TOXICITY OF INSECTICIDES TO OOMYZUS SOKOLOWSKII, A PARASITOID OF DIAMONDBACK MOTH

Toxicity of eleven commonly used insecticides (including organophosphates, synthetic pyrethroids, carbamates, insect growth regulators, antibiotics, nereistoxin and microbial insecticides) to Oomyzus sokolowskii was evaluated in the laboratory. All insecticides were applied at concentrations recommended for field application by the producers. Adults were exposed to fresh, dry insecticide film in glass vials for 05, 2 and 24 h, respectively, and were then transferred to clean vials and kept for a further 24 h for observation. Pupae were dipped into insecticides for 10 s, and emergence of adults and the mortality 24 h after emergence were recorded. Results showed that the rates of knockdown by the insecticides to adults were in the following decreasing order: phoxim≌methomylcartapdimethoatedeltamethrin≌cyhalothrinabamectin≌avermectinfenvaleratechlorfluazuron≌Bt, and the order of contact toxicity to the adults were: phoxim≌dimethoate≌methomyldeltamethrin≌cyhalothrincartapabamectin≌avermectinfenvaleratechlorfluazuron≌Bt. Five insecticides (dimethoate, fenvalerate,avermectin, chlorfluazuron and Bt) were shown to be harmless to the pupae, however, dimethoate was toxic to the adults emerging from the treated pupae. 