Safety evaluation of eleven insecticides to Trichogramma nubilale (Hymenoptera: Trichogrammatidae).

The safety of 11 pesticides (indoxacarb, chlorfluazuron, azadirachtin, methoxyfenozide, rotenone, spinosad, acetamiprid, imidacloprid, chlorfenapyr, chlorpyrifos, and triazophos) to Trichogramma nubilale (Hymenoptera: Trichogrammatidae) was evaluated in this study. The acute toxicity to the adults was investigated using dry-film method. The influences of the pesticides on both parasitic ability and different developmental stages were studied using corn leaves residual method, rice moth egg card dipping method, and T. nubilale parasitized rice moth egg dipping method. Results showed that methoxyfenozide, azadirachtin, and indoxacarb were safe for the whole life cycle of T. nubilale. Chlorfluazuron, rotenone, and acetamiprid had different levels of impacts on different developmental stages, and they should be chosen to be used according to their safety time with reduced exposure levels. Rotenone was safe for the adults but it was harmful to the other stages, whose dosage should be reduced when it was used. Acetamiprid could be applied during the pupae stage. Finally, to avoid large kill, spinosad, chlorfenapyr, chlorpyrifos, triazophos, and imidacloprid should not be used as they were not safe for any development stage of T. nubilale.