Transcriptome Analysis and Characterization of Two Detoxification Genes Responding to Imidacloprid in Aphis...

Aphis spiraecola is a major pest of fruit trees worldwide, causing significant yield reductions and economic losses in apple production. Chemical control remains the primary and most effective method for managing A. spiraecola in the field. Imidacloprid, the first neonicotinoid insecticide, effectively targets piercing-sucking pests. However, the time-dependent response of A. spiraecola to imidacloprid exposure has not been well characterized. In this study, we assessed the susceptibility of an A. spiraecola population from Zhengzhou to imidacloprid. Enzymatic assays revealed that the activities of cytochrome P450s, glutathione S-transferases (GSTs), and carboxylesterases (CarEs) were significantly increased following imidacloprid treatment. A synergism assay further demonstrated that the P450 inhibitor PBO and the CarE inhibitor TPP significantly enhanced the imidacloprid toxicity against A. spiraecola. Transcriptome analysis revealed that LC₅₀ imidacloprid treatment induced time-dependent changes in gene expression at 12, 24, and 36 h. A total of 46 P450 genes, 42 esterase genes, and six GST genes were identified in the transcriptome of A. spiraecola. Five detoxification enzyme genes, CYP380C6, CYP6CY19, GSTS3, GSTL, and CarE6, were significantly overexpressed, as confirmed by both transcriptomic and qPCR analysis. Moreover, RNAi-mediated knockdown of CYP6CY19 and CarE6 substantially increased aphid sensitivity to imidacloprid compared with the dsGFP control group. These results demonstrate that CYP6CY19 and CarE6 play an important roles in determining A. spiraecola susceptibility to imidacloprid. Our findings provide a theoretical basis for the rational and scientific use of imidacloprid in aphid management.