Role of host plant volatiles in mate location for three species of longhorned beetles

Abstract

Stressed woody plants represent an ephemeral and unpredictable resource for larvae of some species of longhorned beetles (Coleoptera: Cerambycidae) because prime subcortical tissues are rapidly degraded by a guild of xylophagous competitors. Selection favors efficient mechanisms of host and mate location to expedite colonization of hosts by larvae. Based on previous research, we hypothesize that mate location in some species of the subfamily Cerambycinae involves three sequential behavioral stages: (1) both sexes are attracted to larval hosts by plant volatiles; (2) males attract females over shorter distances with pheromones; and (3) males recognize females by contact pheromones in their epicuticular wax layer. We already have evidence of second-stage and third-stage behaviors in three species in this subfamily whose xylophagous larvae feed in hardwood trees: Xylotrechus colonus, Megacyllene caryae, and Neoclytus mucronatus mucronatus. In this report, we evaluate the first behavioral stage of mate location behavior (i.e., independent response of both sexes to host plant volatiles) for the same three species. Supporting our hypothesis, both males and females responded to volatiles emanating from hickory logs in Y-tube olfactometer bioassays.