Location: Subtropical Horticulture ResearchTitle: Attraction of the redbay ambrosia beetle, Xyleborus glabratus to avocado, lychee, and essential oil lures Author
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2011
Publication Date: 7/26/2011
Citation: Kendra, P.E., Montgomery, W.S., Niogret, J., Pena,, J.E., Capinera, J.L., Brar, G., Epsky, N.D., Heath, R.R. 2011. Attraction of the redbay ambrosia beetle, Xyleborus glabratus to avocado, lychee, and essential oil lures. Journal of Chemical Ecology. 37(9):932-942. Interpretive Summary: The redbay ambrosia beetle (RAB) is an exotic wood-boring pest that transmits laurel wilt, a deadly fungal disease threatening the avocado industry in Florida. There is a critical need for effective lures to detect, monitor and control the spread of this invasive pest. Scientists at the USDA-ARS in Miami, FL conducted field and lab research to identify host-based attractants for RAB. The studies evaluated RAB response to wood from avocado, to wood from lychee, and to lures of two essential oils, manuka and phoebe. RAB response was then related to the chemicals emitted from each test substrate. Results indicated that the current RAB detection system (funnel traps baited with manuka lures) is suboptimal, due to limited longevity of the field lure. Phoebe lures were more effective, but their future availability is uncertain. RAB showed no preference among avocado cultivars (West Indian, Mexican, and Guatemalan races) and preferred to bore into freshly-cut surfaces, suggesting avocado would be most susceptible to attack immediately following pruning. Three volatile chemicals (a-copaene, ß-caryophyllene, and a-humulene) were correlated with field captures. Lychee was more attractive than avocado, and lychee may be a source of additional attractants for RAB. Information from this study will be used by action agencies (Florida DPI, CAPS) engaged in monitoring programs for RAB, and provide the foundation for researchers to develop improved lures for RAB.
Technical Abstract: The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), is an exotic wood-boring insect that vectors the mycopathogen responsible for laurel wilt, a lethal vascular disease of trees in the Lauraceae. High mortality has occurred in native Persea species in the southeastern U.S., and the vector-pathogen complex poses an imminent threat to commercial avocado (P. americana) production in south Florida. There is a critical need for effective attractants to detect, monitor and control this invasive pest. This study combined field tests and laboratory bioassays to evaluate response of female X. glabratus to host-based volatiles from wood of avocado (cultivars of West Indian, Guatemalan, and Mexican races), from wood of lychee (Litchi chinensis, a presumed non-host high in the sesquiterpene a-copaene, a putative attractant), and from commercial lures containing manuka and phoebe oils, two reported attractive baits. Volatile collections and GC-MS analyses were performed to quantify sesquiterpene content of test substrates. In the field, lychee wood captured more beetles than wood from avocado cultivars; phoebe lures captured more beetles than manuka lures (the current monitoring tool). In field and laboratory tests, X. glabratus did not show a preference among avocado races in terms of attraction or host acceptance (initiation of boring). In choice tests, lychee was more attractive than avocado initially, but a higher percentage of beetles bored into avocado, suggesting that lychee emits more powerful olfactory/visual cues, but that avocado contains more of the secondary cues necessary for host recognition. Emissions of a-copaene, ß-caryophyllene, and a-humulene were correlated with field captures, and lychee wood may be a source of additional semiochemicals for X. glabratus.