Identification of pheromone components of Plagionotus detri-tus

The longhorn beetle <i>Plagionotus detritus</i> (L.) occurs from Europe to the Middle East. Our principal aim was to identify the male-produced aggregation-sex attractant pheromone of this species. A pheromone-based monitoring system could support plant protection in areas where it might become a pest, and natural conservation in areas where it is endangered. Headspace volatiles were collected from live beetles and analyzed by coupled gas chromatography-electroantennogram detection, and gas chromatography-mass spectrometry. Two components of the extracts that elicited responses from antennae of <i>P. detritus</i>, (<i>R</i>)-3-hydroxyhexan-2-one and (<i>S</i>)-2-hydroxyoctan-3-one<i> </i>were identified, synthesized, and field tested. The blend of the two components attracted both sexes of <i>P. detritus </i>in field bioassays, and a predatory clerid beetle, <i>Clerus mutillarius</i> F., was attracted by both compounds. Another longhorn beetle species, <i>Xylotrechus antilope</i> Schönh. was significantly attracted to traps baited with (<i>S</i>)-2-hydroxyoctan-3-one alone or the blend containing this compound. These results show that the pheromone components and blends play key roles in longhorn beetle life history and ecology, and the community of species with which they live.