An odorant binding protein mediates Bactrocera dorsalis olfactory sensitivity to host plant volatiles and male attractant compounds.

Odorant-binding proteins (OBPs) are believed to play critical roles in host-seeking behavior. However, little attention was paid to its different functions in male and female. The antenna-specific OBP gene from Bactrocera dorsalis, BdorOBP13, was cloned and its expression profile was examined. The results showed that BdorOBP13 was exclusively expressed in male and female adults, which exhibited a high transcript level in antennae. After injection of BdorOBP13 dsRNA, its transcript level in males and females decreased significantly. Electrophysiological responses of RNAi-injected flies to, methyl eugenol (male attractant) and γ-octalactone (female attractant) decreased significantly. However, no significant changes in the electrophysiological response were observed in RNAi-injected flies to benzothiazole, (+),dipentene, and ethyl tiglate. The behavioral bioassay showed that males treated with RNAi significantly reduced their preference to methyl eugenol, while RNAi-injected females showed a significantly lower preference to γ-octalactone, suggesting that BdorOBP13 may have different functions between males and females: it may be involved in the detection of methyl eugenol in males but is involved in the detection of γ-octalactone in females. These findings improve our understanding of insect OBPs and their roles in insect chemosensation, which may provide us with new molecular targets in the management of B. dorsalis.