Sex pheromones and reproductive isolation in four european small ermine moths

Reproductive isolation among four sympatric small ermine moths (Yponomeuta) is analyzed in terms of niches in the sexual communication channel. Potential pheromone components were identified from pheromone gland secretions ofY. evonymellus,Y. cagnagellus,Y. padelius, andY. vigintipunctatus by gas chromatography with flame ionization and electroantennographic detection and tested for behavioral activity in the field. The species were found to share (Z)-11-tetradecenyl acetate (Z11-14: OAc) in combination with varying proportions of theE isomer as primary sex pheromone components.Y. cagnagellus differs from the rest of the species by having only a small amount (1.5%) ofE isomer relative toZ isomer in its pheromone. The closely relatedY. padelius has a three-component pheromone including large amounts (ca. 400%) of (Z)-11-hexadecenyl acetate (Z11-16:OAc) in addition toZ11-14: OAc (100%) andE11-14: OAc (34%).Z11-16: OAc appears to reduce trap catches ofY. evonymellus andY. vigintipunctatus when added to the pheromone. Although these species are the two most distantly related European small ermine moths, they seem to share the same sex pheromone, i.e.,Z11-14∶OAc (+20%E) and (Z)-11-tetradecenol. Our interpretation is that this might have been the sex pheromone of the ancestor of today'sYponomeuta species.