Geranyl hexanoate, the female-produced pheromone of Agriotes sordidus Illiger (Coleoptera: Elateridae) and its activity on both sexes

Analysis of the pheromone gland extract of females of the click beetle Agriotes sordidus (Illiger), revealed the presence of geranyl hexanoate (GH) and (E,E)-farnesyl hexanoate (FH) in an approximate ratio of 1:1. In the female-released volatiles collected by headspace extraction, GH was a dominant component with FH present only in trace amounts. In field trapping tests GH on its own captured high numbers of A. sordidus adults, whereas the addition of FH in various proportions had no effect on captures. A closer scrutiny of adults caught in GH-baited traps revealed that 10–40 % of them were females. Significantly higher numbers of both female and male beetles were attracted to traps baited with GH as compared to unbaited controls showing a clear dose–response relationship with higher doses catching more beetles. In electroantennogram (EAG) tests responses of female and male antennae to a number of known click beetle pheromone components showed the same trend in both sexes, giving the highest answers to GH. This suggests that female and male antennae are similar with respect to the perception of pheromone components, and that GH shows some activity as an aggregation pheromone.