Identification of pheromone-like compounds in male reproductive organs of the oriental locust Locusta migratoria

Despite the great economical interest of locusts in agriculture, knowledge on their chemoreception sys- tems is still poor. Phenylacetonitrile is recognised as a pheromone of the desert locust Schistocerca gre- garia, triggering gregarization, promoting aggregation and inhibiting courtship. However, in the other major locust species, Locusta migratoria, pheromones have not been reported. We have identified the two isomers of naphthylpropionitrile from the male reproductive organs of L. migratoria. Chemical syn- thesis has confirmed the identity of the two compounds. Both isomers show significant affinity to CSP91, a protein reported in the testis, but not to three other proteins of the same family (CSP180, CSP540 and CSP884) expressed in female accessory glands. The striking similarity of these compounds with phenyl- acetonitrile and the unusual nature of such chemicals strongly suggest that naphthylpropionitrile could be pheromones for L. migratoria, while their site of expression and binding activity indicate a role in com- munication between sexes.