Asian longhorned beetle poses threat to New England maples

Signs of fall are beginning to appear in the northeastern United States.  Glimpses of colorful leaves are showing and a crisp autumn smell hangs in the air.  Maple trees make up much of New England’s landscape and are integral to both thriving tourist and maple syrup industries.  Now, a new study just out in the Canadian Journal of Forest Research suggests that if left uncontrolled, the Asian longhorned beetle (ALB) can “readily disperse into natural forest landscapes and alter the makeup of North America’s hardwood forest region.”

The study focuses on the ongoing ALB infestation in Worcester, Massachusetts, the only outbreak so far in which the beetles have invaded nearby closed-canopy forests.  ALB infestations have famously occurred in cities including New York, Boston and in Chicago. Native to eastern China, the ALB was first discovered in the U.S. in 1996, probably arriving in wood packaging material shipped from Asia.  As described on the Center for Invasive Species Research website, the wood-boring beetle often kills otherwise healthy trees by girdling them and creating holes in the bark, leaving the trees vulnerable to additional attacks by other insects or disease.  The U.S. Department of Agriculture has been working to control or eradicate ALB populations and raise public awareness and cooperation as seen in the agency’s public service announcement in the video below.

In urban environments, the ALB invades a wide variety of hardwood trees but in forests it favors maple trees.  At one of the study’s research sites in a suburb of Worcester, nearly two-thirds of all maple trees were infested.  According to a National Science Foundation (NSF) press release about the recent study, the Worcester ALB outbreak is the largest so far in North America with more than 19,600 trees infested.  Eradication efforts involve harvesting affected trees and have led to shifts in forest composition from maple to oak.

Says co-author David Orwig, a forest ecologist at NSF’s Harvard Forest Long-Term Ecological Research site in the NSF release:

“If the ALB continues to spread outside Worcester, the abundance of red maples could provide a pathway for its dispersal throughout New England and other parts of eastern North America.”

Photo: NSF Harvard Forest LTER site