Adverse effect of insecticides on the rate of parasitization, emergence and sex ratio of F₁ progeny from Trichogramma chilonis ishii and T. japonicum Ashmead

The rate of parasitization and percentage of emergence were less affected in T. chilonis than that of T. japonicum. But the female percentage was always higher in case of T. japonicum. When pupal stage was treated all the biological characteristics of F1 progeny were least affected irrespective of any group of insecticides. However, the F₁ progeny from treated parental female was highly affected. Amongst all the insecticides, γBHC had the least toxic effect on the rate of parasitization and F₁ sex ratio of both parasitoids whereas in case of emergence, it was deltamethrin. All the biological characteristics were highly affected by quinalphos. The adverse effect of insecticides on the sex ratio of the parasitoids was more pronounced in quinalphos – in which the percentage of female come down to 15.9% from 55.7% in control. In other six insecticides, the percentage of female in sex ratio varied between 41.8 – 52.3% and the treatments varied significantly among themselves.