Influence of host plant volatiles on the response and production of pheromones for a longhorn beetle species

Research on longhorn beetle (Coleoptera: Cerambycidae) chemical ecology has shown that for some species, host volatiles are required for or increase attraction to pheromones. Typically the species where this effect is most pronounced are those infesting conifers. To explore if this phenomenon extended to cerambycids that infest angiosperms, we developed a reconstructed blend of oak volatiles to test in combination with pheromones. We also tested whether ethanol functions as a kairomonal cue for the species occurring at our field sites, because results from other workers support ethanol as a general attractant for many cerambycids, including angiosperm-infesting species. Our field results for at least one angiosperm-infesting species, Phymatodes obliquus, suggest that the pheromone of this species is not synergized by either host odors or ethanol. We also tested the effect of the presence or absence of host material on pheromone production by males of this species, using beetles held on twigs of a known host, western black oak, Quercus kellogii.