Intra- and interspecific activities of semiochemicals from the sex pheromone gland of the Welsh Clearwing, Synanthedon scoliaeformis.

Analysis of the sex pheromone gland of virgin Synanthedon scoliaeformis females by gas chromatography/mass spectrometry revealed six compounds structurally related to sex pheromone components of other clearwing moths: (E,Z)-2,13-octadecadienyl acetate (E2,Z13-18:OAc), (E,Z)-2,13-octadecadienol, octadecanol acetate, octadecanol, (Z,Z)-3,13-octadecadienyl acetate (Z3,Z13-18:OAc), and (Z)-13-octadecenyl acetate. Trapping tests demonstrated that E2,Z13-18:OAc is the sex pheromone of S. scoliaeformis and is essential for attracting males; addition of the other compounds did not enhance catch. Synanthedon scoliaeformis and S. tipuliformis are the only Palearctic clearwing moths whose distribution range and seasonal flight periods overlap and that are known to use E2,Z13-18:OAc in sex pheromonal communication. Hourly monitoring of male catches in traps revealed that sex pheromone communication in S. scoliaeformis and S. tipuliformis species follows different diurnal patterns. Z3,Z13-18:OAc, found in S. scoliaeformis females, is a known behavioral antagonist against S. tipuliformis males, while (E,Z)-3,13-octadecadienyl acetate, a minor sex pheromone component of S. tipuliformis, is an antagonist against S. scoliaeformis males. The effect of sex pheromones and antagonists, combined with different diurnal mate searching times, contribute to the specificity of sex communication channels in these two clearwing moth species.