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Parks Use Science to Battle Aliens.

Plant-eating beetle curbs the spread of purple loosestrife.

CORNELL UNIVERSITY, N.Y.--Nonnative plant species are invading the nation's parks at an alarming rate, displacing native vegetation and threatening the wildlife that depend on them. At some, such as Sleeping Bear Dunes National Lakeshore in Michigan, as much as 23 percent of the ground is covered with alien species, and the rate of expansion is increasing dramatically.

Biocontrol--using a nonnative plant species' natural enemies to combat it--is just one method that most federal agencies, including the National Park Service, are employing to curb the rising problem. But does it make sense to introduce one more exotic species in hopes of controlling another?

"The science is good behind it, and it's predictable," said Bernd Blossey, an assistant professor of natural resources at Cornell University in New York. "Carefully done, it's a safe method and much better than pumping herbicides into the environment."

One such biocontrol program that Blossey has been involved with since its inception in 1985, is the use of several insects to control purple loosestrife. The fast-growing plant has invaded wetlands in all of the lower 48 states except Florida since being introduced from Europe in the early 1800s as both a contaminant in ship ballast and as an herbal treatment for ailments including dysentery and ulcers. The plant establishes itself easily; a single mature plant can produce more than 2 million seeds annually.

Mike Ielmini, the national invasive species coordinator for the U.S. Fish and Wildlife Service's National Wildlife Refuge System, presumes that the only reason the plant has not taken root in Florida is because the climate may be too warm. He said, however, that he has seen the plant in Florida, probably the result of people planting it purposefully. Indeed, the plant's attractive purple flowers have made it popular in land-scaping--another factor contributing to its spread. Selling the plant is now illegal in 19 states, Blossey said.

The purple loosestrife-eating beetles have been released in more than 2,000 test sites in at least 30 states, including areas outside of Acadia National Park in Maine, Delaware Water Gap National Recreation Area in Pennsylvania, and Kenilworth Aquatic Gardens, part of the National Capital Parks in Washington, D.C., according to Blossey. Though success rates vary, in some areas, the beetles have reduced the plant to "5 percent or less" of its former abundance, he said.

Terry Cacek, an integrated pest management specialist with the Park Service, said that although the agency does not have a well-developed policy on bio-control, containing nonnative species within the system is becoming a higher priority. "Funding [for nonnative species control] has increased dramatically; it's roughly tripled in the last few years," Cacek said. Last year, Congress appropriated $1.2 million to establish four new Exotic Plant Management Teams (EPMT), which travel to different parks working to control nonnative species. Previously, the Park Service had just one EPMT, and the agency is hoping to add six more by 2002.

"The real problem for national parks," said Brian Klatt, who is researching the beetles at the University of Michigan's biological gardens, "is that purple loosestrife and other exotics displace native vegetation, which is critical feeding and nesting habitat for water-fowl, muskrat, or just about anything."

Because introducing an alien species into the environment is risky, testing biological control agents for plant pests is carefully controlled by the U.S. Department of Agriculture with consultation by other federal agencies. Decades of research are involved, first in a host country and then in the United States. The experiments ensure, among other things, that the new species will not begin attacking another native species.

The beetle research has been ongoing for 15 years, and the scientists expect it to take a minimum of ten years before any definitive success is measured.

"It's a lengthy process, but I'm confident that we're doing something good," Blossey said.
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Copyright 2001 Gale, Cengage Learning. All rights reserved.

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Title Annotation:nonnative plant problem
Publication:National Parks
Article Type:Brief Article
Geographic Code:1USA
Date:Mar 1, 2001
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