Selectivity of Insecticides Against Adult Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) on Cassava

In this study, the effects of various chemical and biological insecticides on adults of the parasitoid species Trichogramma pretiosum (Riley) were examined in cassava. The chemical insecticides zeta-cypermethrin, lufenuron + profenofós, imidacloprid, thiamethoxam, and teflubenzuron and the biological agents Bacillus thuringiensis and Baculovirus erinnyis were evaluated. For each treatment group, the effects were evaluated using T. pretiosum mortality rates, longevity of females, the number of eggs parasitized by the F0 generation, and number of emergent F1 parasitoids. The insecticides were classified using the International Organization for Biological Control categories. The tested insecticides had little effect on longevity and survival of adults, but all affected parasitism (F0) and were moderately harmful to the parasitoid. In relation to the emergent (F1) generation, the pesticides were either harmless or slightly harmful, except for zeta-cypermethrin which was classified as harmful with a 100% reduction in parasitoid emergence. The results indicate that the tested insecticides were moderately harmful to T. pretiosum in the laboratory; future studies will examine the effects of the insecticides under semi-field and field conditions to confirm their toxicity.