Odorant-Binding Protein 56 h Contributes to the Behavioral Response of Frankliniella occidentalis to Neryl ( S )-2-Methylbutanoate

The western flower thrips, Frankliniella occidentalis, poses a serious threat to global agriculture because of its feeding damage and virus transmission. Its major aggregation pheromone component neryl (S)-2-methylbutanoate (NMB) is a strong attractant for adult females. However, the molecular mechanisms underlying NMB detection, particularly the role of odorant-binding proteins, remain poorly defined. This study identified and functionally characterized FoccOBP56h as a key mediator of the behavioral response to NMB. qRT-PCR showed that FoccOBP56h is predominantly expressed in the antennae and is significantly upregulated following NMB exposure. Fluorescence binding assays revealed that recombinant FoccOBP56h exhibited high affinity for NMB. Molecular docking and site-directed mutagenesis indicated that Asn90, Met104, and Val105 are important for NMB binding. RNAi-mediated knockdown of FoccOBP56h significantly reduced female attraction to NMB. These findings identify FoccOBP56h as a promising molecular target involved in NMB detection, providing a foundation for developing semiochemical-based strategies for insect behavior manipulation in pest management.