Effect of insecticides on biological attributes of the egg parasitoid Telenomus remus (Hymenoptera: Platygastridae)

The egg parasitoid Telenomus remus (Hymenoptera: Platygastridae) is one of the most important natural enemies of Spodoptera frugiperda (Lepidoptera: Noctuidae). The application of chemical insecticides is the main strategy to control this insect pest, although it can affect T. remus and harm integrated pest management (IPM) programmes. This study evaluated the acute lethal (mortality) and sublethal (parasitism and emergence rate, sex ratio, and longevity) effects caused by chlorfenapyr, spinosad, and thiamethoxam + lambda-cyhalothrin by tarsal contact on T. remus adults. The lethal concentration (LC50) of the insecticides showed that thiamethoxam + lambda-cyhalothrin had the highest lethal toxicity on T. remus adults. However, sublethal effects on the F-0 generation showed that all insecticides (chlorfenapyr, spinosad, and thiamethoxam + lambda-cyhalothrin) were classified as innocuous, without significant differences in the parasitism rate, emergence rate, and sex ratio compared to the control. Nevertheless, the risk quotient (RQ, mg ai L-1) classified the insecticides thiamethoxam + lambda-cyhalothrin and chlorfenapyr as toxic to T. remus. In contrast, spinosad was classified as slightly to moderately toxic. Also, thiamethoxam + lambda-cyhalothrin, chlorfenapyr, and spinosad did not affect the biological development of T. remus. These results can be used as a basis for integrating chemical and biological control to manage S. frugiperda in an attempt to preserve natural enemies in the field.