Trap catches of woodboring beetles and predators affected by release rates of cerambycid pheromones

Detection programs for nonnative species of woodboring beetles require effective and affordable traps and lures. 3-Hydroxyhexan-2-one, 3-hydroxyoctan-2-one, and syn-2,3-hexanediol are 3 semiochemicals that are broadly attractive to longhorn beetles, and associated species of ambrosia beetles and predators. We determined the dose responses of insects to traps baited with ethanol and various combinations of these pheromones released at high rates versus low or medium rates. Five species of longhorn beetles exhibited positive dose-dependent responses with trap catches increasing with increased release rates. In contrast, 2 species of longhorn beetles exhibited a negative dose-dependent response to these pheromones. Curius dentatus Newman and Euderces pini Olivier (Coleoptera: Cerambycidae) were unaffected by release rates. Similar response patterns were observed with some species of ambrosia beetles (Coleoptera: Curculionidae), a powderpost beetle (Coleoptera: Bostrichidae), 3 predator species (Coleoptera: Carabidae, Cleridae, Trogossitidae), and an assassin bug (Hemiptera: Reduviidae). The reasons for these responses are unclear. However, the variation in dose-dependent responses by beetles may be important in optimizing the efficiency of detection programs with respect to lure costs and numbers of traps that should be deployed.