Bark and ambrosia beetle (Coleoptera : Scolytidae) responses to volatiles from aging loblolly pine billets

Many species of bark and ambrosia beetles use host volatiles as cues for br eeding site location. In a study where the objectives were to identify the different volatiles released by Pinus taeda L. billets as they age, to dete rmine the arrival sequence of scolytids (Colcoptera: Scolytidae), and to co rrelate volatile emission by the billets with beetle catches, 25 species of scolytids were trapped. Bark beetles were more attracted to the billets in the beginning of the period. whereas ambrosia beetles arrived later. Among the bark beetles, Dendroctonus terebrans (Olivier) was significantly more attracted during the Ist 3 wk after tree felling, Hylastes tenuis Eichhoff in the Ist 2 wk. Pityophtorus pulicarius (Zimmermann) in weeks 2 and 3, and Ips grandicollis (Eichhoff) was more attracted on weeks 3 and 4. Among the ambrosia beetles, Xyleborinus saxeseni (Ratzeburg) was more attracted to b illets during weeks 4-6, whereas Xyleborus pubescens Zimmermann and Xylebor us californicus Wood were more attracted during week 6. The billets showed marked decline in attractiveness to all scolytids after 8 wk. Volatiles col lected during the beetle trapping periods included 15 hydrocarbon monoterpe nes, 18 oxygenated monoterpenes, 4-allylanisole, and ethanol. The hydrocarb on monoterpenes and 4-allylanisole decreased sharply over time, but oxygena ted monoterpenes and ethanol increased up to weeks 4-6, after which they al so decreased. Good correlations between certain billet volatiles and catche s for some beetle species were obtained, but their biological significance could not be determined.