Six years of population dynamics of the emerald ash borer beetle (Agrilus planipennis Fairmaire) at Point Pelee National Park, Canada

The emerald ash borer (EAB) is a wood boring beetle that was introduced to North America from Asia in the 1990s and is rapidly killing North American ash trees. Few studies have documented the variability of an intact EAB infestation over time. Point Pelee National Park was in the early stages of EAB infestation when this study was initiated in 2008, presenting an opportunity to monitor the natural progression of an EAB infestation. We monitored the change in the number of EAB beetles that emerged from a subset of ash trees in Point Pelee during the study period by counting the number of exit holes. In the first season, we determined the year in which the holes were produced: 2008, 2007 or 2006. This study therefor describes six years of population dynamics (2006-2011 inclusive). The population first increased, which was expected for a newly established area with abundant resources. However, the number of emerging EAB beetles began to decrease in 2010 despite the presence of continued resources for larval development. It is thought that gravid females may be migrating out of the study plots because of a lack of preferred oviposition sites despite the presence of suitable resources. Sunlight has been suggested as an important factor for oviposition site selection. Olfactory and visual cues may also play a role in EAB host selection. Investigated characteristics that may have interacting effects on host selection by gravid EAB females are relative tree height, openness of surrounding habitat, and tree size (diameter).