Wild deer in North Dakota were found to have surprising levels of neonicotinoids, probably originating from contaminated forage plants or water.įive manufacturers in Europe, the United States, and Japan dominate the neonic market. “Neonics could have a catastrophic effect on white-tailed deer populations,” says Jennifer Sass, a senior scientist with the Natural Resources Defense Council, an environmental group. After all, animals with malformed jaws and undersized reproductive organs may have trouble eating or breeding. Published in Scientific Reports in March of 2019, the results were big news for anyone who managed or hunted game around farmland, and for anyone concerned about the impacts of farm chemicals on wildlife. He surmised the wild animals had been contaminated by their forage plants or water. Jenks was surprised to find they contained imidacloprid at levels more than three times higher than those that produced abnormalities in his captive herd. But the team also examined the spleens of wild deer collected, over an eight-year period, by North Dakota game officials. Some of the deer had gotten doses of imidacloprid far higher than any yet reported in natural streams or wetlands. Both fawns and adults with higher levels had been less active while alive-which in the wild would have made them more vulnerable to predators. More than a third of the fawns died prematurely, and those fawns had much higher spleen levels of imidacloprid than the survivors. When they euthanized the herd after two years, the researchers found that animals with higher levels of the pesticide in their spleens had shorter jawbones, decreased body weight, and undersized organs, including genitals. Graduate student Elise Hughes Berheim and wildlife ecologist Jonathan Jenks mixed imidacloprid at a range of doses into the animals’ water. The scientists ran a first-of-its-kind experiment on a captive herd of white-tailed deer, consisting of 21 adult females and 63 fawns born to those females during the course of the experiment. In 2015, a team of scientists at South Dakota State University set out to determine how a neonic called imidacloprid-which is used on corn, soy, wheat, and cotton-might affect large herbivores. One of the first signs that neonics can affect large animals came from another study Lundgren worked on, also involving deer-but captive ones this time. In his barn this winter, Lundgren has been compiling some of the newest evidence-data suggesting that a significant number of wild deer in the upper Midwest have neonics in their spleens. Evidence is growing that compounds tailored to take out invertebrates can also harm mammals, birds, and fish. The chemicals accumulate in soils and waterways, where a wide range of wildlife is exposed to them. Over the past several years, scientists have found that only about 5 percent of neonic seed coatings are taken up by crop plants. One purple seed can kill over 100,000 bees. Corn seeds treated with the neonicotinoid pesticide clothianidin. hasn’t yet taken such decisive action, it’s becoming increasingly clear that bees and other beneficial insects aren’t the only animals at risk. The evidence of harm is strong enough that the European Union has banned outdoor use of three popular neonics. Bees, essential for crop pollination, have been especially hard hit. History tells us that such broad-spectrum pesticides may have unintended consequences, and scores of studies suggest that neonics, along with climate change and habitat destruction, are contributing to the steady decline of insects across North America and Europe. Insects chew or suck on their preferred portion, then curl up and die. Deployed as coatings on seeds for crops that cover more than 150 million acres in the United States, neonics are taken up by all plant parts: roots, stems, leaves, fruit, pollen, and nectar. They’re now the most widely used pesticides in the world, effective against aphids and leafhoppers and a wide range of worms, beetles, and borers.
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