Evaluation of repellents for redbay ambrosia beetle and tea shot-hole borer (Coleoptera: Curculionidae: Scolytinae)

Redbay ambrosia beetle (Xyleborus glabratus Eichhoff) and tea shot-hole borer (Euwallacea perbrevis Schedl) vector the fungal pathogens that cause laurel wilt and Fusarium dieback, respectively. These two vascular diseases can severely impact avocado, woody ornamentals, and native forest trees. Incorporation of a repellent into pest management programs may reduce beetle infestation and the incidence of these diseases. Previously, we identified piperitone as a new repellent for Euwallacea in Florida. Subsequent studies compared efficacy of piperitone to two other repellents, verbenone and α-farnesene. In replicated 12-week field tests, Euwallacea captures in traps baited with lures were compared to captures in traps containing lures plus one of the three repellents. In addition, SuperQ collections followed by GC analyses were performed to quantify emissions from repellent dispensers over a 12-week period. Farnesene was found to be ineffective; however, piperitone and verbenone were equally effective, reducing captures by 50-70% for 10-12 weeks. A series of parallel field tests in progress indicate that piperitone is also effective against redbay ambrosia beetle. Since piperitone is less expensive than verbenone, the standard beetle repellent, these studies identify an economical alternative for management of both ambrosia beetle pests.