Temperature-altering Effects of Synthetic Insecticides On the Parasitoid Wasp Telenomus Podisi for the Biocontrol of Pentatomids in Soybean Crops

Abstract

The impact of climate change has led to growing global concern about the interaction of temperature and xenobiotics in agricultural toxicological studies. Thus, lethal, sublethal and transgenerational effects of six insecticide formulations used in the management of the stink bug complex in soybean crops were evaluated firstly on different life stages of the parasitoid Telenomus podisi Ashmead at three levels of temperature. Telenomus podisi adults in F₀ generation, when exposed to insecticides including acephate, spinosad and thiamethoxam + lambda-cyhalothrin, showed accumulated mortality of 100% at 15, 25 and 30 °C. On the other hand, methoxyfenozide + spinetoram caused average mortalities of 88.75% at 15 °C, 38.75% at 25 and 30 °C. The mortality caused by chlorfenapyr was increased by 70% with increasing temperature. Surviving adults in lethal toxicity bioassay did not show differences in egg parasitism of F₀ generation and emergence of F₁ generation at 15, 25 and 30 °C; however, the insecticide formulation based on methoxyfenozide + spinetoram showed the lowest level of parasitism and emergence. Our results demonstrated significant changes in the sex ratio as the temperature increased, but no differences were observed when compared with the insecticides tested. A significant interaction between insecticides and temperatures was discovered by contaminating the host’s parasitized eggs, corresponding to the pupal stage of T. podisi. Generally, the highest emergence reduction values were found at 30 °C. Our results highlighted the temperature-dependent impact of synthetic insecticides on parasitoids, which should be considered in toxicological risk assessments, under integrated pest management and climate change scenarios.