Cd exposure confers β-cypermethrin tolerance in Lymantria dispar by activating the ROS/CnCC signaling pathway-mediated P450 detoxification

Heavy metal pollutants are important abiotic environmental factors affecting pest habitats. In this study, Cd pre-exposure significantly increased the tolerance of Lymantria dispar larvae to β-cypermethrin, but did not significantly alter their tolerance to λ-cyhalothrin and bifenthrin. The activation of P450 by Cd exposure is the key mechanism that induces insecticide cross-tolerance in L. dispar larvae. Both before and after β-cypermethrin treatment, Cd exposure significantly increased the expression of CYP6AB224 and CYP6AB226 in L. dispar larvae. Silencing CYP6AB224 and CYP6AB226 reduced the tolerance of Cd-treated L. dispar larvae to β-cypermethrin. Transgenic CYP6AB224 and CYP6AB226 genes significantly increased the tolerance of Drosophila and Sf9 cells to β-cypermethrin, and the recombinant proteins of both genes could significantly metabolise β-cypermethrin. Cd exposure significantly increased the expression of CnCC and Maf. CnCC was found to be a key transcription factor regulating CYP6AB224- and CYP6AB226-activated insecticide cross-tolerance in Cd-treated larvae. Decreasing reactive oxygen species (ROS) levels in the Cd-treated larvae or increasing ROS levels in the untreated larvae reduced or enhanced the expression of CnCC, CYP6AB224 and CYP6AB226 and β-cypermethrin tolerance in L. dispar larvae, respectively. Collectively, Cd exposure confers β-cypermethrin tolerance in L. dispar larvae through the ROS/CnCC signalling pathway-mediated P450 detoxification.