Evaluation of potential strategies to SLow Ash Mortality (SLAM) caused by emerald ash borer (Agrilus planipennis): SLAM in an urban forest

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive pest native to Asia, has killed millions of ash (Fraxinus spp.) trees in North America since it was first discovered there in 2002. As of autumn 2011, A. planipennis has been detected in 15 US states and two Canadian provinces. A pilot project to slow the onset and progression of ash mortality, termed SLAM (SLow Ash Mortality), has been implemented in localized A. planipennis populations. Here we use spatially explicit simulations to evaluate the potential of a recently developed systemic insecticide to protect the ash resource in urban forests as a component of the SLAM approach. Over a 10-year horizon, simulations showed ash survival varied depending on: (i) how soon insecticide treatment began after the A. planipennis introduction; (ii) the proportion of trees treated; and (iii) the distribution of treated trees relative to the A. planipennis introduction point. Annual treatment of 20% of ash trees annually protected 99% of trees after 10 years, and the cumulative costs of treatment were substantially lower than costs of removing dead or severely declining ash trees.