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Trapping Project Targets Invasive Species

UNIVERSITY PARK, PA, June 9, 2009 - In the battle against invasive pests, detection often is the first step in gaining the upper hand. So when a large infestation of Asian longhorned beetles was found in Worchester, Ma. last August, the USDA began a trapping project and invited researchers from Penn State’s College of Agricultural Sciences and other institutions to participate. 

Asian longhorned beetles (ALB) are a serious invasive species that kills hardwood trees such as maple, box elder, horsechestnut, elm, and poplar. Invasive species are organisms that adapt quickly to a new environment, reproduce and spread rapidly into new locations, often displacing the organisms that were originally there. 

According to Kelli Hoover, associate professor of entomology at Penn State and a researcher on the project, the Asian longhorned beetle was probably introduced into the United States from wood pallets and other wood packing material accompanying cargo shipments from Asia. Adults are easy to spot. “About one to 1 1/2 inches long, Asian longhorned beetles have long antennae and are shiny black with white markings,” Hoover says. “After mating, adult females chew depressions into the bark of trees where they lay their eggs. Once the eggs hatch, small white larvae bore their way through the bark into the tree, feeding deeper into the tree's heartwood forming tunnels, or galleries, in the trunk and branches. This damage weakens the integrity of the tree and will eventually kill it if the infestation is severe enough.” 

Hoover says that over the course of a year, a larva will mature and then pupate near the surface, under the bark. From the pupa, an adult beetle emerges, chewing its way out of the tree and forming characteristic round holes approximately 3/8 of an inch in diameter. “Many holes will appear on a heavily infested tree, usually accompanied by sawdust and sap oozing from the holes. The beetles emerge from June through October with adults flying in search of mates and new egg-laying sites to complete their life cycle.” 

In the past, the only way to detect ALB infestations was to look for signs of the beetles, such as exit holes, which require careful inspection of each tree. This process is slow, very expensive and requires a large group of tree climbers. The goal of the new trapping project is to develop pheromone traps that will attract ALB. Pheromones are chemicals produced and used by insects to communicate with each other. The chemicals are specific to each insect species, and even sometimes to insect genders. Researchers at Penn State University, in collaboration with the, plan to prove beetles are attracted to a combination of male-produced pheromone and plant odors. 

In Worcester, Ma,, as well as other areas where ALB infestations were found, early detection of beetles is critical so that infested trees can be removed before the beetles emerge and spread. These pheromone traps will help in early detection as well as in locating infested trees. 

Once a beetle is found inside a trap, nearby trees can be examined to find the source of the infestation. The traps will be hung in trees in Worcester from June until September. These include forested areas as well as some street trees and trees around industrial parks, in the vicinity of the infested area where trees have already been cut down. Researchers will be testing different chemical combinations in the traps to determine which one will attract the highest number of beetles. If these traps and chemical combinations prove effective, they can potentially be used in the future in areas at risk for ALB infestations. 

The project is being funded by a grant from the USDA ‘s Animal and Plant Health Inspection Service, Plant Protection and Quarantine program. The collaborative includes researchers from Penn State, USDA’s Forest Service Northern Research Station, Agricultural Research Service and Animal and Plant Health Inspection Service, DCR Massachusetts, and the Asian Longhorned Beetle Eradiation Program in Worcester, MA. 

For more information on the project, contact

For more information on ALB, visit the Pennsylvania Integrated Pest Management’s Biosecurity web page at http://paipm.cas.psu.edu/21.htm.