An assessment of the connectivity and susceptibility of riparian ash in the southern Lower Peninsula of Michigan: Implications for the dispersal of the emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae)

Following the discovery of Agrilus planipennis Fairmaire in southeastern Michigan in 2002, extensive efforts have been launched to determine areas of potential risk and to identify the mechanisms governing A. planipennis dispersal. A study to assess the spatial arrangement and availability of ash forest patches across the landscape of Southern Lower Michigan was conducted. Spatial pattern analysis was performed to evaluate the connectivity of riparian and upland ash forests. Riparian ash forests were found to offer greater connectivity among similar patch types. A second study was designed to estimate the ability of riparian and upland ash forests to produce A. planipennis adults. Ash in riparian forests had a significantly higher ability to produce adult beetles. A high degree of connectedness and the ability to support the development of high densities of A. planipennis increases the likelihood of intensified insect dispersal along riparian corridors.