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Title: Suitability of California bay laurel and other species as potential hosts for the non-native redbay ambrosia beetle and granulate ambrosia beetle

item MAYFIELD, ALBERT - Us Forest Service (FS)
item MACKENZIE, MARTIN - Us Forest Service (FS)
item CANNON, PHILIP - Us Forest Service (FS)
item OAK, STEVEN - Us Forest Service (FS)
item HORN, SCOTT - Us Forest Service (FS)
item HWANG, JAESOON - Clemson University
item Kendra, Paul

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2012
Publication Date: 7/12/2013
Citation: Mayfield III, A. E., M. MacKenzie, P. Cannon, S. Oak, S. Horn, J. Hwang, and P. E. Kendra. 2013. Suitability of California bay laurel and other species as hosts for the non-native redbay ambrosia beetle and granulate ambrosia beetle.Agr. Forest Entomol. 15 (3): 227-235.

Interpretive Summary: The redbay ambrosia beetle (RAB) is an exotic wood-boring pest that transmits laurel wilt, a deadly fungal disease of trees in the laurel family, including native forest species like redbay, swampbay, and sassafras, but also commercial avocado. Currently the beetle is found in the southeastern U.S., but its range continues to expand. Concern exists that RAB may be transported to the western U.S. and threaten California bay laurel (a dominant hardwood tree of the Pacific coast) as well as the California avocado industry. Scientists from the USDA Forest Service and USDA Agricultural Research Service conducted studies to determine if bay laurel is a suitable host for RAB. In field tests, freshly-cut logs of bay laurel were highly attractive to RAB and the beetles readily bored into them. When the infested logs were held in the laboratory, it was shown that RAB was able to reproduce successfully in bay laurel. These results suggest that California bay laurel is a potential host for RAB, and that bay laurel and California avocado groves may be at risk for laurel wilt disease should RAB be introduced to the west coast. This information reinforces the need for better detection and quarantine measures to prevent the spread of this invasive insect pest.

Technical Abstract: The redbay ambrosia beetle (Xyleborus glabratus Eichhoff) is a non-native invasive forest pest and vector of the pathogen that causes laurel wilt, a deadly disease of trees in the family Lauraceae in the southeastern United States (U.S.). Concern exists that X. glabratus and its fungal symbiont could be transported to the western U.S. via infested wood and cause widespread damage to California bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.), a valuable Lauraceous tree common to a variety of forest cover types in California, Oregon and Washington. This study evaluated in-flight attraction, attack density, and emergence of X. glabratus and another invasive ambrosia beetle (Xylosandrus crassiusculus (Motschulsky)) on cut bolts of California bay laurel and eight related tree species in an infested stand in South Carolina. Mean catch of X. glabratus on California bay laurel bolts was not significantly different from catches on bolts of known X. glabratus hosts sassafras (Sassafras albidum (Nutt.) Nees) and swampbay (Persea palustris (Raf.) Sarg.). Mean attack density and adult emergence of both X. glabratus and Xylosandrus crassiusculus from California bay laurel was equal to or significantly greater than all other species tested. Both beetle species readily reproduced in California bay laurel as evidenced by the production of males. Our results suggest California bay laurel may be negatively impacted by both of these invasive ambrosia beetle species if they become established in the tree’s native range.