A cDNA of PBAN receptor (Plx-PBANR) isolated from female pheromone gland of the diamondback moth encodes 338 amino acids and has 7 transmembranes, belonging to G-protein coupled receptor family. The fact that Plx-PBANR expression was only found in female pheromone gland revealed that pheromone gland is the only molecular target of Plx-PBAN. Plx-PBANR expressing cells increased level of Ca2+ influx when challenged with PBANs. When RNAi fragment for PBANR was injected into pupae, suppression of PBANR expression was maintained for at least 2 days at post-emergence. Injection of RNA fragment for inhibition of Plx-PBANR expression also inhibited mating behavior and suppressed sex pheromone production, suggesting that some molecular target was affected by reduced Plx-PBANR expression. We cloned partial Δ9 and Δ11 desaturase gene and investigated expression level in Plx-PBANR-RNAi moth. It is of interest that desaturases expression was reduced by RNA fragment injection. These results suggest of PBANR expression affects the molecular biological events of PBAN and eventually suppresses mating behavior.