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 Sf 9 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. Environmental Implication Heavy metals have been reported to produce cross-tolerance in agricultural insects to insecticides. The growing demand for chemical pest control necessitates expanding research on the widespread occurrence of cross-tolerance to insecticides among pests, particularly forest pests, in areas polluted with heavy metals. In this study, Cd pre-exposure enhanced the cross-tolerance of Lymantria dispar larvae to β-cypermethrin. Cd pre-exposure activated the P450 detoxification system of L. dispar larvae. CYP6AB224 and CYP6AB226 were key detoxify genes to the formation of cross-tolerance. ROS-CnCC signaling pathway was proved to be responsible for activation of detoxify genes.