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Title: Improved lure for redbay ambrosia beetle developed by enrichment of a-copaene content

Author
item Kendra, Paul
item Montgomery, Wayne
item DEYRUP, MARK - Archbold Biological Station
item WAKARCHUK, DAVID - Synergy Resource Solution

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2015
Publication Date: 5/27/2016
Citation: Kendra, P. E., W. S. Montgomery, M. A. Deyrup, and D. Wakarchuk. 2016. Improved lure for redbay ambrosia beetle developed by enrichment of a-copaene content. Journal of Pest Science.89(2):427-438

Interpretive Summary: The redbay ambrosia beetle (RAB) carries a fungus that causes laurel wilt, a lethal disease of U.S. trees in the laurel family. Over the past decade, laurel wilt has decimated redbay and swampbay forests along the southeastern coastal plain, and currently threatens avocado in Florida, an industry worth $23.5 million annually for the state. Effective lures are needed to detect RAB and control its spread. Cubeb oil is the best lure available, but its specific attractants have not been confirmed. Scientists at the USDA-ARS (Miami, FL), in collaboration with Archbold Biological Station (Lake Placid, FL) and Synergy Semiochemicals Corp. (British Columbia, Canada), used fractional distillation to separate the components of cubeb oil. In laboratory tests, fractions high in a-copaene and a-cubebene were found to be most attractive. These results led to the development of a new lure containing 50% a-copaene. In field tests, the copaene lure captured 3 times more RAB than the current cubeb lure, and lasted for 3 months. This information will benefit action agencies that monitor for RAB by providing a more attractive, long lasting lure for better pest detection

Technical Abstract: Over the past decade, the exotic redbay ambrosia beetle, Xyleborus glabratus Eichhoff, has become a serious invasive pest in the USA, now established in seven southeastern states. Females are the primary vectors of a fungal pathogen, Raffaelea lauricola, that causes laurel wilt, a lethal disease of trees in the family Lauraceae. Laurel wilt has caused extensive mortality in native Persea species, including redbay (P. borbonia), swampbay (P. palustris), and silkbay (P. humilis), and currently threatens avocado (P. americana) in Florida. With continued spread, laurel wilt may impact additional Lauraceae throughout the Americas. The most effective lures for X. glabratus contain cubeb oil, an essential oil composed of a complex mixture of terpenoids. To elucidate the primary attractants of X. glabratus, fractional distillation was used to separate whole cubeb oil into 17 fractions, which were then used as substrates for electroantennographic (EAG) analyses and binary-choice bioassays to assess olfactory and behavioral responses, respectively. Although fractions containing monoterpenes elicited the strongest EAG responses, significant attraction of X. glabratus was observed only with fractions that contained high percentages of the sesquiterpenes a-copaene and a-cubebene. This information was used to prepare two prototype lures, one of which contained copaiba oil, and the other a proprietary essential oil product with 50% (-)-a-copaene content. In field trials, the copaiba and commercial cubeb lures captured equal numbers of X. glabratus, but the 50% copaene lure captured significantly more beetles and had field longevity of three months.