Sex Pheromone Mediates Resource Partitioning Between and .

The spotted-wing drosophila, and the cosmopolitan vinegar fly feed on soft fruit and berries and widely overlap in geographic range. The presence of reduces egg-laying in , possibly because outcompetes larvae feeding in the same fruit substrate. Flies use pheromones to communicate for mating, but pheromones also serve a role in reproductive isolation between related species. We asked whether a pheromone also modulates oviposition behaviour in . A dual-choice oviposition assay confirms that lays fewer eggs on blueberries exposed to flies and further shows that female flies have a stronger effect than male flies. This was corroborated by treating berries with synthetic pheromones. Avoidance of oviposition is mediated by the female pheromone ()-4-undecenal (Z4-11Al). Significantly fewer eggs were laid on berries treated with synthetic Z4-11Al. In comparison, the male pheromone ()-11-octadecenyl acetate (cVA) had no effect on oviposition. Z4-11Al is a highly volatile compound that is perceived via olfaction and it is accordingly behaviourally active at a distance from the source. is known to engage in mutual niche construction with the yeast , which strongly attracts flies. Adding Z4-11Al to fermenting significantly decreased flight attraction in a laboratory wind tunnel and a field trapping assay. That a pheromone regulates oviposition in demonstrates that heterospecific pheromone communication contributes to reproductive isolation and resource partitioning in cognate species. Stimulo-deterrent diversion or push-pull methods, building on combined use of attractant and deterrent compounds, have shown promise for control of . A pheromone that specifically reduces attraction and oviposition adds to the toolbox for integrated management.