The spatial dynamics of invasive species spread

The problem of invasive species spread requires timely analysis of the biological dynamics that lead to spatial dispersion. Here, a spatial dynamic model captures the invasive behavior of the recently introduced emerald ash borer (EAB) (Agrilus planipennis) and its impacts on host ash (Fraxinus spp.) trees. Parasite-host system dynamics are extended spatially using the Spatial Modeling Environment. The resulting model can serve as a repository for changing knowledge about EAB biology and behavior. Studies of the rapid EAB infestation in Michigan are used to inform simulations of its spread in DuPage County, Illinois, USA. We use a geographic information system to create heterogeneous host landscapes and to test alternative policy scenarios. We test the effectiveness of three suppression scenarios: the Michigan eradication strategy, firewood quarantines, and ash tree thinning. Simulations demonstrate that EAB spatial spread accelerates with degraded host capacity, with results pointing to firewood quarantines as the most effective solution.