Overexpression of multiple odorant binding and chemosensory protein genes contributed to multi-insecticide resistance in Aphis gossypii Glover

The cotton aphid, Aphis gossypii, has evolved multi-insecticide resistance due to prolonged chemical control, yet mechanisms beyond metabolic and target-site resistance remain underexplored. This study investigates the role of olfactory binding proteins (OBPs) and chemosensory proteins (CSPs) in a multi-insecticide resistance strain (MRS). The MRS exhibited 9.63- to 192.38-fold resistance to sulfoxaflor, imidacloprid, acetamiprid, and thiamethoxam compared to a susceptible strain (SS). RT-qPCR analysis revealed significant upregulation of OBP3, OBP7, OBP9, CSP1, CSP6, and CSP8 in the MRS strain, with tissue-specific expression patterns (OBPs in heads; CSPs in heads/epidermis) and developmental stage variation. Insecticide exposure induced time-dependent overexpression of these genes. RNA interference (RNAi) silencing of OBPs and CSPs significant increase 12.54-48.65 % in aphid mortality under LC₅₀ insecticide exposure compared to untreated controls, confirming their functional role in resistance. Binding affinities and molecular docking analyses further confirmed that these proteins can interact with insecticides, suggesting their potential role in sequestering insecticides. This study provides evidence that OBPs and CSPs contribute to MRS in A. gossypii via insecticide sequestration and detoxification, offering novel molecular targets for resistance management strategies.