Multigenerational responses of wheat aphids to multiple stresses: interactions between sublethal thermal stress types and a low insecticide dose

The interaction between thermal stress and chemical insecticides in agricultural pests has become more common owing to the global warming and human activities. Although research has shown the interaction of constant temperature or single thermal stress with insecticides, the ecological effects of sublethal thermal stress and low-dose insecticide interaction, which are more applicate to field conditions, are limited. Therefore, this study investigates the interaction of sublethal thermal stress (TS) (34 °C/180 min, 36 °C/30 min, and 38 °C/10 min) and low-dose imidacloprid (IM) applications in the maternal and offspring phenotype of the important grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae). In the F0 generation, single TS significantly reduced the longevity, fecundity, survivorship, and population parameters of S. avenae, and the interaction between TS and IM (TS-IM) had a significant negative effect on the intrinsic rate of increase in the order 34 °C/180 min + IM > 36 °C/30 min + IM > 38 °C/10 min + IM. In the F1 generation, the development duration of nymph was increased and the intrinsic rate of increase was reduced after F0 underwent TS. However, the intrinsic rate of increase of F1 generation showed the greatest decrease under 38 °C/10 min + IM, and the lowest decrease under 34 °C/180 min + IM. The results of this study reveal the significance of evaluating together different abiotic factors, such as the interaction between thermal stress and insecticides, in the risk assessment of climate change, emphasizing the importance of the combination of different stresses in pest control.