NPFF2 regulate thiamethoxam resistance by over-expressing CYP6CX4 in Bemisia tabaci

The whitefly, Bemisia tabaci, as a globally significant agricultural pest, poses a serious threat to various food crops and thus causes enormous economic losses to global agricultural production. In recent decades, with the long-term and extensive use of chemical pesticides, B. tabaci has developed high levels resistance to thiamethoxam. Therefore, an in-depth analysis of the molecular mechanisms involved in insecticide detoxification within B. tabaci is of great theoretical and practical significance. Neuropeptide FF receptor 2 (NPFF2), a G protein-coupled receptor (GPCR), plays a key role in the neonicotinoid resistance of B. tabaci. Whether NPFF2 is involved in the resistance to thiamethoxam remains unclear. In this study, we cloned the full-length NPFF2 gene of B. tabaci, and further confirmed its vital role in thiamethoxam resistance via Quantitative real-time PCR and RNA interference assays. To investigate the signaling pathway of NPFF2 involved in thiamethoxam resistance in B. tabaci. The expression of six published detoxification-related genes (UGT354A1, UGT352A3, CYP6CX1, CYP6CX2, CYP6CX3 and CYP6CX4) were determined in the resistant and susceptible strains. The results showed that the expression of CYP6CX4 was over-expressed in resistant, and decreased by knockdown of NPFF2. Additionally, in a metabolism assay in vitro, the CYP6CX4 protein could metabolize 52.64% of thiamethoxam with a clothianidin-guanidine hydrochloride metabolite via UPLC-QTOF/MS. Overall, our study reveals a novel NPFF2 - CYP6CX4 signaling pathway underlying thiamethoxam resistance in B.tabaci, providing a theoretical basis for its resistance monitoring and novel control target development.