Odorant-binding protein MusiOBP10 contributes to the aggregation pheromone sensing in both nymphal and adult Megalurothrips usitatus (Bagnall).

Odorant-binding proteins (OBPs) play a critical role in insect chemoreception by facilitating the transport of odorant molecules to olfactory receptors, thereby initiating signal transduction. Megalurothrips usitatus is a significant pest posing a major threat to leguminous crops, with both nymphs and adults exhibiting aggregation behavior on cowpea. However, the specific functional role of OBPs in modulating this behavior remains unclear. Here, behavioral assays revealed that both nymphs and adults of M. usitatus showed significant attraction to the aggregation pheromone (2E,6E)-farnesyl acetate. Exposure to this aggregation pheromone significantly upregulated MusiOBP10 expression in M. usitatus. MusiOBP10 knockdown with RNA interference (RNAi) eliminated M. usitatus' attraction to (2E,6E)-farnesyl acetate. Furthermore, binding assays revealed that MusiOBP10 exhibits exceptionally high binding affinity for (2E,6E)-farnesyl acetate. Molecular docking results indicated that MusiOBP10 binds to (2E,6E)-farnesyl acetate primarily through van der Waals interactions. Molecular dynamic simulations identified six candidate key residues within the MusiOBP10-(2E,6E)-farnesyl acetate complex. Computational alanine scanning and site-directed mutagenesis verified four key amino acid residues critical for the binding of MusiOBP10 to (2E,6E)-farnesyl acetate, with the C-terminal residue Phe122 playing a particularly influential role. In conclusion, MusiOBP10 plays a critical role in the perception of the aggregation pheromone in M. usitatus. These findings have improved our molecular understanding of aggregation pheromone recognition by M. usitatus, and have facilitated the development of OBP-based behavioral interference strategies to manage this pest.