CYP4C1 contributes to the tolerance of Sitobion avenae to imidacloprid seed-treated wheat

Imidacloprid seed dressing is a highly effective technology for controlling wheat aphids and has been extensively promoted and applied in the wheat-producing regions of China. However, the control effect of imidacloprid seed dressing on wheat aphids is unstable. Understanding the tolerance mechanism of wheat aphids to imidacloprid seed-treated wheat remains unclear. In this study, the tolerance mechanism was investigated. Based on the transcriptome sequencing results, two cytochrome P450s, one UDP-glucuronosyltransferase, one octopamine receptor, and one esterase gene were significantly up-regulated in S. avenae on imidacloprid seed-treated wheat. Following imidacloprid seed dressing, S. avenae exhibited a 2.69-fold increase in the expression of a single cytochrome P450 gene ( SaCYP4C1 ). The coding sequence of SaCYP4C1 is 1563 bp and encodes 521 amino acids. Phylogenetic analysis revealed that CYP4C1 in S. avenae and seven other aphids cluster into one large branch. SaCYP4C1 was significantly induced (1.73-fold) by imidacloprid at a concentration of 0.114 mg L –1 (0.1 ×LC 50 ). The silencing of S. avenae by RNAi indicated a significantly reduced P450 activity in S. avenae . The survival rate and fecundity of S. avenae on imidacloprid seed-treated wheat were significantly reduced by SaCYP4C1 down-regulation, thereby reducing the adaptability of S. avenae. This study demonstrates the tolerance mechanisms of S. avenae to imidacloprid seed dressing, providing a reference for the effective application of imidacloprid dressing technology in controlling S. avenae .