Sublethal and Intergenerational Effects of Combined Exposure to Nitenpyram, Pymetrozine, and Beta-Cypermethrin on Aphis gossypii: Life Table Parameters, Physiological Responses, and Gene Expression

Compared with single insecticides, insecticide mixtures can enhance efficacy, broaden the spectrum of activity, and potentially delay resistance evolution in Aphis gossypii. However, their sublethal and intergenerational effects remain poorly understood. Here, the life table analysis was used to evaluate the effects of mixture treatments prepared from sublethal (LC20) and low-lethal (LC50) doses of nitenpyram, pymetrozine, and beta-cypermethrin on the directly exposed F0 generation of A. gossypii and its effects on the F1 progeny. Total protein, free amino acid, and vitellogenin (Vg) contents were measured, and the sequence and expression of Vg and vitellogenin receptor (VgR) genes were analyzed. Exposure to the mixture treatments significantly reduced longevity and fecundity in both generations while increasing total protein and free amino acid contents. Domain prediction confirmed the conserved structural features of AgVg and AgVgR, and phylogenetic analysis showed that both clustered with homologs from closely related aphid species. RT-qPCR further revealed that the mixture treatments significantly suppressed AgVg and AgVgR expression. In conclusion, exposure to the mixture treatments affects both directly exposed individuals and their progeny, providing a basis for evaluating the ecological consequences of insecticide mixtures and optimizing their use within integrated pest management strategies for A. gossypii.