OBP2 in the Midlegs of the Male Bactrocera dorsalis Is Involved in the Perception of the Female-Biased Sex Pheromone 4-Allyl-2,6-dimethoxyphenol

Short-range semiochemicals convey individual-specific information, which is important for final successful courtship and copulation. In this study, an electroantennography (EAG) instrument was used to determine the legs of male that might participate in the perception of 4-allyl-2,6-dimethoxyphenol (4-DMP), a female-biased cuticular hydrocarbon (CHC) component. By performing comparative RNA-seq analysis, nine differentially expressed OBPs between 4-DMP-stimulated (M ) and unstimulated (M) male flies were screened out. Among the four downregulated OBPs, OBP2 exhibited the strongest binding to 4-DMP than OBP4, OBP19a, and OBP56h. Functional analyses confirmed that the reduction in transcript abundance of OBP2 led to a significant decrease in behavioral responses of male flies to 4-DMP. simulation revealed dramatic changes in the key residues and conformation between the two complexes, implying that OBP2 might activate different receptors after binding to 4-DMP or methyl eugenol (ME). The results of this study suggest that OBP2 mediates behavioral responses to 4-DMP and could be a promising molecular target for strategies of pest control.