A pest survey led by researchers at the University of Georgia and the Georgia Forestry Commission has found that an exotic wood-boring ambrosia beetle that can attack living trees and has the potential to cause economic damage across the country has established a population in the state.
And worse, said Kamal Gandhi, they're probably here to stay-and increase in numbers. "More than likely, we won't be able to eradicate them from Georgia," said Gandhi, an assistant professor in UGA's Warnell School of Forestry and Natural Resources. Gandhi was part of the team that conducted the 2009 Cooperative Agricultural Pest Survey, an annual multi-agency insect sampling that involves the Georgia Forestry Commission, Georgia Department of Agriculture, University of Georgia, and the U.S. Department of Agriculture Animal and Plant Health Inspection Service.
The 2009 sampling-detailed in the December edition of The Coleopterists Bulletin-found a troubling number of the camphor shot borer (Xylosandrus mutilatus) in the six counties used in the survey. While researchers found just three adult ambrosia beetles in the 2007 survey, they found 56 in 2009. The non-native wood boring ambrosia beetles have been proven to be particularly damaging, with previous studies estimating around $50 million in annual timber losses in some areas in North America. Stowing away in wood packaging around cargo, waste and soil from Asia, the ambrosia beetles also bring with them an exotic pathogenic fungi that can kill trees. Finding them during the CAPS sampling, Gandhi said, worries tree experts around the state.
"This is alarming because they're also bringing their exotic fungi, they are hard to detect and they can establish their populations quickly in a new area," she said.
The survey focused on locations in Clarke, Clayton, Douglas, Elbert, Fulton and Oconee counties. The survey was conducted between mid-April and September. None of the beetles were found during the 2008 CAPS sampling.
The exotic ambrosia beetles can attack more than 200 plant species and a wide variety of native trees. Gandhi said she and her colleagues don't know that the beetles have started killing Georgian trees-but they are fully capable of doing so. The fact that no one is reporting suspicious trees yet indicates that the beetles' population is still low. More monitoring is needed in the deeper parts of the forests, she said.
The destructive beetle in question was first detected in North America in 1999 in Mississippi. Since that time, it also has been found in Alabama, Arkansas, Florida, Louisiana and Texas, indicating that it has already rooted itself across the Southeast.
James Johnson, Georgia Forestry Commission forest health coordinator, said that other states have reported minimal problems so far, and anticipates that Georgia will experience similar findings.
But he puts the potential problem in perspective: "Some estimates indicate that one out of every hundred new species introduced may cause problems, and a small portion of these can cause catastrophic problems. It is often difficult or impossible to tell which species have the potential to cause the severe problems, but we have some history on this species from other southeastern states."