The Attractiveness of Manuka Oil and Ethanol, Alone and in Combination, to Xyleborus Glabratus (coleoptera: Curculionidae: Scolytinae) and Other Curculionidae

The increasing volume of international commerce in the last century has resulted in an exchange of organisms at an alarming rate. Among those exhibiting a significant threat to forests are the bark and ambrosia beetles and their associated fungi. Between 1985 and 2005, 18 scolytinae species introductions to the U.S. were recorded, and others have been documented since (Haack 2006; Rabaglia et al. 2010). The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) and the associated laurel wilt fungus (Raffaela lauricola Harrington, Fraedrich & Aghayeva) (Harrington et al. 2008), is one such insect-fungus species complex. First detected in Port Wentworth, Georgia in 2002, the beetle and pathogen have since spread to North and South Carolina, Alabama, Mississippi, and Florida (Bates et al. 2013). Female beetles carry the symbiotic fungus in mandibular mycangia and inoculate hosts upon attack during gallery formation, ultimately resulting in death of the host (Fraedrich et al. 2008). Beetles readily attack and transmit the lethal laurel wilt fungus to healthy redbay [Persea borbonia (L.) Spreng; Laurales: Laura-ceae] and swamp bay [Persea palustris (Raf.) Sarg.], and to a lesser degree, other members of the family Lauraceae, including sassafras [Sassafras albidum (Nutt.) Nees] and avocado (Persea americana Mill.) (Fraedrich et al. 2008; Hanula et al. 2008; Kendra et al. 2011a). Confirmed cases of the disease have been reported in Florida's commercial avocado (Persea ameri-cana Mill.) plantations, and there is considerable concern over the risk posed to the $ 23.5 million/year avocado industry (USDA Economic Research Service 2013). Early detection of this destructive pest is an integral part of managing populations. Xyleborus glabratus is not known to possess a long range sex pheromone and this aspect of its biology limits trapping efforts to using host volatiles. Unlike other Xyleborini, it is not attracted to ethanol [Hanula et al. 2008, 2011; Kendra et al. 2014]. It is, however, attracted to manuka oil (from Leptospermum scoparium Forst. & Forst. [Myrtaceae]), phoebe oil (from Phoebe porosa Mex. [Lauraceae]), and cubeb oil (from Piper cubeba L. [Piperaceae]) species which possess sesquiterpenes also present in Lauraceae species in the U.S. (Hanula & Sul-livan 2008; Hanula et al. 2013; Kendra et al. 2011a, b). Unfortunately, because most Xyle-borini are attracted to ethanol, national pest survey programs use ethanol and do not incorporate any of these extracts (Miller & Rabaglia 2009). The objectives of this study were to determine if the addition of manuka oil to …