Location: Subtropical Horticulture ResearchTitle: North American Lauraceae: Terpenoid emissions, relative attraction and boring preferences of redbay ambrosia beetle, Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae) Author
|Mayfield Iii, Albert|
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2014
Publication Date: 7/9/2014
Citation: Kendra, P.E., Montgomery, W.S., Niogret, J., Pruett, G.E., Mayfield Iii, A.E., Mackenzie, M., Deyrup, M.A., Bauchan, G.R., Ploetz, R.C., Epsky, N.D. 2014. North American Lauraceae: Terpenoid emissions, relative attraction and boring preferences of redbay ambrosia beetle, Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae). PLoS One. 9(7):e102086. Interpretive Summary: The redbay ambrosia beetle (RAB) is an exotic wood-boring pest that transmits laurel wilt, a deadly fungal disease of American trees in the laurel family (Lauraceae), including native forest species and commercial avocado. Scientists at the USDA-ARS (Miami, FL), in collaboration with the USDA Forest Service, the University of Florida, and Archbold Biological Station, conducted research to compare attraction and boring preferences of RAB to nine species of Lauraceae: avocado (3 cultivars representative of the botanical races), redbay, swampbay, silkbay, California bay laurel, sassafras, spicebush, camphor tree, and lancewood. In addition, they performed chemical analyses on the wood samples to relate chemical emissions with behavioral responses of the beetle. Species most at risk for attack by RAB included silkbay, swampbay, redbay, and California bay laurel. With avocado, the Guatemalan cultivar was more attractive than the other two varieties, but boring response among the three was equivalent. The results indicated that four host chemicals (a-cubabene, a-copaene, a-humulene, and calamenene) were correlated with attraction, and that camphor tree may contain a chemical repellent to RAB. Information from this research should facilitate improvement of field lures for RAB detection, and development of attract-and-kill bait stations for RAB control.
Technical Abstract: The invasive redbay ambrosia beetle, Xyleborus glabratus, is the primary vector of Raffaelea lauricola, a symbiotic fungus and the etiologic agent of laurel wilt. This lethal disease has caused severe mortality of redbay (Persea borbonia) and swampbay (P. palustris) trees in the southeastern USA, threatens avocado (P. americana) production in Florida, and has potential to impact additional New World species. To date, all North American hosts of X. glabratus and suscepts of laurel wilt are members of the family Lauraceae. This comparative study combined field tests and laboratory bioassays to evaluate attraction and boring preferences of female X. glabratus using freshly-cut bolts from nine species of Lauraceae: avocado (one cultivar of each botanical race), redbay, swampbay, silkbay (Persea humilis), California bay laurel (Umbellularia californica), sassafras (Sassafras albidum), northern spicebush (Lindera benzoin), camphor tree (Cinnamomum camphora), and lancewood (Nectandra coriacea). In addition, volatile collections and gas chromatography-mass spectroscopy (GC-MS) were conducted to quantify terpenoid emissions from test bolts, and electroantennography (EAG) was performed to measure olfactory responses of X. glabratus to terpenoids identified by GC-MS. Significant differences were observed among treatments in both field and laboratory tests. Silkbay and camphor tree attracted the highest numbers of the beetle in the field, and lancewood and spicebush the lowest, whereas boring activity was greatest on silkbay, bay laurel, swampbay, and redbay, and lowest on lancewood, spicebush, and camphor tree. The Guatemalan cultivar of avocado was more attractive than those of the other races, but boring response among the three was equivalent. The results suggest that camphor tree may contain a chemical deterrent to boring, and that different cues are associated with host location and host acceptance. Emissions of a-cubebene, a-copaene, a-humulene, and calamenene were positively correlated with attraction, and EAG analyses confirmed chemoreception of terpenoids by antennal receptors of X. glabratus.