Divergence of the potential invasion range of emerald ash borer and its host distribution in North America under climate change

Climate change is likely to induce range divergence of invasive herbivore insects and native host trees given their different response rates to temperature increase. In this study we used the invasion of emerald ash borer (EAB, Agrilus planipennis Fairmaire), which is host-specific to ash (Fraxinus spp.), to demonstrate the significant implications of this climate change induced insect-host divergence for management of invasive species. The least constrained climatic limits of EAB were derived from its native range in East Asia, then projected to North America under the current and future climate conditions, and finally compared with the assumedly static ash distribution. Results suggest that the divergence between the invasion range of EAB and the distribution of ash in North America is likely to enlarge as climate change proceeds. In this case, many original ash stands could remain intact in the southern range, possibly forming refugia of the host species. The realization of this prediction, however, requires that the spread of EAB be reduced by continued management effort to allow climate change to take effect in time. Our study highlights the important role climate change has in the course of biological invasion and herbivore-host dynamics, which provides key information for continental scale pest risk prediction and strategic planning.