Persistent toxicity of insecticides on biotic potential of Trichogramma brasiliensis Ashmead (Hymenoptera: Trichogrammatidae), an egg parasitoid of tomato fruit borer.

摘要

Insecticides hamper the effectiveness of Trichogramma brasiliensis not only through direct mortality but also as a result of sublethal effects on the parasitization capability and per cent emergence. Survived females from treated leaves were later exposed to fresh radiated Corcyra cephalonica Stainton (Lepidoptera: Gelechidae) eggs. The persistent toxicity of endosulfan, monocrotophos, cypermethrin, dimethoate and neem seed kernel extract on per cent parasitization and emergence lasted for 9, 9, 5, 3 and 4 days after treatment, respectively. The effect of persistent toxicity on fecundity and fertility was observed from zero day after treatment. 2 hours of exposure period gave significantly high parasitization and emergence up to 3 days after treatment.