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.
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.
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