Sex pheromones and sex attractants of species within the genera Idolus Desbrochers des Loges and Dalopius Eschscholtz (Coleoptera: Elateridae) in the western United States

Most known click beetle (Coleoptera: Elateridae) sex pheromones have been identified from economically important European species. We hypothesized that pheromone components might be conserved between New and Old World species, and so tested blends of known pheromones in California and Washington states. Males of the endemic species Idolus californicus and Idolus columbianus (subfamily Elaterinae) were attracted to blends of neryl esters, many of which are known pheromones of related European species. Electroantennogram assays determined that antennae of male beetles responded strongly to two neryl esters, and in field bioassays, males of both species were specifically attracted to neryl hexanoate. Female I. californicus were found to produce both neryl hexanoate and neryl octanoate, and lures that contained neryl hexanoate alone or in blends attracted male beetles. Neryl octanoate was not attractive, and neither synergized nor antagonized attraction to neryl hexanoate. Males of Dalopius spp. also were captured in traps baited with lures containing neryl octanoate. Our results support the hypothesis that the neryl ester pheromone motif is conserved among taxonomically related European and North American elaterids in the tribe Elaterinae, which should aid in the identification of pheromones of pest species within the tribe.