Influence of Fermenting Bait and Vertical Position of Traps on Attraction of Cerambycid Beetles to Pheromone Lures

Because larvae of cerambycid beetles feed within woody plants, they are difficult to detect, and are readily transported in lumber and other wooden products. As a result, increasing numbers of exotic cerambycid species are being introduced into new regions of the world through international commerce, and many of these species pose a threat to woody plants in natural and managed forests. There is a great need for effective methods for detecting exotic and potentially invasive cerambycid species, and for monitoring native species for conservation purposes. Here, we describe a field experiment in east-central Illinois which tested whether attraction of beetles to a blend of synthesized cerambycid pheromones would be enhanced by volatiles from fermenting bait composed of crushed fruit, sugars, yeast, and wood chips. A second experiment tested the same treatments, but also assessed how trap catch was influenced by the vertical position of traps within forests (understory versus within the canopy). During the two experiments, 885 cerambycid beetles of 37 species were caught, with Xylotrechus colonus (F.) (subfamily Cerambycinae) being the most numerous (∼52% of total). Adults of several cerambycid species were significantly attracted by the pheromone blend, but the fermenting bait significantly enhanced attraction only for X. colonus and Graphisurus fasciatus (Degeer) (subfamily Lamiinae). Traps in the forest understory caught the greatest number of X. colonus and G. fasciatus, whereas more adults of the cerambycine Neoclytus mucronatus mucronatus (F.) were caught in the forest canopy rather than the understory.