Incidence of infestation and larval success of emerald ash borer (Agrilus planipennis) on white fringetree (Chionanthus virginicus), Chinese fringetree (Chionanthus retusus) and devilwood (Osmanthus americanus)

We compared the incidence of infestation by emerald ash borer on white fringetree to that of its Asian congener, Chinese fringetree, C. retusus and a North American relative, devilwood, Osmanthus americanus. We also conducted laboratory bioassays to determine the suitability of these hosts for emerald ash borer larvae.  At Spring Grove Cemetery and Arboretum in Cincinnati, Ohio, 9 of 28 white fringetrees examined had exit holes from EAB and other signs of infestation, and a dead adult was found in one tree. In contrast, none of the 11 Chinese fringetrees examined had evidence of either EAB infestation, which was also the case for the five devilwood individuals examined. Similar results were found at The Morton Arboretum in Lisle, Illinois, where 7 of 16 white fringetrees examined had EAB infestation, while none of the three Chinese fringetrees examined were infested by either insect. A 40-day laboratory bioassay confirmed that white fringetree was an acceptable larval host, producing fourth instar larvae that were smaller than those produced on a highly susceptible cultivar of green ash, Fraxinus pennsylvanica (cv. Patmore). No larvae survived on Chinese fringetree, and neonates were only capable of producing feeding galleries of less than 2 cm long. Two larvae survived the bioassay on devilwood, reaching the second instar and excavating galleries up to 52 cm long. Future work should be aimed at biotic and abiotic factors influencing the susceptibility and long term fate of white fringetree in the face of EAB attack, as well as further examinations of close relatives for their vulnerability to EAB.