Effects of Ultraviolet Light and Pheromone Release Rate in Trapping Coconut Rhinoceros Beetles, Oryctes rhinoceros (Coleoptera: Scarabaeidae), on Guam

Siderhurst, Matthew S
Moore, Aubrey
Quitugua, Roland
Chang, Eric B
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Hawaii Entomological Society
Coconut rhinoceros beetle (CRB), Oryctes rhinoceros L., is a serious pest of coconut and oil palms throughout Southeast Asia and the Pacific. CRB was found on Guam in 2007 and, despite suppression efforts, has subsequently spread across the island. The CRB population on Guam is genetically different from other populations in Asia and the Pacific, and is considered a new invasive biotype (termed CRB-G). CRB-G is apparently resistant to Oryctes rhinoceros nudivirus, the preferred biocontrol agent for this pest. CRB populations are typically controlled with a combination of biocontrol, pheromone traps, and breeding site removal. A field trial was performed at six locations on Guam to test potential improvements to standard CRB pheromone trapping with oryctalure (ethyl 4-methyloctanoate). Two modifications were tested, 1) addition of ultraviolet light emitting diodes (UV LEDs), and 2) reduction of pheromone release rate. Addition of UV LED light sources to pheromone traps significantly increased trap catch by 2.85 times. Reduction in oryctalure release rate by up to an order of magnitude did not significantly change CRB capture rate. Further, when linear regression analyses of CRB trap capture rate as a function of pheromone release rate were conducted for traps with and without UV LEDs separately, only a very weak relationship between trap capture and oryctalure release rate was observed and only when a UV LED was present. Results suggest that addition of UV LED light sources to pheromone traps could improve detection trapping of CRB and that reduction of pheromone release rate could extend service life of lures without changing capture rate.
Oryctalure, UV-light, LEDs, population monitoring
Proceedings of the Hawaiian Entomological Society (2021) 53:21–32
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