Functional characterization of BodoCSP3 in odorant recognition and host‐seeking behavior of the insect pest Bradysia odoriphaga (Diptera: Sciaridae)

Abstract BACKGROUND Chemosensory proteins ( CSPs ) are integral components of the insect olfactory system, facilitating the recognition, binding, and transport of odorant molecules to odorant receptors ( ORs ), thereby modulating various insect behavioral responses. In this study, we focused on characterizing the function of BodoCSP3 , a CSP cloned and identified from the pest Bradysia odoriphaga . BodoCSP3 was found to be highly expressed in the adult antennae, suggesting a potential role in olfaction. RESULTS Fluorescence competitive binding assays demonstrated that BodoCSP3 exhibits strong binding affinities to two host plant volatiles: dimethyl trisulfide and ethyl dodecanoate. Molecular docking combined with three‐dimensional structural analysis implicated specific hydrophobic residues in mediating these molecular recognition events. Site‐directed mutagenesis followed by fluorescence binding assays confirmed that the amino acid residues Ile73, Leu69, Tyr120, Lys117, and Tyr116 are critical for the binding of BodoCSP3 to both volatiles. Furthermore, RNA interference and behavioral assays revealed that Bradysia odoriphaga exhibits a dose‐dependent attraction to dimethyl trisulfide and ethyl dodecanoate. CONCLUSION The results indicated that BodoCSP3 mediates the recognition of host plant volatiles in Bradysia odoriphaga . These findings underscore the potential for developing effective and environmentally sustainable insect control strategies through the modulation of BodoCSP3 ‐mediated behavior. © 2025 Society of Chemical Industry.