Silencing Doublesex expression triggers three-level pheromonal feminization in Nasonia vitripennis males.

Doublesex (Dsx) has a conserved function in controlling sexual morphological differences in insects, but our knowledge of its role in regulating sexual behaviour is primarily limited to Drosophila . Here, we show with the parasitoid wasp Nasonia vitripennis that males whose Dsx gene had been silenced ( NvDsx -i) underwent a three-level pheromonal feminization: (i) NvDsx -i males were no longer able to attract females from a distance, owing to drastically reduced titres of the long-range sex pheromone; (ii) NvDsx -i males were courted by wild-type males as though they were females, which correlated with a lower abundance of alkenes in their cuticular hydrocarbon (CHC) profiles. Supplementation with realistic amounts of synthetic ( Z )-9-hentriacontene ( Z 9C31), the most significantly reduced alkene in NvDsx -i males, to NvDsx -i males interrupted courtship by wild-type conspecific males. Supplementation of female CHC profiles with Z 9C31 reduced courtship and mating attempts by wild-type males. These results prove that Z 9C31 is crucial for sex discrimination in N. vitripennis ; and (iii) Nvdsx -i males were hampered in eliciting female receptivity and thus experienced severely reduced mating success, suggesting that they are unable to produce the to-date unidentified oral aphrodisiac pheromone reported in N. vitripennis males. We conclude that Dsx is a multi-level key regulator of pheromone-mediated sexual communication in N. vitripennis .