KINGSTON, R.I. November 24, 2008 The United States has been under assault for decades by a wide variety of alien plants and animals, and it is not often that one of these aliens faces a counterpunch. But in a collaborative project with several other institutions, the University of Rhode Island has scored a knockout.
The birch leafminer, an insect pest that regularly disfigures birch trees, has been virtually eradicated in the Northeast. And the credit goes to entomologists from URI and other institutions who successfully introduced a biological control agent.
"Birch leafminers are no longer a pest in the Northeast," said Richard Casagrande, URI professor of plant sciences, who along with research associates Lisa Tewksbury and Heather Faubert were responsible for implementing and monitoring the introduction in Rhode Island over the last 20 years.
The program consisted of introducing a natural enemy of the birch leafminer, a parasitoid called Lathrolestes nigricollis, which was brought to the U.S. from Europe where it effectively controls the birch leafminer.
Now the same can be said for Rhode Island, Massachusetts, Connecticut, New York, Pennsylvania and northern New Jersey. The URI scientists recently coordinated a survey that has documented complete control of this pest in these states.
"We have not seen any damage in Rhode Island in four years," Casagrande said, "and it is highly unlikely that we'll see problems with it again."
According to scientists, the birch leafminer arrived in the U.S. in 1923, probably in a shipment of plant material sent to Connecticut. From there it spread throughout the Northeast and into the Midwest. In the 1970s, Roger Fuester and colleagues at the Delaware Beneficial Insects Rearing Lab introduced several European parasitoids to fight the pest, and one of them, Lathrolestes nigricollis, became established in the Mid-Atlantic States. Later, groups from URI, the University of Massachusetts, and the New
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University of Rhode Island