Modeling spatial dynamics of the emerald ash borer beetle (Coleoptera: Buprestidae) at Point Pelee National Park, Canada

The Emerald Ash Borer (EAB) beetle (Agrilus planipennis Fairmaire) is an invasive pest which has killed millions of ash trees since its discovery in 2002. It was detected in Point Pelee National Park on the north shore of Lake Erie in Ontario, Canada in the summer of 2007. Six rectangular plots containing a total of 610 ash trees were established in the park to detect EAB attack gradients in north-south and east-west directions. Each plot extended from the open beach habitat into the dense forest to determine the effect of openness on EAB dispersal over time. Data was collected in the summers of 2008 and 2009. Crown health and exit hole density were used as indicators of EAB presence. In 2008, exit holes could be assigned to three discrete wear classes that corresponded with the year of beetle emergence (2006, 2007, or 2008). Thus, exit hole data collected over the two field seasons represented four years of beetle emergence. Crown health and exit hole data were analysed using Surfer, a surface mapping program, to determine the presence of trends in the cardinal directions. A north-south gradient may be due to the spread of the beetle through the park from a point origin, whereas an east-west gradient probably reflects the effects of habitat variables. Tracking the progression of an early-stage EAB infestation to determine gradients due to forest density can help predict dispersal patterns and therefore aid EAB detection in similar habitats.