Path: bloom-picayune.mit.edu!snorkelwacker.mit.edu!americast.com!americast.com!americast-post Newsgroups: americast.twt.news From: americast-post@AmeriCast.Com Organization: American Cybercasting Approved: americast-post@AmeriCast.com Subject: Milfoil has met the weevil and lost Date: Sun, 15 Nov 92 16:56:27 EST Message-ID: \SE A;SCIENCE/HEALTH \SS (WS) \HD Milfoil has met the weevil and lost \BY Dean Rebuffoni \CR MINNEAPOLIS-ST. PAUL STAR TRIBUNE Scientists have discovered a tiny weevil native to North America that eats Eurasian water milfoil, the alien plant that has infested hundreds of lakes across the continent. Raymond Newman, a professor of fisheries and wildlife at the University of Minnesota, found several of the insects at a lake in Carver County, Minn., last summer. He had observed the weevil's larvae boring into the stems of milfoil, causing the plant's tissue to rot. The weevil also might be responsible for the recent decline of large populations of milfoil in several lakes in New England, said Sallie Sheldon, a biology professor at Middlebury College in Vermont. She is credited with having discovered the weevil's appetite for milfoil. Miss Sheldon stressed that she, Mr. Newman and other scientists have not completed studies to clearly ascertain the effects of the insect on the plant. She also emphasized that federal officials would have to approve any program to introduce the weevil into waters infested by Eurasian water milfoil. But it appears the insect, known to scientists as Euhrychiopsis lecontei, is naturally present in many lakes in the northern tier states and adjacent Canadian provinces. It also appears that the weevil naturally eats a native species of water milfoil but has shifted to Eurasian water milfoil as that exotic plant has spread across the continent. "It will take a while to [determine] whether the weevil definitely has reduced populations of Eurasian water milfoil," Miss Sheldon said. "But we're definitely encouraged by what we've seen so far." Miss Sheldon is one of 14 scientists who, backed by federal funds, are trying to find ways to control milfoil. They are working with Mr. Newman, who is backed by funds approved by the state legislature and the Sea Grant Program at the University of Minnesota. Eurasian water milfoil, a native of Europe, Asia and North Africa, was first discovered in the United States in the 1940s. About 40 states and several Canadian provinces now have infestations. After it was found in Minnesota in 1987 it has spread to more than 50 lakes and two streams in the state. The prolific, fast-growing plant crowds out native aquatic vegetation. It also can form large, dense masses in shallow water, hindering anglers and swimmers. Miss Sheldon's work has included introducing the weevil into several lakes and ponds in Vermont, where tentative studies suggest that the insect has reduced milfoil infestations. The emphasis of her work is on finding a natural means of controlling the alien weed. Mr. Newman's research includes trying to find a chemical that might lure the weevil to milfoil. Miss Sheldon said that while the weevil's life history is not fully known, it appears that the insect spends most of its life underwater. An adult weevil is only one-eighth of an inch long, and a female lays a large number of eggs on the growing tip of a milfoil plant. "The weevil's larvae will burrow into the tip and, as it gets older, starts hollowing out all the tissue in the plant's stem," she said. "Adult weevils feed all over the plant." * Distributed by Scripps Howard. This article is copyright 1992 The Washington Times. Redistribution to other sites is not permitted except by arrangement with American Cybercasting Corporation. For more information, send-email to usa@AmeriCast.COM