J. (1972) Diserimination between parasitized and unparasitized hosts by Pleolophus basizonu.r (Hymenoptera: Ichneumonidae). 

Proceedings of the Entomological Society of Ontario \02.83-91. 

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release against Neodiprion sertifer (Hymenoptera: Diprionidae) in Ontario. Canadian Entomologist 

\05.833-836. 

Griffiths, K.J. (1976) Interactions between Pleolophus basizonus and Lophyropleaus IUleator (Hymenoptera: Ichneumonidae). two parasitoids of 

Neodiprion sertifer (Hymenoptera: Diprionidae). Entomophaga 21.13-17. 

Grirfiths, K.J.; Lyons. L.A. (1968) The establishment of Lophyroplectus IuJeaJor (Hymenoptera: Ichneumonidae) on Neodiprion serrife, 

(Hymenoptera: Diprionidae) in Ontario. CaruuJUm Entomologist 100.1095-1009. 

Griffiths. K.l.; Lyons. L.A. (1980) Funher rcleru;es of LophyropleclUJi luteator (Hymenoptera: Ichneumonidac). an introduced parasite of 

Neodiprion smifer (Hymenoptera: Diprionidae). Canadian Entomologist 112,421-426 

Griffiths. K.1.; Rose. A.H.; Bird. F.T. (1971) Neodiprion serrifer (Geoff.). European pine sawfly (Hymenoptera: Diprionidae). In: Biological 

control programmes against insects and weeds in Canada 1959- 1968. Commonwtalth InstiJute of Biologiazl 

Control Technical Communication 4.150-162. 

Kaupp. W.J. (1981) Studies on the ecology of the nuclear polyhedrosis virus of the European pine sawny. Neodiprion sertife, (Geoff.). Ph.D. 

Thesis. Oxford University. U.K. 

Kraemer. M.E.; Coppel, H.C.; Hall, D.J. (1979) The establishment of Lophyroplectus luteator, a larval parasitoid of the European pine 

sawfly. Neodiprion serrifer. in Wisconsin. University of Wisconsin FOlTSt RestJ1rch Note 225,3 pp. 

Lindquist, O.H.; Miller, W.1. (1979) The pine sawny that carne to dinner. Your Forests 12(1).\0- I 1. 

Lyons, L.A. (1977a) On the population dynamics of Neodiprioll sawflies. In: Kulman, H.M.; Chiang. H.C. (Eds.). Insect ecology - papers 

presented in the A.C. Hodson Lectures. University of Millnesota Agriculture Experiment Statioll Technical 

Bulletin 310,48-55. 

Lyons. L.A. (1977b) Parasitism of Neodiprioll sertifer (Hymenoptera: Diprionidae) by Exenlerus spp. (Hymenoptera: Ichneumonidae) in 

Ontario, 1962-1972, with notes on the parasites. Canadian Entomologist 109,555-564. 

Lyons. L.A.; Sullivan, C.R.; Wallace. D.R.; Griffiths, K.J. (1971) Problems in the management of forest pest populations. Proceedings of 

the Tall Timbers Conference on Ecological Animal Control 1971, pp. 129-140. 

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M-X-118,35 pp. 

Manineau, R.; Lavallee. A. (1975) Quebec region. Canadian Forestry Service, Annual Report of the Forestlnseet and Disease Survey 1974, 

pp.37-56. 

McOugan, D.M.; Coppel, H.C. (1962) Biological control of forest insects. 1910-1958. In: A review of the biological control attempts against 


2.35-127. 

Monro, H.A.A.; Kirby, C.S. (1963) Fumigation of nursery slock as a possible means of retarding the spread of Ihe European pine sawfly. 

Canadian Department of Forestry, Entomology and Pathology Branch Bi-monthly Progress Report 

19(3).2. 

Otvos, I.S.; Griffiths. K.J. (1979) Cocoon parasitoid of the European pine sawfly introduced into Newfoundland from Ontario. Canadiall 

Forestry Service, Bi·monthly Research Notes 35(4),20-21. 

Pschorn·Walcher. H.; Eichhorn. O. (1971) Untersuchungen uber die Eiparasitien (Hym., Chalcidoidea) der rotgclben Kiefern-Buschhornblattwespe 

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Umweltschutz 44(7).97- 103. 

Pschorn·Walcher, H.; Eichhorn, O. (1973) Studies on the biology and ecology or the egg parasites (Hym.: Chalcidoidea) of the pine sawfly 

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Pest Status 

Background 



Neodiprion swainei (Middleton), Swaine 

Jack Pine Sawfly (Hymenoptera: 

Diprionidae) 

R.J. FINNEGAN and W.A. SMIRNOFF 

At the time of the last review by McLeod & Smirnoff (1971), the population of 

Neodiprion swainei (Middleton), Swaine jack pine sawfly, was approaching endemic 

levels over most of its range in eastern Ontario and southwestern Quebec, where it has 

occurred extensively since the early 1950s. This was thought to be due partly to the 

natural collapse of a prolonged infestation and partly to the application of chemical 

insecticides in 1965 (Mcleod 1968). Mcleod & Smirnoff (1971) had expected a 

recurrence of N. swainei in the 19705, but this did not materialize, probably due to earlier 

applications of chemical insecticides against both Swaine jack pine sawfly, N. swainei, 

(McNeil et al. 1979) and spruce budworm, Choristoneurafumiferana (Clem.). (Mcleod 

1975) in the same general area. The population remained low throughout the 1970s. with 

the occurrence of only a few localized light infestations in northern Ontario and western 

Quebec. 

Parasitoids, predators, and pathogens have all been introduced in attempts to control 

sawfly populations. McLeod & Smirnoff (1971) reported that "Before 1958, only small 

numbers of Ple%phus basizonlls (Grav.) and Drino bohemica Mesn. were released 

against Neodiprion swainei in a few localities in Ontario. However, massive releases of 

these two parasitoids, as well as Exenterlls amictorius Panzer and Dahlbominus fuseipennis 

(Zett.) were also made in the early 1940s against Diprion hercyniae Htg. in both 

Ontario and Quebec. All four species have been recovered from N. swainei in a number 

of localities in Quebec since 1958 ... but none in Ontario. E. amictorius and P. basizonus 

were most abundant, D. fllseipennis was less common, and only one specimen of D. 

bohemica was found". A brief description of the interaction of each parasitoid with N. 

swainei was given. Mcleod & Smirnoff also reported on the discovery and successive 

recoveries of the Borrelina viral pathogen. The results of one experimental aerial 

dispersion of the virus in 1960 and a second in 1964 were reported as "excellent" and 

"not as good" respectively. The ecology of the virus was briefly considered, stating that 

certain predators, such as wasps and pentatomids act as vectors of the virus. In 

conclusion, McLeod & Smirnoff stated that the releases of E. amictorillS and P. 

basizonus seemed to have been beneficial, and that the use of virus as a control was 

promising. 

During the past decade, no further release of parasitoids, and few recoveries, were 

made. Nonetheless, considerable research was completed during this period. In anticipation 

of an impending resurgence of the N. swainei population in Quebec, two foreign 

species of predacious red wood ants, Formica lugubris Zett. and F. obscuripes Forel,

342 R. J. Finnegan and W. A. Smirnoff 

Parasitolds 

Predators 

were introduced into susceptible stands of jack pine Pinus banksiana Lamb., in the St. 

Maurice river valley. Observations were reported on other insect predators as well as on 

birds and small mammals. Studies on the virulence. formulation of sprays. and application of 

pathogens were also continued. 

Mcleod (1971) examined the variation of N. swainei cocoon survival and found that 

only about 10% of the mortality was caused by parasitoids. Later. Mcleod (1972) 

compared host discrimination with density responses during oviposition by parasitoids 

of N. swainei; he observed that the ability of females to discriminate against hosts 

containing previously deposited parasitoid progeny was variable. Although there was 

no discrimination at the beginning of the spinning period of N. swainei. it was quickly 

acquired and persisted to the end of the spinning period. 

Price (1970a, 1970b, 1970c) showed that "Female parasitic insects in the genera 

Pleolophus, Ensasys, and Matrus (Hymenoptera: Ichneumonidae) search the ground 

cover for hosts and avoid areas they had already inspected" and that "females respond to 

their own trail odour, and recognition occurs also between conspecific, congeneric and 

intergeneric individuals". Later Price (1971) discussed the niche breadth and dominance 

of parasitic insects sharing the same host species. In 1972, he indicated that as a result of 

recognition of repellent trail odours. females of P. basizonus are able to discriminate 

against parasitized hosts of N. swainei between narrow limits "set by the probability of a 

female finding an unparasitized host". and that they showed "mutual interference in egg 

laying at high parasitoid density" (Price 1972a). He also reported on the immediate and 

long-term effects of chemical insecticide application on insect parasites in jack pine 

stands in Quebec (Price 1972b); on the activity patterns and impact of paras ito ids on N. 

swainei (Price 1972c); and on the utilization of the same host by different insect parasites 

(Price 1972d). 

Finnegan (1971) reported on preliminary studies on the use of predacious ants to control 

forest pests in Quebec, and concluded that none of the species found was particularly 

promising. He further discussed (Finnegan 1974) both the harmful and beneficial aspects of 

red wood ants as insect predators, the reason for their effectiveness, and recommendations 

for selecting desirable species for propagation. Finnegan (1975, 1977) later introduced 

two species of red wood ants, F. lugubris from central Europe and F. obscuripes from 

southern Manitoba, into a jack pine stand at Lac it la Chienne, about 70 km southwest of 

La Tuque, Quebec, in the St. Maurice river watershed. The two species of ants belong to 

the F. rufa group and are aggressive predators of sawfly larvae, cocoons, and adults, as 

well as a variety of other defoliating insects (Cotti 1963, Finnegan 1978, McNeil et al. 

1978). These introductions were made in anticipation of a recurrence of N. swainei 

infestations in the late 1970s. When the initial introductions had become established, 

additional releases (from Europe and Manitoba) were made in subsequent years. Table 

89 shows the dates and approximate numbers of each ant species (workers and sexuals) 

released in the St. Maurice river watershed. The status of each species in 1981 is also given 

in Table 89, based on the number, average size, and insect vigour of the nests. Two 

secondary introductions of F. obscuripes (emanating from the first) were made in 1980 in 

the Gilardo Dam area, about 75 km west of La Tuque, Quebec. 

I1nytzky (1974) reported on the species of ants found in a young jack pine stand in 

Quebec, and on their distribution, population level, and predation of N. swainei. He 

studied 10 species of ants, of which F. fusca L. was the most abundant, and found that 

together with several other Formica species and Camponolus herculeanus (L.) they 

carried emerging and ovipositing adults, as well as cocoons, into their nests. He concluded that 

ants may be an important factor regulating N. swainei populations.

Pathogens 

Table 89 

Neodiprioll slI'ainei (Middleton), 343 

Open releases and recoveries of predacious red wood ants against Swaine jack pine sawfly, 

Neodiprion swainei (Middleton), in the St. Maurice river watershed in Quebec 

Approximate 

Status in 1981 

Ant 

species 

Date of 

release 

number 

released Recovery 

Estimated 

increase 

Formica 1972 4 ()()() ()()() About 20 nests 15-fold 

obscuripes Forel established (with 

sexuals present) 

1975 1 ()()() ()()() About 75 nests 20-fold 

established (with 

sexuals present) 

F. lugubris Zett. 1973 1 ()()() ()()() Ten nests established 

(with few sexuals) 

1975 2 ()()() (added to previous ? 

queens nests) 

1976 5 ()()() (added to previous ? 

queens nests) 

Mcleod (1971) reported, in a preliminary analysis of the variation in cocoon survival 

of N. swainei, that small animal predators accounted for about 47% of the mortality of 

cocoons, and insect predators for about 16%. Mcleod (1974) also found that populations of 

resident breeding birds in jack pine stands in Quebec varied little from 1964 to 1973, but 

that the mole population showed a steady, statistically significant increase over the 9 

years of sawfly infestation. 

Tostowaryk (1971a) described in detail the life history and behaviour of Podisus 

modestus (Dallas), a predacious pentatomid, which preys on N. swainei larvae as well as 

on other defoliators. He gave details of the habits and abundance of the predator, and 

also discussed the relationship between parasitism and predation of diprionid sawflies 

(Tostowaryk 1971b). Experimental results of the functional response of P. modestus to 

densities of N. swainei and N. pratti banksianae Rohwer (Tostowaryk 1971c) showed 

that the response was two-fold: a domed curve when the sawfly larvae were active and 

relatively large with respect to the size of the predator, and a negatively accelerated 

curve when the sawfly larvae were freshly killed and relatively small with respect to the 

predator's size. He also presented a list of coleopterous predators of N. swainei 

(Tostowaryk 1972), and stated that it seemed these predators responded in a densityindependent 

manner to the prey. Tostowaryk (1973) continued his observations on 

carabids found in jack pine stands. He noted that the three most common species of 

carabids preyed to a limited extent on cocoons of N. swainei. 

A highly pathogenic strain of a Borrelina species of virus was studied (Smimoff 1961a, 

Mcleod & Smimoff 1971) and a formulation suitable for aerial dispersion was developed 

(Smimoff 1964). Aerial dispersion of the virus provided excellent control of the insect 

(Smirnoff et al. 1962). The dosages used were 4.5 IIha and 3711ha, at a concentration of 

2 x 1()6 polybedralml. Cold weather during and after treatment caused a reduction in 

larval mortality, but because of trans-ovum and trans-ovarial transmission of the 

disease from parent to progeny, there was a long-term control effect (Smimoff 1962).


Table 90 

Neodiprioll swainei (Middleton). 345 

and a decrease in free glycerol, potassium, and especially total lipids (energy resources), 

which were decreased by 50% (Smirnoff 1971b). 

Results showed that biochemical analysis can be used to determine the pathological 

state of an N. swainei population; to follow, metabolically, the evolution of a virosis in 

the insect, thus permitting a prognosis of its population; and to evaluate whether the 

population is expanding or decreasing. The metabolic study done during 1979 and 1980 

indicated that the N. swainei population of the Saguenay - Lac St-Jean region, Quebec, 

is expanding. 

The influence of urea fertilization on the physiology and growth of jack pine and on the 

behaviour of N. swainei (either healthy or virus-infected) was determined. It was found 

that a treatment with urea in natural forest stands increased the length and weight of jack 

pine needles proportionally to the amount of nitrogen assimilated. Three years after 

nitrogen fertilization, the ingestion of foliage by N. swainei was reduced by approximately 

50%, and the natural mortality of the tenthredinid was increased by 50%. It was found 

that the sensitivity of larvae to virus infection, as well as the mortality, increased. Also, 

modifications in the physiological state of jack pine needles provoked changes in insect 

behaviour. For example, adults seemed to have more difficulty in laying eggs (twisted 

ovipositor) on needles of fertilized trees than on unfertilized ones (Smirnoff & Bernier 

1973, Smirnoff & Valero 1975). 

Large-scale transplantations of red wood ants over long distances have only been tried a 

few times on the North American continent, and the costs involved can only be roughly 

estimated. The transplantations from central Europe were made co-operatively with 

scientific institutions (University of Pavia in Pavia, Italy, and CIBC in Delemont, 

Switzerland) and as a consequence had many unrevealed costs. The introduction from 

southern Manitoba, on the other hand, was funded completely by the Laurentian Forest 

Research Centre. Because the operations were experimental and of a scientific nature, 

no charges were made for the ant colonies collected. However, future large-scale 

operations may have to take this factor into consideration. 

The total costs can be divided among four operations: collecting, packaging, transportation, 

and release. The relative importance of each can vary considerably according 

to time involved, distances to be covered and accessibility of sites. Table 90 gives 

estimates of two large transplantations made to the province of Quebec: one from 

Manitoba in 1972, the other from Italy in 1973. 

As there has not been any measurable N. swainei popUlation in recent years in jack 

pine stands chosen for the introduction of ants, it has not yet been possible to measure 

Cost estimates for the transplantation of red wood ant colonies 

Collecting Dispersal Approximate 

Date (man days) Transportation (man days) Packaging total costs 

1972 25 Southern Manitoba to Quebec. 10 $1 ()()() $6500 

with motor vehicle and trailer 

- $2 ()()() 

1973 40 Northern Italy to Quebec 10 $1 ()()() $9500 

motor vehicles and by air 

- $5 ()()()

348 R. J. Finnegan and W. A. Smirnorr 

Smimoff, W.A.; Valero. J. (1975) Effets II moyen tenne de la fertilisation par urCe ou par potassium sur P;n/IS banks;ana L. el Ie 

comportement de ses insectcs devastateurs: tels que Neodiprion swa;nei (Hymenoptera: Tenthredinidae) 

et TOllmcye//a IlIImismalicum (Homoptcra: Coccidac). Calladian lO/lmal Forest Research 5,236-244. 

Smirnoff, W.A.; Feltes, J.J.; Haliburton, W. (1962) A virus disease of Swaine's jack pine sawfly. Neodiprion swaine; Midd. sprayed from an 

aircraft. Canadiall Entomologist 94,4TI-486. 

Tostowaryk, W. (1971a) Life history and behavior of PodisllS modUlUS (Hemiptera: Pentatomidae) in boreal forcst in Quebec. CQlladian 


Tostowaryk, W. (1971b) Relationship between parasitism and predation of diprionid sawflies. Annals of the Elltom%gica/ Society of 

America 64,1424-1427. 

Tostowaryk, W. (1971c) The crfect of prey defense on the functional response of Podisus modutus (Hemiptera: Pentatomidae) to densities 

of the sawflies. Neodiprioll swainti and N. prall; banksiallQ (Hymenoptera: Neodiprionidae). Canadian 


Tostowaryk, W. (1972) Coleopterous predators of the Swaine jack pine sawDy Ntodiprion swainei Middleton (Hymenoptera: Diprionidae). 

Canadian Journal of Zoology 50,1139-1146. 

Tostowaryk, W. (1973) Population estimation and feeding behaviour of adult carnbids in jack pine stands. Quebec. CallQdian Forestry Service 

InfomuJtion Report Q·X·32. 23 pp.

Pest Status 

Chapter 60 

Operophtera bruceata (Hulst), Bruce 

Spanworm (Lepidoptera: Geometridae) 

W.G.H.IVES 

The Bruce spanworm, Operophlera bruceala (Hulst), attacks a variety of deciduous 

trees (Prentice 1963), and is very similar in appearance to the winter moth, Operophlera 

brumala (L.). Adults of the two species can be distinguished by differences in genitalia 

in males and in vestigial wing length in females (Eidt el al. 1966). Pupae can be separated 

by differences in the form of the cremaster, and larvae can be distinguished by the 

placement of the ocelli (Eidt & Embree 1968). In eastern Canada, sugar maples, Acer 

saccharum Marsh., and beech trees, Fagus grandi/olia Ehrh., are favoured hosts, but in 

western Canada, trembling aspen. Populus Iremuloides Michx., seems to be the principal 

host, particularly in Alberta. Although the Bruce spanworrn is not usually considered a 

major pest, a number of localized infestations, as well as more extensive outbreaks in 

which damage has been primarily due to this insect, have been reported by the Forest 

Insect and Disease Survey (Anon. 1952-79). The following account of infestation 

history is based on these reports, except where otherwise noted. 

In central and eastern Canada. the first reported damage occurred in a small stand of 

sugar maple near Merrivale, Ontario, in 1951 and 1952. In Newfoundland a small 

infestation was reported on white birch, Belula papyri/era Marsh., in 1956. The first 

reported damage in the maritimes occurred in 1962, when a patch of sugar maple in 

Nova Scotia was severely defoliated. and a larger area of defoliation was reported in 

New Brunswick. Infestations in both Maritime Provinces increased in scope and intensity 

in 1963, and the outbreak reached its peak in 1964, when over 200 000 ha of severe 

defoliation occurred in Nova Scotia alone (Harrington 1968). Declines in populations 

were noted in 1965, and by 1966 the outbreak had collapsed. A short-lived outbreak also 

occurred in Quebec, where the insect reached epidemic proportions in many areas in 

1963. However, populations were lower in 1964, and only small pockets of defoliation 

were reported in 1965. At its peak, this outbreak covered some 39 000 km 2 (Martineau & 

Monnier 1966). In Ontario, where infestations of Bruce spanworrn were first reported, 

no further damage occurred until 1963, when a small pocket of aspen defoliation was 

reported near Sudbury. In 1965, three widely separated areas of severe sugar maple 

defoliation occurred: one was in Algonquin Park; another was on an island in Lake 

Huron; and the third was on hilltops and ridges near Sault Stet Marie. The outbreak 

decreased in intensity in 1966 and collapsed completely in 1967. 

In western Canada, damage to trembling aspen attributable to the Bruce spanworm 

was first reported from the Obed area of Alberta in 1956. Widespread areas of defoliation. 

much of it severe, were reported in 1957 and again in 1958, when about 130000 kml 

were moderately or heavily infested (Brown 1962). In 1959 some infestations had 

subsided, and all outbreaks collapsed in 1960. Severe defoliation of trembling aspen in 

northern British Columbia was reported in 1958 and 1959, but these infestations also 

collapsed in 1960. 

No further significant damage attributable to the Bruce spanworm was reported until 

1968, when extensive areas of moderate to severe defoliation of trembling aspen were 

again observed in Alberta. Both the intensity and size of this outbreak increased in 1969. 

Extensive damage also occurred in 1970, but only patches of aspen were severely 

defoliated in 1971. In Quebec, several maple groves were infested in 1970, and these 

were completely stripped in 1971 and again in 1972. The insect was somewhat less 

349

350 W. G. H. Ivcs 

Background 

Field Trials 

abundant in 1973. and populations continued to decline in 1974 and 1975. In Ontario, 

pockets of severe defoliation of sugar maple, white birch, and beech were reported along 

the south boundary of Algonquin Park in 1974, and the outbreak expanded and intensified in 

1975, apparently collapsing in 1976. Severe defoliation of trembling aspen also occurred 

in the Lake Nipigon area in 1976. The outbreak increased in area in 1977, but populations 

declined in most areas in 1978. In Alberta, severe defoliation by Bruce spanworm was 

again noted in the Obed area in 1978, and this outbreak continued in 1979 and 1980. 

Most of the reported outbreaks of Bruce spanworm have been of short duration. 

Consequently there was little if any tree mortality, even when defoliation was complete. 

One of the reasons for the short duration of the outbreaks, at least in eastern Canada, 

appears to be a nuclear polyhedrosis virus (NPV) which was described by Smirnoff 

(1964). The virus apparently causes appreciable mortality and thus hastens the collapse 

of the outbreaks. Although there were several reports of the virus occurring in the 

maritimes and in Quebec, none of the Forest Insect and Disease Survey reports from 

western Canada mentioned virus, and no experimental assessments of its virulence 

could be found in the literature. A small-scale field experiment, using NPV from eastern 

Canada, was therefore conducted in the Obed area of Alberta in 1979. 

A small supply of NPV was obtained by infecting larvae reared in a laboratory 

(J.c. Cunningham 1979 personal communications). Bruce spanworm eggs were obtained 

by collecting moss from around the base of infested trees near Obed in the fall of 1978. 

The eggs were incubated during the winter, and the emerging larvae were reared on an 

artificial diet in plastic cups. A total of 5 000 fifth-instar larvae was infected with virus. 

The dead larvae were collected and the virus purified by differential centrifugation; 4 x 

1011 polyhedral inclusion bodies (PIB) were obtained. The results of the field trial have 

already been described (Ives & Cunningham 1980) and only a brief description of the 

experiment need be given here. A strip of moderately infested trembling aspen, mostly 

under 10 m in height, was selected for the virus trials. Various concentrations of virus in 

an aqueous formulation containing 50 gil Shade® (Sandoz Inc.), 1 % Chevron® sticker 

and 25% v/v animal feed-grade molasses were applied until liquid dripped from the 

foliage (about 350 lIha) with a backpack mist blower. Virus concentrations of 10' and 10' 

PIB/ml were applied on 24 May. The larvae were in the first instar, the temperature was 

19°C, relative humidity 42%, and wind speed 0-8 kmlh. Leaves on the trees receiving 

10' PIB/ml were 1.5-2.0 em in diameter. The remaining trees had not yet flushed. A 

second application of virus, on a different group of trees, was made on 1 June. Larvae 

were in the second and third instars, the temperature was 21°C, R.H. 29%, and wind 

speed 3-11 kmlh. The leaves were fully flushed, and three concentrations of virus (IO', 

10', and 10' PIB/ml) were tested. 

Two methods of assessing impact were used: determination of percentage mortality 

by rearing of individual larvae until death or pupation, and estimation of percentage 

defoliation by examining large numbers of individual leaves to determine the approximate 

amount eaten. Neither method was completely satisfactory. Aseptic techniques were 

not used in the collection of larvae, and all larvae for each sample were placed in the same 

container, so that contamination after collection probably occurred. The foliage samples 

were not collected until mid-August, and there was some evidence that the petioles of 

the more severely damaged leaves had fallen by then. Consequently, the larval rearings 

may have tended to overestimate rates of infection, while the defoliation may have been 

underestimated. A further complication was the presence of naturally occurring virus.

Evaluation of Control Attempt 



0l'('rol'illt'rtl bruceattl (Hulst). 351 

Two samples of late-instar larvae were collected about 0.4 km from the experimental 

area. Microscopic examination of living larvae from those samples revealed that 13 and 

2t % respectively were infected with NPV (Ives & Cunningham 1980). 

The percentages of virus-caused mortality of larvae collected 7 days after the 24 May 

application were 80 and 98% for larvae receiving 10' and 10' PIB/ml, compared to a 

mean of 52% for the two untreated check areas. Corresponding mortalities among larvae 

collected 10 days after the 1 June application were 94. 100. and 100% for dosages of 10'. 

to' and to" PIB/ml respectively, compared to a mean mortality of 68% for larvae 

collected in the check area. All treatments afforded some degree of foliage protection, 

but only the 24 May application of 10' PIB/ml and the 1 June application of to' PIB/ml 

provided protection that could be detected visually. 

Bruce spanworm NPV appears to be virulent, on the basis of the limited amount of 

information available. However, it is expensive to produce, because it must be propagated 

in a small host. Its use in artificially regulating populations of Bruce spanworm does not 

currently seem to be practical, partly because of cost and partly because the rate of 

natural virus infection usually appears to terminate outbreaks before appreciable damage 

occurs. 

Ultimately, this NPV might have potential as an applied biological insecticide, but this 

will not occur unless more economical methods for propagating insect viruses are 

developed. No further testing of this virus is recommended in the immediate future. 

Anonymous (1952 - 1979) Annual reports of the Forest Insect and Disease Survey. 1951-1976. Ottawa. Ontario; Canadian Forestry Senice. 

Brown. C.E. (1962) The life history and dispersal of the Bruce spanworm. Operophtera bruceala (Hulst) (Lepidoptera: Geometridae). 


Eidt. D.C.; Embree, D.G. (1968) Distinguishing larvae and pupae of the winter moth. Operophtera brumata. and the Bruce spanworm. O. 

bruceata (Lepidoptera: Geometridae). Canadian Entomologist 100.536-539. 

Eidt, D.C.; Embree. D.G.; Smith. C.C. (1966) Distinguishing adults ofthe winter moth, Operophtera brumata (L.). and Bruce spanworm. O. 

brumata (Hulst) (Lepidoptera: Geomelridae). Canadian Entomologist 98.258-261. 

Harrington. W. (1968) Relation of light trap catches of Bruce spanworm to infestations in ccntral Nova Seotia. Canadian Department of 

Fisheries and Forestry Bi-monthly Research Notes 24(5),39-40. 

I vcs, W. G. H. ; Cunningham, J. C. (1980) Application of nuclear polyhedrosis virus to control Bruce spanworm (Lepidoptera: Geometridae). 

Canadian Entomologist 112,741-744. 

Martineau. R.; Monnier. C. (1966) Recent outbreak of the Bruce spanworm in Quebec. Canadian Department of Forestry and Rural 

Development Bi-monthly Research Notes 22(6).5. 

Prentice. R.M. (1963) Forest Lepidoptera of Canada recorded by the Forest Insect Survey. Canadian Department of Forest Entomology and 

Pathology Branch, Ottawa, Publication 1013. 

Smirnoff. W.A. (1964) A nuc\eopolyhedrosis virus of Operophtera bruceata (Hulst) (Lepidoptera: Geometridae). Journal of Insect 

Pathology 6.384-386.

Blank Page 

352

Pest Status 

Background 

Chapter 61 

Operophtera brumata (L.), Winter Moth 

(Lepidoptera: Geometridae) 

D.O. EMBREE and I.S. OTVOS 

The winter moth. Operophtera brumata (L.). was accidentally introduced into Nova 

Scotia. probably in the mid 1930s. and later spread to New Brunswick and Prince 

Edward Island. Recently it has been found in British Columbia. and in western Oregon 

in the United States. 

Populations of the insect in the maritimes have remained consistently low during the 

20-year review period because of the establishment and population build-up of the 

tachinid parasitoid Cyzenis albicans (Fall.) and the ichneumonid parasitoid 

Agrypon flaveolatum (Gravely) in 1961 (Embree 1971a). The gradual spread of the 

insect since it was first detected in 1949 has virtually ceased and it is almost non-existent 

in forested areas. However. populations have persisted in apple. Malus spp .• orchards 

and on shade trees. particularly oaks. Quercus spp .• and lindens. TWa spp .• (Sterner & 

Davidson 1981). Chemical control is occasionally required in orchards but generally 

parasitoid numbers have remained sufficiently high to keep the winter moth under 

control. 

In British Columbia. the winter moth is found in and around Victoria on Vancouver 

Island and in Richmond near Vancouver. As in Nova Scotia (Hawboldt & Cuming 1950), 

the insect was initially misidentified and was not suspected to be O. brumata until 1976. 

4 years after it was causing significant damage to Garry oak. Quercus garryana Doug!.. 

in Victoria. By 1977 the outbreak had expanded over large areas and an estimated 120 

kml were severely affected in Victoria on the Saanich Peninsula. The centre of the 

outbreak appeared to be in the Wilkinson Road area in Victoria where several commercial 

nurseries are located. suggesting that the insect might have been introduced into British 

Columbia on nursery stock (Gillespie & Finlayson 1981). In British Columbia the larvae 

were found to feed on Acer. Crataegus. Malus, Prunus, Populus, Quercus. and Salix 

spp .• and other deciduous trees and shrubs and to pose a threat to commercial orchards 

and shade trees in urban areas. Parasitism by native species of parasitoids is less than 5% 

(Gillespie et al. 1978). 

In the United States. outbreaks of this pest are confined to Multnomach, Clackamus. 

and Washington counties in western Oregon. where the insect is found in abandoned 

orchards and is becoming a pest of filberts. Corylus spp. 

Biological control of the winter moth in the maritimes by the introduced parasitoids C. 

albicans and A. flaveolatum has been successful and remains so because it is helped by 

the behaviour of the winter moth which results in most of the host larvae starving before 

suitable food is available. Most of the time. winter moth hatching occurs before budburst of 

its principal forest host. red oak. Quercus rubra L.. and other forest species. because less 

heat is required for hatching than for budburst. Over 98% of the newly hatched larvae 

may starve because they cannot feed on closed buds and the few survivors are then 

controlled by the parasitoids (Embree 1965). 

On hatching. larvae initially spin downwards and are then carried up to the tree 

foliage on rising air currents. Such currents are most apt to occur in the early morning 

when the air begins to warm and rise. By mid-morning. when the land is fully heated. 

353

354 D. G. Embree and I. S. Olvos 


Agrypon fla.-eo/atum 

(Grav.) 

(Hymenoptera: 


Cyzenis a1bicans 

(FaIl.) (Dlptera: 

Tachinidae) 

wind patterns develop. Winter moth hatching is synchronized to this pattern of wind 

movement, with hatching beginning at dawn and virtually ceasing by mid-morning. By 

this efficient means larvae are transported from hatching sites in crevices and lichens on 

the lower tree trunks to the tree crowns. Once there, the larvae either survive or die 

depending on whether the buds have opened. The wind may also transport the larvae 

several miles, but once established on the foliage, they do not dislodge easily until the 

late fifth instar in early summer, when they drop to the ground to pupate (Embree 1970). 

No other means of dispersal exists because the females, which are active in November 

and December, have vestigial wings and are flightless. 

No releases of parasitoids have been made in the maritimes since 1965 (Embree 1971b). 

Releases of parasitoids in British Columbia were conducted in 1979 and 1980 and are 

listed in Table 91. 

The British Columbia operation was financed and administered by the Crop Protection 

Branch (formerly Entomology and Plant Pathology Branch) of the British Columbia 

Ministry of Agriculture and Food in co-operation with the Pacific and Maritimes Forest 

Research Centres of the Canadian Forestry Service. Collections of last instar larvae 

were made in apple orchards in Nova Scotia in 1978 and 1979. Collections were also 

made in Germany by the Commonwealth Institute of Biological Control. 

Winter moth pupae were sent to the Biocontrol Unit of the Research Branch of 

Agriculture Canada in Ottawa, where pupae were cold-treated and then reared under 

quarantine conditions. Only the adult parasitoids were shipped to British Columbia from 

the German collection but about two-thirds of the Nova Scotia collection were sent to 

Victoria for parasitoid rearing. The remainder were reared in Ottawa and the adults of 

the two parasitoids were sent to Victoria. 

Based on studies in Nova Scotia, the control strategy in British Columbia has been to 

treat the infested area with repeated releases, each consisting of a minimum of 50 mated 

females of each species. 

This parasitoid beromes decreasingly effective as host densities increase, and is therefore most 

effective at low population density (Embree 1966). The adult parasitoids develop in 

winter moth pupae and emerge the following spring to parasitize early instars of host 

larvae. 

The first introduction of A. Jlaveolatum was in 1979 when a total of 1654 males and 

1 700 females was released at 33 locations in the greater Victoria area in stands infested 

with winter moth. Fifty pairs of parasitoids were released in each location after being 

held in mating cages for 1-3 days. The parasitoids in the cages were provided with twigs 

of cherry blossoms and bottles of sugared water with feeding wicks. In 1980 an additional 

2213 males and 2 813 females were released at 25 locations; of these a small proportion 

came from Germany, and the rest from Nova Scotia. This parasitoid has not yet been 

recovered in British Columbia. 

This parasitoid exhibits a sigmoid functional response curve and is most effective at high 

host densities (Embree 1966). The female, which can lay as many as 1300 eggs, oviposits 

in the vicinity of feeding damage by defoliators. Associated species such as the fall 

cankerworm, Alsophila pometaria (Harr.), which are resistant to parasitism by C. 

albicans, also consume the parasitoid eggs. With increasing winter moth populations C. 

albicans becomes increasingly effective.

Blank Page 

358

Pest Status 

Background 

Chapter 62 

Orgyia leucostigma (J.E. Smith), 

Whitemarked Tussock Moth (Lepidoptera: 

Lymantriidae) 

D.G. EMBREE, D.E. ELGEE and G.F. ESTABROOKS 

The whitemarked tussock moth, Orgyia leucostigma (J.E. Smith), is a noxious insect in 

eastern Canada, particularly in Nova Scotia. It is primarily a forest pest, capable of 

killing entire stands of mature balsam fir, Abies balsamea (L.) Mill., in a year and of 

defoliating extensive areas of hardwoods. It is particularly devastating to balsam fir 

Christmas trees which it deforms, defoliates, or kills. The white marked tussock moth is 

also a pest in urban areas where it feeds on a wide variety of hardwood shade trees, 

crawls over houses and lawns, and spins unsightly cocoons on trees and shrubs. Some 

people are allergic to the larval setae. Moreover, O. leucostigma is a pest of blueberries 

and is the target of an extensive spray programme to protect the commercial crop. 

Egg masses are laid on empty female cocoons and covered with froth. On hatching, 

larvae feed gregariously on the froth. Once this is consumed, larvae spin downwards on 

silken threads and are carried great distances by the wind. On occasion, during severe 

outbreaks, swarms of airborne larvae appear as a grey mist and the insects can cover the 

surface of small lakes and ponds when they land. 

The larvae feed on a wide variety of hardwoods and conifers such as tamarack, Larix 

laricina (Du Roi) K. Koch, but their primary host is balsam fir. Larvae feed in the shade 

on the underside of leaves and twigs. This feeding habit causes a unique form of damage 

to balsam fir Christmas trees because larvae also feed on the thin bark of developing 

leaders and upper lateral branches causing them to warp downwards. The result is a 

pronounced crook in the stems of surviving trees, visible for years afterwards. In heavy 

infestations, trees are festooned with silk. 

Pupation usually occurs on the underside of twigs and branches or on the stems of host 

trees, but it can occur almost anywhere, the yellowish white cocoons often being spun 

on fences, houses, or logs. Females remain on the surface of their cocoons when they 

emerge, mate with winged males, and lay from 100 to over 500 eggs. 

Outbreaks are controlled ultimately by a nuclear polyhedrosis virus (NPV). These outbreaks 

of O. leucostigma, at least in Nova Scotia, appear to originate in balsam fir 

stands at high elevations and occur at intervals of 6-10 years between outbreaks. The 

infestation spreads by wind-borne larvae and eventually large areas of balsam fir and 

hardwoods are defoliated. Such outbreaks become widespread and last for 5-6 years, 

then collapse because of the gradual spread of the virus disease. The initial infestation 

collapses in about 3 years, subsequent infestations in 2-3 years, and in the final stages of 

the outbreak infestations appear and collapse in the same year. 

Over 25 species of parasitoids attack the whitemarked tussock moth but the only 

control they have over populations is to kill survivors following the collapse of outbreaks 

caused by NPV. As a result, whitemarked tussock moth populations are reduced suddenly 

to extremely low levels, which delays the build-up of subsequent outbreaks. 

359

360 D. G. Embree. D. E. Elgee and G. F. Estabrooks 

Field Trials 


No attempt has been made to control this insect through the introduction of additional 

parasitoid species. The emphasis has been on establishing control through the manipulation 

of the virus (Cunningham 1972, Elgee 1975). Virus suspensions can be used as 

insecticides and have been tested successfully on small trees. 

A major attempt at biological control was made in 1975 to initiate an epizootic in a large 

population of the whitemarked tussock moth in the hope of shortening the length of an 

outbreak; it has been reported by Kurstak (in press). During the previous year the 

suspected start of a general outbreak of the whitemarked tussock moth was detected in an 

IS-ha stand of balsam fir near Castlereagh, Colchester County, Nova Scotia. A virus 

suspension was prepared from third-instar larvae reared from eggs collected at the site 

and infected with the Nova Scotia strain of NPV: the virus had been saved and stored 

from the last outbreak in 1965. 

On the evening of 9 July 1975, 204 I of an NPV suspension containing IO.S x HY' 

polyhedral inclusion bodies (PIB) per millilitre mixed with 204 I of a virus spray adjuvant 

manufactured by Sandoz Inc. and a fluorescent dye were sprayed from 30 m on IS ha of 

mature balsam fir with a Cessna Ag-truck aircraft equipped with a boom and nozzle 

sprayer. Whitemarked tussock moth larvae were mainly first instars with some early 

second instars. 

There were no true controls (untreated areas) but larvae collected before the spray 

application and reared were free from disease. Twenty-four sample trees were established 

in a line bisecting the spray block. However, one edge of the block was not sprayed so 

that trees 20-24 were outside the block. No disease was detected in larvae collected on 

tree 24 and only light mortality (33%) occurred on trees 20-23. Mortality of larvae 

collected 1 day after spraying from trees 1-19, and reared on foliage from the sprayed 

area, averaged 84%, whereas that of survivors collected 2 weeks later was 64%. Field 

populations declined by 95%, as compared to 67% on the unsprayed trees, and defoliation 

was light. From the air, the outline of the sprayed area was clearly discernible in a 

severe outbreak that developed around the initial Castlereagh infestation. No appreciable 

population reappeared in the sprayed area. The outbreak in the surrounding areas intensified 

in 1976, covering a radius of 16 km, but collapsed from the virus disease in all but 

the periphery during the same year. 

Early in 1976, virus suspensions were dispersed at two locations along the periphery 

of the 1975 outbreak using an explosive device. Canisters containing 1.9 I of suspension 

were fired into the air using a home-made mortar and exploded over the forest canopy. 

Virus particles were dispersed over an area of 1000-2000 m l depending on wind velocity. 

However, by this time the virus was already present in the population. Eventually the 

outbreak spread throughout the province, collapsing everywhere by 1975. 

The experiment showed that the virus can be used as an effective biological insecticide. 

but whether it can be used to initiate a widespread epizootic is uncertain. The rapid 

spread of the O. ieucosligma infestation in 1975 resulted from dispersion of newly hatched 

larvae, most of which occurred before spraying took place. Moreover. low populations 

of larvae existed in the area immediately surrounding the initial 18 ha of detected outbreak. 

The outbreak in 1976 was widespread and extremely intense; even though it collapsed 

just 2 years after it appeared, it is unlikely that the source of the epizootic was the IS-ha 

spray block. Had the initial outbreak been detected in 1973 and sprayed in 1974 a clearer



Orgyilllelicosligll/(/ (J. E. Smith), 361 

understanding of the role of the virus in whitemarked tussock moth epidemiology might 

have been gained. 

The pattern of development of whitemarked tussock moth outbreaks presents an 

opportunity for an elegant approach to biological control; but there are major difficulties. 

The most promising strategy is to artificially accelerate the normal virus epizootic that 

has occurred consistently in every past outbreak of this insect. The obvious advantage 

of such a strategy is that the virus is used as an inoculum rather than as a blanket 

insecticide. The resulting epizootic will be one that inevitably would have occurred 

later, a consideration that might ease the registration approval of this NPV by Canadian 

authorities. 

Historically each whitemarked tussock moth outbreak in Nova Scotia appears to have 

begun in one or two small locations (epicentres). Virus material from the 1974-79 outbreak 

has been stored and the techniques of introducing the virus into a developing 

outbreak have been shown to be workable. However, two major problems must be 

addressed: first, early detection of epicentres requires constant monitoring of likely 

sites for a period of up to 10 years; and second, whitemarked tussock moth hatching 

occurs over a period of at least 2 weeks, so although larvae feed on the froth covering of 

egg masses for 2 or 3 days, many larvae are likely to disperse before the virus is applied 

during peak egg hatching. 

A second strategy might be to employ sex pheromones that could be used to disrupt 

mating in epicentres. Success would depend on the almost immediate detection of these 

epicentres before they become large enough to develop a reservoir of dispersing larvae. 

Cunningham, J.e. (1972) Preliminary studies of nuclear polyhedrosis viruses infecting the whitemarked tussock moth, Orgyia lel/costigma. 

Canadian Forestry Service In.tect Pathology Research Institl/te, Sal/It Ste. Marie, Ontario, Information 

Report. 

Elgee, D.E. (1975) Persistence of a virus of the whitemarked tussock moth on balsam fir foliage. Canadian Forestr}' Service Bi-monthly 

Research Notes 31(5),33-34. 

Kurstak, E. (in press) Microbial and viral pesticides. New York; Marcel Dekker.

Blank Page 

362

Pest Status 

Background 

Field Trials 

Nuclear polyhedrosis 

virus 

Chapter 63 

Orgyia pseudotsugata (McDunnough), 

Douglas-fir Tussock Moth (Lepidoptera: 

Lymantriidae) 

J.C. CUNNINGHAM and R.F. SHEPHERD 

The Douglas-fir tussock moth, Orgyia pseudotsugata (McDunn.), occurs in the semiarid 

interior of British Columbia and in parts of Washington, Idaho, California, Nevada, 

Colorado, Arizona, and New Mexico in the United States. In Canada, Douglas fir, 

Pseudotsuga menziesii (Mirb.) Franco, is the preferred host; but Engelmann spruce, 

Picea engelmannii Parry, is also attacked and later instar larvae will feed on ponderosa 

pine, Pinus ponderosa Laws., when forced to abandon totally defoliated Douglas fir. 

Small larvae eat the underside of new needles. The later instar larvae may eat entire 

older needles or sever them near the base and leave them entwined in silk webbing. 

Heavily infested trees have a reddish-brown appearance. Trees may die after 1 year of 

defoliation, but mortality occurs more commonly after 2 or more years of severe 

defoliation (Johnson & Ross 1967). Severely damaged trees are also susceptible to 

attack by the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins. 

Since 1916, when the first records were kept (Sugden 1957), six outbreaks of Douglasfir 

tussock moth occurred in British Columbia. The latest outbreak began in 1971 and 

collapsed in 1976; a further outbreak was predicted for 1981 (Sterner & Davidson 1981). 

Characteristically, high populations of Douglas-fir tussock moth appear in relatively 

small patches of forest of 1-5 ha. The infestation normally extends from these areas in 

subsequent years, but more striking is the appearance of new outbreaks often many 

kilometres from the original sites. After an average of 5 years (3-6) outbreaks collapse, 

the factors responsible being nuclear polyhedrosis virus (NPV), egg parasitoids, and 

starvation. However, following several years of severe defoliation, the trees frequently 

die before this population collapse occurs. Hence attempts to regulate the population 

with biological or chemical agents should be made early in the outbreak cycle. 

Two types of nuclear polyhedrosis virus (NPV) have been found in populations of 

Douglas-fir tussock moth. In one type the rod-shaped virus particles are embedded 

singly in polyhedral inclusion bodies (PIB) and in the other they are embedded in 

bundles (Hughes & Addison 1970). These are referred to as single-embedded NPV 

(SNPV) and multiple-embedded NPV (MNPV). An SNPV isolated from the whitemarked 

tussock moth. O. leucostigma (J.E. Smith), is also pathogenic for Douglas-fir tussock 

moth larvae. 

Small-scale ground-spray trials in 1962 with field-collected NPV (possibly a mixture 

of SNPV and MNPV) gave encouraging results (Morris 1963). The first aerial spray trial 

in British Columbia was conducted in 1974 using Douglas-fir tussock moth MNPV 

363

366 J. C. Cunningham and R. F. Shepherd 



Some of the treatments were designated operational and others experimental. 

Twenty-one days after spraying, larval mortality due to the B.t. treatments averaged 

34% with a high of 57% with Thuricide® and a low of 13% with Dipel®. A double 

application of both materials and a higher volume of Thuricide® gave about 20% more 

control than single applications or the lower volume. Increasing the dosage of Dipel® 

gave no significant change, but using molasses in the tank mix instead of sorbitol gave a 

significant increase in the effectiveness of Dipel® and brought it to the same level as 

Thuricide® . 

Neither single nor double applications of Dipel® provided adequate foliage protection- 

59% defoliation was recorded on untreated check plots and 50-58% on Dipel®-treated 

plots. Better foliage protection was recorded with Thuricide 81 with only 18-25% defoliation 

on treated trees. 

The various operational and experimental treatments with B.t. gave a wide range of 

results. However, the best population reductions due to treatment were less than 60%. 

This did not provide adequate foliage protection and did not prevent the Douglas-fir 

tussock moth population increasing to high densities in the next generation. 

Results with B.t. on Douglas-fir tussock moth in 1975 were considered unsatisfactory 

and applications of B.t. on other defoliating lepidopterous forest pests during the last 

decade in British Columbia have generally proved disappointing. Recent improvements 

in application technology of B.t. have resulted in improved control of spruce budworm, 

Choristoneurafumiferana (Oem.), and similar improvements may eventually be possible 

with Douglas-fir tussock moth. On the other hand, results with NPV are already most 

encouraging and it appears that this biological control agent can now provide a useful 

tool for the regulation of Douglas-fir tussock moth populations. 

Douglas-fir tussock moth MNPV was registered by the Environmental Protection 

Agency in the United States in 1975 under the name TM Biocontrol-1. It is proposed to 

apply for Canadian registration in 1982. At present this virus is not commercially 

produced and this poses two major problems that need solving: a source of supply; and 

production at a reasonable cost. Small amounts, sufficient to treat about 400 ha annually, 

are produced at the Forest Pest Management Institute, Sault Ste. Marie, Ontario, and 

larger amounts are produced for use in the United States by staff of the U.S. Forest 

Service, Corvallis, Oregon. A figure of $40 US per hectare was quoted for production at 

Corvallis in late 1980 (M.E. Martignoni personal communication) and this figure is 

probably even higher for material from Sault Ste. Marie. This cost figure is based on a 

dosage of 250 x 10' PIBlha. This dosage can probably be reduced to 125 x 10 9 PIBlha 

(I1nytzky et al. 1977), and possibly even lower. 

The mountainous terrain and consistently low relative humidity encountered in the 

interior of British Columbia pose problems for aerial application of pest control agents 

and particularly for application of aqueous spray formulations. Use of an oil-based 

formulation should be investigated, for this may well enhance the deposit and facilitate 

application of lower dosages. 

Ideally, application of a virus initiates an epizootic in the pest insect population, 

regulating the pest either in the year of application if applied on early-instar larvae, or in 

the subsequent year. Some NPVs have the potential to initiate epizootics and others 

have not; the status of Douglas-fir tussock moth NPV has not been established and the


Orgyia psellClolsllgata (McDunnough). 367 

virus has been applied in the same manner as a chemical pesticide. Although adequate 

control has been achieved, the material is too scarce and too costly to be applied in this 

way. Alternative methods should be investigated, such as seeding the NPV into the 

insect population. This could be tested by spraying widely spaced swaths to give partial 

coverage of the infested forest. Spread of the disease would then be relied on to regulate 

the Douglas·fir tussock moth population. 

Among the few viruses currently being developed as biological control agents of 

forest insect pests in Canada, Douglas.fir tussock moth NPVs have proved to be 

effective pest management tools. Further testing and an attempt to register MNPV in 

Canada for operational use are strongly advocated. Improved production methods, 

lower dosage rates, and different strategies for its use may reduce the cost of treatment 

and make MNPV more attractive to forest managers. 

Furtht!r efficacy trials with B.t. may be warranted, as better strains and improved 

application technology become available. This work, however, should have lower 

priority than the virus work described above. 

Abbott, W.S. (1925) A method of computing the effectiveness of an insecticide. Journal of Economic Entomology 18.265-267. 

Hughes, K.M.; Addison. R.B. (1970) Two nuclear polyhedrosis viruses of the Douglas·fir tussock moth. Journal of Invertebrate Pathology 

16,196-294. 

I1nytzky, S.; McPhee. J.R.; Cunningham. J.C. (19n) Comparison of field'propagated nuclear polyhedrosis virus from Douglas-fir tussock 

moth with laboratory-produced virus. Canadian Department of Fisherits and Forts"y Bi-monthly 

Research Notts 33(1).5-6. 

Johnson. P.C.; Ross. D.A. (1967) Douglas-fir tussock moth. Hemerocampa (Orgyia) pseudotsugata McDunnough. In: Davidson. A.G.; 

Prentice. R.M. (Camps. and Eds.) Important forest insects and diseases of mutual concern to Canada. the 

United States and Mexico. Onawa; Canadian Department of Forestry and Rural Development. pp. 

105-107. 

Morris. O.N. (1963) The natural and artificial control of the Douglas-fir tussock moth. Orgyia pseudotsugata McDunnough. by a nuclear 

polyhedrosis virus. Journal of Insect Pathology 5.401-414. 

Shepherd, R.F. (Ed.) (1980) Operational field trials against Douglas-fir tussock moth with chemical and biological insecticides. Canadian 

Forestry Service. Victoria. British Columbia. Information Report BC-X-201. 19 pp. 

Stelzer. M.; Neisess. J.; Cunningham. J.C.; McPhee. J.R. (1m) Field evaluation of baculovirus stocks against Douglas-fir tussock moth in 

British Columbia. Journal of Economic Entomology 70.243-246. 

Sterner. T.E.; Davidson. A .G. (camp.) (1981) Forest insect and disease conditions in Canada 1980. Canadian Fortslry Service Forest Insect and 

Disease Survey. 43 pp. 

Sugden, B.A. (1957) A brief history of the Douglas-fir tussock moth, Hemerocampa pseudotsugata McD., in British Columbia. Proceedings 

of the Entomological Society of British Columbia 54.37-39.

Blank Page 

368

Pest Status 

Background 

Chapter 64 

Pristiphora erichsonii (Hartig), Larch 

Sawfly (Hymenoptera: Tenthredinidae) 

W.G.H. IVES and J.A. MULDREW 

The larch sawfly, Pristiphora erichsonii (Htg.), is a major pest of larches, LArix spp., 

in North America. It is the principal defoliator of tamarack, L. laricina (Du Roi) K. 

Koch, and also attacks western larch, L. occidentalis Nutt., and alpine larch, L. Iyallii 

ParI. Plantings of the various European and Asian species and their hybrids are also 

vulnerable (Turnock & Muldrew 1971a). Outbreaks have been recorded in Canada since 

late in the nineteenth century. Early outbreaks have been discussed by McGugan & 

Coppel (1962), and Turnock & Muldrew (1971a) summarized depredations for the 

decade 1959-68. Conditions since then have been outlined in the annual reports of the 

Forest Insect and Disease Survey (Anon. 1970-79). The folIowing account of infestation 

history from 1969 to 1980 is based primarily on these reports. Areas in which infestations 

of the larch sawfly have caused moderate or severe defoliation during this period are 

shown in Fig. 18. 

In Newfoundland, tamarack stands in the western and central parts of the province 

were moderately or severely defoliated in 1975, but most infestations colIapsed in 1976. 

A resurgence occurred along the west coast in 1979. In Labrador, an outbreak developed in 

1975, and by 1978 some tree mortality had been reported. In the maritimes, remnants of 

an earlier outbreak persisted into the period, particularly in southern New Brunswick 

and central Nova Scotia. In eastern Prince Edward Island, infestations increased in 

1970 and populations did not colI apse until 1976. By this time over 30% of the trees were 

dead, and many more had dead tops. In Nova Scotia, populations started increasing in 

1970 and by 1975 tamarack stands in most of the province were affected. Populations in 

the eastern half of the province colIapsed in 1976, but the decline was more gradual in the 

western half and some infestations still persisted in 1980. In New Brunswick, larch 

sawfly damage during the period 1969-80 was confined to a number of relatively smalI 

pockets. In Quebec, several extensive areas with medium or high populations were 

reported between 1974 and 1977. In most of Ontario, outbreaks from the previous 

decade persisted into the early part of the present period, but most populations had 

colIapsed by 1972. However, an upsurge in populations was soon noted in southern 

Ontario, where severe defoliation of larch was reported from 1974 to 1978, particularly 

in plantations of European larch. In Manitoba, old infestations also persisted into the 

early part of the period, particularly in the southeastern part of the province. A moderate to 

severe infestation occurred south of The Pas between 1972 and 1975. Only pockets of 

tamarack defoliation were noted in Saskatchewan between 1969 and 1980. Small 

pockets of defoliation were also reported in Alberta and in the Northwest Territories 

during the latter part of the period. A few infestations in British Columbia persisted in 

the early part of the period. The larch sawfly was extremely scarce on western larch until 

1976, when a population build-up occurred near Sparwood. This infestation collapsed in 

1980. 

The origin of larch sawfly in North America remains a matter of debate. Earlyentomologists 

(Fletcher 1885,1906, Fyles 1892, 1906, Hewitt 1912) considered the insect to be a 

recent introduction, and a number of workers still share this belief (Tumock 1972, 

Turnock & Muldrew 1973). The first larch sawfly outbreaks were noted in 1880 on the 

369

Pristiphora erichsollii (Hartig). 371 

eastern seaboard of the United States, and the insect appeared to spread westward 

(Coppel & Leius 1955, Nairn et ar. 1962). Reports of these early outbreaks indicated 

that their effects were particularly devastating. However, some entomologists have 

doubted the validity of the assumption of recent introduction, and feel that the insect has 

been here for a long time. Graham (1956) examined growth rings ofan old tamarack from 

northern Michigan and believed that he was able to trace evidence of sawfly attack as far 

back as 1734. Graham (1930) and Graham & Knight (1965) also reported growth 

reductions in tamarack before 1880, which they attributed to larch sawfly defoliation; 

however, the periods of supposed defoliation do not agree completely. Similarly, 

Daviault (1948, 1974) examined some old tamarack from Quebec and noted severe 

growth suppression, which he attributed to larch sawfly attack, about 1829 to 1845. 

However, Nairn el ar. (I962) pointed out that it is practically impossible to separate the 

effects of larch sawfly defoliation from growth suppression caused by unfavourable 

environmental conditions. Although some of their growth records, particularly those for 

Isle Pierre, British Columbia, show periods of growth suppression prior to the known 

occurrence of larch sawfly in the area, they did not claim that this suppression was due 

to larch sawfly attack. Lejeune & Martin (1948) also examined discs cut from trees up 

to 159 years old. They found evidence of outbreaks in Manitoba from 1908 to 1915 and 

from 1941 to the time of examination (1948) but apparently there was no evidence of 

earlier attacks. 

Wong (1974) believed that the larch sawfly reached North America during the Miocene 

Period via the Bering land bridge. He examined large numbers of larch sawfly adults and 

identified, on the basis of morphological characteristics, five distinct strains. Two 

strains occur only in North America, one is confined to Eurasia, and two occur in both 

North America and Eurasia, presumably as a result of an unintentional introduction 

in about 1910. 

The early attacks by the larch sawfly (Fyles 1892, Graham 1956) clearly demonstrate 

the severe impact that the insect can have on the successful production of larch. As a 

consequence, long-term population studies were undertaken in southeastern Manitoba 

to evaluate the effects of various factors on survival of the different life stages. These 

studies showed that none of the "native" agents behaved in a density-dependent manner 

and the populations fluctuated unpredictably (Ives 1976). The "native" factors are as 

follows. Egg survival is affected by adverse temperatures and several invertebrate 

predators, but both types of mortality are relatively unimportant. Feeding larvae are 

attacked by various vertebrate and invertebrate predators, larvae may be dislodged by 

storms, and starvation may cause mortality during severe outbreaks. Some disease 

organisms, including fungi, bacteria, microsporidia, and rickettsiae attack feeding larvae, 

but their effects are usually negligible. The only "native" parasitoid of any consequence in 

these studies was the tachinid Bessa harveyi (Tns.), which attacks late-instar larvae. 

However, the rates of attack were not related to population trends. Long-term sampling 

of parasitoids of larch sawfly in Manitoba and Saskatchewan by the Forest Insect and 

Disease Survey also failed to show any relationship between parasitism and population 

trends (Ives personal communication). Although parasitism was quite high, it was identical 

(44 %) for both increasing and decreasing larch sawfly populations. Elsewhere in Canada, 

Eclytus ornatus Hlmgr. (which may be a recent introduction from Europe) is a larval 

parasitoid of some importance in Newfoundland, and the pteromalid Trilneplis klugii 

(Ratz.) is occasionally an important cocoon parasitoid in drier sites in British Columbia 

(Turnock & Muldrew 1971a). Fully fed larvae dropping to spin cocoons are susceptible to 

predation and heat prostration, and some may drown in pools of surface water. Survival 

in the cocoon phase is affected by a number of factors. Those of minor importance include 

invertebrate predation and fungal diseases. The principal sources of mortality in this 

phase, apart from introduced parasitoids discussed later, are high water tables and

372 W. G. H. Ives and J. A. Muldrew 

predation by small mammals. The combined effects of these were key factors in determining 

population trends (Ives 1976). 

These factors clearly demonstrated the paucity of regulating factors in Canadian larch 

sawfly populations. Hewitt (191O) had been studying the larch sawfly in England before 

his appointment as Dominion Entomologist. He had found the ichneumonid Mesoleills 

tenthredinis Morl. to be an effective parasitoid of the larch sawfly and, as it was absent 

from Canada, he made arrangements for its importation and release between 1910 and 

1913. The releases in Manitoba were successful and parasitism by M. tenthredinis 

gradually increased to nearly 90% by 1927 (Graham 1931) and seemed to be a factor in 

terminating the outbreak. However, when the larch sawfly again reached outbreak 

proportions, about 1940, it was noted that M. tenthredinis was no longer an effective 

parasitoid due to encapsulation of the eggs by host blood cells which prevented hatching 

(Muldrew 1953). This encapsulation reaction gradually spread across continental North 

America, and at present only larch sawfly populations in Newfoundland and cordilleran 

British Columbia remain highly susceptible to M. tenthredinis (Bronskill 1960. Carroll 

1964). The lack of quarantine precautions at the time of the initial release was probably 

the cause of this change in susceptibility. Instead of releasing adult parasitoids. the 

release in Manitoba was made by placing host cocoons in a bog near Aweme to let the 

parasitoids emerge naturally (Hewitt 1917). Because not all the cocoons were parasitized. 

sawfly adults were released as well. This seemed harmless enough, as an outbreak was 

in progress at the time. However, subsequent research (Maw 1960) indicated that some 

of these adults probably possessed the encapsulation ability. Their progeny gradually 

spread across Canada, and have now become the predominant strain in most areas 

(Wong 1974). 

The decrease in effectiveness of M. tenthredinis prompted a renewed interest in 

biological control. Redistribution of B. harveyi and T. killgii was undertaken (Turnock 

& Muldrew 1971a) but the results were disappointing. A decision was therefore made in 

1957 to renew the search for suitable candidates in Europe and Japan. A number of 

species were considered, but only two releases were successful; a Bavarian strain of M. 

tenthredinis and another ichneumonid, Olesicampe benefactor Hinz. In addition, the 

masked shrew, Sora cinereus cinereus Kerr, was successfully introduced into Newfoundland 

from New Brunswick. 

During the collection of possible parasitoids in Europe, a number of M. tenthredinis 

were obtained. Laboratory experiments showed that those from Bavaria were only 

slightly encapsulated by their hosts, as were the progeny of back-crosses of this strain 

with M. tenthredinis originating from the earlier introductions. Two releases were made 

in Manitoba in 1963 near Hodgson and in 1964 near Rennie (Turnock & Muldrew 1971a). 

Increases in parasitism (the two "races" are morphologically indistinguishable) clearly 

indicated that the Rennie release was successful. M. tenthredinis from the early release 

were more abundant in the Hodgson area and trends following the 1963 release of the 

Bavarian M. tenthredinis were inconclusive. 

A number of successful releases of O. benefactor were made between 1961 and 1968 

(Turnock & Muldrew 1971a). Parasitoids collected in Europe were released in Manitoba 

near Pine Falls in 1961 and near Riverton in 1%2 and 1963, and in Saskatchewan near 

Crutwell in 1964. Relocations of parasitoids collected near Riverton and Pine Falls were 

made as follows: Manitoba in 1967 and 1968; Saskat('hewan in 1965; and the maritimes 

in 1967 and 1968. 

A hyperparasitoid, Mesochorus dimidiatus Hlmgr., has been responsible for limiting 

the effectiveness of O. benefactor in Europe, and extreme care was exercised in the 

initial releases to ensure that none of the hyperparasitoids were inadvertently released. 

However, M. dimidiatus was recovered from the Pine Falls release area in 1966. 

Apparently M. dimidiatus was a rare but widely distributed holarctic species in Canada 

before the release of O. benefactor. and has now been recorded in most areas where this


Olesicampe benefactor 

Hinz. 

(Hymenoptera: 


Pri.slip/lOra erichsonii (Hartig), 373 

parasitoid has been released. Rates of hyperparasitism by M. dimidiatus usually increase 

rapidly and there is reason to be concerned about the future effectiveness of O. benefactor. 

The masked shrew, S. cinereus cinereus, was successfully introduced into Newfoundland 

in 1958, when 12 females and 10 males were released near St. George's. Most of the 

individuals in the initial release survived the first winter and their progeny have prospered 

and spread and now probably occupy most of the suitable habitats throughout the island. 

Biological control studies of the larch sawfly during the period 1969 to 1980 have 

consisted of the redistribution of O. benefactor and Mesoleius tenthredinis, plus follow-up 

studies of these parasitoids and of the masked shrew in Newfoundland. 

Most of the redistributions of parasitoids involved O. benefactor (Table 95). The 

population increase and dispersal of O. benefactor are discussed in detail by Muldrew 

(in press). He has incorporated additional data that were not analysed by Turnock & 

Muldrew (1971a), so that his values for maximum dispersal in 1966 and 1967 are greater. 

He reports that the rate of dispersal was about 1 km after 4 years, 3 km after 5 years, and 

5 km after 6 years. Follow-up sampling until 1974 showed that the rate of dispersal 

increased dramatically between 1969 and 1971 (Fig. 19). In 1969. the maximum recorded 

distance was 87 km (at the Rennie life-table plot). Sampling in 1970 was inadequate for 

assessing dispersal but O. benefactor was recovered in northern Minnesota 293 km 

south of the release point (Kulman et al. 1974, Thompson & Kulman 1976). Extensive 

sampling by Muldrew in 1971 detected O. benefactor at Ignace, Ontario, 357 km from 

the release point. The maximum detected dispersal distance by 1972 was 476 km. 

However, larch sawfly populations began declining throughout the area in 1972, while 

hyperparasitism by Mesochorus dimidiatus increased. Apparently these factors influence 

the rate of spread, as the maximum recorded distance increased by only 64 km, to 540 km, 

by 1974. 

The dotted lines in Fig. 19 show the approximate maximum rates of parasitism at 

different distances from the release point. Until 1969 , the points are clustered around the 

lines, but the scatter increases for 1971, 1972, and 1974. Part of this increased variability 

was attributable to the relatively slow spread of O. benefactor into southern Manitoba. 

Muldrew (in press) surmised that the direction of the prevailing winds and abundance of 

tamarack may have been the main reasons for the slow dispersal into this area. However 

by 1974 the rates of parasitism in southern Manitoba had increased considerably, and 

there was already some indication of a relative decline in rates of parasitism elsewhere, 

possibly due to hyperparasitism by M. dimidiatus. Although not shown in Fig. 19 the 

rates of M. dimidiatus parasitism increased dramatically from 1969 to 1974. In 1969, 

about 80% of O. benefactor near the release point were parasitized by M. dimidiatus. In 

1971, high rates of hyperparasitization had extended to nearly 200 km from the release 

point. By 1972, the high levels of M. dimidiatus attack had extended to over 300 km. 

Muldrew (personal communication) indicatedM. dimidiatus probably transferred to O. 

benefactor at a number of locations. The apparently rapid rate of dispersal between 1969 

and 1971, and the variable levels of hyperparasitism from 1971 to 1974 both agree with 

this hypothesis. There was little additional increase of M. dimidiatus parasitism in 1974, 

but the apparent decrease in O. benefactor parasitism is probably attributable to the 

hyperparasitoid. 

Information on increases in parasitism and dispersal from other release points is 

rather limited. A release of 694 males and 737 females was made near The Pas, Manitoba

374 W. G. H. (ves and J. A. Muldrew 

Table 95 

Species and province 

Redistribution releases and recoveries of Olesicampe benefactor Hinz and Mesoleius 

tenthredinis Morl. against Pristiphora erichsonii (Htg.) 

Location of release Numbers released 


Year Origin Lat. long. Males Females Total recovery 

"N OW 

Olt!sicampt! btlU!factor Hinz 

Prince Edward Island 1971 Nova Scotia 46001' 62°44' 157 117 274 1974 

1972 Nova Scotia 46"29' 63°58' 198 189 387 

Nova Scotia 1973 Nova Scotia 45°14' 62"49' 393 457 8SO 

1975 Nova Scotia 45°43' 63"09' 63 1976 

1975 Nova Scotia 45°16' 63°18' 20 1976 

1976 Nova Scotia 45"21' 61°54' 45 1977 

1976 Nova Scotia 45°19' 62°15' 69 1977 

Ontario 1976 Minnesota 79"18' 44004' 182 213 395 1977 

1978 Manitoba 75°11' 45°12' 30 32 62 

Manitoba 1969 Manitoba 49"48' 97"08' 60 53 113 1974 

1970 Man. and Sask. 49"19' 96000' 421 443 864 1970 

1971 Manitoba 50003' 96°13' 245 262 S07 Already present 

1972 Manitoba 49"19' 96000' 75 74 149 

Alberta 1972 Manitoba 54°43' 110004' 1283" 

1972 Manitoba 54"27' 113°58' 1139" 1973 

1972 Manitoba 55001' 119"06' 469- 1973 

1973 Alberta 54·30' 112°57' 118 122 240 1974 

1975 Manitoba 53"32' 117'04' 51 86 137 1975 

1981 Alberta 59"55' 111°43' 36 

Northwest Territories 1m Manitoba 60")6' 116006' 856- 

1981 Alberta 60"01' 112"07' 332 1981 

1981 Alberta 60"01' 110058' 30 

British Columbia 1980 Alberta 49"42' 114·55' 170 

1980 Alberta 49"29' 115004' 145 

1980 Alberta 49"38' 114·56' 150 

Mtsoltius Itnlhrt!dinis Morley 

Manitoba 1970 Man. and Sask. 4919' 96000' 63 85 148 

1971 Manitoba 49"19' 96000' 98 170 268 

1m Manitoba 49"19' 96000' 9 42 51 

• Estimates only - "small" cocoons were placed in the field, adult parasitoid emergence holes were counted 

and proportions of O. benefactor and Mesochorus'dimidiatus were based on reared samples. 

Meso/eius tenthred;n;s 

Morley 

(Hymenoptera: 

Ichneumonldae) 

in 1968. O. benefactor had dispersed 18 km by 1973 and 57 km by 1975,7 years after the 

release. Another release, consisting of 51 males and 86 females, was made near Obed 

Lake, Alberta, in 1975. O. benefactor parasitism near the release area reached 88% by 

1979 and 93 % by 1980. Seventeen per cent of the larch sawfly larvae in a bog 15 km east of 

the release site were parasitized by O. benefactor in 1980. None had been found in this bog 

in 1979. 

Dispersal from The Pas and Obed Lake releases, 18 km and 15 km in 5 years, is 

considerably greater than the 3 km in 5 years recorded for the initial release at Pine Falls. 

This may simply be due to a different set of environmental conditions, but it could 

indicate that O. benefactor has become better adapted to the Canadian environment. 

Redistributions are shown in Table 95.


Sorex cinereus 

cinereus Kerr 

(lnsedivora: Sorlddae) 


The masked shrew, introduced into Newfoundland in 1958, has continued to spread. 

Survey reports for 1969 and 1970 (Anon. 1970-79) mentioned the concern of local 

residents as high initial numbers were noted in each area: by 1971 the shrew had spread 

over 95% of the island. Populations on the island, excluding the first 2 or 3 years' data, 

averaged about eight shrews per hectare, which seems to be unusually high. However, 

the 18-year average populations of the masked shrew in the Rennie life-table plot (Ives 

1981) was 5.2/ha. If one includes populations of the closely related arctic shrew, Sora 

arcticus Kerr, which averaged 1.8/ha, the total of 7.01ba is comparable. Populations of 

the masked shrew in Newfoundland therefore seem to have stabilized, and can be 

expected to fluctuate in the future in response to environmental conditions. 

O. benefactor and larch sawfly populations have probably not yet reached an equilibrium, 

even at the original release point near Pine Falls. As shown in Fig. 19, the level of O. 

benefactor parasitism at or near the release point reached 90% in 1967. It remained at or 

near this level until 1972, but larch.sawfly populations collapsed in 1973, presumably as a 

result of the continued high rates of parasitism (rves 1976). No larvae or cocoons were 

obtained near the plot in 1973 or 1974, although intensive sampling was conducted 

(Muldrew in press). Detailed studies were discontinued after 1974, and further trends 

are based on limited sampling. In 1977, a collection of 72 fourth- and fifth-instar larvae 

was made near the original release site at Pine Falls. None was parasitized by O. 

benefactor. In 1978, collections of larvae from the same area yielded 1730 cocoons. 

Parasitism by O. benefactor was 1.5%, hyperparasitism by Mesochorus dimidiatus was 

86%. A total of 237 third- to fifth-instar larvae collected 8 km north of the release point in 

1978 contained no O. benefactor, but 19% of 424 fourth- and fifth-instar larvae from an 

area 8 km south of the release point were parasitized. NinetY7three per cent of these O. 

benefactor larvae were parasitized by M. dimidiatus. In 1980, a total of 535 cocoons 

was obtained from the same location; 15% of these contained O. benefactor, of which 

75% were parasitized by M. dimidiatus. No O. benefactor were present in 150 cocoons 

obtained by rearing late-instar larvae collected in 1980 near the Seddon's Comer lifetable 

plot, about 70 km south of the Pine Falls release point. 

Although the above data are rather fragmented, there is some evidence that O. 

benefactor is in danger of local extinction over a fairly wide area. Should this happen, it 

is possible that the larch sawfly may increase in abundance if environmental conditions 

are favourable. No population sampling of the larch sawfly was done in the Pine Falls 

release area in 1980, but observations by Ives indicated that this population increase 

may already be taking place. It remains to be seen whether or not O. benefactor will be 

able to prevent an outbreak in spite of the adverse influence of M. dimidiatus. O. 

benefactor is host specific, but M. dimidiatus is not (Pschorn-Walcher & Zinnert 1971). 

Because of this, one would expect M. dimidiatus to be able to persist on alternate hosts, 

thus obtaining a "head start" on any re-invading O. benefactor. Under these circumstances, 

M. dimidiatus would probably be able to control O. benefactor, thus permitting larch 

sawfly populations to reach outbreak proportions. However, a crude model developed 

by Ives (1976) indicated that the two parasitoids should reach an equilibrium with each 

other and with the larch sawfly. According to the model, the larch sawfly populations 

would fluctuate in response to density-independent environmental factors, but should not 

reach outbreak proportions in the presence of O. benefactor, even when M. dimidiatus is 

present. It is too early to tell which hypothesis is correct. 

The impact of the masked shrew on larch sawfly populations in Newfoundland has not 

been assessed in detail (Warren 1971). The fact that larch sawfly infestations reached

i'risliphora erichsonii (Hartig). 377 

outbreak proportions late in the decade 1971-1980 clearly indicates that the shrews 

were not able to control the insect. However, as Warren (1971) indicated, "the shrew has 

been a valuable predator of larch sawfly, and, despite some evidence of reduced 

parasitism, there has been an important net gain in cocoons destroyed". Ives (1976) 

showed that mortality during the cocoon and adult stages was largely responsible for 

determining population trends. Small mammal predation is often a major component of 

this mortality, thus agreeing with Warren's assessment of the effect of the masked shrew 

in Newfoundland. 

Although there is some indication that larch sawfly popUlations in and around the Pine 

Falls release site may now be on the increase, there has been a period of several years 

when this insect was extremely difficult to find. It was probably not as rare as in Europe, 

but it was much less common than it has been in recent memory. Two recent papers 

illustrate just how rare the larch sawfly can be in alpine areas of Europe. Lovis (1975) 

collected only six larch sawfly (out of a total of 2816 larch insects) during a 3-year study 

of insects attacking native European larch in Switzerland. Auer (1971) studied the 

population dynamics of the larch bud moth, Zeiraphera diniana Gn., in the Upper 

Engadine Valley in Switzerland between 1949 and 1968. He presented population curves 

for eight larch insects for the period 1952 to 1968. The larch sawfly was apparently too 

rare to be included. 

The infestation patterns of the larch sawfly have been discussed by Turnock (1972). 

He did not consider the effects of O. benefactor, but with slight changes his discussion is 

still valid. He recognized three types of life systems: I) the stable latent type with a 

diverse environment and a rich parasitoid complex, characteristic of infestations on larch 

in alpine Europe; 2) the stable permanent type with a paucity of specific parasitoids, 

characteristic of many North American outbreaks before 1920; and 3) the temporary type 

with an intermediate parasitoid complex which includes one (or two) very effective larval 

parasitoid(s). characteristic of European plantings. infestations on western larch in 

British Columbia and on tamarack in the rest of Canada following the first successful 

introduction of an ichneumonid parasitoid between 1910 and 1913 (and in southeastern 

Manitoba following the successful introduction of O. benefaclor there in 1961). As this 

discussion of life systems illustrates, entomologists have been able to achieve at least 

partial biological control ofthe larch sawfly in North America. To continue this control, it 

may be necessary to seek ways in which biotic agents in the environment can be manipulated. 

Turnock & Muldrew (1971b) and Turnock et al. (1976) recognized four ways in 

which insect parasites or predators might be manipulated in order to help achieve 

biological control: 1) colonization releases; 2) inoculative releases; 3) inundative releases; 

and 4) enhancement of biotic agents by environmental manipulation. In the case of the 

larch sawfly, the last three approaches offer the most promise. Because of the presence 

of M. dimidiatus, any releases of O. benefactor would need to be relatively large if they 

were to be effective. Releases intermediate in size between inoculative and inundative. 

say 2 000-3000 mated females, should be able to control infestations in plantations in 2 

or 3 years, if released when defoliation first becomes noticeable. However, this approach 

would necessitate a permanent facility capable of producing parasitoids on demand. 

Reliance on field populations would be too uncertain, especially as M. dimidiatus will 

almost certainly reduce the numbers of O. benefactor adults obtainable. The Bavarian 

strain of Mesoleius tenthredinis could probably be managed in a similar manner. Both 

species might even be able to sustain themselves in the field, and thus afford more or less 

permanent protection. In Manitoba O. benefactor appeared to suppress M. tenthredinis 

by sheer numbers. but this seems unlikely to happen again. 

Enhancement of environmental conditions might be a particularly effective method 

for increasing the effectiveness of avian and small mammalian predators in plantations. 

Buckner (1971) discussed this situation as it related to forest insects in general. Birds 

might be encouraged to nest in plantations by providing suitable nesting sites. Bruns

378 W. G. HIves and J. A. Muldrew 


(1960) reported that this approach appeared to be effective in controlling pine insects in 

Germany. In the case of small mammals, research would have to be conducted to ensure 

that voles do not attack larches. Neither of us has observed evidence of this, but some 

tree species are severely damaged by voles. If high vole populations are not a threat to 

the trees it should be possible to enhance the environment by providing adequate cover, 

either in the form of slash or between-row vegetation, as several workers have shown 

that mouse and shrew populations are highest in areas with adequate cover (Morris 

1955, Beer 1961, Coulianos & Johnels 1962). Any such manipulation would have to be 

done carefully, to avoid creating an environment favouring snowshoe hares. However, 

it should be possible to improve the environment of the plantations as habitats for voles 

and shrews but not hares. This would increase the amount ofsmall mammal predation, 

which should reduce the frequency of larch sawfly outbreaks. 

In low-lying situations it may be possible to flood the plantations at critical times in the 

larch sawfly's life cycle, as suggested by Buckner (1971). Hooding the plantations for 

short periods in the fall, soon after cocoon formation, or in the spring when the insects 

are in the pupal stage would have a marked effect on larch sawfly survival (Lejeune et 01. 

1955) but would not seriously damage the tamarack trees if carefully timed. It would also 

adversely affect small mammal populations, but this could be minimized by careful 

timing. If flooding could be done just before parasitoids are released, it might 

increase their effectiveness considerably, as the initial rate of parasitism would be 

higher. 

Finally, should serious infestations develop that may endanger the trees in plantations, 

it may still be possible to control the larch sawfly without unduly affecting the other 

biotic agents. In the case of M. tenthredinis, spraying with a larval insecticide (preferably 

one that does not kill adult Hymenoptera) when most ofthe larch sawfly larvae are in the 

first to third instars would reduce the sawfly populations but should not have an undue 

adverse effect on the parasitoids, as they attack mainly fourth- and fifth-instar larvae. 

Because of the prolonged period of larch sawfly emergence it would not be feasible to kill 

all the larvae, but it should be possible to reduce populations appreciably and thus 

enhance the effectiveness of M. tenthredinis. The use of chemicals in the presence of O. 

benefactor would be more difficult. Probably the most productive approach would be to 

reduce sawfly populations only to the extent that defoliation would not exceed 70%. This 

would save the trees, but should not have an unduly adverse effect on the parasitoids. 

The Bavarian strain of M. tenthredinis was released near Rennie, Hodgson, and St. 

Labre. It is known to have become established at Rennie, but how far it spread before 

being overwhelmed by O. benefactor is not known. The extremely low density of larch 

sawfly in the vicinity of the Rennie plot for several years after its establishment may 

mean that its numbers were markedly reduced, if not eliminated. No follow-up studies 

were conducted in the St. Labre area, so it is not known if the Bavarian strain (from the 

Rennie plot) became established or not. 

It is therefore recommended that the Bavarian strain of M. tenthredinis be released in 

the Pine Falls area as soon as larch sawfly populations in the Bavarian plantations are 

high enough to make collection feasible. The results of the release at the Rennie plot 

looked extremely encouraging and a second attempt to establish this strain seems 

warranted. In Europe, M. tenthredinis is the most important insect parasite of the larch 

sawfly (Pschom-Walcher & Zinnert 1971) and there seems to be a reasonable chance of 

the Bavarian strain assuming this position in Canada, now that Mesochorus dimidiatus 

seems destined to limit the effectiveness of Q. benefactor. 

O. benefactor has been widely redistributed in various parts of Canada, from the 

maritimes to British Columbia. There does not seem to be much point in continuing with


Maw, M.G. (1960) Notes on the larch sawfly, Pristiphora erichsonii (Htg.) (Hymenoptera: Tenthredinidae), in Great Britain. Entomologist's 

Gazette 11,43-49. 

McGugan, B.M.; Coppel. H.C. (1962) Biological control of forest insects - 1910-1958. In: A review of the biological control allempts 

against insects and weeds in Canada. Commonwealth Institute of Biological Control Technical Communication 

2,35-127. 

Morris, R.F, (1955) Population studies on some small forest mammals in eastern Canada. Journal of Mammalogy 36,21-35. 

Muldrew, J.A. (1953) The natural immunity of the larch sawRy (Pristiphora erichsonii (Htg.» to the introduced parasite Mesoleius 

tenthredinis Morley, in Manitoba and Saskatchewan. Canadian Journal of Zoology 31,313-332. 

Muldrew, J.A. (In press) Dispersal of Olesicampe benefactor Hinz, an introduced parasite of the larch sawfly. Canadian Forestry Service. 

Northern Forest Research Centre. Edmonton. Infonnation Report. 

Nairn. L.D.; Reeks. W.A.; Webb. F.E.; Hildahl, V. (1962) History of larch sawfly outbreaks and their effects on tamarack stands in 

Manitoba and Saskatchewan. Canadwn Entomologist 94.242-255. 

Pschom-Walcher, H.; Zinnen. K.D. (1971) Investigations on the ecology and natural control of the larch sawRy (Pristiphora erichsonii Htg., 

Hym.: Tenthredinidae) in central Europe. Pan II: Natural enemies: their biology and ecology, and their 

role as monality factors in P. erichsonii. Commonwealth Institute of Biological Control Technical 

Bulletin 14,1-50. 

Thompson, L.C.; Kulman, H.M. (1976) Parasite complex of the larch sawRy in Minnesota. Environmental Entomology 5.1121-1127. 

Tumock, W.J. (1972) Geographical and historical variability in population pallems and life systems of the larch sawRy (Hymenoptera: 

Tenthredinidae). Canadian Entomologist 104,1883-1900. 

Turnock, W.J.; Muldrew, J.A. (1971a) Pristiphora erichsonii (Hanig), larch sawfly (Hymenoptera: Tenthredinidae). In: Biological control 

programmes against insects and weeds in Canada, 1959-1968. Commonweahh Institute of Biological 

Control Technical Communication 4,175-194. 

Tumock, W.J.; Muldrew, J.A. (1971b) Parasites. In: Toward integrated control. US Depanment of Agriculture Forest Service Research 

Paper NE-I94. Nonheastem Forest Experiment Station, Upper Darby, Pennsylvania. pp. 59-87. 

Tumock, W.J.; Muldrew, J. A. (1973) Characteristics of Bessa harveyi (Diptera: Tachinidae) suggesting the historic introduction of the larch 

sawfly to Nonh America. Manitoba Entomologist 6,49-53. 

Tumock, W.J.; Taylor, K.L.; Schroder, D.; Dahlsten, D.L. (1976) Biological control of pests of coniferous forests. In: Huffaker, C.B.; 

Messenger, P.S. (Eels.). Theory and practice of biological control. New York; Academic Press, pp. 

289-311. 

Warren, G.L. (19ul) Introduction of the masked shrew to imrrove control of forest insects in Newfoundland. Proceedings of the Tall Timbers 

Conference on Ecologica Animal Control by Habitat Management 2,185-202. 

Wong, H.R. (1974) The identification and origin of the strains of the larch sawRY' Pristiphora erichsonii (Hymenoptera: Tenthredinidae), in 

North America. Canadian Entomologist HI6.1121-1131.

Pest Status 

Background 

Chapter 65 

Pristiphora geniculata (Htg. ), Mountain 

Ash Sawfly (Hymenoptera: Tenthredinidae) 

F.W. QUEDNAU 

The mountain-ash sawfly, Pristiphora geniculata (Hartig), is a major defoliator of 

mountain-ash, mainly Sorbus americana Marsh, and S. aucuparia L. These tree species 

have little industrial importance but are planted widely as shade and ornamental trees. 

The mountain-ash sawfly was accidentally introduced into the United States in 1926 

(Schaffner 1936) and was first recorded in Canada in southern Quebec in 1934 (Petch 

1935). Its present Canadian range is from Newfoundland to southwestern Ontario (Fig. 

20). There has never been a serious outbreak. The sawfly causes noticeable and occasionaJly 

complete defoliation of mountain-ash, but this seldom causes mortality of the 

tree. To owners of such trees and to municipal park authorities, the insect is a considerable 

nuisance and often requires localized control by chemical methods. An account of the 

biology of mountain-ash sawfly in eastern Canada was given by Forbes & Daviault 

(1964). P. geniculata usually has one generation a year, but there may be a partial second 

generation depending on the climate. 

The decision to embark on a biological control programme in Quebec against P. geniculata 

was determined by the policy to reduce chemical control in urban forestry and by the 

success of biological control in Manitoba against the closely related larch sawfly, P. 

erichsonii (Htg.), on tamarack, Larix laricina (Du Roi) K. Koch (Muldrew 1967, 1973). 

Data furnished by the CIBC European Station suggested that the ichneumonid wasp 

Olesicampe geniculatae Quednau & Lim, would be a primary candidate for introduction 

into Canada. Another parasitoid species under consideration was the ichneumonid wasp 

Rhorus sp. No.3. 

During the first years of attempts to colonize these parasitoid species in Quebec, 

infestation levels of mountain-ash sawfly were very low. Furthermore, in 1972 O. geniculatae 

was not found in sufficient numbers in Europe to warrant a shipment to Canada. 

However, in 1973, heavy infestations of P. geniculata occurred in several localities near 

Quebec City. Because of the scarcity in Europe of P. geniculata, laboratory massrearings 

of the sawfly were carried out in Quebec in order to obtain host material that 

could be sent to Europe to increase the host populations there. The rearing techniques 

were essentially the same as those described for the larch sawfly by Heron & Drouin 

(1969). In 1974 the Laurentian Forest Research Centre sent 6 000 cocoons of Canadian P. 

geniculata to CIBC in Switzerland and another 30 000 cocoons in 1976. This insect 

material was reared to the adult stage in Europe and the sawfly females were placed in 

plastic bags tied over branches of mountain-ash trees in the Waldviertel area in Austria, 

where O. geniculatae and other parasitoid species of the mountain-ash sawfly were known' 

to occur in significant numbers during the previous years. As a result, in 1977 large 

numbers of O. geniculatae and Rhorus sp. No.3 were received in Quebec. 

381


Rhorus sp. No.3 

(Hymenoptera: 

[chneumonidae) 

Table 96 

0IeSaHnpe genJculBtae 

Quednau & Lim 

(Hymenoptera: 

[chneumonidae) 

The utilization of the parasitoid material is summarized in Table 96. 

Pristiphora geniclllata (Htg.), 383 

Parasitoids utilized for releases against mountain-ash sawfly, Pristiphora geniculoJa (Htg.), 

at Beaumont, Quebec (Iat. 46°50'N, long. 71002'W) 

Species Year Origin 

Rhorus sp. No.3 1973 Austria 


and Austria 

1975 Austria 

1976 Austria 

1977 Austria 

Olesicampe geniclliatae 1974 Switzerland 

and Austria 

1975 Austria 

1976 Austria 

1977 Austria 

No. and sex of 

parasitoids received 

Male Female 

5 

29 

12 

67 

35 

22 

5 

32 

16 

83 

35 

16 

2 3 

92 117 

315 551 

This is a solitary endoparasitoid, probably specific to P. geniculata. The egg is laid 

through the ocellus into the head capsule of the host larva. This wasp is closely related to 

R. iapponicus Roman, a parasitoid of the larch sawfly, the biology of which was 

described by Pschorn-Walcher & Zinnert (1971). Rhorus sp. No.3 was received in 

Quebec from 1973 to 1977. Cage releases were made at Beaumont nurseries. A male was 

recovered in the field in 1978, but the parasitoid apparently did not become permanently 

established. It is difficult to mate this insect in captivity. 

This is also an internal solitary parasitoid that prefers the first- and second-instar larvae 

of the mountain-ash sawfly for attack. It is specific to this host. In the early colonization 

work in Quebec only small numbers of the parasitoid were available and shipments from 

Europe were often not well synchronized with host populations in Quebec. No recoveries 

were obtained from these first releases. Major implantations of this parasitoid were 

made in 1977 at Beaumont nurseries. The female parasitoids were mated in the laboratory 

and released in batches in large tents of woven plastic screening built over mountain-ash 

trees, in which host densities were artificially increased by adding young colonies of P. 

genicuiata larvae collected from other areas. Small bottles of water were fastened to the 

branches of the trees in the tents. The host material was exchanged and new parasitoids 

added each day. The parasitized P. geniclliata larvae were brought to the laboratory, 

given plenty of mountain-ash foliage that was kept fresh in water bottles, and reared to 

about fourth instar. This method excluded natural predators. The sawfly larvae were 

then returned to the field and placed in wire baskets (100 per basket) containing some 

foliage. The baskets were tied to the branches of mountain-ash trees in the area chosen 

for implantation. Parasitized larvae eventually fell to the ground and formed cocoons. 

Successful establishment of this parasitoid depends on massive initial implantations 

to give the parasitoid a good chance to multiply in the field. A female O. genicu/atae can 

lay up to 400 eggs and live up to 3 weeks in the laboratory at 22°C and 75% relative

384 F. W. Quednau 


humidity (F.W. Quednau unpublished). The biology of this species is essentially the 

same as that reported for o. benefactor Hinz by Pschorn-Walcher & Zinnert (1971). 

O. geniculatae may have a partial second generation each year in the field. 

Whereas the colonization of Rhorus sp. No.3 was unsuccessful, O. geniculatae became 

firmly established at Beaumont nurseries, and within 4 years parasitized a large proportion of 

hosts. A brief history of this event follows. 

At the beginning of massive implantations in 1m, population densities of P. geniculata 

were medium to heavy, and 1 year later were light to medium. In the fall of 1978 it was 

found from dissections of sawfly cocoons that the percentage of parasitism at the release 

centre had dropped to 25-30%, compared to 60-75% in 1977, as a result ofthe dilution 

of the parasitoid population in the area. It was estimated that within 1 year O. geniculatae 

spread about 500 m from the original release centre. In 1979 infestations by the mountainash 

sawfly were only light at Beaumont. Of30soil samples of 0.1 m l each, taken near the 

original release point of the parasitoid, only 10 contained living cocoons (range 1-5) and 

parasitism was about 73%, much higher than in 1978. Other sampling plots about 500 m 

from the release point yielded 30-35% parasitism in 1979. In 1980, in the same locality, 

dissections of mountain-ash sawfly larvae that were still in colonies (about third instar) 

were made. The infestation level was from 700 to 1 250 young colonies of the sawfly per 

hectare. Percentage parasitism obtained from these dissections was 88.7-93.5% in all the 

plots containing mountain-ash in the nursery (up to 500 m radius from the release centre). 

No second generation of P. geniculata was observed in 1980. From an evaluation of host 

cocoons collected in the fall of 1980 it was found that the number of P. geniculata cocoons 

had further diminished as compared with 1979 and few were unparasitized. 

Preliminary indications for 1981 are that O. geniculatae has spread about 30 km from 

the original release site and could be recovered at Ste-Foy, Charlesbourg, La Durantaye, 

St-Charles de Bellechasse, St-Michel de Bellechasse, St-Etienne de Lauzon, and Chutes 

Mt. Ste-Anne where parasitism was 81, 24, SO, 30, 82,70, and 4% respectively. A quantitative 

evaluation of the impact of the parasitoid on its host population has not been carried out 

so far. However, preliminary measures of pest numbers in consecutive years in the 

original release site at Beaumont indicate a drastic decline of the host populaton (from 

500 colonieslha in 1980 to an estimated 30 colonieslha in 1981), which must be attributed 

primarily to the action of the parasitoid. Comparative population counts of P. geniculata 

at St-Edouard de Frampton, where the environmental structure is very similar to that at 

Beaumont, but is situated outside the action radius of o. geniculatae, indicate very high 

levels of infestation in 1981. 

The cost of chemical insecticide treatment against P. geniculala would be at least 

$2OOlha. For this reason most owners of property with mountain-ash do not use chemical 

treatments. The mass production of O. geniculatae would need extensive manual labour 

and costs cannot be calculated accurately at present. However, as the parasitoid spreads 

on its own, its implantation could be highly beneficial. 

During the evaluation work in summer 1980, a large number of the larvae of 

O. geniculatae found in the hosts were dead or appeared sick. At this stage it was decided 

to rear adults from P. geniculata cocoons collected from Beaumont in order to determine 

the percentage parasitism by O. geniculatae and to find out whether a hyperparasitoid was 

present. Emergence of the insects in 1981 revealed up to 90% total parasitism, but about 

60% of the parasitoids obtained were Mesochorus globu/alorThnb. This latter species is a 

hyperparasitoid with a wide distribution in Canada. It attacks various other species of 

Olesicampe associated with nematine sawflies.

Blank Page 

386

Pest Status 

Chapter 66 

Rhyacionia buoliana (Schiff.), 

European Pine Shoot Moth 

(Lepidoptera: Tortricidae) 

P.D. SYME 

The European pine shoot moth, Rhyacionia buoliana (Schiff.), has been known as a 

destructive pest of hard pine, Pinus spp., plantations in North America since it was 

identified in 1914 (Busk 1914). Its history and biology have been the subjects of extensive 

investigations prior to 1969 and are well summarized by McGugan & Coppel (1962), 

Pointing & Green (1962), Miller (1967), and Syme (1971). The status of R. buoliana has 

been under continual surveillance and has been recorded in the Annual Reports of the 

Forest Insect and Disease Survey. The known distribution is shown in Fig. 21 for eastern 

Canada and British Columbia. 

The European pine shoot moth has one generation per year and adults appear in the 

field over a 4·week period that begins between the first and third weeks in June. Eggs are 

laid singly or in small groups on the twigs or needle sheaths of the new growth. Incubation 

requires 2 weeks. First- and second-instar larvae mine needle bases on the new growth. 

Later they migrate to the new buds where they feed before overwintering as half-grown 

larvae within the bud. Feeding is resumed in the spring and is extended to additional 

buds before pupation takes place in May. 

R. buoliana is primarily a pest of pine plantations. In North America, red pine, Pinus 

resinosa Ait., is the most seriously damaged. Scots, Austrian, ponderosa, and ornamental 

Mugho pines, P. sy/vestris L., P. nigra Arnold, P. ponderosa Laws., and P. mugo 

Turra, respectively, are moderately susceptible; whereas pitch, Virginia, jack, and eastern 

white pines, P. rigida Mill., P. virginiana, P. banksiana Lamb., and P. strobus L., respectively, 

are relatively resistant. The needle-mining larvae cause a browning of the foliage, 

but this apparently has little effect on the vigour of the host. Feeding on the terminal bud 

causes serious injury to the main stem form and repeated destruction of the entire 

terminal cluster during the summer months initially causes profusion of shoot growth 

(witch's broom) and eventually a spike top when the leader dies. Various degrees of 

crookedness result from the lateral branches or buds assuming dominance over terminal 

shoots. Attack usually becomes less intensive as trees increase in height. 

In Canada, the European pine shoot moth is an important pest of pine plantations in 

southern Ontario, but it also exists in southern Quebec, primarily on ornamentals 

(Beique 1960). However, the Forest Insect and Disease Survey has not collected the 

moth in Quebec since 1968. Presumably the distribution within that province is unchanged 

but the prevalence is markedly decreased since 1968. In British Columbia the insect is 

well established, mostly on ornamental stock, in the Vancouver-Victoria area and to a 

lesser degree in the Okanagan Valley north to Kamloops (C.E. Brown 1981 personal 

communication). The European pine shoot moth was first reported in the maritimes at 

Bear River, Nova Scotia, in 1925 (Reeks et a1."1951), and has spread to cover all Nova 

Scotia, Prince Edward Island, and most of the southern half of New Brunswick. It has 

become a serious pest of Scots and red pine plantations in Prince Edward Island and 

Nova Scotia, where increased plantings have intensified the problem. However, there 

has been little spread in New Brunswick in the last decade and abundance has remained 

at a low level (L.P. Magasi 1981 personal communications). Since 1968 the European 

387

388 P. D. Symc

Rhyaciollia blloliallll (Schiff.). 3M!) 

pine shoot moth has remained an unimportant pest of ornamental pines in the cities of St. 

John's and Comer Brook in Newfoundland (A.G. Raske 1981 personal communication). 

The progressive distribution of the shoot moth in North America since 1968 suggests 

that the shipping of infested nursery stock has contributed strongly to its dispersal, 

resulting in a rapidly spreading but spotty distribution. This was particularly evident in 

the Maritime Provinces. The Forest Insect and Disease Survey has recorded the spread 

in that area as well as in British Columbia. Declining populations were noted in Quebec. 

In Ontario, the nothern limit of continuous distribution has held, as predicted (Green 

1962), at about the -29"C mean minimum temperature isotherm. The populations on 

Manitoulin and Cockburn islands in the North Channel of Lake Huron have collapsed 

because the host trees have outgrown susceptibility, and populations declined generally 

throughout the province during the 1970s. Changes in the economics and marketing of 

red pine, at least in Ontario, have further reduced the importance of the European pine 

shoot moth; deformed stems may be acceptable under some circumstances. 

In the rest of Canada, the situation remains static. In New Brunswick it is not known 

why the insect has not penetrated to the northern part of the province, although a lack of 

susceptible hosts could be an important factor. 

Background Although considerable work was done on various biological aspects of the European 

pine shoot moth before 1968 (Syme 1971), the research emphasis and the parasitoid 

monitoring capability changed after 1969. For example, studies on R. buolialla in 

Ontario were virtually confined to the effects of wild carrot, Daucus carola L.. and 

other flowering plants on the effectiveness of Orgi/us obscuralor (Nees), the most 

effective introduced parasitoid of the pest. Meanwhile, the earlier literature on the 

biology. behaviour, history, distribution, ecology. damage, and control were well reviewed 

(Pointing & Green 1962, Pointing & Miller 1967, Miller 1967, Syme 1971). Since 1973 

virtually no new research has been done in Canada on either the European pine shoot 

moth or its parasitoids. 

Releases and Recoveries The following brief descriptions of species of parasitoid include recoveries or significant 

range extensions of species released before 1968, and significant developments and 

findings on their possible effectiveness determined since 1968. The origin and numbers of 

released parasitoids are summarized in Tables 97 and 98. With the exceptions of O. 

obscurator (Nees), Lypha dubia (Fall.), and Parasierola lIigri/emllr (Ashm.). little can 

be reported. 

Table 97 Open releases and recoveries in Ontario of parasitoids against Rllyacionill bllolimuJ (Schiff.) 

Species Year of release Origin No. Released Year of recovery 

Agathis binominata 

Mues. 1969 Ontario 52 

1970 Ontario 33 1973 

Lyplla dubio (FaiL) 1969 Germany 496 1970 

Orgilus obscurator (Nees) 1969 Germany 218 



1972 Germany 82 1978 

Parasierola nigrifemur 

(Ashm.) 1974 Argentina (l}5

390 P. D. Syme 

Table 98 

Eulimneria runfernur 

(Thorn.) 

(Hymenoptera: 


Lypha dubla (FaD.) 

(Diptera: Tachinfdae) 

Orgilus obscurator 

(Nees) 

(Hymenoptera: 

8racooidae) 

Laboratory and field cage studies in Ontario or parasitoids against Rhyacionia 

buoliana (Schiff.) 

Species Year Origin Number 

Orgilus obscurator (Nees) 1969 Germany 778 





Parasierola nigri/emur (Ashm.) 1973 Argentina 56 

E. Tuft/emur was released before 1959 at Toronto, Niagra Falls, and Elmira (McGugan & 

Coppe11962) but has not been released since. Although it had spread significantly west 

of the release point by 1968 (Syme 1971), collapse of host insect populations made the 

parasitoid difficult to find. It was taken only once (1972) at Elmira and twice (1969,1971) 

near Drayton, 16 km NW of Elmira, always in small numbers. Because this parasitoid 

interacts with O. obscuTator. to the latter's detriment, and in view of the relatively 

greater importance of O. obscurator. E. ruft/emur is considered detrimental to the 

control effectiveness of the two parasitoids. 

This species was described in 1810 from Sweden (Stone et 01. 1965) and is recorded by 

Thompson (1951) from many species of Lepidoptera in Europe. It is a primary larval 

parasitoid that deposits living larvae on twigs or foliage near host larvae. The wide range 

of host habitats suggests that a complex of closely related species may be involved. Small 

numbers were released in Nova Scotia against the winter moth, Operophtera brumata 

(L.), but none was recovered (Embree 1971). 

L. dubia attacks late-instar larvae of the European pine shoot moth, and after rapid 

development within the host the parasitoid larva drops to the ground to pupate. It spends 

most ofthe summer and all winter in the ground as a fully developed adult, which emerges 

at about the time the R. buoliana begins feeding in the spring. There is a pre-oviposition 

period of about 4 weeks. 

Studies in Europe showed that there was no serious interference by this species with 

Orgi/us obscurator, the most effective introduced parasitoid in Ontario, and that L. dubia 

is one ofthe more effective parasitoids in northern Germany (Adlung & Sailer 1963, D. 

Schroeder, CISC, Delemont, Switzerland, personal communication). 

The parasitoid had also been released against R. buoliana in the United States in the 

years 1933-38 and again in 1962 and 1963, but has not been recorded (Dowden 1962). 

Although 90% of 1 200 puparia set out at Elmira in 1968 successfully emerged (Syme 

1971), only a few were recovered and only enough in 1970 to say that at least one pair of 

flies had successfully emerged and mated! No parasitoids have been recaptured from a 

release at Vance Tract, Wellington County, Ontario. Thus L. dubia, despite its effectiveness 

in northern Germany, does not seem to be effective against the European pine shoot 

moth in North America. 

O. obscurator is an internal solitary parasitoid that attacks first-instar larvae. Its life 

history has been described by Juillet (1960). Early introduction of the parasitoid and 

movement of nursery stock infested with R. buoliana resulted in a wide distribution of O. 

obscurator in Ontario (McGugan & Coppel 1962). In 1968 it was present virtually

c 

.2 

5 

:g 

Cij 

c 

Rhyacion;a buoliuna (Schiff.), 391

392 P. D. Syme 

Temelucha inlemlptor 

(Grav.) 

(Hymenoptera: 


ParageroIa nigrifemur 

(Ashm.) 

(Hymenoptera: 

Bethylldae) 

throughout the range of European pine shoot moth in Ontario and collections since that 

date have confirmed this (Fig. 22). It was also well established throughout Quebec, in the 

maritimes, and in Michigan, where it had not been released (Syme 1971). 

Since 1968, this parasitoid has become widespread throughout Nova Scotia and 

Prince Edward Island and has been found in the southeastern corner of New Brunswick 

(L.P. Magasi 1981 personal communication). In Newfoundland it has been recovered 

twice, both times at St. John's (A.G. Raske 1981 personal communication). No releases 

have ever been made of this parasitoid in either the maritimes or Newfoundland. Thus, 

the hypothesis expressed by McGugan & Coppel (1962) and Syme (1971), that the 

parasitoid and its host are easily dispersed by planting infested nursery stock, is clearly 

reinforced by the events of later years. It is also known that O. obscurator disperses well 

on its own, for at Cockburn Island in Lake Huron, where it had been released in 1966 

(Syme 1971), it was recovered 5 years later (1971) at Sand Bay, 12 km from the release 

point. Here it parasitized 39% of the European pine shoot moth, indicating it had been 

present for some years. In 1972 no R. buo[iana could be found at Sand Bay. 

In British Columbia, where again no intentional releases have ever been made, O. 

obscllrator occurs in the general area of Vancouver-Victoria (C.E. Brown 1981 

personal communication) (Fig. 22). 

In Ontario, where further studies have been made of the beneficial effects of wild 

carrot and other flowering plants on the longevity and increased fecundity of O. obsauator 

(Syme 1977), several situations were studied since 1968 that supported this technique of 

enhancing parasitoid attack. At one small plantation in Brantford Township, Brant 

County, where D. carota was plentiful, O. obscllralor was released during the summer 

of 1972. The population was not sampled in 1973 or 1974, but by 1975 parasitism had 

risen to 60% and no European pine shoot moth population remained in 1976. In three 

other plantations replete with D. carota, parasitism rose to over 50% in 3 to 4 years with 

the concurrent demise of the European pine shoot moth population. 

It seems apparent that the presence of a suitable source of food in the form of D. 

carota can, under otherwise favourable conditions, increase the effectiveness of O. 

obscllrator to a level virtually able to eliminate the European pine shoot moth population. 

On the basis of these results, workers in Nova Scotia are attempting to establish wild 

carrot in pine plantations, but the results are not yet fully known (L.P. Magasi 1981 

personal communication). 

This primary internal larval parasitoid with cleptoparasitic habits (Syme 1971) has not 

been released since 1961. It persists at Elmira, Ontario, where it competes to the 

detriment of O. obscllralor. T. interrllptor was virtually always in a host with O. obscllrator, 

resulting in the death of the latter. Thus, in a field experiment designed to show the effects 

of D. carola, on O. obscllralor at Elmira, from 1966 to 1978, T. interrllptor parasitized up 

to 50% of the hosts already attacked by O. obscuralor, preventing the latter from 

attaining levels of parasitism over 40% necessary to cause the collapse of host populations. 

Thus it confounded the field trial that otherwise showed promise of demonstrating the 

beneficial effects of D. carota on O. obscurator. 

This external, multivoltine gregarious parasitoid had been found to be very effective 

against European pine shoot moth in Argentina (Brewer & Varas 1971). With background 

supplied by E.M. deBrewer, Department of Entomology, Cordoba National University, 

laboratory tests in Canada (Sault Ste. Marie) demonstrated that P. nigrifemur showed 

no tendency to select for hosts parasitized by O. obscllralor. Thus it has no cleptoparasitic 

tendencies (Syme 1974). Consequently, on 21 August 1974,695 adults (unsexed) 

were released at a site 4.5 km north of Elsinore, Amabel Township, Bruce County,

Agatbis binominata 

(Mues.) (Hymenoptera: 

Braconidae) 


Rhyacionia buoliana (Schiff.) 393 

Ontario. The trees averaged 1.4 m in height and there was an abundance of flowering 

plants including D. carola. In that same year, in October, two adult P. nigrifemur were 

found during the annual fall sample, but they were not associated with any apparent 

hosts. No parasitized hosts were found during the next 2 years. We can only conclude 

that the attempted introduction was a failure. 

Although this native parasitoid was released at Vance Tract, Wellington County, Ontario 

in 1%9 and 1970, only a single larva was recovered in 1973 and none in 1975, 76 or 77. 

Reasons for its failure to establish are speculative. 

The difficulties of evaluating the impact of biological control agents on the European pine 

shoot moth were discussed by Syme (1971) and can be summarized by stating that the 

host-pest relationship and pest damage change drastically with time. In the absence of 

any further trials of exotic parasitoids or further behavioural studies, the well-established 

European species O. obscuralor seems to offer the greatest promise for effective 

localized biological control in Canada. Several cases have been documented in which, in 

the presence of D. carota flowers. O. obscuralor has brought about complete collapse of 

the R. buoliana infestation within a few years. 

As O. obscuralor is a univoltine internal parasitoid, chemical control applied to the 

host larval stage in the spring will remove a proportionate part of the parasitoid population. 

Chemical control of the early-instar needle-mining stage will have a negative impact on 

the parasitoid adult population, which would be actively searching for hosts. This would 

depress the parasitoid population disproportionately. Thus if chemical control is required 

within an integrated pest management scheme, the spring wandering stage of the European 

pine shoot moth would be the time to spray and cause the least potential damage to O. 

obscurator. Similarly, a systemic insecticide applied in the spring would have the least 

effect on O. obscuralor, but any insecticide will depress the parasitoid population to some 

extent. 

It should be pointed out here, however, that wild carrot is listed in the secondary 

noxious class of the Canada Seed Act of 1961 and is listed in The Weed Control Acts of 

Manitoba, Nova Scotia, Ontario, and Quebec. It is detrimental to cattle when they 

ingest large quantities, and taints the milk, but Dale (1974) has pointed out that it is not a 

weed of cultivated fields and prime agricultural land and that there are no reports of 

cattle grazing on it from choice. Further, it does not compete in a well-established turf 

and is not found where ploughing is an annual event. 

Wild carrot may also affect commercial production of carrot either by transmitting 

pests or harbouring diseases common to both cultivated and wild varieties, or by causing 

the production of poor seed of commercial varieties when hybridization occurs (Frankton 

1955). However, in Canada carrot seed is grown commercially only in British Columbia 

(Dale 1974). 

On the positive side Dale (1974) indicates that D. carola has a relatively high nutritive 

value and should be regarded with greater tolerance when found in pastures among 

plants of low nutritive value. Thus foresters concerned with the establishment of red pine 

might well question the status of wild carrot as a noxious weed.

394 P. D. Symc 



The parasitoid O. obscuralor appears to be ubiquitous and the methods for manipulating 

D. carola are published (Syme 1976), so it remains for the system to be practised and 

refined. The method may in some instances be labour-intensive. However, if a plantation is 

established where D. carola already occurs, the plantation manager may preserve the 

wild carrot to favour O. obscuralor at virtually no cost. 

This unique method whereby the probability of control can be enhanced by manipulating the 

environment into which a parasitoid is introduced, thus favouring its survival and 

effectiveness, represents a new working principle that requires emphasis in future 

research as well as in methodology associated with biological control attempts. 

Adlung, K.G.; Sailer, R.I. (1963) Forest entomological studies in German afforestation areas, with special regard to pine shoot moth 

parasitoids of Rhyacionfu buoliana (Schiff.). Allgemeine Forst- und Jagdzeirung 134.229-238. 

Beique, R. (1960) The importance of the European pine shoot moth Rhyacionia boo/funa (Schiff.) in Quebec City and vicinity. Canadfun 


Brewer. M.; Varas, D. (1971) Cria masiva de Parasierola nigrifemur (Ash.), (Hym., Bethylidac) -primeras liberuciones en Calamuchita, 

Cordoba, Argentina. Revista Peruana de Entomologia 14,352-361. 

Busk, A. (1914) A destructive pine moth introduced from Europe. Journal of Economic Entomology 7,340-341. 

Dale, H.M. (1974) The biology of Canadian weeds. 5. Daucus carota. Canadian Journal of Plant Science 54,673-685. 

Dowden, P.B. (1962) Parasites and predators of forest insects liberated in the United States through 1960. US Department of AgriculTUre 

Handbook 226, 70 pp. 

Embree, D.G. (1971) OperopltJera brumata (L.), winter moth (Lepidoptera: Geometridae). In: Biological control programmes against 

insects and weeds in Canada, 1959-1968. Commonwealth Instirute of Biological Control Technical 

Communication 4,167-175. 

Frankton, C.(l955) Weeds of Canada. Ottawa, Ontario; Queen's Printer, 196 pp. 

Green, G. W. (1962) Low winter temperatures and the European pine shoot moth. Rhyacionia buoliana (SehUf.) in Ontario. Canadian 


Juillet, J.A. (1960) Immature stages, life histories, and behaviour of two hymenopterous parasites of the European pine shoot moth, 

Rhyacionia buolfuna (Schiff.) (Lepidoptera: Olethreutidae). Canadian Entomologist 92,342-346. 

McGugan, B.M.; Coppel, H.C. (1962) Biological control of forest insects, 1910-1958. In: A review ofthe biological control attempts against 


2,35-127. 

Miller, W.E. (1967) The European pine shoot moth - ecology and control in the Lake States. Forest Science Monograph 14,72 pp. 

Pointing, P.J.; Green, G.W. (1962) A review of the history and biology of the European pine shoot moth, Rhyacionia buoliana (Schiff.) 

(Lepidoptera: Olethreutidae) in Ontario. Proceedings of the Entomological Society of Ontario 92,58-69. 

Pointing, P.J.; Miller, W.E. (1967) European pine shoot moth. In: Important forest insects and disease of mutual concern to Canada, the 

United States and Mexico. Canadian Department of Forestry and Rural Development Publication 

1180,162-166. 

Reeks, W.A.; Forbes, R.S.; Cuming, F.G. (1951) Canadfun Department of Forestry and Rural Development Annual Report, Forest Insect 

and Disease Survey 1950, pp. 5-20. 

Stone, A.; Sabrosky, C.W.; Wirth, W.W.; Foote, R.H.; Coulson, J.R. (1965) A catalogue of the Diptera of America, nonh of Mexico. US 

Department of AgriculTUre Handbook 276, 1696 pp. 

Syme, P.O. (1971) Rhyacionia buoliana (Schiff.), European pinc shoot moth (Lepidoptera: Olethrcutidae). In: Biological rontrol programmes 

against insects and weeds in Canada, 1959-1968. Commonwealth Institute of Biological Control Technical 

Communication 4,194-205. 

Syme, P.O. (1974) Interaction between three parasitoids of the European pine shoot moth. Canadian Forestry Service Bi-monthly Research 

Notes 30(2),9-10. 

Syme, P.O. (1976) Red pine and the European pine shoot moth in Ontario. Canadian Forestry Service Information Report O-X-244, 17 pp. 

Syme, P.O. (1977) Observations on the longevity and fecundity of Orgilus obscurator (Hymenoptera: Braconidae) and the effects of certain 

foods on longevity. Canadfun Entomologist 109,995-1000. 

Thompson, W.R. (1951) A catalogue of the parasites and predators of insect pests. Sect. 2, Pt. 1. Hosts of the Coleoptera and Diptera. 

Commonwealth Institute of Biological Control, 147 pp.

396 Appendix 

Raske, A.G., Newfoundland Forest Research Centre, Canadian Forestry Service, Environment Canada, Bolt 6028, St. John's, Newfoundland 

AIC SX8. 

Schooley, H.O., Pctawawa National Forestry Institute, Canadian Forestry Service, Environment Canada, Chalk River. Ontario KOJ lJO. 

Schroeder, D., European Station, Commonwealth Institute of Biological Control. I Chemin des Grillons, CH·2800 Delemont, Switzerland. 

Shemanchuk, J.A., Researeh Station, Agriculture Canada, Bolt 3000, Lethbridge, Albena TlJ 4BI. 

Shepherd, R.F .• Pacific Forest Research Centre. Canadian Forestry Service. Environment Canada, S06 Wcst Burnside Road, Victoria, 

British Columbia V8Z IMS. 

Smirnoff, W.A.. Laurentian Forest Research Centre, Canadian Forestry Service, Environment Canada, Bolt 3800. Stc·Foy. Quebec GlV 4C7. 

Syme, P.D .• Great Lakes Forest Research Centre, Canadian Forestry Service, Environment Canada. Bolt 490. Sault Stc. Marie, Ontario 

P6A SM7. 

Thompson. L.S .• Researeh Station. Agriculture Canada, Bolt 1210. Charlottetown, Prince Edward Island CIA 7M8. 

Tumock, W.J., Research Station, Agriculture Canada, 19S Dafoe Road, Winnipeg, Manitoba R3T 2M9. 

TyrreD, D., Forest Pest Management Institute, Canadian Forestry Service. Environment Canada, Bolt 490. Sault Ste. Marie. Ontario P6A 5M7. 

Van Sickle, G.A .• Pacific Forest Researeh Centre, Canadian Forestry Service. Environment Canada. 506 West Burnside Road, Victoria, 

British Columbia V8Z IMS. 

Vanyo I.W., Maritimes Forest Researeh Centre. Canadian Forestry Service. Environment Canada. Bolt 4000. Fredericton. New Brunswick 

E3B SP1. 

Watson. A.K .• Macdonald Campus, Faculty of Agriculture. McGill University, Ste-Anne de Bellevue, Quebec H9K lCO. 

Whisler, H.C .• Depanmcnt of Botany, University of Washington. Seattle. Washington. USA 9819S. 

Wilkinson. A.T.S, Research Station, Agriculture Canada. 6660 N.W. Marine Drive, Vancouver. British Columbia V6T IX2. 

Wilson. G.G., Forest Pest Management Institute. Canadian Forestry Service. Environment Canada, Bolt 490. Sault SIC. Marie, Ontario P6A 5M7. 

Wylie, H.G., Research Station, Agriculture Canada, 19S Dafoe Road, Winnipeg, Manitoba R3T 2M9. 

Zebold, S.L. Depanment of Botany. University of Washington, Seattle, Washington. USA 9819S.

Index of Species 

Abies amabilu 229 

abdulghani, Telraphleps 

Abiesbalsamea 229,235,236.241.242,251,252,254.256. 

263,271.321,359 

Abiesfirma 267 

Abies/raseri 229 

Abies grandis 229 

Abies lasiocarpa 229 

Abies spp. 226.229.267 

abielu. Neodiprion 

abruplorius. Exenterus 

absinth - see Arlemisia absinlhium 

absinthium. Arlemisia 

acanthium. Onopordum 

acanthoides. Carduus 

acaulis. Silene 

Acernegundo 315 

Acersaccharum 314.349,350 

Acerspp. 353 

Aceriaacropliloni 105 

Achilleafilipendulina 114 

Achilleaplarmica 114 

Achromobaclerspp. 35 

Acleris varian a 321 

Acrididae 5 

acridophagus, Nosema 

acroplili. Puccinia 

A cropli/on repens 97, 105·110 

acropli/oni, Auria 

acroplilonica, Aulacida 

AClinocephalus lipulae 85 

Acyrthosiphon neerlandicum 160 

Acyllhosiphonpuum 4,7 

Acyrthosiphum cyparissiae 168 

Adalia IUleopicla 230 

Adalia ronina 230 

Adalia lelraspilola 230 

Adelges merkeris 234 

Adelges nusslini 234 

Adelges piceae 215,220,229·234,321 

adelgid - see Adelges spp. 

adelphocoridis, Perulenus 

Adelphocoris lineolalus 4,5,9·10 

adonidis, Emomosce/is 

adslriclus, Pleroslichus 

Aedes aegypli 24 

Aedes dorsalis 23 

Aedes jlavescens 24 

Aedes sierrensis 24 

Aedes triseriatus 24 

Aedes vexans 23 

atgypli, Aedes 

atreus, Monodontomerus 

atrogenes, Enterobacler 

atlhiopoides, Microclonus 

a/finu. Exenttrus 

a/finis, Urophora 

Agapela zoegana 129,136 

Agalhis binominQla 218,389,393 

AgQlhis cincta 287,289 

Agathispumila 218,281·282,283.287 

Agriahousei 217,218.267,268.271 

Agri/ushyperici 98,172.174,176 

Agromyza/rontella 4,11·13 

Agropyron crislalum 121 

Agropyron repens 121 

Agryponjla\'eolatum 218.353.354·355.356 

alba, Populus 

alba. Silene 

albicans. Cyzenis 

a/Monica. PhyllOlrela 

albipes. Gryocenlrus 

Albugo Iragopogi 112 

alder-see Alnus spp. 

aldrichi, Sarcophaga 

alfalfa 7.9. 10. II. 41. 45. 46 

alfalfa blotch leafminer - see Agromyza /rontella 

alfalfa mosaic virus 205 

alfalfa plant bug - see Ade/phocoris lineolalus 

alfalfa weevil-see Hypera po.flica 

A/nusspp. 287 

alpine larch - see Larix Iyafli 

Aisophilapomelaria 223.354 

aisophilae. Telenomus 

Allicacarduorum 98.139-140.143 

amabilis, Abies 

amabilis fir - see Abies amabilis 

amaranthoides. Axyris 

Amerboa moschata 129 

Ambrosiaartemisii/olia 100.111-112 

Ambrosia cllamissonu III 

Ambrosiapsilostacltya III 

Ambrosia lenui/olia III 

Ambrosia Irifida III 

Ambrosiaspp. III 

americana. Entomoscelis 

americana. Sorbus 

americana. Ulmus 

amiclOrius. Exenterus 

ampelus. Mericia 

amp/iala, Tingis 

amy/ovorus. Bacillus 

Anaitisp/agiala 96.172.174.176.177 

Anaslalus disparis 218.306-307,308.309 

andalusica. Hadena 

annual sow-thistle -see Soncllus oleraceus 

Anopheles spp. 225 

antelope 183 

Amltemis lillcloria 114 

antiqua, Delia 4 

antirrltinii. Gymnaelron 

antisypltililica, Euphorbia 

ants 162,313-seealsoFormicaspp. 

anurus. Balhyplecles 

Apanteles arisba 70 

Apanleles circuTnscriplus group 70 

Apanteles circuTnscriptus 70 

Apanteles coleophorae 218. 287 

Apanteles corvinus 218. 287 

Apanteles /umi/eranae 271 

Apanle/esg/omeralus 16.17 

Apanteles lacleicolor 305. 308 

Apanteles laelus 70 

Apanteles laeviceps 34 

Apanteles melanoscellus 302 

Apanteies me.wxamlws 21 R. 287 

Apanteles mililaru 34 

Apanteies ornigu 69. 70 

Apanleles pedias 70 

Apanteles pllllellae 15. 17. 18 

397

398 Index of Species 

Apanlt'les rubecula 15.17. 18 

Apanlt'les solilarius 299.301 

Apanlt'les xylinus 50 

Apanteles spp. 58.286.287.288.289.302 

Aphidecla. oblilerala 230 

Aphidencyrllls aphidivertls 173 

Apllidius cardui 173 

aphidivmlS, AphidencYrlllS 

Aphidoletes thompsoni 230 

AphisclJ/oris 97.172-173.174.176,177 

Aphiseuphorbiae 168 

Aphlhona cyparissiae 168 

Apillhona czwalinae 168 

Apillhonaf!ava 168 

Apillhona spp. 168 

apple 25.69.101.211.353 

Archipscerasil'oranus 260 

Archipsoporana 226 

arclicus, Sorex 

A renelra rufipes "emalis 34 

arisba. Apameles 

armyworm-see Mameslraconfigurata 

Arlemisiaabsinlilium 113-114 

Artemisiacana 114 

A rlemisia dracun,ulus 114 

A rlemisia longifolia 114 

A rtemisia vulgaris 114 

Artemisiaspp. 114 

artemisiifolia, Ambrosia 

artichoke plume moth - see Platyptilia cardl/idaClyla 

artichoke - see Cynara scolymus 

Artogeia rapae 4. 15-18.81 

arvense, Cirsium 

arvense, Thlaspi 

arvensevar. inlegrifolium, Cirsium 

arvensis, Convolvulus 

an'ensis, Sonehus 

arvensis s. str .• Sonehus 

arvensis var. glabreseens, Sonehus 

Asclepias syriaeQ 99-see also milkweed 

aspen - see Populus spp. 

asper, Sonehus 

aster yellows 205 

alalanlae fulveseens, Theronia 

Athrycia cinerea 50.54 

A thrycia erythroeera 53 

Atilryeia impressa 53 

allantieus, CeUlorhyneilus 

alralula, Leueopis 

atricapilano, Coehylis 

Queuparia,Sorbus 

Aulacidaacroptiloniea 105.109 

auricularia, Forfieula 

Austrian pine - see Pinus nigra 

Axyrisamaranliloides 121 

azurea, Cassida 

Bacillus amylovorus 211 

Bacilluscereus 35,313 

Bacillus sphaerieus 35 

Baeilluslhuringiensis vii,3,15,18,33,35,57.58,79,80,87, 

215.217,218-219,221,222,224,225,237,238-247.264. 

265,274,276,278,308,309.313.314-315.317.318,356. 

365-366.367 

BacillllS Ihuringiensis var. israelellsis 20.21 

Bacillus IhurillgiellSiHar. kurslaki 15.238 

bacu10virus-see viruses 

bakeri, Copidosoma 

Balauslium sp. 231 

ball cactus - see Mammillaria vivipara 

Ballia el/c/Jaris 231 

balsam fir-see Abies balsamea 

balsam fir sawny - see Neodiprion abietis 

balsam poplar-see Popl/lllS balsamifera 

balsam woolly ade1gid - see A delges piceae 

balsamea, Abies 

balsamifera, Populus 

Ballel,us f!aveseells 50.51.54 

ballksialla. Pill us 

bardus, Larinus 

barley 155 

basizOIllIS, PleolopllllS 

bassialla, BeaUl'eria 

balalas, Ipomoea 

BalhypleCles allllTllS 41 

BalhypleCles curculionis 41. 42 

BalhypleCles slenosligma 41 

Bayeriaeapiligena 168 

BeQuveriabassiana 219.223,313.344 

Beal/variasp. 302 

beech - see FagllS grandifolia 

begini, DiglypllllS 

benefaclor, Olesieampe 

bertha armyworm - sec ,\-Iamestra eonfigurata 

Bessa haTl'eyi 371.372 

Belulalenta 291 

Betula papyrifera 285, 291. 349.350 

Betula populi folia 287. 291 

Belula verrueosa 291 

Belulaspp. 291 

bieolor, Eupleetrus 

bieolor, Metriona 

bieolor, Mieroetonus 

biebersteinii, Centaurta 

biennis, Chorisloneura 

Bigoniehetasetipennis 39,40 

bimaeulatipennis, Sympiesis 

bindweed - see Com'olulus arvensis 

binominata, Agathis 

binuc/eatum, Nosema 

bipinllalllS, Cosmos 

birch-see Betula spp. 

birch casebearer - see Coleophora serratella 

birch leafminer - sec Fen,usa pusilla 

birds 85,129.187.258.313.343.377-378 

Bislonfiduearius 168 

bivillalus, Melanoplus 

black cottonwood - sec Populus triehoearpa 

black spruce - see Pieea mariana 

bladder campion - see Silene eucubalus 

blaneardella, PI,yllonoryeter 

Blepharipa pralensis 306 

Blondelia lIigripes 53 

blueberry 359 

bohemiea, Drino 

borealis, Campoplex 

borealis, LygllS 

Borrelinavirus - see viruses 

Braehymeria intermedia 306 

Brachypterolus puliearillS 180, 181

Brassica campestris - sec canola. rape 

Brassica hina - see mustard 

Brassica juncea - see mustard 

Brassicanapus 211-see alsocanola. rape 

brassicae, Mamestra 

breili, Harmonia 

brel'ifaciens, Clostridium 

broad leaved toadnax - sec Linaria dalmatica 

browntail moth -see Euproctis chrysorrllOea 

Bruce span worm - see Operopll/era bruceata 

bruceala, Operophtera 

brumala, Operopll/era 

Brussels sprouts 17 

buckthorn -see Rhamnus cathartica 

buckwheat 222 

bUCl'rus, Catcoblastis 

bUdworm - see Acleris I'ariana, Choristmleura spp. 

buffalo weed - see Ambrosia tri{tda 

bull thistle - see Cirsillm l'll/gare 

bllllalus. Geocoris 

blloliana, Rhyacionia 

cabbage 51 

cabbage looper - see TriclropllLria tli 

cabbage moth -see Mamestra brassicae 

cabbage worm - see A rtogeia rapae 

Cacloblastis bllcyrus 183·184 

CaclOblastis doddi 183-184 

cactus - see Mammillaria I·i\·ipara, Oputrtia spp. 

calcilrapaevar. cenraurea, Puccitlia 

calidllm, Calosoma 

California encephalitis 23 

califomica. Coccinella 

caliginosus, Harpalus 

Caloplrasia Illnuia 97.98. 180-182 

Calosoma calidum 34 

Calosoma sycoplranra 309 

calycinum, Hypericum 

Calyslegia spp. 155. 157 

Camnula pelillcida 4, 61-62 

campion - see Silene cucuballlS 

Campolelis flavicinclus 34 

Campolelis sp. 34 

Camponol/IS lrerCIIleanrlS 342 

Campoplegini sp. 53 

Campoplex borealis 218.287 

Campoplex spp. 218. 286. 287.288. 289 

Campylomma verbasci 211 

cana, Artemisia 

Canada thistle - sce Cirsium arl'(mse 

canadensis. Exenrerus 

x canadensis, PoplI/lLr 

cankerworm - see Alsophiia pomelaria 

cano1a 49 

capi/igena, Bayeria 

capsulae. DasitlellTa 

carabids 162.343 

cardui, Aplridius 

.carelui. Uroplrora 

carduidactyla. Plalyplilia 

carduorum. Allica 

CardUUSaCalllhoides 97.115-125 

CarduusnUlans 96.97.99. J(XI. J06.109. 115·125 

CarduuiS nutaniS ssp. macrolepis 116 

Carduus personala 117. 118 

('meill/u p),ctlOceplra/lls 124 

Carel,ll/.r tetlllifloTlu 124 

Carc/Illlsspp. 117.145 

caritlalCl. EtIlylia 

Carolina poplar - sec POlmlus x canadensis 

carolCl, DallCilS 

carrot 222.389.392.393.394 

carthami, I'uccinia 

CarthamlLHinclOriu.r 129. 139 

cascbcilrcr -sec Coleop/rora spp. 

Cassiela aZllrea 203.2o.t 

Cassiela hemisphaerica 203 

Cassida rubiginosa 139. 141. 145 

cassielea. Cllelymorp/ra 

Ctllhartica. Rhamnus 

Celyp/ra rosaceana 206.108 

Centaureabiebersleitlii 130.132-133 

Cetllaurea cineraria 129 

CetllaureadiffrlSa 96.97.99.106.127-137 

Centaureajurineafolia 133 

Cetllaureamacll/osa 96.97.99.106.127-137 

Cetllallrea tligra 129 

Cetllaureaxpralensis 106 

CetllUllTea ragusina 129 

Cetllallrea reperrs - see A croptilon repens 

Cetllaurea rhetlana 130 

Centallrea I'Qllfsiaca 130. 132. 133 

Centallreaspp. 129 

centallreae. P'lccinia 

Cephaloglyplalaricis 218.268-269 

CephaloglYPla mllrinanae 218.268.269 

Cephalosporium coccorum 233 

Cel}halosporillm sp. 233 

cerasil·oratlllS. Archips 

cereilileilfbeetie-see Oulemamelanopus 

cerealella. Sitolroga 

cereals 7 -see also grain 

cerellS. Bacillus 

Ceroma.riasp. 53 

Index of Species 399 

CellllrorlryneilidillS IlOrrid,lS- sec Triclrosirocalus horridus 

CeulOr/r ynclllls atlatllicus 200 

CeulOrl,yncllllslilllra 97.139.140-141.143.144.145 

Clraelogena sp. ciaripennis group 50 

ClraelOgena sp. 50 

chaleilOtIla, Marellanria 

Chamaesplreciaempiformis 98.163-165.168 

Chamaesplreciatenrhrediniformis 98.160.163-165.167.168 

Clramaesplrecia spp. 161 

chamissOllis. Ambrosia 

Clrelinielea viltig('r 183 

Chelymorpha cassielea 156 

chitletuis, Di/lIItlllls 

Chiritia gllllalCl 156 

ell loris, Aphis 

ClrorislOnellrtl bietltlis 248 

ClrorislCmeura diversana 267 

Clroristotlellra fumiferana 215. 217. 218. 219. 220. 221. 222. 

224.226.235-237.238-276.277.295.321.341.346.366 

ClroriSlOtlellra mllritlana 226.267 

ClrorislOnellra occidenralis 215. 217.219. 221. 257.277-279 

ClrorisICJtlellra pitlll.r 260 

ClrorislOm'llraspp. 226.260.267 

chrysanthemums 77 

chrysocepllala. Psylliodes 

Clrrysocllari.r cllSpieiogasler 69


Chrysoc/laris laricinellae 69.218.281.282.283 

Chrysoc/laris pUllclifacies II. 12. 13 

Chrysoc/laris IricinclIlS 69 

Chrysocharis spp. 287 

Cllrysolina hyperici 96. 171. 173-175. 176 

Cllrysolinaquadrigemina 96.97.171.172.173.174.175.176 

Cllrysolina I'arians 98 

Chrysopa sp. 74 

chrysorrhoea, Euproclis 

cincla, Agalhis 

cinclipes. Exelasles 

cinclillrorax. Cirrospilus 

cilleraria. Celllaurea 

cinerea. Alhrycia 

cinereus cinereus. Sorex 

cinerosella, Euzophera 

cinnabar moth -see Tyria jacobaeae 

CirculiferlenellllS 191 

circumscriplllS. Apallleles 

CirrospilllS cinclillrorax 69 

Cirrospilus spp. 287 

Cirsiumarvense 97.98,101,102.109,139-146,195 

Cirsium arvense var. integrifolium 140 

Cirsiumdrummondii 142 

Cirsiumflodmanii 106 

Cirsium spinosum 118 

Cirsium vulgare 96.118.147-153 

Cirsiumspp. 116.117,142,145 

claripennis, Chaelogena 

c1earwinged grasshopper - see Camnula pellucida 

clear winged moth - see Chamaesphecia lenlhrediniformis 

Cleonuspiger 141.145 

cloacae, Enterobacler 

Clostridium brevifaciens 313 

Coccinellacalifornica 7 

Coccinellaseplempunclala 5.231 

Coccinella Irifasciala 7 

Coccinella undecimpunclala 7 

coccorum, Cephalosporium 

coccus, Daclylopius 

codling moth - see Cydia pomonella 

Coelomomyces psorophorae 23,24 

cole crops 15.18 

Coleophora fuscedinella 285 

Coleophoraklimeschiella 98.191-192 

Coleophoralaricella 215,218.220.222.281-284 

Coleophoraparthenica 98.191.192 

Coleophoraserralella 215,218,220,222,285-289 

coleophorae, Apanteles 

colesi, Mieroclonus 

coli, Escherichia 

Collops vi"alus 74 

comata. Slipa 

common buckthorn - see Rhamnus calhartica 

common mullein - see Verbascum Ihapsus 

common ragweed - see Ambrosia arlemisiifolia 

commUl'is. Meleorus 

Compsilura concinnala 16.301.305.306 

compla. Linnaemya 

concinnala. Compsilura 

confera, Leuzea 

configurata, Mames"a 

confusus, DaclylopillS 

congesla, Colesia 

conica. Sympiesis 

Conidiobolus sp. 261 

ccmquisilOr, flopleclis 

cOllSobrina. Emeslia 

Contarinia sc1,lechlendaliana 208 

Contarillia sonchi - see Contarinia schlechlendaliana 

com'o/l'uli, Er)'siphe 

COI'I'oll'uillS an'etlSis 155 

COIII'o/l'ulus sepium 156 

Com'oil'ulusspp. 155,157 

corOllala f. sp. al'ellae. Puccinia 

Copidoso",a bakeri 34 

corvillus. Apallleles 

Corylus spp. - see filbert 

cosmos III 

Cosmos bipimralus 111. 114 

COlesia cOllgesla 53 

COlesia glomerala 53 

COlesia lael'ieips 50 

Colesia melanoscelus 306 

cOllonwood - see POPUlllS spp. 

crane fly - see Tipula paludosa 

Cralaegusspp. 101,353 

creeping red fescue 180 

aislalllm. Agropyroll 

Cremifallia IIigrocellulala 231 

cricket paralysis virus 248 

crislala. Siphona 

crown rust of oats-see Puccinia coronala f.sp. al'enae 

Cruciferae 31.32,74 

allfiferae. Phyllolrela 

cruciferous garden crops 31 

cserei, Silene 

cucubalus. Silene 

Cucullia verbasci 211.212 

cucumber mosaic virus 205 

cucumbers 77, 78 

Culex pipiens 4. 19-21,24 

Culex quillquefascialus 24 

Culex reSlllallS 19 

Clliisela illomala 4.23-24 

culpalor, Slellic/lllellmoll 

cunea, Hyphan"ia 

Cllnealum, Nosema 

cllrclliiollis. Balhyplecles 

curly top virus 191 

cllSpidogaster, Clrrysoc/,aris 

cutworm - see Euxoa messoria 

cyanella, Lema 

Cyanus segelum 129 

Cyclops vemalis 23 

C)'diapomonella 4.25-27 

Cynarascolymus 106.109.129,139 

cyparissiae. AC)'rlhosiphum 

C)"parissiae, Aphlholla 

C)"parissias. Euphorbia 

cypress spurge - see Euphorbia cyparissias 

Cyrtacanthacridinae 62 

Cystiphora sonchi 97.206.207,208 

Cyrtoga.ftersp. 11 

cytoplasmic polyhedrosis virus - see viruses 

Cyzenisalbicans 217,218.353,354-355.356 

czwalinae, Aphthona 

Dacnusa dryas 11, 12. 13 

Dactylopius coccus 183

pellucida. Cyrtacanthacridinae. Melanoplus spp .• 

Oedopodinae 

great ragweed - see Ambrosia trifida 

greenhouse whitefly-see Trialeurodes vaporariorum 

Gregarina longa 85 

gregarines 61 

grey birch - see Betula populi/olia 

ground beetles 85 

ground squirrel 183 

grylli. Entomophthora 

Grypocentrus albipes 218.291.292.293·294 

gunata. Chirida 

Gymnaetronantirrhinii ISO. 181 

Gymnaetron tetrum 211 

Gypsophila repens 203 

Habrocytus semotus 287 

Habrocytuselevatus 141 

Habrocytus spp. 287 

Hadenaandalusica 204 

Hadena Iweago 204 

Hadrobunus maculosus 34 

hares 378 

Harmonia breiti 231 

Harpaluscaliginosus 34 

harveyi. Bessa 

hastata, Rheumaptera 

hay 79.204 

Helianthus sp. III 

sect. Helioscopa, Euphorbia 

heliothidis. Heterorhabditis 

hemipterus, Eupteromalus 

hemlock looper - see Lambdina {/Scellaria {/Scellaria 

herculean us, Camponotus 

hercyniae, Borrelinavirus 

hercyniae, Diprion 

hercyniae, Gilpinia 

Herpetomonas swainei 344 

Heterorhabditis heliothidis 220 

hilaris, Theronia 

Hirmocystis ventricosa 85 

Hirsutellathompsoni 261 

histrionanna, Dichelia 

Horismenus/raternus 69 

horridus, TrichosirocaIus 

honensis. Miscogaster 

housefly -see Musca domestica 

housei, Agria 

Howardulaphyllotretae 74 

Howardula sp. 73 

Hylemya seneciella 98, 197. 199. 200 

Hyleseuphorbiae 96.97.98.159.161·163.168 

Hyperapostica 4.41·43 

hyperici, Agrilus 

hyperici. Chrysolina 

Hypericumcalycinum 173 

Hypericum densiflorum 173 

Hyperieumper/oratum 96.97.98.99.171·177 

Hypericum rhodopaeum 173 

Hyphantria cunea 260 

iberica, Salsola 

impexus, Pullus 

imponed cabbageworm - see Anogeia rapae 

impressa, Athrycia 

ineertus, Tetrastiehus 

inornata, Culiseta 

insulare, Diadegma 

intermedia. Brachymeria 

intermedius. Diglyphus 

interruptor, Temelucha 

Ipomoea batatas - see sweet potato 

iridescent virus - see viruses 

isaea, Diglyphus 

Itoplectis conquisitor 81.306 

Itoplectis spp. 287 

jaceae, Larinus 

jaceae, Puccinia 

jack pine - see Pinus banksiana 

jack pine bud worm - see Choristoneura pinus 

jacobaeae, Longitarsus 

jacobaeae, Senecio 

jaeobaeae, Tyria 

Japanese fir-see Abiesfirma 

japonicus, Dicladocen/S 

jugoslavica, Sphenoptera 

julis, Tetrastiehus 

jurinea/olia, Centaurea 

kali var. tenui/olia, Salsola 

kasoehstaniea, Urophora 

kinghead - see Ambrosia trifida 

Klebsiella pneumoniae 35 

klimeschiella, Coleophora 

klugii, Tritneptis 

knapweed 95. 102-see also Acroptilon repens, Centaurea 

spp. 

knapweed root moth - see Agapeta zoegana 

kuvanae, Ooencyrtus 

lateicolor, Apanteles 

Lactuca sativa var. capita 114 

laetus, Apanteles 

laevieeps, Apanleles 

laevicips, Cotesia 

Lambdina {/Scellaria {!Seellaria 219. 226 

Lambdina {/Seellaria lugubrosa 226 

lapponicus, Rhorus 

larch - see Larix spp. 

larch case bearer - see Coleophora larieella 

large tooth aspen - see Populus grandidentata 

larieella, Coleophora 

laricina, Larix 

laricinellae, Chrysoeharis 

laricinel/um, Diadegma 

laricis. Cephaloglypta 

Laricobius eriehsonii 231 

Larinus bardus 105 

Larinusjaceaf 105 

Larix laricina 233.281.359.369.371.381 

Larix Iyallii 369 

Larix oecidentalis 281, 369 

Larix spp. 226. 369 

larvarum. Eulophus 

/arvarum, Exorista 

lan'arum, Fusarium 

lasioearpa, Abies 

Lathrolestes nigrieollis 218.291·294 

lathyris, Euphorbia 

Index of Species 403


lawn 85 

leafy spurge 95, 100, 102-see also EuphorbiQ esulQ·virgata 

complex 

leatherjacket-see TipulQ spp. 

LebiQ viridis 140 

LecQnium tiliae 215 

lecontei, Neodiprion 

legume crops 45 -see also alfalfa, red clover, sainfoin, sweet 

clover 

Leiobunum villQtum 34 

LemQcyanella 101,142,144 

Lespesia sp. 50 

lettuce 107,109,114 

Leucoma SQlicis 215,220,222,299·302,305 

Leucopis atrQlulQ 232 

Leucopis n .sp. nr. melQnopus 232 

Leucopis obscurQ 232 

leucostigma, OrgyiQ 

LeuzeQcon/erQ 129 

leviventris, Meteorus 

LinQriQ dQlmQticQ 98, 179·182 

LinQriQ l'ulgQris 97,179·182 

linden-see Tiliaspp. 

lineola, Thymelicus 

lineolaris, Lygus 

lineolatus, Adelphocoris 

Linnaemyacompta 34 

Liothrips sp. 111 

Lissonotasp. 218,267,268,270 

litura, Ceutorhynchus 

lituratus, Exochomus 

LobesiaeuphorbianQ 168 

locustae, MalamebQ 

locustae, Nosema 

loewi, Dasineura 

Lombardy poplar-see Populus nigra var. italica 

longa, GregarinQ 

longi/oliQ, Artemisia 

Longitarsus /lavicomis 198 

LongitaTSusjacobaeae 96,196,198·200 

Lophyroplectus luteator 218,313,334,335,338,339 

lugubris, FormicQ 

luna, Patasson 

lunula, Calophasia 

luteago, Hadena 

luteator, Lophyroplectus 

luteopicta, Adalia 

lyalli, Larix 

Lygus borealis 45 

Lygus deserlinus 45 

Lygus lineolaris 45 

Lygus rugulipennis 45 

Lygus shulli 45 

Lygus unctuosus 45 

Lygus spp. 4,45·47 

Lymantriadispar 216,217,218,219,220,221,222,225,268, 

303·310 

LyphQdubia 217,218,389,390 

Lysiphlebus/aborum 173 

maculipes, Pnigalio 

maculosa, Centaurea 

maculosus, Hadrobunus 

Malacosomadisstria 215,217,219,221 

MalQmeba locustae 61 

Malus spp. - see apple 

MamestrQ brassicae 49,5 I, 52, 53, 54, 85 

Mamestra configurata 4,49·55 

mammals, small 258,372 

Mammillaria vil'iparQ 183 

Manduca quinquemaculata 4,57·59 

Manitoba maple -see Acer negundo 

Mantis religiosa 5 

maple-sec Acerspp. 

mQrcescens, Serratia 

Marchantia cha/chonta 31 

mQrianum, Silybum 

maritima, Silene 

MaTSsoninasonchi 206 

marylandensis, Sympiesis 

masked shrew - see Sorex cinereus cinereus 

Matricaria matricarioides 114 

mQtricarioides, Matricaria 

MQtrusspp. 342 

maura, UrophorQ 

maxima, Tipula 

mediator, Microplitis 

MedicQgo sativa - see alfalfa 

Medicago sp. 11 

medullana, Peloclrrista 

Megaselia paludosa 87 

Meigelliamlltabilis 31,32 

Meigelliasp. 32 

Melandrium spp. 203 

Melanoplusbivillatus 61 

Melanopluspackardii 61 

Melanoplussanguinipes 61 

MelQnoplusspp. 4,61·62 

melanopus, Leucopis 

melanopus, Oulema 4 

melanoscelus, Cotesia 

melanoscellus, Apanteles 

Melilotus sp. 11 

Melitara dentata 183 

mella, Exorista 

menziesi;, PselldotsugQ 

Mericiaampelus 50,51,54 

merkeri, Adelges 

mermithids 73,74 

MeroslOmaspp. 19,21 

Mesochorus dimidiatus 372-373, 377, 378 

Mesochorus globulQtor 384, 385 

Mesochorusspp. 74 

Mesoleius tenthredinis 218,372,373,374,378,379 

mesoxanthus, Apanteles 

messaniellQ, Phyllonorycter 

messoria, Euxoa 4 

Meteoruscommunis 34 

Meteorus lel'iventris 34,53 

Meteorus versicolor 305,308 

MetrionQ bicolor 156 

MetrionQ purpurata 156 

MetzneriapaucipunctellQ 97,132-133,134,135 

mice 129,132,162,187,378 

Microctonus aethiopoides 41,42 

Microctonus bicolor 74,75,76 

Microctonuscolesi 41.42 

Microctollus villatQe 73 

M;croctonus sp. Z 74,75 

Microplitis mediator 51,53,54

.\ticroplitis pluu!llae 16. 17 

M icroplitis tubereulifer 53 

microsporidia 31. 61. 260-261, 262-265 

migratory grasshopper-sec Melanoplus sunguinipes 

militaris. Apunteles 

milkweed 222 

.'.finoamurinata 168 

minUlum. Trichogramma 

Miscogasterhortf?flsis 11, 12, 13 

modestus. Podi.ws 

moles 343 

MonodontomeTiu aereus 308 

montium. Tipula 

mosehata, Amberboa 

mosquito - see Aedes spp .. Anopheles spp., Culex spp., 

Culiseta spp. 

mountain ash - sec Sorbus spp. 

mountain-ash sawfly -see Pristiphora geniculala 

mountain pine beetle - see Dendroetonus ponderosae 

Mugho pine-see Pinusmugo 

mugo. Pinus 

mullein - see VerbasClim Ihapsus 

mullein leafbug-sce Campy/omma verbosci 

mullein shark moth -see Cucullia verbasci 

mullilineatum. Zagrammosoma 

murinanae. Cephaloglypta 

murinana. Choristoneura 

murinala. Minoa 

Mu.rca domeslica 4.63-64 

M uscina slabu/ans 34 

mustard 31 

mUlabi/is. Meigenia 

Nabisferus II 

nana. Diadegma 

nebulosus. Euloplllls 

necalrix. Vairimorpha 

neerlandicum. AcyrtllOsiphon 

negundo. Acer 

nematodes 220,225 - see also OD-136. mermithids 

Neodiprionabielis 216,217,221. 222.321-322 

Neodiprion lecontei 215,217.220.221.222,225,323-329 

Neodiprion pralli banksianae 343 

Neodiprionsmifer 215.217.218.220.221. 225. 331-340 

NeodiprionsK'ainei 215.217.218.219.221.222.341-348 

Neopleclanacarpocapsae 87 

ni. Trichop/usia 

Nicoliana sp. 211 

nigra. Centaurea 

nigra. Pinus 

nigra var. italica. Populus 

nigricana. Epinota 

nigrifemur. Parasierola 

nigripes. Blondelia 

nigrocellu/ata. Cremifania 

nigricollis. Lathrolestes 

nil·ale. Fusarium 

noclij7ora. Silene 

nodding thistle - see Carduus nUlatlS 

northern house mosquito - see Cu/ex pipiens 

Nosema acridophagu.r 6 I 

Nosema binucleatum 85 

Nosemacuneatum 61 

Nosemadisstriae 313.314.315.317.318 

Nosema fumiferanae 257.260.262-264 

Nosema locustae 61.62.260 

Nosemapyraustae 260 

Nosemaspp. 35.51.61,141.142 

Notanisomorplla sp. II 

muslini. Ade/ges 

nlllans. Carduus 

nUlans ssp. macro/epis. Carduus 

oak - see Quercus spp. 

oak leafmincr-see Phyllonorcyler messaniella 

oats 155.185.188.205 

Obereaerylhrocepha/a 97.165-167.168 

oblilerala. Aphidecla 

obscura. Leucopis 

obscurator. Orgilus 

obscuripes. Formica 

occidentalis. CllOristOlleura 

ocridentalis. Larix 

Odiellus pictus 34 

Oedopodinae 62 

officinale. Taraxacum 

o/eracea. Tipula 

o/eraceus, Sonchus 

Index of Species 405 

O/esicampe benefactor 218.370.372.373-375.376-377.378, 

379.384 

Olesicampe genicu/alae 218.381.382.383-385 

Oncope/lus /ascialus 99 

onion maggot-see Delia amiqua 

onions 29.30 

Onopordum acanthium 106 

Onopordumspp. 116.117 

OoencyrlUS kUl'anae 218.305.306.307-308,309 

Operophtera bruceata 216.217. 221. 349-351 

Operophtera brumata 215.217. 218.220.222, 349, 353-357. 

390 

opilio. Pha/angium 

oporana. Archips 

Opumia/ragi/is 183 

Opumia polyacamha 183-184 

Orgilusobscurator 218.389.390-392.393,394 

Orgi/usspp. 287 

Orgyia/eucostigma 216.217,219,221,222.359-361.364 

Orgyia pseudotsugata 216.217.219.221,222,225,363-367 

ornatus. Eclytus 

ornigis. Aponte/es 

Oulema melanopus 4.65-67 

Oxydia trychiata 233 

Pacific silver fir - see Abies amabi/is 

Packard grasshopper - see Me/anop/us packardii 

packardii. Melanoplus 

Paecilomyces [arinosus 344 

pallipes. Peristenus 

paludosa, Megaselia 

pa/udosa. Tipula 4 

sect. Paralias. Euphorbia 

Paranguinapicridis 97.105,106-109 

Parasetigena si/"estris 306 

Parasiero/a nigrifemur 218.389,390.392-393 

parasitoids 275 

parthenica, Co/eop/lOra 

Palasson luna 41.42 

patula. Tagete.s 

paucipunctella. Metzneria 

pea aphid - see Acyrthosiphon pis"m


pear 211 

pecoseruis, Phryxe 

pedalis, Pimpla 

pedias, Apanleles 

Pellochrislamedullana 129,136 

pellucida, Camnula 

Penicillium sp. 233 

pentatomids 162 

peplus, EuphorbiD 

perennial sow-thistle -see Sonchus arveruis 

perforalum, Hypericum 

Perislenus adelphocoridis 9-10 

Perislenus digoneulis 45,46 

Perislenus pallipes 9,45,46 

Perislenus pseudopal/ipes 45 

Perislenus rubricollis 9·10,45 

Perislenus stygicus 45,46 

Perislenus spp. 46 

persimi/is, Phyloseiulus 

peslifer, Salsola 

Pelrona resinella 224 

Pllalangium opilio 34 

Phobocampe disparis 306 

Phryxe pecoseruis 50 

Phryxe vulgaris 16,50,53,81,82 

Phyllonorycler blancardella 4,69-71, 101 

Phyllonorycler messaniella 70 

Phyllolrela albionica 73 

Phyllolrela cruciferae 73,74,75 

Phyllolreta robusla 73 

Phyllolretastriolata 73,74,75,76 

Phyllolrela undulata 74 

Phyllolrekl vittata 74 

Phyllolretaspp. 4,5,73-76 

phyllotrekle, Howardula 

phytonomi, Entomophlhora 

Phyloseiulus persimilis 77-78,89 

Picea engelmannii 363 

Piceaglauca 233,243,251,252,253,254,255,256,262,263, 

295 

Picea mariDna 233,235,256 

Picea ruberu 243,244 

Picea spp. 226.235.236,267,295,321 

piceae, Abies 

piceae, Adelges 

picornovirus-see viruses 

picridis. Paranguina 

pictus, Odiellus 

piger, Cleonus 

pigweed -see Axyris amaranthoides 

Pimpla pedalis 306 

pincushion cactus-see Mammillaria vivipara 

pine-see Pinusspp. 

pine beetle -see Dedrocolonus ponderosae 

Pinus banksiana 323,325.334,338,339,342,345.387 

pinus, Choris/oneura 

Pinus mugo 387 

Pinus nigra 387 

Pinus ponderosa 363.387 

Pinus resinosa 323,325.326.327,334.338,339.387 

Pinus rigida 387 

Pinus strobus 387 

Pinus sylveslris 323,334.338.339 

Pinus virginiDna 387 

Pinus spp. 226,323,387 

pipieru, Clllex 

pisllm. AcyrtllOsipllOn 

pitch pine -see Pinus rigida 

plagia/a, Anailis 

plains prickly·pear cactus-see Opllnlia polyacantha 

plant bugs-see Lygllsspp. 

Plalyptiliacardllidaclyla 147 

Pleclocephalus 129 

Pleislophoraschllbergi 260,263·264.315 

Pleolophus basizonus 218,333,335.337,338,341,342 

Pleolophusspp. 342 

pllimarius, Dianthus 

plume less thistle - see Carduus acantllOides 

PlllIeliaxyloslella 4.15-18 

plluellae, Apallleles 

pllllellae, Microplilis 

pnellmoniae, Klebsiella 

Pnigalio jlal'ipes 69 

Pnigalio maclllipes 11.69 

P"igalio Ilroplalae 69 

P"igalio n.sp. 11 

Podislls modeslIlS 343 

polyacalllha, Opllntia 

pomerlaria, Alsophiia 

pomonella, Cydia 

ponderosa pine - see Pi"us ponderosa 

ponderosa, Pinus 

ponderosae, Dendroclo"us 

poplar - see Popllius spp. 

Popllius alba 299. 301 

Popllius balsamifera 299 

Popllius x canaderuis 299. 30 1 

Popllius delloides 299 

Populus grandidentala 299.301 

Populus nigra var. ilalica 299 

Popllius lremuloides 299.301.302.311.314.315.316.349 

Populus lrichocarpa 299, 302 

Populusspp. 299,317.353 

Porizon spp. - see Campoplex spp. 

poslica, Hypera 

potato 211 

praleruis, Blepharipa 

x praleruis, Centaurea 

pratti ba"ksianae, Neodiprion 

prickly-pear - see OpllTllia spp. 

Priopoda nigricollis - see Lalhrolestes nigricollis 

Prisliphoraerichsonii 215.217,218.220.222.369-380.381 

Prisliphorageniclliala 216.218,220.222.381-385 

protozoa 219.223.225. 274-see also individualspecies 

Pru"us spp. 353 

Pselldomonas j1lloresceru 35 

Pseudomonasspp. 35.313 

pseudopallipes, Perislenus 

Pseudotsuga menziesii 171,277.363 

pseudotsugae, De"droclo"us 

pseudosugala, Orgyia 

psi/oslachya, Ambrosia 

psorophorae, Coelomomyces 

Psylliodes chrysocephala 74 

Psylliodes pllncllliula 73,75 

ptarmica, Achillea 

Pleromalus puparllm 16 

Pleroslichus adslriclUS 31 

publicarius, Brachyplerus 

Puccinia acroplili 105.109

Puccinia calcilrapae Vilr. centaureae 129 

Pllct"illiacarlhami 129,130 

Pllceilliacentaurrae 129,130 

Pllceillia coronaUl f. sp. al'enae IllS 

Pucciniajacear 129.130.136 

Puccilliaplmcli/ormis 141,145 

pulcherrima, Euphorbia 

pulchripes, Diglyplllls 

pulrx, Daphnia 

PUI/IIS impexus 232 

pumila, Agalhis 

pumilio, ScymmlS 

pUllcli/acies, Chr),socharis 

puncli/ormis, Pllccillia 

pllnellliala, Psylliodes 

pl/parum, PteromalllS 

purpurata, Metriona 

plIsilla, FenllSa 

pycnocephalllS, CardllllS 

qlladri/asciata, UropllOra 

qllCldrigemina, Chry.wlilla 

qlladriplISlIIlata, lVillthemia 

QuercllS garryalla 353 

QuercllS rubra 353 

QuercllS spp. 353 

quillqlle/ascialllS, Culex 

qllillquemaclI/Clla, Malldllca 4 

radicans, ZoophtllOra 

ragllSilla, Centaurea 

ragweed -see Ambrosia spp. 

ragwort -see Smecio jacobaea 

rain bilrrel mosquito-see Culex pipiens 

raoi, Tetraph/eps 

rapae, Artogeia 

rape 31,49,73,74,75,205 

rapeseed - see rape 

red clover 9 

red oak -see QllefL'llS rubra 

red pine - see PimlS rfsillosa 

red spruce - see Piefa rubens 

red turnip beetle - see Elltomoscflis americana 

red wood ants - see Fannica spp. 

redheaded pine sawny - see Neodiprion lecontei 

rdigiosa, Mantis 

repens, Acroptil()fI 

repellS, Agropyroll 

repens, Centaurea 

repens, Gypsophi/a 

resillel/a, Petrona 

resillosa. PillllS 

restuans. Culex 

RhClmmlS cathartica 185-189 

rhellalla. Centaurea 

Rheumaptera hastata 308 

RhillocylillSconicllS 96,97.100.115.116.117.119·124.125 

rlrodopaellm. Hypaicum 

RhorllS lapponicllS 383 

RllOfllSsp.no3 381.383.384 

RllOrllSsp. 218 

Rhyaeioniabuoliana 215. 217.211l. 220. 222. 224.387-394 

RhynchaenllS distans 105 

rickellsia 220 

rigida. PinllS 

ritro. Echinops 

robin 187 

robllSla. Phyl/otrelCl 

Rogas Irislis 81 

roll ilia. Adalia 

rosaceana. Ce/)'pha 

roses 77 

rubecu/a. Apantdes 

rubens, Picea 

rubiginosa. Cassida 

rubra. QllercllS 

rubricollis, PerislmllS 

rll/a consobrina. Vespu/a 

rllfa. Galeruca 

ru{i/emllr. EII/imlleriii 

rllfipennis. DI'IIdroclolluS 

ru{ipes l'ernalis, Armelra 

rufopicla, Winthemia 

ruglllipennis. LygllS 

Russian knapweed - see Acropli/on repens 

Russian pigweed - see Axyris amaralllhoides 

Russian thistle - see Salsola pesli/er 

rye ISS 

saccharum, Acer 

sainfoin 9 

SI. John 's-wort - see Hypericum per/oralum 

SI. Louis encephalitis 19,20,21 

salicis, Leucoma 

Salixspp. 299,301. 353 

Salsola iberica - see Salso/a pesli/er 

Salsola kali var. tenui/olia - see Salso/a peslifer 

Salsolapesti/a 91l,191·193 

sUlrgllillipes, MelalloplllS 

seplempullclata, Coccillel/a 6 

Sarcophaga aldrichi 306.313 

satin moth - Leucoma salicis 

salim var. capila, Laclllca 

sawny-see Neodiprionspp., Gilpinia hercyniae 

SeambllS spp. 2117 

sehlechtendaliana, Conlarinia 

scill/bergi, P/eisltJphora 

Sclerolinasc/eroliorum 129.136 

scleroliorum, Sc/erolina 

sco/ymllS, Cynara 

Scolosia velu/ala 187, 188 

Scots pine - see PimlS sy/veslris 

ScymnllS pumilio 233 

segelum, CyanllS 

sfguierana, Euphorbia 

semOIIlS. HabrocYl1IS 

sl'IIeciella. Hylemya 

Smecio jacobaea 96.98,99.195·201 

sepillm, Convoil'ul,lS 

srptempullctata. Coccillella 

SeplOria soncl!i·arwII.fis 206 

Seploria sonchi/olia 206 

sfricellS. SpermophagllS 

sericeicornis, Sympiesis 

serratella, ColeopllOra 

Serratia marcescetlS 313 

sali/a. Neodipri()fI 

setipennis, Bigonichela 

short ragweed - see Ambrosia artemisiifolia 

slrlllli, LygllS 

Index of Species 407


sibericus. Dendrolimu.r 

sierrensis. Aedes 

Silene a(aulis 203 

Silene alba 203 

Silene cserei 203 

Silenecllcubalus 203-204 

Silene glauca 203 

Silene maritima 203 

Silene noctif/ora 203 

Silene spp. 203.204 

silver poplar - see Popllius alba 

silvestris. Parasetigena 

Silybummarianum 100 

Silybum spp. 166. 117. 145 

simi/is. Diprion 

Siphona cristala 53 

Siphonaf/avifrons 53 

Siphonageniculala 85.86,87-88 

Silotroga cerealella 270 

skipper - see Thymelicus lineola 

Solidago giganlea 99 

So/idagospp. 160,195 

so/ilarius, Apanteles 

solslilia/is, Urophora 

sonchi, Contarinia 

sonchi, Cysliphora 

sonchi, Marssonina 

sonchi-arvensis, Seploria 

sonchifofia, Seploria 

Sonchus arvensis 97,98,205-209 

Sonchusarvensiss.str. 205 

Sonchus arvensis var. g/abrescens 205 

Sonchus asper 205-209 

Sonchuso/eraceus 205-209 

Sonchus lenerrimus 206 

Sonchusspp. 206 

SorbusamericaM 381 

Sorbusaucuparia 381 

Sorex arClicus 376 

Sorex cinereus cinereus 295,372, 373, 376, 371 

sorghum 155 

Sorospore/la uvella 35 

Spalangia endius 63 

spanworm - see Operophlera bruceala 

Spermophagus sericeus 155 

sphaericus, Bacillus 

sphaerosperma, Entomophlhora 

Sphenop/erajugos/al'ica 97,129,133,134,135 

spider mite -see Te/ranychus urlicae 

spiders 162 

spini, Thecla 

spinosu.m, Cirsiu.m 

spiny annual sow-thistle - see Sonchus asper 

spotted knapweed - see Centaurea macu/osa 

spotted knapweed root moth - see Agapela zoegana 

spotted tentiform leafminer - see Phyllonorycler blancardella 

spruce - see Picea spp. 

spruce budworm - see Chorisloneura fumiferana 

spurge - see Euphorbia spp. 

spurge hawkmoth-see Hyleseuphorbiae 

slabu/ans, Muscina 

starlings 34,85 

Slenichneu.mon cu/palor 53 

SlenichneumonsculellalOr-see Syspasis sculellalor 

stenosligma, Balhyp/ectus 

stinkweed - see Thlaspi arl'(!nse 

Stipacoma/a 121 

strawberries 7 

SlreplOCOCC/lS faecalis 35 

strio/ata, Phyllotreta 

strobus, PilllLr 

stygicus, Perislenus 

stylata, UropllOra 

subalpine fir-see Abies lasiocarpa 

subnodicomi.r, Tipula 

sublilicomis, Diadromus 

sugar beet 191 

sugar maple - see Acer saccharum 

sunflower III 

swuralis, Entomoscelis 

swuralis. Eutanyacra 

Swaine jack pine sawfly - see Neodiprion swainei 

swainei, Herpelomonas 

swainei. Neodiprion 

sweet clover 9 

sweet potato 157 

sycophanta, Calosoma 

sylveslris, Pillus 

Sympiesis bimaculatipennis 69 

Sympiesis conica 69 

Sympiesis marylandensis 69 

Sympiesi.r sericeicornis 69. 70 

syriaca, Asclepias 

Syspasis scU/ellator 81. 82, 83 

Tachina lan'arum - see Exorista larvarum 

Tagetespalula 114 

tamarack -sec Larix laridna 

Tanacelum I'ulgare 114 

tansy ragwort -sec Senecio jacobaea 

Taraxacum offidnale 206 

Telenomusalsophi/ae 223 

Telenomussp. 306 

Temelucha interruplor 392 

tene/lus, Circulifer 

lenerrimus, Sonchus 

lenthrediniformis, Chamaesphecia 

lenthredinis, Mesoleius 

lenuif/oru.r, Carduus 

tenuifolia, Ambrosia 

Tephrilis dilacerala 98.206.207.208 

Telracampe diprioni - see Dipriocampe diprioni 

Telranychus ur/icae 4,77-18 

Telraphleps abdulghalli 233 

Telrapltieps raoi 233 

letraspilota, Adalia 

Tetrastichus incerlUS 41.42 

Tetrasticllus julis 65-67 

Telraslichus sp. 69 

Ie/rum, Gymnaelron 

Ihapsu.r, Verbascum 

Theclaspini 181,188 

Thelohania sp. 260,344 

Therion giganteum 53 

Theronia alalanlae fulvescens 306 

Theronia hi/aris 306 

thistle - see Carduus spp., Cirsium spp .• Salsola pes/ifer, 

Sonchus spp. 

Thalspi arvense 121 

thomp.roni, Aphidoletes


Malacosoma disstria 221,313,314 

Mamestra configurata 51 

Neodiprion abietis 221,321-322 

Neodiprion lecontei 215.220,221,222-223,225,323-328 

Neodiprion sertifer 221,331, 334, 337-338, 339 

Neodiprion swainei 221,341,343-345,346 

neodiprionid sawflies 219 

Operophlera bruceata 221,350-351 

Operophlera brumala 356 

Orgyia leucos/igma 219,221,222-223,359-361 

Orgyia pseudotsugata 219, 221, 222, 225, 258, 363-365, 

365-367 

Thylmelicus lineola 79 

Trichoplusia ni 16, 18 

picornovirus of Melanoplus bivittatus 61 

tobacco streak virus 205 

villata, Tipula 

villalae, Microclonus 

villatum, Leiobunum 

villatus, Col/ops 

vitliger, Chelinidea 

vivipara, Mammillaria 

vole 378 

vulgare, Cirsium 

vulgare, Tanacetum 

vulgaris, Anemisia 

vulgaris, Linaria 

vulgaris, Phryxe 

wasps 162 

websleri, Diglyphus 

western equine encephalomyelitis 23 

western larch -see Larix occidentalis 

western spruce bud worm -see Choristoneura occidentalis 

wheat 139, 155,205 

white birch - see Betu/Q papyrifera 

white elm - see Ulmus americana 

white spruce -see Picea glauco 

whitefly - see Trialeurodes vaporariorum 

whitemarked tussock moth - see Orgyia leucostigma 

wild carrot - see carrot 

willow -see Salix spp. 

winter moth -see Operophtera brumata 

Winthemia deilephilae 34 

Winthemia quadripustulata 50,53 

Winthemia rufopicla 34,50 

xylinus, Apanteles 

xylostel/a, Plutel/a 

yellow toadflax - see Linaria vulgaris 

Zagrammosoma multilineatum 69 

zea, Heliothis 

Zeiraphera diniana 3TI 

Zeiraphera spp. 226 

Zeuxidiplosis giardi 98 

zoegana, Agapeta 

Zoophthora radicans 79,261,262 

Zygogramma tonuosa 111

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