E)-6, 10-dimethyl-5,9-undecadien-2-ol (fuscumol) is an important component of male-produced aggregation pheromones for several species of cerambycid beetles in the genus Tetropium (subfamily Aseminae ⁄ Spondylidinae). Here, we describe the experiments that tested the hypothesis that fuscumol and ⁄ or fuscumol acetate also are general attractants for species in the cerambycid subfamily Lamiinae. At field sites in northwestern Indiana and central Texas (USA), panel traps baited with fuscumol or its acetate captured 331 lamiine beetles, compared to 11 beetles captured in control traps. Three species were attracted to traps baited with fuscumol as a single component, whereas another four species were attracted to fuscumol acetate alone. Surprisingly, fuscumol acetate also attracted two species in the subfamily Cerambycinae: Xylotrechus colonus (Fabricius) (males of which produce a pheromone composed only of stereoisomers of 2,3-hexanediol and 3-hydroxyhexan-2-one), and Obrium maculatum (Olivier) (for which a pheromone has yet to be identified). In an independent field experiment in east-central Illinois (USA), traps baited with fuscumol and ⁄ or its acetate captured 136 beetles of eight lamiine species, all but one species of which were also captured in the other experiment. Blending fuscumol and its acetate did not inhibit responses of species to either of the individual compounds, but synergized their activity for one species. Our results support the hypothesis that fuscumol and fuscumol acetate are widespread pheromone components or attractants for a variety of cerambycid species, especially lamiines in the tribe Acanthocinini.

Little is known of the reproductive behavior of longhorned beetles (Coleoptera: Cerambycidae) in the subfamily Prioninae. Mallodon dasystomus (Say), the hardwood stump borer, is a widely distributed prionine that is native to the southern U.S. Here, we explored the chemically-mediated mating behavior of M. dasystomus, and tested the hypothesis that males recognize females by a contact pheromone. In mating bioassays, all males tested attempted to mate with females only after contacting females with their antennae. Moreover, all males attempted to mate with solvent-washed dead females treated with as little as 0.15 ± 0.03 female equivalents of conspecific cuticular extracts, confirming that compounds on the cuticle of females are essential for mate recognition. Cuticular hydrocarbon profiles of females contained 13 compounds that were not present in profiles of males. Among the female-specific compounds, two co-dominant methyl-branched alkanes, 2-methylhexacosane (2Me-C(26)) and 2-methyloctacosane (2Me-C(28)), accounted for 17% of the total hydrocarbons. Our strategy for identifying the contact pheromone was to synthesize and test the bioactivity of female specific compounds, starting with the most abundant. In bioassays, males displayed mating behavior in response to synthetic 2Me-C(26) and 2Me-C(28) when tested individually. Furthermore, when these compounds were tested in combination, they elicited the full progression of mating behaviors, suggesting that 2Me-C(26) and 2Me-C(28) make up the contact pheromone. These findings are further evidence of the critical role of contact pheromones in mating systems of longhorned beetles.

Thousand cankers disease (TCD) is a pest complex formed by the association of the walnut twig beetle (WTB), Pityophthorus juglandis Blackman (Coleoptera: Curculionidae: Scolytinae), with the fungal pathogen Geosmithia morbida Kolařík, Freeland, Utley and Tisserat (Ascomycota: Hypocreales: Bionectriaceae). Current monitoring and detection efforts for WTB rely on a pheromone lure that is effective over a limited distance while plant- and fungal-derived volatiles that may facilitate host location remain poorly understood. In this study, we test the hypothesis that adult beetles are attracted to volatiles of black walnut, Juglans nigra L. (Juglandaceae), and the pathogen, G. morbida. We measured the response of beetles to head-space volatiles collected from leaves and stems of 12 genotypes of black walnut and found genotypic variation in the attractiveness of host trees to adult WTB. Volatile profiles of the most attractive genotypes contained more α-pinene and β-pinene, and adult beetles were attracted to both of these compounds in olfactometer bioassays. In bioassays, we also demonstrated that adult WTB are attracted to volatiles of G. morbida. These findings suggest that, in addition to the aggregation pheromone, dispersing WTB potentially use host plant and fungal volatiles to locate suitable larval hosts. Finally, we conducted a field experiment to determine the extent to which ethanol, a common attractant for bark beetles, and limonene, a known bark beetle repellent, influence the behavior of adult WTB to pheromone-baited traps. Although ethanol did not increase trap capture, WTB were repelled by limonene, suggesting that this compound could be used to manipulate and manage WTB populations.

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