Predicted taxonomic patterns in pheromone production by longhorned beetles

Abstract

Males of five species of three tribes in the longhorned beetle subfamily Cerambycinae produce volatile pheromones that share a structural motif (hydroxyl or carbonyl groups at carbons two and three in straight-chains of six, eight, or ten carbons). Pheromone gland pores are present on the prothoraces of males, but are absent in females, suggesting that male-specific gland pores could provide a convenient morphological indication that a species uses volatile pheromones. In this article, we assess the taxonomic distribution of gland pores within the Cerambycinae by examining males and females of 65 species in 24 tribes using scanning electron microscopy. Gland pores were present in males and absent in females of 49 species, but absent in both sexes of the remaining 16 species. Pores were confined to indentations in the cuticle. Among the species that had male-specific gland pores were four species already known to produce volatile compounds consistent with the structural motif. These findings support the initial assumption that gland pores are associated with the production of pheromones by males. There were apparently no taxonomic patterns in the presence of gland pores. These findings suggest that volatile pheromones play an important role in reproduction for many species of the Cerambycinae, and that the trait is evolutionarily labile.

Using Generic Pheromone Lures to Expedite Identification of Aggregation Pheromones for the Cerambycid Beetles Xylotrechus nauticus, Phymatodes lecontei, and Neoclytus modestus modestus

“…3; Ray et al 2006). Pores were present on the pleura of all five species, but also on the episterna and sterna of X. nauticus, P. lecontei, P. d. decussatus, and B. gemmulatus, and the pronota of B. gemmulatus and N. m. modestus.…”

“…Specimens were prepared for SEM as described by Ray et al (2006), and imaged with a Phillips XL30 environmental scanning electron microscope equipped with a field-emission electron gun (FEI Company, Hillsboro, OR, USA) operated at 5.0 kV. To further confirm that pores in the prothorax of male X. nauticus and P. lecontei were associated with pheromone glands, we sectioned prothoraces of both sexes of each species for light microscopy.…”

“…These pheromones are comprised of one to three compounds that share a similar structural motif consisting of molecules that are six, eight, or 10 carbons in length, with hydroxyl or carbonyl groups at C 2 and C 3 (reviewed by Lacey et al 2004Lacey et al , 2007a. The pheromones are produced by sex-specific glands in the prothorax of males that discharge through pores situated within depressions in the cuticle (Ray et al 2006;Lacey et al 2007b). A morphological survey of 65 cerambycine species revealed that 49 species in 14 tribes had analogous male-specific prothoracic pores, suggesting that volatile pheromones may play an important role in reproduction or other behaviors for many species in this subfamily (Ray et al 2006).…”

“…The pheromones are produced by sex-specific glands in the prothorax of males that discharge through pores situated within depressions in the cuticle (Ray et al 2006;Lacey et al 2007b). A morphological survey of 65 cerambycine species revealed that 49 species in 14 tribes had analogous male-specific prothoracic pores, suggesting that volatile pheromones may play an important role in reproduction or other behaviors for many species in this subfamily (Ray et al 2006). The Cerambycinae is represented by at least 1,100 species in North America alone (excluding Mexico;Yanega 1996).…”

“…We chose six-carbon compounds for this first test of the hypothesis, rather than eight-or ten-carbon homologs, because all 10 North American cerambycine species that we have worked with previously were found to produce C 6 pheromones (Lacey et al 2004(Lacey et al , 2007aRay et al 2006;unpublished data). Thus, 2,3-hexanediols, 2-hydroxyhexan-3-ones, and 3-hydroxyhexan-2-ones were synthesized and deployed as trap lures in field bioassays.…”