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Beetles help fight invasive weed toxic to cattleDES MOINES, Iowa (AP)--For years, cattle farmers in northwest Iowa have struggled with a scourge that eats away at their grazeable land. The problem is an invasive weed called leafy spurge. The nonnative plant, with origins in Europe and Asia, pushes out prairie grass and offers a toxic alternative that cattle won't eat. Enter the beetles. The U.S. Department of Agriculture and the non-profit Nature Conservancy released the Aphthona flea beetles in limited areas about 10 years ago and have found they're experts at gobbling up leafy spurge, a weed with milky, latex sap that causes lesions in cows that eat it. It's a slow process, but the beetles are helping native grass that suits bovine palates regain a foothold. The effort has been proven effective in parts of North Dakota, South Dakota, Nebraska and Montana as well as Iowa. "Leafy spurge is just such an aggressive weed," said Scott Moats, who works for the Nature Conservancy in northwest Iowa and Nebraska. "We still don't really know how it got here, to the U.S. But if you don't control it, it eats into your forage space like crazy." Left alone, leafy spurge has no natural environmental check and can spread quickly. And even when the beetles were set loose in northwest Iowa, it took years to see much of a tangible result. "It's a really aggressive invader," said David Kazner, a research entomologist with the U.S. Department of Agriculture in Sidney, Mont. "It will take over a variety of different habitats and the biggest problem is that the cattle just won't feed on it. They don't like it." It's actually baby beetles, in their larvae stage, that do the most damage to the plant. The larvae are planted near the foot of leafy spurge plants and through the winter and the spring as they feed and grow, they eat away at the plants' water and sap. By the time adult beetles emerge from their cocoons in the late spring and summer, they begin to munch on the plants' leaves and exterior, killing the weed and allowing native grass to grow. To be as effective as possible, several hundred beetles are needed to start, and they reproduce quickly. Once they establish a self-sustaining population, they can be collected and redistributed to other areas where leafy spurge has sprung up. In addition to being effective, the beetles are relatively inexpensive. That's important because leafy spurge is so prolific, it's too expensive to kill with chemicals. The beetles do have problems in areas with sandy soil, which allows the leafy spurge to grow deeper roots. In northwest Iowa, though, where much of the state's beef is raised, the beetles have been a welcome addition. "The downside is it's a long-term game, because there are probably 50 years worth of spurge seed built up around here," Moats said. "The good thing is that they're working. And we're not seeing any other invasive weeds." 3/10/08 Date: 3/5/08
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