Seasonal variation in effects of herbivory

Invasive herbivores can dramatically impact the nitrogen economy of native hosts. In eastern forests of the United States, the foundational conifer eastern hemlock (Tsuga canadensis) is under threat of extirpation by the invasive hemlock woolly adelgid (HWA: Adelges tsugae). A recent study published in AoB PLANTS by Schaeffer et al. suggests that HWA-induced mobilization of nitrogen to local feeding sites and its rapid depletion may be a significant contributor to eastern hemlock mortality in US forests.