Monday, December 11, 2006

Field surveys of emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) density and canopy dieback in three North American ash species

Andrea C. Anulewicz, agiusand@msu.edu1, Deborah G. McCullough, mccullo6@msu.edu2, and David Cappaert, cappaert@comcast.net2. (1) Michigan State University, Department of Entomology and Department of Forestry, 243 Natural Science, East Lansing, MI, (2) Michigan State University, Entomology, Forestry, 243 Natural Science Building, East Lansing, MI

Emerald ash borer (Agrilus planipennis Fairmaire), an Asian species discovered in June 2002, is established in much of southeastern Michigan and Windsor, Ontario. Larval feeding under the bark disrupts vascular tissue, eventually girdling and killing ash trees (Fraxinus sp.). An estimated 15 million green ash (F. pennsylvanica), white ash (F. americana), black ash (F. nigra) and blue ash (F. quadrangulata) trees in southeastern Michigan are dead or dying. Given the extensive damage that A. planipennis has already caused to the Fraxinus resource in southeast Michigan, an important question is whether A. planipennis preferentially feeds or oviposits on certain North American species of Fraxinus. Understanding the preference hierarchy and the underlying mechanisms of A. planipennis attraction among the Fraxinus species will increase our ability to accurately assess stand susceptibility and develop survey protocols based on species composition. To assess host preference, I quantified the density of A. planipennis exit holes and woodpecker attacks on larvae at four sites where green and white ash street trees were planted together and at two woodlots where white and blue ash trees co-occurred. I monitored canopy dieback and changes in exit and woodpeck attack densities from 2003 to 2006. Canopy dieback and density of A. planipennis were significantly greater on green ash street trees than white ash street trees and increased in both species over time. Canopy dieback was positively correlated with density of exits and woodpecks. Agrilus planipennis density was also significantly greater in white ash woodlot trees than blue ash woodlot trees.

Species 1: Coleoptera Buprestidae Agrilus planipennis (emerald ash borer, ash borer)
Species 2: Oleales Oleaceae Fraxinus (ash)