Abstract
(Z)-4-undecenal (Z4-11Al) is the volatile pheromone produced by females of the vinegar fly Drosophila melanogaster. Female flies emit Z4-11Al at few nanograms per hour, for species-specific communication and mate-finding. Tests with synthetic Z4-11Al show that it has a characteristic off-flavour, which we perceive even at the small amounts produced by one female fly. Since only females produce Z4-11Al, and not males, we can reliably distinguish between single D. melanogaster males and females, according to their scent. A wine-tasting panel finds that we sense as little as 1 ng synthetic Z4-11Al in a glass of wine, and 10 ng Z4-11Al is perceived as a loud off-flavour. This corroborates the observation that a glass of wine is spoilt by a single D. melanogaster fly falling into it, which we here show is caused by Z4-11Al. The biological role of Z4-11Al or structurally related aldehydes in humans and the basis for this semiochemical convergence remains yet unclear.
