Suitability ofCalifornia bay laurel and other species as hosts for the non‐native redbay ambrosia beetle and granulate ambrosia beetle

Abstract

The redbay ambrosia beetle Xyleborus glabratus Eichhoff is a non‐native vector of the pathogen that causes laurel wilt, a deadly disease of trees in the family Lauraceae in the southeastern U.S.A. Concern exists that X. glabratus and its fungal symbiont could be transported to the western U.S.A. and cause damage to California bay laurel Umbellularia californica (Hook. & Arn.) Nutt. in California and Washington. The present 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 forest in South Carolina. Xylosandrus crassiusculus is not a vector of the laurel wilt pathogen but is a pest of nursery and ornamental trees. 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 beetle species from California bay laurel was equal to or greater than all other tree species tested. Both beetle species readily produced brood in California bay laurel bolts. The results obtained in the present study suggest that California bay laurel may be negatively impacted by both of these invasive ambrosia beetles if they become established in the tree's native range.

North American Lauraceae: Terpenoid Emissions, Relative Attraction and Boring Preferences of Redbay Ambrosia Beetle, Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae)

“…Although breeding populations of X. glabratus have not been detected west of Mississippi, future expansion of the pest range could have a severe negative effect on California bay laurel, which is a significant component of Pacific Coastal forests in California and Oregon. The strong attraction and boring behaviors that were observed with this species in the present study corroborate results from parallel tests conducted in South Carolina [25]. Notably, that latter study demonstrated that California bay laurel is not only attractive to X. glabratus , but is also a suitable reproductive host; and previous work indicated that the species is susceptible to laurel wilt after artificial inoculations of R. lauricola [57].…”

“…Both species were as attractive as swampbay, redbay, and California bay laurel in the field trial, but exhibited lower rates of boring activity in the laboratory bioassay (80% and 67%, respectively). At a field site in South Carolina, the numbers of X. glabratus entrance holes were significantly lower on sassafras than on swampbay bolts in 2010 [26], but were significantly higher on sassafras bolts than on swampbay in 2011 [25]. A possible explanation for these seemingly conflicting results is that severe depletion of swampbay trees between 2010 and 2011 may have led to the selection of beetles that could successfully colonize a ‘less preferred’ host.…”

An Uncertain Future for American Lauraceae: A Lethal Threat from Redbay Ambrosia Beetle and Laurel Wilt Disease (A Review)

“…Eleven US species in the Lauraceae have been reported as hosts of X. glabratus and/or shown susceptibility to laurel wilt disease, either in nature (insect vectored) or in the laboratory (by artificial inoculation with the pathogen) [1,2,6,19,35,36]. In addition, several other Lauraceae (primarily species of Persea) from outside the US have been evaluated for attraction or boring by X. glabratus under experimental conditions [37].…”

First Report ofXyleborus glabratus(Coleoptera: Curculionidae: Scolytinae) and Laurel Wilt in Louisiana, USA: The Disease Continues Westward on Sassafras

“…Furthermore, a climate match analysis concluded that X. glabratus was particularly associated with plants that occur in subtropical and warm temperate areas, and thus, it was thought that the beetle would essentially be constrained to the coastal plains of the Southeast (Koch & Smith 2008). However, recent findings suggest that sassafras may be an attractive host for X. glabratus (Mayfield et al 2013), and observations in Georgia, Alabama, and Louisiana suggest that the beetle effectively locates and utilizes sassafras as a reproductive host (Bates et al 2013;Cameron et al 2014). In addition, a study of the cold tolerance of X. glabratus concluded that the beetle may be able to survive extremely low temperatures and could possibly spread as far north as southern Ontario (Formby et al 2013), which would encompass much of the natural geographic range of sassafras (Griggs 1990).…”