Bark beetle attraction to semiochemical baits

The black turpentine beetle, Dendroctonus terebrans (Olivier) (Coleoptera: Curculionidae), is a native wood-borer of pine trees in the eastern U.S. This bark beetle’s impact on exotic ornamental pines suggests it may become a severe pest if introduced beyond its native range. Semiochemical traps are known to capture black turpentine beetles; however, attempts to manage them with baited traps have failed. We compared beetle attraction to pine-derived turpentine versus the "sirex" pinene blend, a synthetic mixture of alpha- and beta-pinene. Lures were deployed on multi-funnel traps and rotated once every week. We used four treatments: turpentine paired with ethanol, "sirex" paired with ethanol, turpentine alone, and un-baited control. Turpentine paired with ethanol captured significantly more black turpentine beetles than the other lures. The "sirex" lures were no more attractive to the beetle than un-baited traps. Additionally, Xyleborus pubescens was attracted to both pine turpentine and the "sirex" pinene blend, but Myoplatypus flavicornis was only attracted to the pinene blend. The "sirex" lure and turpentine share the same main compounds, alpha-pinene and beta-pinene, but turpentine has minor compounds that are absent from "sirex". Therefore, these results suggest that the black turpentine beetle and some other bark beetles respond to minor components of host-derived compounds. This finding indicates that minority compounds should not be overlooked when designing semiochemical lures for D. terebrans.