Impacts of laurel wilt disease on arthropod herbivores of North American Lauraceae.
For approximately 15 years, Raffaelea lauricola and its vector, Xyleborus glabratus (redbay ambrosia beetle), have been causing extensive mortality of North American plants in the Lauraceae. All species of Lauraceae native to the USA that have been tested thus far are susceptible to the pathogen. Ecological impacts will likely continue to radiate outwards through ecosystems, yet there is no database of at-risk arthropod species that could be affected by this ecological disturbance. Endangerment risks remain unquantified, even for known obligate specialists of laurel wilt susceptible hosts, such as the palamedes swallowtail (Papilio palamedes Drury). We used exhaustive literature searches and expert-based quality control measures to catalogue native arthropod herbivores of Lauraceae species. Arthropods were assigned an endangerment risk rating based on the extent of their specialization on susceptible hosts. Overall, 178 native arthropod species from 7 orders were catalogued as herbivores that could be impacted by declines of their Lauraceous host plants. Twenty-four insect species were identified as obligate specialists of Lauraceae. A further four species were categorized moderate risk of endangerment because they have one host that is not affected by laurel wilt. As a case study, we also quantified the impacts of laurel wilt on palamedes swallowtail populations. The mean number of palamedes swallowtails encountered in transects through laurel wilt infested stands was nearly sixfold less than in uninfested stands. This suggests dire consequences for the palamedes swallowtail, and warrants concern for the other 24 native species that are obligate specialists of laurel wilt susceptible host plants.