Effects of several insecticides on the larval parasitoid, Cotesia plutellae Kurdjumov, of diamondback moth, Plutella xylostella (L.)

Insecticide resistance in diamondback moth (DBM), Plutella xylostella (L.) is one of the most important problems in the management of DBM. To retard or avoid the development of insecticide resistance in DBM, it is becoming more important to preserve natural enemies. We evaluated the toxicity of several insecticides on cocoons and adults of larval parasitoid, Cotesia plutellae Kurdjumov and effects of insecticides on parasitism. Under the experimental conditions, most insecticides applied at recommended concentrations showed high insecticidal activity against adults, but were less toxic to cocoons. However, parasitism by surviving adults was seriously affected.