Cerambycid beetles in the subfamily Cerambycinae are known to respond to aggregation-sex pheromones emitted by the males. Our experiment targeted two cerambycine species whose pheromones are composed primarily of (R)-3-hydroxyhexan-2-one: Neoclytus mucronatus mucronatus (F.) and Xylotrechus colonus (F.). The pheromone of X. colonus included (R)-2-methylbutan-1-ol as a minor component, and the same compound antagonizes attraction of N. mucronatus to racemic 3-hydroxyhexan-2-one. The purpose of the experiment was to determine dose-dependent effect of 2-methylbutan-1-ol (2-MB) on attraction of the two species of 3-hydroxyhexan-2-one (3-KT). Panel traps were arranged in linear transects. In one experiment, traps were baited with varying dosages of 3-KT or 2-MB (i.e., lures with varying release rates). In a second experiment, the dose of 3-KT was varied along with a constant dose of 2-MB. In a third experiment, the dose of 2-MB was varied along with a constant dose of 3-KT. N. mucronatus was most strongly attracted to an intermediate dose of 3-KT, but in the presence of 2-MB higher doses of 3-KT were the strongest attractants. In contrast, adult X. colonus were attracted to a range of 3-KT doses, but in the presence of 2-MG were only attracted to an intermediate dose of 3-KT. Attraction of either species to 3-KT was not influenced by the dose of 2-MB. These findings demonstrate that lure release rate can greatly influence the trapping efficiency for cerambycids. Care must be taken in combining pheromone components, or pheromone components of heterospecifics, which may further alter attraction to traps.
