Decoding the genetic and chemical basis of sexual attractiveness in parasitic wasps.

Attracting a mate is critical in all species that sexually reproduce. Most animals, particularly insects, do this using chemical compounds called pheromones which can be sensed by potential mates. But how these vast range of different compounds encode and convey the information needed to secure a partner is not fully understood, and the genes that drive this complex communication mechanism are largely unknown. To address this knowledge gap, Sun et al. studied the parasitic wasp Nasonia vitripennis. Like other insects, female N. vitripennis contain a wide range of chemical compounds on their cuticle, the outer waxy layer coating their surface. Sun et al. set out to find exactly which of these compounds, known as cuticular hydrocarbons, are involved in sexual communication. They did this by simultaneously inactivating two related genes that they hypothesized to be responsible for synthesizing and maintaining chemical compounds on the cuticle of insects. The genetic modification altered the pattern of chemicals on the surface of the female wasps by specifically up- and down-regulating compounds with similar branching structures. The mutant females were also much less sexually attractive to male wasps. These findings suggest that the chemical pattern identified by Sun et al. is responsible for communicating and maintaining sexual attractiveness in N. vitripennis female wasps. This is a significant stepping stone towards unravelling how sexual attractiveness can be encoded in complex mixtures of pheromones. The results also have important implications for agriculture, as this parasitic wasp species is routinely used to exterminate particular fly populations that cause agricultural damage. The work by Sun et al. provides new insights into how these wasps sexually communicate, which may help scientists improve their rearing conditions and sustain them over multiple generations. This could contribute to a wider application of this more sustainable, eco-friendly alternative to destructive agricultural pesticides.