Trans-3-hexen-1-ol as a potential attractant for the adzuki bean weevil, Callosobruchus chinensis: Evidence from...

Odorant-binding proteins (OBPs) play a crucial role in insect host plant location, mating, and oviposition, making them essential for survival, promising targets for pest management. In this study, we explored the potential role of an odorant-binding protein (OBP) in the adzuki bean weevil, Callosobruchus chinensis, a major pest of stored legumes worldwide. Quantitative real-time PCR (qRT-PCR) revealed that the OBP19 gene is highly expressed in the antennae of both sexes. Functional analyses of the recombinant CchiOBP19 protein demonstrated binding affinity to three cowpea volatiles - vanillin, β-ionone and trans-3-hexen-1-ol, with the latter identified as a novel ligand exhibiting stable conformational interaction. Site-directed mutagenesis of four key amino acid residues (M109, N116, W117, and F118) abolished the protein's binding affinity, highlighting their critical role in ligand interaction. Electrophysiological and behavioral assays confirmed that trans-3-hexen-1-ol elicits strong antennal responses and attracts both males and females. These findings suggest that trans-3-hexen-1-ol holds promise as a behavioral attractant for C. chinensis, providing a novel avenue for pest management strategies.