Identification of β-ionone as an oviposition preference cue in Spodoptera litura using SlitPBP3-based reverse chemical ecology.

BACKGROUND: Screening and identifying compounds that modulate oviposition by female Spodoptera litura moths is a promising strategy for the selective management of this pest. Reverse chemical ecology provides an efficient and target-oriented approach for identifying bioactive semiochemicals by exploiting the functionally relevant olfactory binding proteins. RESULTS: Scanning electron microscopy revealed the presence of multiple types of sensilla on the ovipositor of female S. litura, providing morphological support for the selection of ovipositor-expressed olfactory genes as screening targets. In the present study, we used SlitPBP3, an olfactory gene expressed in the ovipositor of female S. litura during the calling stage, as a molecular target for screening oviposition-related compounds. Structure-based virtual screening combined with fluorescence competitive binding assays demonstrated that SlitPBP3 showed preferential binding to β-ionone among the tested compounds. Site-directed mutagenesis further revealed that residues F12 and F118 are critical for the interaction between SlitPBP3 and β-ionone. Functional assays showed that RNA interference-mediated silencing of SlitPBP3 significantly reduced the oviposition preference index of female moths for β-ionone-treated substrates. Notably, female moths continued to preferentially oviposit on β-ionone-treated substrates even after antennal ablation, indicating that chemosensory perception during oviposition can occur independently of antennal input. CONCLUSION: The present study establishes SlitPBP3 as a practical screening target within a reverse chemical ecology framework and identifies β-ionone as an oviposition-stimulatory cue with potential value for developing female-oriented behavioral management strategies against S. litura. © 2026 Society of Chemical Industry.