Spicing things up: Ecological impact of laurel wilt on insect diversity and community composition of northern spicebush

Laurel wilt, a fungal disease caused by an invasive pathogen, Harringtonia lauricola sp. nov., has devastated populations of plants in the family Lauraceae in the southeastern U.S. In 2019, laurel wilt was found in Tennessee on Sassafras albidum (Nutt.) Nees (sassafras). This pathogen is known to be transmitted by Xyleborus glabratus Eichhoff (redbay ambrosia beetle). Laurel wilt has recently been observed on Lindera benzoin (L.) Blume (northern spicebush). Spicebush is endemic to the eastern U.S. and has cultural significance and history in traditional practices by Native Americans and Appalachian region residents. Spicebush is also important from an ecological standpoint. Some species, such as larvae of Papilio troilus L. (spicebush swallowtails), feed almost exclusively on spicebush or sassafras. Other insects may also exhibit a specialized dependence on spicebush. However, insect diversity and community composition on spicebush is poorly known. Because no treatment for laurel wilt currently exists, it has the potential to spread throughout the native range of spicebush. If spicebush is lost due to laurel wilt, it is critical to have basic knowledge of associated insects to gauge which species may become threatened, endangered, or even locally or regionally extinct. Therefore, a multi-year study designed to determine insect diversity and community composition on spicebush was initiated in Tennessee. So far, several observed native insect species were determined to rely on spicebush. The spread of laurel wilt could result in the loss of these native species. This research will inform protection of spicebush and associated insects in natural areas.