Response of Pityophthorus puberulus (Coleoptera: Curculionidae: Scolytinae) to pheromones and terpenes

In field studies conducted to improve trapping programs for the white pine cone beetle, Conophthorus coniperda (Schwarz), a twig beetle, Pityophthorus puberulus (LeConte), a common associate of eastern white pine, Pinus strobus L. (Pinaceae), in seed orchards, was also captured. In these experiments, P. puberulus was attracted to traps containing the sex pheromone pityol with or without the monoterpenes (−)-α-pinene and (−)-β-pinene, but attraction to traps was inhibited when S-(−)-limonene was present. We speculate that limonene may play an important role in host recognition and suitability, by indicating a resource suitable for C. coniperda but unsuitable for P. puberulus.

Field evaluation of host kairomones and pheromones for capture of Conophthorus coniperda (Coleoptera: Scolytidae)

Field studies were conducted to determine the attractiveness of monoterpenes and pheromones to the white pine cone beetle, Conophthorus coniperda (Schwarz), the most destructive cone and seed pest of eastern white pine, Pinus strobus L. (Pinaceae). Limonene was identified as a new attractant that acts synergistically when added to the female-produced sex pheromone, pityol. Trap catches were higher with increasing release rates of S-(–)-limonene. The enantiomers of limonene showed equivalent efficacy on mean trap catch. (–)-β-Pinene was not attractive and may be repellent to both sexes, and (–)-α-pinene was shown to have no effect on female response when added to pityol or pityol + S-(–)-limonene. The pheromones trans-verbenol, trans-pinocarveol, and myrtenol were not attractive to C. coniperda.

RESPONSE OF CONE AND TWIG BEETLES (COLEOPTERA: SCOLYTIDAE) AND A PREDATOR (COLEOPTERA: CLERIDAE) TO PITYOL, CONOPHTHORIN, AND VERBENONE

Field studies were conducted in the United States and Canada to determine the response of the white pine cone beetle, Conophthorus coniperda (Schwarz), and the red pine cone beetle, Conophthorus resinosae Hopkins, to two potential inhibitors, conophthorin and verbenone, of pheromone communication. Trap catches of male C. coniperda and C. resinosae were significantly reduced and generally declined with increasing concentrations of conophthorin in traps baited with the pityol, a female-produced pheromone. Verbenone did not significantly reduce trap catches of C. coniperda. Conophthorin, but not verbenone, significantly reduced cone attacks by C. coniperda when placed near cone clusters. The twig beetles, Pityophthorus cariniceps LeConte and Pityophthorus puberulus (LeConte), responded to traps with pityol and α-pinene baits alone or with conophthorin. Thanasimus dubius (F) (Coleoptera: Cleridae) was attracted to the pityol and α-pinene, but conophthorin had no effect on attraction of this generalist bark beetle predator. Verbenone significantly reduced trap catches of T. dubius in pityol-baited traps.

EVIDENCE FOR A FEMALE-PRODUCED PHEROMONE IN THE WHITE PINE CONE BEETLE, CONOPHTHORUS CONIPERDA (SCHWARZ), AND IN THE RED PINE CONE BEETLE, C. RESINOSAE HOPKINS (COLEOPTERA: SCOLYTIDAE)

Evidence for a female-produced sex pheromone in the white pine cone beetle, Conophthorus coniperda (Schwarz), and the red pine cone beetle, C. resinosae Hopkins, was obtained from laboratory bioassays and field experiments conducted with C. coniperda beetles from Ontario and North Carolina. In an olfactometer, males from both species responded significantly more to volatiles from females than to volatiles from males or cones. Generally, females did not differ in their response to female-, male-, or cone-produced volatiles. Both sexes responded to host volatiles. The strong response by male C. coniperda to females was confirmed in field tests.

CYTOTAXONOMY OF CONOPHTHORUS (COLEOPTERA: SCOLYTIDAE) IN EASTERN NORTH AMERICA

The male meiotic karyotypic formula of Conophthorus coniperda (Schwarz) (Coleoptera: Scolytidae) is 9AA + XY. This karyotype differs from C. resinosae Hopkins and C. banksianae McPherson, both of which have the karyotypic formula of 8AA + XY. Supernumerary chromosomes were found in different populations of C. resinosae and C. banksianae but were absent in C. coniperda. No geographic variation in the karyotypes of the three species was observed. The karyotypic formulae confirm the designations of C. coniperda and C. resinosae by morphological characters, but do not support the designation of C. banksianae as a distinct species.