Expression and ligand-binding characterization of two chemosensory proteins (TabsCSP8 and TabsCSP19) in Tuta absoluta

Chemosensory proteins (CSPs) are small soluble proteins in insects that facilitate the recognition of exogenous ligands, playing crucial roles in olfaction and potentially in detoxification processes. Tuta absoluta is a globally significant pest; however, its CSP gene family remains inadequately characterized. In this study, we identified 23 full-length CSP genes (TabsCSP1-TabsCSP23) through genome-wide analysis. Phylogenetic analysis revealed that TabsCSPs are distributed among different lepidopteran clades, supporting the evolutionary conservation of the CSP family and suggesting possible lineage-specific divergence within T. absoluta. Expression profiling revealed that TabsCSP8 was significantly upregulated following spinosad exposure, whereas TabsCSP19 was significantly upregulated following Bacillus thuringiensis (Bt) exposure. Developmental expression profiling revealed that TabsCSP8 was highly expressed in adults and 1st instar larvae, while TabsCSP19 showed high expression in adults. Tissue expression profiling further indicated that both TabsCSP8 and TabsCSP19 were predominantly expressed in larval heads and epidermis. Fluorescence competitive binding assays revealed that TabsCSP8 exhibited strong binding affinities to chlorpyrifos (CPF) and moderate binding affinities to the main sex pheromone component (3E,8Z,11Z)-tetradecatrien-1-yl acetate (TDTA), but no detectable binding to the other tested ligands. TabsCSP19 showed no detectable binding to any of the tested ligands. Docking analysis showed that TabsCSP8 interacted with CPF and TDTA mainly through conventional hydrogen bonds and hydrophobic interactions. Collectively, our findings reveal that CSPs in T. absoluta are involved not only in chemoreception but also in insecticide response, underscoring their dual functional roles in environmental adaptation. This study provides valuable molecular insights that could inform the development of novel CSP-based strategies for eco-friendly pest management.