Hostname: page-component-8448b6f56d-qsmjn Total loading time: 0 Render date: 2024-04-23T16:14:04.179Z Has data issue: false hasContentIssue false
  • English
  • Français

Egg parasitoids for augmentative biological control of lepidopteran vegetable pests in Africa: Research status and needs

Published online by Cambridge University Press:  19 September 2011

S. Sithanantham ,
T. H. Abera ,
J. Baumgärtner ,
S. A. Hassan ,
B. Löhr ,
J. C. Monje ,
W. A. Overholt ,
A. V. N. Paul ,
Fang Hao Wan  and
C. P. W. Zebitz
S. Sithanantham
Affiliation:
International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, Nairobi, Kenya
T. H. Abera
Affiliation:
International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, Nairobi, Kenya
J. Baumgärtner
Affiliation:
International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, Nairobi, Kenya
S. A. Hassan
Affiliation:
Institute for Biological Pest Control, Heinrichstr. 243, D-64287 Darmstadt, Germany
B. Löhr
Affiliation:
International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, Nairobi, Kenya
J. C. Monje
Affiliation:
Institute of Phytomedicine, University of Hohenheim, D-70593 Stuttgart, Germany
W. A. Overholt
Affiliation:
International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, Nairobi, Kenya
A. V. N. Paul
Affiliation:
Indian Agricultural Research Institute, New Delhi - 110012, India
Fang Hao Wan
Affiliation:
Chinese Academy of Agricultural Sciences, CAAS, Beijing 100081, China
C. P. W. Zebitz
Affiliation:
Institute of Phytomedicine, University of Hohenheim, D-70593 Stuttgart, Germany
Get access

Abstract

Among the important constraints to vegetable production in Africa are the lepidopteran pests, in particular Helicoverpa armigera (Hb.) and Plutella xylostella (L.) which cause direct yield loss as well as cosmetic damage. Egg parasitoids, especially Trichogramma spp., shown promise as biocontrol agents against both species in previous studies. In Africa, surveys have so far recorded 18 species of Trichogramma, eight of Trichogrammatoidea and seven of Telenomus besides one species each of Baryscopus and Oencyrtus. For effective utilisation of egg parasitoids in vegetable ecosystems in Africa, the experience gained elsewhere should be suitably utilised, and complementary research undertaken. This paper examines the scope for use of egg parasitoids in Africa, focusing on five research areas. Firstly, surveys should be undertaken to collect, characterise, and catalogue the different species and strains of egg parasitoids occurring in the region. Secondly, the pest status of target Lepidoptera and the potential demand for use of egg parasitoids in the major ecologies should be assessed. Thirdly, the local and/or exotic species/strains with good potential to control H. armigera and P. xylostella need to be identified, and fourthly, analyses aimed at selecting appropriate mass production and delivery systems for Trichogramma use in major vegetable crops should be undertaken. Finally, optimisation of inundative release strategies should be researched on. The scope for research collaboration within Africa and internationally is discussed.

Résumé

Les Lépidoptères ravageurs, en particulier Helicoverpa armigera (Hb.) et Plutella xylostella (L.), responsables de pertes directes de récoltes et de dégâts esthétiques, sont l'une des contraintes majeures de la production maraîchère en Afrique. Lors d'études antérieures, les parasitoïdes d'oeufs, notamment Trichogramma spp., ont montré des potentialités comme agent de régulation biologique contre ces deux espèces. En Afrique, des enquêtes ont à ce jour permis de recenser 18 espèces de trichogrammes, huit espèces de Trichogrammatoidea, sept de Telenomus et, une de Baryscopus et d'Oencyrtus. Afin d'utiliser efficacement les parasitoïdes d'oeufs dans les écosystèmes maraîchers en Afrique, l'expérience acquise ailleurs pourrait être avantageusement utilisée, et des recherches complémentaires entreprises. Cet article examinera possibilité d'utiliser les parasitoïdes d'oeufs en Afrique, en s'intéressant à 5 domaines de recherches. Premièrement, des enquêtes pourraient être entreprises afin de collecter, identifier et inventorier les différentes espèces et souches de parasitoïdes d'oeufs présents dans la région. Deuxièmement, le statut de ravageur des Lépidoptères cibles et l'intérêt d'utiliser des parasitoïdes d'oeufs dans les principales conditions écologiques devraient être évalués. Troisièmement, les espèces ou les souches indigènes et/ou exotiques avec un bon potentiel de contrôle d'H. armigera et P. xylostella devront être identifiées. Quatrièmement, il serait souhaitable d'entreprendre des analyses destinées à sélectionner une production de masse et des systèmes de livraison appropriés pour l'utilisation des trichogrammes dans les principales productions maraîchères. Finalement, l'optimisation des stratégies de lâchers inondatifs devrait être approfondie. Il est également recommandé d'établir des collaborations de recherches internationales.

Keywords

vegetable productionegg parasitoidsTrichogrammaTrichogrammatoideaHelicoverpa armigeraPlutella xylostellabiological diversityproduction maraîchèreparasitoïdes d'oeufsTrichogrammaTrichogrammatoideaHelicoverpa armigeraPlutella xylostelladiversité biologique
Type
Mini Review
Information
International Journal of Tropical Insect Science , Volume 21 , Issue 3 , September 2001 , pp. 189 - 205
Copyright
Copyright © ICIPE 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abbas, M.S.T. (1989) Studies on Trichogramma buesi as a biological control agent against Pieris rapae in Egypt. Entomophaga 34, 447–451.CrossRefGoogle Scholar
Abbas, M.S.T. (1990) Interactions between host, egg and larval parasitoids and nuclear polyhedrosis virus. Bull. Entomol. Soc. Egypt 16, 133–141.Google Scholar
Abera, T.H., Sithanantham, S., Ogol, C.K.P.O., Monje, J.C. and Zebitz, C.P.W. (2000) Survey for native trichogrammatid species in Kenya, p. 389. In Proceedings of XXI International Congress of Entomology, Iguassu, Brazil, August 20–26, 2000 (Compiled by Gazzoni, D.L.).Google Scholar
Andow, D.O.A. and Prokrym, D.O.R. (1990) Plant structural complexity and host finding by a parasitoid. Oecologia 82, 162–165.CrossRefGoogle ScholarPubMed
Anonymous (1998) Cooperative Research Centre for Tropical Pest Management. Annual report 1997–1998. 6 pp. University of Queensland, Australia.Google Scholar
Bigler, F. (1994) Quality control in Trichogramma production, pp. 93–111. In Biological Control with Egg Parasitoids (Edited by Wajnberg, E. and Hassan, S. A.) CAB International, Berkshire, UK.Google Scholar
Bin, F. and Johnson, N. F. (1982) Some new species of Telenomus (Hym; Scelionidae) egg-parasitoids of tropical pyralid pests (Lep; Pyralidae). Redia 65, 229–252.Google Scholar
Bosque Perez, N.A., Ubeku, J. A. and Polaszek, A. (1994) Survey for parasites of Sesamia calamistis (Lep.: Noctuidae) and Eldana saccharina (Lep.: Pyralidae) in South western Nigeria. Entomophaga 39, 367–376.CrossRefGoogle Scholar
Bouse, L. F. and Morrison, R. K. (1985) Transport, storage, and release of Trichogramma pretiosum. Southwestern Entomologist 8, 36–48 (suppl.).Google Scholar
Campbell, C.D., Walgenbach, J. F. and Kennedy, G. G. (1991) Effect of parasitoids on lepidopterous pests in insecticide treated and untreated tomatoes in Western North Carolina, J. Econ. Entomol. 84, 1662–1667.CrossRefGoogle Scholar
Chambers, B. Q., Samways, M. J. and Ironside, D. A. (1995) Egg distribution of the fruit borers Cryptophlebia leucoptreta (Meyrick) and C. batrochopa (Meyrick) (Lepidoptera: Tortricidae) and their egg parasitoid Trichogrammatoidea cryptophlebiae Nagaraja (Hymenoptera: Trichogrammatidae) in Macadamia trees in Malawi. African Entomology 3, 181–188.Google Scholar
Conlong, D. O. E and Hastings, H. (1994) Evaluation of egg parasitoids in the biological control of Eldana saccharina Walker (Lepidoptera: Pyralidae), pp. 168–172. In Proceedings of the Fifty Eighth Annual Entomology Congress. Entomological Society of South Africa.Google Scholar
El-Hafez, A. A. and El-Hafez, A.B.D. (1995) A comparision of thermal requirements and some biological aspects of Trichogramma evanescens Westwood and Trichogrammatoidea bactrae Nagaraja reared from eggs of the pink and spiny bollworms. Ann. Agric. Sci., Cairo 40, 901–912.Google Scholar
Farrell, G., Kibata, G.N. and Sutherland, J.A. (1995) A Review of Crop Protection Research in Kenya. KARI/ ODA Crop Protection Project, National Agricultural Research Laboratories, KARI, Kenya. 165 pp.Google Scholar
Feijen, H. R. and Schulten, G.M. (1981) Egg parasitoids of rice pests in Malawi. Int. Rice Res. Newsl. 6, 17–18.Google Scholar
Franz, J. M., Bogenschütz, H., Hassan, S.A., Huang, P. and Naton, E. (1980) Results of a joint pesticide test programme by the working group: Pesticide and beneficial arthropods. Entomophaga 25, 231–236.CrossRefGoogle Scholar
Qing, Guang Li and Oloo, G.W. (1990) Host preference studies on Trichogramma sp. nr mwanzai Schulten and Feijen (Hymenoptera: Trichogrammatidae) in Kenya. Insect Sci. Applic. 11, 757–763.Google Scholar
Gupta, M., Siripala, P. D. and Pawar, A. D. (1984) Biological control of tomato fruit borer, Heliothis armigera Hb. (Noctuidae: Lepidoptera) using releases of egg parasites, Trichogramma spp. Plant Prot. Bull. India 36, 29–31.Google Scholar
Hamburg, H.V., Kfir, R. and Hamburg, V.H. (1991) The relative abundance of Telenomus ullyetti (Hymenoptera: Scelionidae) and Trichogrammatoidea lutea (Hymenoptera: Trichogrammatidae), parasitising the eggs of Heliothis armigera on cotton in South Africa. Colloques de l'INRA 56, 49–52.Google Scholar
Hassan, S.A. (1993) The mass rearing and utilization of Trichogramma to control lepidopterous pests: Achievements and outlook. Pestic. Sci. 37, 387–391.CrossRefGoogle Scholar
Hassan, S.A. and Wührer, B.G. (1997) Present status of research and commercial utilization of egg parasitoids of the genus Trichogramma in Germany. Gesunde Pflanzen 49, 68–75.Google Scholar
HCDA (1998) Export market statistics figures for fresh fruits, vegetables and cut flowers from Kenya by sea and air in 1997: Horticultural Crops Development Authority, (HCDA) Nairobi, Kenya.Google Scholar
Hirai, K. (1991) Trichogramma parasitising Pieris rapae crucivora Boisduval. Colloquies de l'INRA 56, 71–72.Google Scholar
Hoffmann, M. P., Wilson, L. T., Zalom, F. G., Hilton, R. J. and Weakley, C. V. (1990) Parasitoid helps control fruitworm in Sacramento Valley processing tomatoes. California Agriculture 44, 20–23.CrossRefGoogle Scholar
Howarth, F.G. (1991) Environmental impacts of classical biological control. Annu. Rev. Entomol. 36, 485–509.CrossRefGoogle Scholar
ICIPE (1997) Annual Report 1995/97, The International Centre of Insect Physiology and Ecology, Nairobi, Kenya. 331 pp.Google Scholar
Tkin, R., Schulten, G.G.M., and Borhegyi, I. D. E (1993) Report of Regional Seminar on the Development and Application of Integrated Pest Management on Vegetables in Africa, 23 – 30 November 1992, Dakar, Senegal. FAO Plant Prot. Bull. Rome 41, 155–160.Google Scholar
Kanour, W.W. and Burbutis, P.P. (1984) Trichogramma nubilale (Hym, Trichogrammatidae) field releases in corn and a hypothetical model for control of European corn borer (Lep., Pyralidae). J. Econ. Entomol. 77, 103–107.CrossRefGoogle Scholar
Kay, I.R. (1989) Seasonal incidence of Heliothis spp. (Lepidoptera: Noctuidae) on tomatoes in North Queensland. J. Australian Entomol. Soc. 28, 193–194.CrossRefGoogle Scholar
Kazmer, D.J. and Luck, R.F. (1991) Female body size, fitness and biological control quality: Field experiments with Trichogramma pretiosum. Colloques de l'INRA 56, 37–40.Google Scholar
Kfir, R. (1990) Parasites of the spotted stalk borer, Chilo partellus (Lepidoptera: Pyralidae) in South Africa. Entomophaga 35, 403–410.CrossRefGoogle Scholar
Kfir, R. (1991) Selecting parasites for biological control of lepidopterous stalk borers in summer grain crops in South Africa Redia 74, 231–236.Google Scholar
Kfir, R. (1995) Parasitoids of the African stem borer, Busseola fusca (Lepidoptera: Noctuidae) in South Africa. Bull. Entomol. Res. 85, 369–377.CrossRefGoogle Scholar
Klemm, U. and Schmutterer, H. (1993) Effects of neem preparations on Plutella xylostella L. and its natural enemies of the genus Trichogramma. Z. Pflanzenkr. Pflanzensch. 100, 113–128.Google Scholar
Krishnamoorthy, A. and Mani, M. (1996) Biosuppression of Helicoverpa armigera (Hübner) on tomato using two egg parasitoids, Trichogramma brasiliensis (Ashm.) and T. pretiosum (Riley). J. Entomol. Res. 20, 37–41.Google Scholar
Laing, J.E. and Bigler, F. (1991) Quality control of massproduced Trichogramma species, pp. 111–118. In Proceedings of the 5th Workshop of the IOBC Global Working Group, Quality Control of Mass Reared Arthropods. IOBC, Wageningen, The Netherlands.Google Scholar
Li, Li-Ying (1994) Worldwide use of Trichogramma for biological control on different crops: A survey, pp. 37–53. In Biological Control with Egg Parasitoids. CAB International, Oxon, UK.Google Scholar
Zhi-Cheng, Liu, Liu, Jian-Feng, Yang, Wu-Hong, Li, Dun-Song and Wang, Chun-Xia (1996) Research on technological process of Trichogramma produced with artificial host egg and quality standard. Natural Enemies of Insects 15, 23–25 (Chinese).Google Scholar
Maini, S. and Burgio, G. (1991) Biological control of the European corn borer in protected pepper by Trichogramma maidis Pint & Voeg. and Bacillue thuringiensis Beri, subsp. kurstaki. Colloques de l'INRA 56, 213–215.Google Scholar
Manjunath, T.M., Bhatnagar, V.S., Pawar, C.S. and Sithanantham, S. (1989) Economic importance of Heliothis spp. in India and assessment of their natural enemies and host plants, pp. 197–228. In Proceedings of the International Workshop on Biological Control of Heliothis, New Delhi, India. USDA.Google Scholar
Meierrose, C., Silva, I. and Araujo, J. (1991) Egg parasitoids from Heliothis armigera on tomato in Southern Portugal. I. Field studies with naturally occurring Trichogramma sp. and Telenomus sp. Colloques de l'INRA 56, 221–226.Google Scholar
Mimouni, F. (1991) Genetic variations in host infestation efficiency in two Trichogramma species from Morocco. Redia 74, 393–400.Google Scholar
Mirzalieva, K. H. R and Mirzaliev, B.T. (1988) The use of Trichogramma on tomatoes. Zashchita Rastenii Moskva 11, 30–31.Google Scholar
Mohyuddin, A. I. and Greathead, D.J. (1970) An annotated list of the parasites of graminaceous stemborers in East Africa, with a discussion of their potential in biological control. Entomophaga 15, 241–274.CrossRefGoogle Scholar
Monje, J. C., Romeis, J., Shanower, T. G. and Zebitz, C. P. W (1998) Trichogramma species attacking Helicoverpa armigera in sorghum-pigeonpea intercrops in South India. Bundesanstalt für biologischen pflansenschutz Berlin-Dahlem 356, 31–34.Google Scholar
Munir, B., Abdelrahamana, A., Mohamed, A.H., Stam, A. and Ooi, P. A. C (2000) Introduction of Trichogramma pretiosum Riley against Heliothis armigera (Hb.) in the Sudan, pp. 70–73. In Proceedings of the 3rd International Conference on Plant Protection in the Tropics, Genting Highlands. MARDI, Malaysia.Google Scholar
Nagaraja, H. (1978) Studies on Trichogrammatoidea (Hymenoptera: Trichogrammatidae). Oriental Insects, 12, 13–31.CrossRefGoogle Scholar
Navarajan, P. (1988) Toxicity of different pesticides to parasitoids of the genus Trichogramma. Trichogramma and Other Egg Parasites. Les Colloques de l'INRA, 43, 423–432.Google Scholar
Newton, P. J. (1988) Inversely density-dependent egg parasitism in patchy distribution of the citrus pest Cryptophlebia leucoptreta (Lepidoptera: Tortricidae) and its agricultural efficiency, J. Appl. Ecol. 25, 145–162.CrossRefGoogle Scholar
Ngi-Song, A. J. (1990) A model of parasitism by Tricliogramma species nr mwanzai Schulten & Feijen (Hymenoptera: Trichogrammatidae) on the stalk borer, Chilo partelhis Swinhoe (Lepidoptera: Pyralide) on sorghum. M.Phil. Thesis, International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya.Google Scholar
Ochiel, G.R.S. (1989) Biology of Tricliogramma species near exiguum Pinto & Platner (Hymenoptera-Trichogrammatidae) on some lepidopterous hosts in South Nyanza, Kenya. M.Phil. Thesis, International Centre of Insect Physiology and Ecology (ICIPE) Nairobi, Kenya.Google Scholar
Oloo, G.W. (1984) Development, progeny production, and sex-ratio in Trichogramma sp. reared on Chilo partelhis and Busseola fusca. 1986 Annual Report, The International Centre of Insect Physiology and Ecology, Nairobi, Kenya. 115 pp.Google Scholar
Oloo, G.W. (1987) Parasitoids for the bio-control of stem borers. 2987 Annual Report, The International Centre of Insect Physiology and Ecology, Nairobi, Kenya. 153 pp.Google Scholar
Oloo, G.W. (1989) The role of natural enemies in population dynamics of Chilo partellus (Swinh.) (Pyralidae) under subsistence farming systems in Kenya. Insect Sci. Applic. 10, 243–251.Google Scholar
Polaszek, A. and Kimani-Njogu, S.W. (1998) Scelionidae, pp. 259–264. In African Cereal Stem Borers. Economic Importance, Taxonomy, Natural Enemies and Control (Edited by Polaszek, A.). CAB International Wallingford, UK.Google Scholar
Pintureau, B. and Babault, M. (1988) Sustématique des espèces africaines des genres Trichogramma Westwook et Trichogrammatoidea Girault (Hym. Trichogrammatidae). Les Colloques de l'INRA, 43, 97–120.Google Scholar
Prinsloo, G. L. (1984) An illustrated guide to the parasitic wasps associated with citrus in the Republic of South Africa. Dept Agric. Sci. Bull. 402.Google Scholar
Rabb, R. L., Stinner, R.E. and Van Der Bosch, R. (1976) Conservation and augmentation of natural enemies, pp. 233–254. In Theory and Practice of Biological Control (Edited by Huffaker, C. B. and Messenger, P. S.). Academic Press, New York.Google Scholar
Rawat, U. S. and Pawar, A. D. (1993) Biocontrol of tomato fruit borer, Heliothis armigera (Hubner) in Himachal Pradesh, India. Plant Prot. Bull, Faridabad 45, 34.Google Scholar
Romeis, J., Shanower, T.G. and Zebitz, C.P.W. (1996) A simple and effective bioassay to study the effect of plant surface chemicals on the behaviour of Trichogramma spp. J. Plant Dis. Prot. 103, 213–216.Google Scholar
Romeis, J., Shanower, T. G. and Zebitz, C. P. W (1997) Volatile plant infochemicals mediate plant preference on Trichogramma chilonis. J. Chem. Entomol. 23, 2455–2465.Google Scholar
Romeis, J., Shanower, T. G. and Zebitz, C. P. W (1998) Physical and chemical plant characters inhibiting the searching behaviour of Trichogramma chilonis (Hymenoptera: Trichogrammatidae). Entomol. Exp. Appl 87, 275–284.CrossRefGoogle Scholar
Romeis, J., Shanower, T. G. and Zebitz, C. P. W (1999) Why Trichogramma (Hymenoptera Trichogrammatidae) egg parasitoids of Helicoverpa armigera (Lepidoptera Noctuidae) fail on chickpea. Bull. Entomol. Res. 89, 89–94.CrossRefGoogle Scholar
Salama, H. S. and Zaki, F. N. (1985) Biological effects of Bacillus thuriengiensis on the egg parasitoid, Trichogramma evanescens. Insect Sci. Applic. 6, 145–148.CrossRefGoogle Scholar
Sato, K., Mochida, O. and Kikuchi, A. (1994) Control of the diamondback moth (Plutella xylostella) (Lepidoptera: Yponomeutidae) by egg parasitoids (Trichogramma) 10. Relationships among the density of Trichogramma chilonis (Hymenoptera: Trichogrammatidae) released, percentage of parasitism, and mortality due to host feeding. Annual Report of the Society of Plant Protection of North Japan, 45, 168–170.Google Scholar
Schulten, G. G. and Feijen, H. R. (1978) Two new species of Trichogramma (Hymenoptera, Trichogrammatidae) from Malawi: Egg parasitoids of Diopsis macrophthalma Dalman (Diptera: Diopsidae). Entomol Berichte, Deel, 38, 25–29.Google Scholar
Schulten, G. G. and Feijen, H. R. (1982) A new species of Trichogramma (Hymenoptera: Trichogrammatidae) from Malawi, parasitizing eggs of Chilo diffusilineus (joannis). Entomol. Berichte, Deel 42, 142–144.Google Scholar
Setamou, M. and Schulthess, F. (1995) The influence of egg parasitoids belonging to the Telenomms busscolne (Hymenoptera: Scelionidae) species complex on Sesamia calamistis (Lepidoptera: Noctuidae) population in maize fields in Southern Benin. Biocontr. Sci. Tcchnol. 5, 69–81.CrossRefGoogle Scholar
Singh, M. and Sithanantham, S. (1984) Statistical procedure for testing the host plant preference by Trichogramma under choice and no choice situation. Int. J. Sci. Eng. 1, 47–63.Google Scholar
Singh, S. P., Joshi, S. P. and Ballal, C. R. (2001) Innovations in mass rearing technology for mass releases, transportation and storage of natural enemies, pp. 1–33. In Biological Control (Edited by Singh, S. P., Bhumannavar, B. S., Poorani, J. and Singh, S. D.). Excel, Mumbai, India.Google Scholar
Sithanantham, S. and Navarajan Paul, A.V. (1989) Control of Heliothis species (Lep., Noctuidae) by augmentative releases of predators and parasites in India, pp. 427–430. In Proceedings of International Workshop on Biological Control of Heliothis, 11–15 November 1985, New Delhi. USDA.Google Scholar
Sithanantham, S. and Varadharajan, G. (1974) Experiments on releasing parasites in combination withinsecticidal application for the control of sugarcane internode borer. Indian Sugar 24, 179–184.Google Scholar
Sithanantham, S., Bhatnagar, V. S., Deepak, J. and Reed, W. (1982) Some aspects of Trichogramma spp. parasitism on eggs of Heliothis armigera Hbn. (Lepidoptera: Noctuidae). In Proceedings of first International Symposium on Trichogramma. INRA, Antibes, France. (Abstract).Google Scholar
Smith, S. M. (1994) Methods and timing of releases of Trichogramma to control lepidopterous pests, pp. 113–144. In Biological Control with Egg Parasitoids (Edited by Wajnberg, E. and Hassan, S. A.). CAB International, Oxon, UK.Google Scholar
Smith, S. M. (1996) Biological control with Trichogramma: advances, successes, and potential of their use. Annu. Rev. Entomol. 41, 375–406.CrossRefGoogle ScholarPubMed
Smith, S. M., Carrow, J. R. and Laing, J. E. (1990) Inundative release of the egg parasitoid, Trichogramma minutum (Hym.: Trichogrammatidae) against forest insect pests such as the spruce budworm, Choristoneura fumiferana (Lep.: Tortricidae): The Ontario Project 1982–1986. Mem. Entomol. Soc. Canada 153, 1–87.Google Scholar
Tsankov, G., Schmidt, G.H. and Mirchev, P. (1995) Impact of parasitoids in egg-batches of Thaumetopoea pityocampa (Den. & Schiff.) in Algeria. Boll. Zool. Agr. Bachicoltura 27, 53–60.Google Scholar
Vaissayre, M. (1977) Contribution a la connaissance du complexe entomophage en culture çotonniere dans le sud-ouest de Madagascar. Coton et Fibres Tropicales 32, 35–58.Google Scholar
Van Den Berg, H. (1993) Natural control of Helicovepa armigera in smallholder crops in East Africa. PhD Thesis, Wageningen Agricultural University, Wageningen.Google Scholar
Van Den Berg, H. and Cock, M. J. W (1993) African bollworm and its natural enemies in Kenya. International Institute of Biological Control Kenya Station and Natural Resources Institute (Overseas Development Administration), CABI, UK.Google Scholar
Van Hansburg, H. and Hassell, M.P. (1984) Density dependence and the augmentative release of egg parasitoids against graminaceous stalk borer. Ecological Entomology 9, 101–108.Google Scholar
Viggiani, G. (1972) Ricerche sugli Hymenoptera: Chalcidoidea. XXXVI. Nuovi Trichogrammatidi africani. Bol. Lab. Ent. Agr. “F. Silvesri”. Portici, 30, 158–164.Google Scholar
Yu, D.S. and Byers, J.R. (1994) Inundative release of Trichogramma brassicae (Hym: Trichogrammatidae) for control of European corn borer in sweet corn. Canadian Entomologist 126, 291–301.CrossRefGoogle Scholar
Zaki, F.N. (1985) Reactions of the egg parasitoid Trichogramma evanescens Westw. to certain insect sex pheromones. Z. Angew. Entomol. 99, 448–453.CrossRefGoogle Scholar