Transcription factor AhR regulates glutathione S-transferases (GSTs) conferring resistance to lambda-cyhalothrin in Cydia pomonella

Transcription factor aryl hydrocarbon receptor (AhR) can enhance insect resistance to insecticides by regulating the detoxification metabolic network. Our previous studies have confirmed that overexpression of cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) are both involved in lambda-cyhalothrin resistance in Cydia pomonella. In this study, we report that AhR regulates GSTs thus conferring lambda-cyhalothrin resistance in C. pomonella. Spatiotemporal expression patterns indicated that AhR gene of C. pomonella (CpAhR) was highly expressed in the Malpighian tubules of larvae. Moreover, the expression of CpAhR was induced by lambda-cyhalothrin exposure and was up-regulated in a lambda-cyhalothrin-resistant population. RNA interference (RNAi) of the expression of CpAhR could effectively decrease the relative expression level of CpGSTe3 and enzyme activity of GSTs, but not P450s, further reducing the tolerance of larvae to lambda-cyhalothrin. Furthermore, {beta}-naphthoflavone (BNF), a novel agonist of AhR, can effectively increase the expression of CpAhR and the activity of the GSTs enzyme, resulting in the enhancement of larvae tolerance to lambda-cyhalothrin. These results demonstrate that lambda-cyhalothrin exposure can effectively activate the expression of CpAhR and increase GSTs enzyme thus leading to the development of resistance to lambda-cyhalothrin, which enriches the theory of insecticide resistance regulation in C. pomonella.