Investigating host-plant resistance against the hemlock woolly adelgid (Adelges tsugae)

The invasive hemlock woolly adelgid (HWA), Adelges tsugae Annand, is responsible for massive mortality of two native hemlock species in the eastern U.S. (eastern hemlock, Carolina hemlock). With the range of HWA now extending to 18 eastern states, many fear the loss of these charismatic and ecologically important trees. Although literature indicates they are wholly susceptible, putative intraspecific resistance is probable, but sources of such resistance are unknown. These studies investigate the feeding behavior of HWA using scanning electron microscopy and foliar wax analyses of the host in relation to host-plant resistance. Determining sources of resistance may advance the efforts to save the hemlock through breeding programs, gene conservation, and replanting.