Evaluation of individual components of plum odor as potential attractants for adult plum curculios

We evaluated olfactory attraction of overwintered plum curculio (PC) adults , Conotrachelus nenuphar, to 16 individual volatile components of unripe pl um odor in the laboratory using a still-air dual-choice bioassay system and in the field using baited cotton dental wicks attached to boll-weevil trap s placed on the ground beneath the canopy of unsprayed apple trees. Two com pounds, ethyl isovalerate and limonene, were significantly attractive in bo th laboratory bioassays and field experiments. In laboratory bioassays, as concentration was decreased across five orders of magnitude, a greater numb er of compounds elicited responses suggestive of attractancy (except at the lowest concentration). Even so, linalool, 2-hexanone, and 3-hydroxy-2-buta none were the only other compounds showing significant attractiveness in la boratory bioassays, but none of these (nor any other compounds) were signif icantly attractive in field assays. We suggest that the use of ethyl isoval erate and/or limonene as odor attractants offers potential to increase the efficacy of current traps for monitoring PCs immigrating into fruit orchard s during spring.