Abstract
In the Central American region, the aggressive, sibling bark beetles Dendroctonus frontalis Zimmermann (Coleoptera:
Curculionidae: Scolytinae) and Dendroctonus mesoamericanus Armendáriz-Toledano & Sullivan (Coleoptera:
Curculionidae: Scolytinae) commonly colonize pines concurrently, and in nature they avoid heterospecific pairing,
although it can be produced in the lab. We performed walking arrestment bioassays in the lab to examine the
capacity of both sexes of both species to discriminate odors from frass expelled from gallery entrances of either
solitary females or conspecific pairs of either species. Males of both species strongly preferred odors of frass from
solitary, conspecific females over those of heterospecific females or pairs of either species. Female D. frontalis did
not discriminate among these frass categories, whereas female D. mesoamericanus preferred frass of conspecific
females. In gas chromatography–electroantennographic detection and gas chromatography–mass spectrometry
analyses, we determined that males of both species could sense a nearly identical spectrum of approximately
16 host- and beetle-produced compounds present in frass of females of one or both species. Only two of these
compounds, endo-brevicomin and ipsdienol, which were present in frass of female D. mesoamericanus and pairs of
either species but absent in frass of solitary D. frontalis females, qualitatively distinguished these categories. Several
known attractants and synergists for either species declined in concentration postpairing. Our results complement
earlier research and indicate how semiochemical composition and concentration in frass might mediate male
discrimination of attack sites of conspecific, unpaired females. Furthermore, our data indicate that semiochemical
responses for walking females differ from those of males and between species.
Keywords
syntopy, pheromone, electroantennogram, reproductive isolation, olfactometer
To read the full article please visit the link below:
Nino-Dominguez, Alicia, Brian T. Sullivan, Jose H. Lopez-Urbina, and Jorge E. Macias-Samano. 2018. “Discrimination of Odors Associated With Conspecific and Heterospecific Frass by Sibling Species Dendroctonus Frontalis (Coleoptera: Curculionidae: Scolytinae) and Dendroctonus Mesoamericanus (Coleoptera: Curculionidae: Scolytinae).” Environmental Entomology 47 (6): 1532–40. https://doi.org/10.1093/ee/nvy146.