Cold tolerance and invasive potential of the redbay ambrosia beetle (<italic>Xyleborus glabratus</italic>) in the eastern United States.

Native Lauraceae (e.g. sassafras, redbay) in the southeastern USA are being severely impacted by laurel wilt disease, which is caused by the pathogen <italic>Raffaelea lauricola</italic> T. C. Harr., Fraedrich and Aghayeva, and its symbiotic vector, the redbay ambrosia beetle (<italic>Xyleborus glabratus</italic> Eichhoff). Cold temperatures are currently the only viable limitation to the establishment of <italic>X. glabratus</italic> in northern populations of sassafras. The observed lower lethal temperature of <italic>X. glabratus</italic> (− 10.0 °C) is warmer than its supercooling point (− 22.0 °C), indicating the beetle is a freeze intolerant and chill susceptible species. Empirically derived <italic>X. glabratus</italic> lower lethal temperature thresholds were combined with host distribution and microhabitat-corrected climate data to produce species distribution models for <italic>X. glabratus</italic> in the eastern USA. Macroclimate data (30-year mean annual minimum temperature) were corrected (− 1.2 °C) to account for thermal buffering afforded to <italic>X. glabratus</italic> while living inside sassafras trees. Only 0.1% of the current US sassafras spatial extent experiences sufficiently harsh winters (locales where mean annual minimum winter temperatures ≤ − 6.2 °C for ≥ 12 h) to exclude <italic>X. glabratus</italic> establishment in our species distribution model. Minimum winter temperatures will likely cause some <italic>X. glabratus</italic> mortality in ~ 52% of the current spatial extent of sassafras, although current data do not allow a quantification of <italic>X. glabratus</italic> mortality in this zone. Conversely, ~ 48% of the current spatial extent of sassafras is unlikely to experience sufficiently cold winter temperatures to cause any significant impediment to <italic>X. glabratus</italic> spread or establishment. A modest climate change scenario (RCP4.5) of + 1.4 °C would result in 91% of the current spatial extent of sassafras in the eastern USA occurring where winter minimum temperatures are unlikely to cause any mortality to <italic>X. glabratus</italic>. [ABSTRACT FROM AUTHOR]