Herbicides May Be Lethal For Endangered Butterfly Species, Study Says

Common herbicides used to maintain the habitat of the endangered Lange’s metalmark butterfly may actually pose a lethal threat to the species, according to a new study. In tests requested by the U.S. Fish and Wildlife Service — which uses the herbicides to combat invasive plants inside a northern California wildlife refuge — scientists at Washington State University found that adult populations of the closely related Behr’s metalmark butterfly dropped by as much as one-third when their larvae were exposed to regular doses of three commonly used herbicides. For small populations, “any kind of reduction like that is going to be a problem,” said John Stark an ecotoxicologist and lead author of the study, published in the journal Environmental Pollution. The scientists could not use the Lange’s metalmarks for testing because of their endangered status. While more than 25,000 of the butterflies were believed to live in the dunes of Antioch Dunes National Wildlife Refuge a century ago, the numbers dropped to 5,000 in the early 1970s and to as low as 45 in 2006. A critical threat facing the butterfly is the loss of the naked stem buckwheat plant, which has been increasingly overgrown by non-native plants, such as the ripgut brome, vetch and yellow starthistle.
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