Effects of field recommended concentrations of three different insecticides on life table parameters of the parasitoid Trichogramma evanescens (Hym.: Trichogrammatidae) under laboratory conditions

Chemical control is the most commonly practice in controlling pests. The application of chemical control is recommended in combination with other reduced risks control techniques such as biological control under Integrated Pest Management programs. Therefore, finding the appropriate chemical insecticide and the right time of spraying seems essential. In this study,three different growth stages of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) including larvae, pre-pupae, and pupae were exposed to the field recommended concentration of deltamethrin, Spirotetramat and flupyradifurone insecticides using insect dipping method. After which, the reproductive, biological characteristics and life table parameters of T. evanescens female adults were estimated. The eggs treated with deltamethrin in all three developmental stage of T. evanescens significantly reduced fecundity rate and oviposition period of the female adult parasitoids. Thegross reproductive rate (GRR), finite rate of increase (λ), intrinsic rates of increase (r), and net reproductive rate (R0) were not affected when larval and pre-pupal stages of T. evanescens were exposed to field recommended concentration of spirotetramat and flupyradifurone in comparison with control. However, the pupal stage showed to be the most susceptible stage and all of the life table parameters were affected upon exposure to three insecticides. Results of this research suggest a relative compatibility of spirotetramat and flupyradifurone with T. evanescens parasitoid. However, experiments under field conditions to evaluate the impact of tested insecticides on T. evanescens are required to confirm the results.