Sublethal effects of insecticides used in strawberry on trichogramma pretiosum (Hymenoptera: Trichogrammatidae)

Abstract

Aim of study: Assessment of toxicity and sublethal effects of registered insecticides currently used in strawberry cultivation in Brazil on Trichogramma pretiosum Riley adults. Area of study: The study was conducted under laboratory conditions in Paraná (Brazil). Material and methods: Previously non-parasitized Duponchelia fovealis Zeller (Lepidoptera: Cambridae) eggs were dipped into insecticide dilutions or control solution. Seven active ingredients were tested: thiamethoxam, abamectin, azadirachtin, spinetoram, chlorfenapyr, lambda-cyhalothrin and chlorpyriphos. Side-effects of pesticides were quantified by measuring mortality on T. pretiosum females in 24 h, longevity after exposure to the insecticides, parasitism and emergence rates, and offspring sex ratio. These traits were also measured on the second generation. Main results: According to IOBC criteria, thiamethoxam was classified as harmless; abamectin, chlorfenapyr and spinetoram as slightly toxic; azadirachtin and lambda-cyhalothrin as moderately toxic and chlorpyriphos as toxic. The emergence rate of T. pretiosum second generation was not significantly affected by thiamethoxam, abamectin, azadirachtin, and chlorfenapyr. Sublethal effects caused by azadirachtin, abamectin and chlorfenapyr were verified in the second generation. Research highlights: The information generated by this study is useful for designing future biological control strategies in integrated pest management programs against D. fovealis.