Olfactory Stimulants for <i>Sirex nigricornis</i> (Hymenoptera: Siricidae) and its Parasitoid, <i>Ibalia leucospoides</i> (Hymenoptera: Ibaliidae), in Odors of Stressed and Bark Beetle–Colonized Pines

Abstract We conducted studies with the native woodwasp Sirex nigricornis F. (Hymenoptera: Siricidae) in Louisiana to identify host-associated olfactory stimulants that may include attractive semiochemicals for this species as well noctilio F., an invasive can attack healthy trees. Loblolly pines (Pinus taeda L.) treated a stressing agent were felled and chipped 1–2 mo after treatment, chips steam–water distilled Clevenger apparatus extract volatile compounds. Using coupled gas chromatography–electroantennographic detection, we analyzed distillates antennae of both S. parasitoid Ibalia leucospoides (Hochenwarth) Ibaliidae) stimulants. In addition, assayed synthetic mixtures containing 23 compounds associated stressed dying pines, including pheromones bark beetles (Coleoptera: Curculionidae: Scolytinae) also use these hosts. Antennae male female responded 29 identifiable volatiles distillates, whereas I. volatiles. Eighteen nigricornis. Olfactory woodchip predominantly hydrocarbon oxygenated monoterpenes, strongest antennal among monoterpenes pine death early decay (e.g., verbenone, fenchone, terpinen-4-ol). Bark beetle (frontalin, endo-brevicomin, ipsenol, ipsdienol) stimulated antennae. The very large number implies our data offer limited assistance targeting individual investigation possible attractants components lure.