Woodpeckers find emerald ash borers a handy food source and may slow the spread of this noxious pest, even ultimately controlling it, suggest researchers from the University of Illinois at Chicago. Their findings are published online in the journal Forest Ecology and Management.
"We found we have a native predator that is able to detect and respond to this new rich food resource," said Charles Flower, UIC postdoctoral research associate in biology and first author of the study.
Since the emerald ash borer was first found feeding on trees in southeastern Michigan in 2002, this Asian invader has been responsible for the death of 30 million trees in the northeastern U.S. and Canada. In Chicago, where the emerald ash borer is already destroying trees, 17 percent of the street trees are ash -- 85,000 trees, with an estimated 300,000 more ash trees on private property.
"In 2006 we started establishing observation plots across Ohio and into Michigan so that we could follow the decline of trees and the impact on the ecosystem," Flower said.
In this study the researchers wanted to see if native bark-foraging birds, including woodpeckers and nuthatches, were feeding on the emerald ash borer. They hoped that unlike other exotic invasive species which run amok in new regions because of the lack of predators to keep them in check, the emerald ash borer might meet its match in native predators -- bark foraging birds like the woodpecker and nuthatch.
This kind of "bio-control" would be as, or perhaps more, efficient than other methods to slow the spread of this pest, said Flower. Chemical treatments are expensive and may cause harm to trees and other fauna, and the introduction of an ash borer predator from its native range in Asia might bring with it a host of new problems, he said.