Characterization of an Aggregation Pheromone inHylesinus pruinosus(Coleoptera: Curculionidae: Scolytinae)

Abstract

We conducted laboratory and field bioassays to characterize the pheromone system of an ash bark beetle, Hylesinus pruinosus Eichhoff (Coleoptera: Curculionidae: Scolytinae). Solitary females in newly initiated galleries in ash logs produced (+)-exo-brevicomin, whereas male beetles paired with females produced (+)-endo-brevicomin, lesser quantities of (+)-exo-brevicomin, and a third compound that could not be identified. Beetles produced these compounds also after exposure to juvenile hormone III, and they were the sole volatile chemicals isolated from beetles or aerations of infested logs that elicited electrophysiological responses from antennae of either sex. In the field, both sexes were strongly attracted to traps baited solely with either racemic or pure (+)-endo-brevicomin. Racemic exo-brevicomin was much less attractive to both sexes than racemic endo-brevicomin, and it did not increase attraction of endo-brevicomin when released in combination. Host odors (volatiles from mechanically damaged ash branches) failed to attract beetles or increase attractiveness of racemic exo-brevicomin. Our evidence suggests that male-produced (+)-endo-brevicomin is the major component of an aggregation pheromone for H. pruinosus, with (+)-exo-brevicomin and the unidentified male compound playing an indeterminate role in the chemical ecology of this species. Our data thus show an instance in which the major aggregation pheromone component of a bark beetle is produced by the secondarily arriving sex, a rare occurrence in bark beetles but one which has been reported previously for the Hylesini.

Spatial Displacement of a Lure Component Can Reduce Catches of Two Nontarget Species During Spring Monitoring of Southern Pine Beetle

“…Thus, it is not necessary for the compound to be released from an attractant-baited trap for D. frontalis catches to be enhanced. However, removal of the endo -brevicomin device from the trap greatly reduced catches of H. pruinosus and E. nigripes, suggesting that these species orient close to the source of endo -brevicomin which is for them an attractant rather than a synergist ( Shepherd et al 2010 ). Simultaneously, T. dubius does not show behavioral responses to endo -brevicomin ( Salom et al 1992 , Sullivan et al 2016 ), and therefore its placement is irrelevant to this species.…”

“…A sympatric species of D. frontalis , the ash bark beetle, Hylesinus pruinosus Eichhoff (Coleoptera: Curculionidae: Scolytinae), employs (+)- endo -brevicomin as an aggregation pheromone component and is strongly attracted to lures with either racemic or (+)- endo -brevicomin ( Shepherd et al 2010 ). Similarly, the sympatric bark beetle predator Enoclerus nigripes (Say) (Coleoptera: Cleridae) is attracted to endo -brevicomin, presumably utilizing this compound as a host-location kairomone.…”

Identification of two aggregation pheromone components from female cypress bark beetles and evaluation of their activity in the laboratory and the field

“…The JHIII topical treatment was prepared by dissolving 10 mg of synthetic JHIII (CAS: 24198-95-6, SC-252931, Santa Cruz Biotechnology, 10410 Finnell Street, Dallas, TX 75220, US) in 250 µL of acetone (analytical reagent grade, Reanal, Budapest, Hungary) to make a 40 µg/µL stock solution. To treat female beetles, 0.5 µL of the solution containing 20 µg JHIII were administrated by a bevel-tip Hamilton syringe to the ventral abdominal surface of females, as described by Shepherd et al (2010). Beetles were incubated in a Petri-dish for one day under ambient conditions.…”

Identification of two female cypress bark beetle pheromone components and evaluation of their activity in the laboratory and the field

“…Earlier we showed that the calling sex of P. aubei is the female (Bozsik and Szőcs 2017), therefore we used females for pheromone extraction in this study. As it is well known that juvenile hormone III (JHIII) triggers pheromone production in many bark beetle species (Shepherd et al 2010;Chiu et al 2018), we prepared extracts of females pre-treated with JHIII and those without treatment (control).…”

“…For treatments, synthetic juvenile hormone III (10 mg, CAS: 24198-95-6, SC-252931, Santa Cruz Biotechnology, 10410 Finnell Street, Dallas, TX 75220, US) was dissolved in in 250 µL acetone (analytical reagent grade, Reanal, Budapest, Hungary). At treatment, 0.5 µL of the solution containing 20 µg JHIII were administrated by a bevel-tip Hamilton syringe to the ventral abdominal surface of females, as described by Shepherd et al (2010). Beetles were incubated in a Petri-dish for one day under ambient conditions.…”