Trichogramma
Systematic position: Insecta, Holometabola, Hymenoptera, Apocrita, Trichogrammatidae.
Geographical distribution: Cosmopolitan.
Morphology: The adults are about 0.5-1.0 in length, usually with yellow-brown bodies and large red eyes. Due to difficulties in separating the species, molecular methods are now increasingly being used for this purpose.
Life history: Species of Trichogramma are endoparasitoids of the eggs of various insects, mostly Lepidoptera, but also beetles, flies and lacewings. Females, which produce 100-300 progeny, live for less than a fortnight, feeding on nectar, other sugary plant exudates and by host feeding. They usually insert single eggs into fresh host-eggs, and development is completed in about 1-2 weeks, dependent on the host. The attacked host egg becomes black as the parasite develops within. This short life cycle results in very rapid population growth.
Economic importance: Species of Trichogramma are efficient biological control agents of various pestiferous Lepidoptera. They are probably the most widely sold and used biocontrol agent. Different species appear to be adapted to different habitats, such as low-growing crops or orchards, or to the various plant structures on which the host eggs are located. Some species are attracted to the insect sex pheromones. Species may vary in their degree of host (e.g. egg) specificity, and sometimes attack non-pest hosts. Their movements on plant surfaces can be curtailed by trichomes and their exudates. Release rates are determined by factors including the weather, the crop and its growth stage, other means of ongoing pest control and the horticultural practices. Species of Trichogramma are usually sold as parasitized eggs glued onto paper cards, which are placed in greenhouses or orchards, the emerging adults then attacking the pests. Several apparently-endemic and heat-tolerant species of Trichogramma occur in Egypt and attack the olive pests Prays oleae and Palpita vitrealis. Trichogramma platneri Nagarkatti was introduced into Israel to control two avocado lepidopterous pests.
Effect of pesticides: Most insecticides (like spinosad) are harmful to Trichogramma, but insect growth regulators have little effect
North Korea has issues a stamp depicting Trichogramma, at http://c7.alamy.com/comp/EAF94X/postage-stamp-from-north-korea-depicting-a beneficial-wasp-trichogramma-EAF94X.jpg.
References
Abbas, M.S.T. (1989) Studies on Trichogramma buesi as a biological control agent against Pieris rapae in Egypt. Entomophaga 34: 447-451.
Consoli, F.L., Parra, J.R.P. and Zucchi, R.A. (eds) 2010. Egg Parasitoids in Agroecosystems with Emphasis on Trichogramma. Springer.
Consoli, F.L., Botelho, P.S.M. and Parra, J.R.P. 2001. Selectivity of insecticides to the egg parasitoid Trichogramma galloi Zucchi, 1988, (Hym., Trichogrammatidae). Journal of Applied Entomology 125: 37-43.
Hegazi, E.M. (and 13 co-authors). 2005. Naturally occurring Trichogramma species in olive farms in Egypt. Insect Science 12: 185-192.
Knutson, A. 2005. The Trichogramma Manual: A Guide to the Use of Trichogramma for Biological Control with Special Reference to Augmentative Releases for Control of Bollworm and Budworm in Cotton. Texas Agricultural Extension Service # B-6071, 42 pp.
Öztemiz, S., Küden, A., Nas, S. and Lavkor, I. 2017.Efficacy of Trichogramma evanescens and Bacillus thuringiensis var. kurstaki in control of Cydia pomonella (L.) in Turkey. Turkish Journal of Agriculture and Forestry 41: 201-207.
Pinto, D. 1999. The systematics of the North American species of Trichogramma (Hymenoptera: Trichogrammatidae). Memoirs of the Entomological Society of Washington 22: 1-287
Polaszek, A., Rugman-Jones., P.F., Stouthamer, R., Hernandez-Suarez, E. and Cabello, T. 2012. Molecular and morphological diagnoses of five species of Trichogramma: biological control agents of Chrysodeixis chalcites (Lepidoptera: Noctuidae) and Tuta absoluta (Lepidoptera: Gelechiidae) in the Canary Islands. BioControl 57: 21-35.
Romeis, J., Babendreier, D., Wäckers, F.L. and Shanower, T.G. 2005. Habitat and plant specificity of Trichogramma egg parasitoids—underlying mechanisms and implications, Basic and Applied Ecology, 6: 215_236.
Sithanantham, S., Abera, T.H., Baumgärtner, J. and Hassan, S.A. 2001. Egg parasitoids for augmentative biological control of lepidopteran vegetable pests in Africa: Research status and needs. International Journal of Tropical Insect Science 21: 189-205.
Smith, S.M. 1996. Biological control with Trichogramma: advances, successes and potential of their use. Annual Review of Entomology 41: 375-406.
Swirski, E., Wysoki, M and Izhar, Y. 1995. Avocado pests in Israel. Proceedings of the World Avocado Congress III, pp. 419-428.
Zaki, F.N. 1985. Reactions of the egg parasitoid Trichogramma evanescens Westw. to certain insect sex pheromones. Journal of Applied Entomology 99: 448-453.
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