Potential for plant odors as repellants for redbay ambrosia beetle, a vector of laurel wilt disease

The redbay ambrosia beetle (RAB), Xyleborus glabratus, is an invasive wood boring pest of trees in the Lauraceae family. RAB inoculates galleries with its primary food source, a symbiotic fungus (Raffaelea lauricola), that it transports within specialized mandibular structures called mycangia. R. lauricola is the causal agent of laurel wilt disease, and susceptible trees infected with the fungus eventually wilt and die back. Early reports indicate that RAB were detected in Port Wentworth, GA in 2002, and by 2004 they were responsible for a decline of redbay trees (Persea borbonia) in both Georgia and South Carolina. Since then, RAB and laurel wilt have spread throughout many southeastern states, including Florida. Such rapid spread of disease among redbay trees, an important wildlife resource, alters ecosystem composition and can lead to abnormal forest succession. Furthermore, several other Lauraceae are accepted hosts including two threatened or endangered trees, Pondspice (Litsea aestivalis) and Pondberry (Lindera melissifolia), as well as avocado (Persea americana), a major fruit crop in southern Florida. Odors of non-host plants have been shown to be repellants of other Scolytinae, and have been successfully used to protect trees from beetle infestation. We investigated the odors of several native Floridian trees occurring in redbay habitat for repellency to X. glabratus in choice tests using olfactometer assays. Several of these were repellant to X. glabratus. Candidate repellant chemicals are being further evaluated by gas chromatography, electroantennography, and subsequent behavioral assays.