1-(1H-pyrrol-2-yl)-1,2-propandione is a crucial pheromone component of the rare North American cerambycid beetle Dryobius sexnotatus

The compound 1-(1H-pyrrol-2-yl)-1,2-propanedione was recently found to be an important pheromone component of several Asian species of longhorned beetles in the subfamily Cerambycinae. Here, we report the first confirmed identification of this pyrrole as a pheromone component of a cerambycine species native to North America, the rare Dryobius sexnotatus Linsley. Headspace volatiles from males contained (R)-3-hydroxyhexan-2-one and the pyrrole (ratio 1:0.13), neither of which were detected in samples from females. A field bioassay confirmed that adults of both sexes were attracted only by the binary blend of racemic 3-ketol with the pyrrole, and not by either compound alone. Adults of another cerambycine, Xylotrechus colonus (F.), were attracted by the ketol, consistent with its being the primary component of the pheromone of this species, and attraction was not influenced by the presence of the pyrrole. This study attests to the effectiveness of pheromone-baited traps in detecting rarely encountered species of cerambycids. It also provides further evidence that the pyrrole represents another conserved pheromone motif within the Cerambycinae