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Insecticides similar to nicotine, known as neonicotinoids, were found commonly in streams throughout the Midwest, according to a new USGS study. This is the first broad-scale investigation of neonicotinoid insecticides in the Midwestern United States and one of the first conducted within the United States.
Effective in killing a broad range of insect pests, use of neonicotinoid insecticides has dramatically increased over the last decade across the United States, particularly in the Midwest. The use of clothianidin, one of the chemicals studied, on corn in Iowa alone has almost doubled between 2011 and 2013.
“Neonicotinoid insecticides are receiving increased attention by scientists as we explore the possible links between pesticides, nutrition, infectious disease, and other stress factors in the environment possibly associated with honeybee dieoffs.” said USGS scientist Kathryn Kuivila, the research team leader.
Neonicotinoid insecticides dissolve easily in water, but do not break down quickly in the environment. This means they are likely to be transported away in runoff from the fields where they were first applied to nearby surface water and groundwater bodies.
In all, nine rivers and streams, including the Mississippi and Missouri Rivers, were included in the study. The rivers studied drain most of Iowa, and parts of Minnesota, Montana, Nebraska, North Dakota, South Dakota, and Wisconsin. These states have the highest use of neonicotinoid insecticides in the Nation, and the chemicals were found in all nine rivers and streams.
Of the three most often found chemicals, clothianidin was the most commonly detected, showing up in 75 percent of the sites and at the highest concentration. Thiamethoxam was found at 47 percent of the sites, and imidacloprid was found at 23 percent. Two, acetamiprid and dinotefuran, were only found once, and the sixth, thiacloprid, was never detected.
Instead of being sprayed on growing or full-grown crops, neonicotinoids can be applied to the seed before planting. The use of treated seeds in the United States has increased to the point where most corn and soybeans planted in the United States have a seed treatment (i.e., coating), many of which include neonicotinoid insecticides.
“We noticed higher levels of these insecticides after rain storms during crop planting, which is similar to the spring flushing of herbicides that has been documented in Midwestern U.S. rivers and streams,” said USGS scientist Michelle Hladik, the report’s lead author. “In fact, the insecticides also were detected prior to their first use during the growing season, which indicates that they can persist from applications in prior years.”
Locations of sites in Iowa sampled for neonicotinoids in 2013. Watersheds for the Mississippi River and Missouri River sites are shown in the inset. Image credit: USGS
One of the chemicals, imidacloprid, is known to be toxic to aquatic organisms at 10-100 nanograms per liter if the aquatic organisms are exposed to it for an extended period of time. Clothianidin and thiamethoxam behave similarly to imidacloprid, and are therefore anticipated to have similar effect levels. Maximum concentrations of clothianidin, thiamethoxam and imidacloprid measured in this study were 257, 185, and 42.7 nanograms per liter, respectively.
The U.S. Environmental Protection Agency has classified all detected neonicotinoids as not likely to be carcinogenic to humans.
The paper, “Widespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region, USA” and has been published in Environmental Pollution. Learn more about the study and the long-term USGS effort to gather information on the environmental occurrence of new pesticides in different geographic, climatic, and use settings here.
Honey Bees, neonicotinoid pesticides now found to be killing baby birds
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Tags: neonicotinoids, silent spring, bees
(NaturalNews) A class of pesticides widely blamed for a worldwide collapse in pollinator populations is also devastating populations of birds, according to a new study conducted by researchers from Radboud University in the Netherlands and the Centre for Field Ornithology and Birdlife Netherlands, and published in the journal Nature on July 16.
The chemicals, known as neonicotinoids, have increasingly come under fire for widespread destruction of organisms other than agricultural pests.
"I think we are the first to show that this insecticide may have wide-scale, significant effects on our environment," researcher Hans de Kroon said.
Systemic poison
In the past 20 years, neonicotinoids have become one of the fastest-growing pesticide classes. In contrast to most other pesticides, which must be sprayed directly onto plants close to the time that insect extermination is desired, neonicotinoids are simply used to treat seeds before planting. As a treated plant grows, it absorbs the poison into every single one of its tissues, making the entire plant toxic.That means that even the plant's flowers, nectar and pollen become deadly, killing pollinators that visit the crop.
"The plants become poison not only for the insects that farmers are targeting, but also for beneficial insects like bees," said Jennifer Sass, a senior scientist with the Natural Resources Defense Council.
In addition, the neonicotinoids can spread into the surrounding soil and persist for years, thereby contaminating future generations of plants - including non-agricultural species.
"So they actually end up in plants that grow on the sides of fields that were never meant to be targeted," Sass said.
Due to concerns over their effects on pollinators, several varieties of neonicotinoid (including imidacloprid, the variety examined in the Nature study), have been banned in many European countries.
A new "silent spring"
The Dutch researchers compared long-term data on chemical concentrations in surface water and on farmland bird populations in several areas of the country. They found that in the areas with the highest imidacloprid contamination, populations of 14 separate bird species declined by an average of 3.5 percent every year. The researchers also looked for a correlation between bird populations and other possible risk factors - such as urbanization of farmland, fertilizer use, or changes in crops planted - but only neonicotinoid concentration was associated with the population drop.The pesticides may be killing birds in two separate ways, the researchers suggested. First, birds could be eating parts of the contaminated plants, particularly seeds; according to a 1992 study by the U.S. Environmental Protection Agency (EPA), sparrows that ate neonicotinoid-treated seeds lost the ability to fly and became immobile. Secondly,neonicotinoids might be destroying the food base of birds that feed on insects and other invertebrates.
The latter explanation is supported by the recent findings of the Task Force on Systemic Pesticides, a multidisciplinary group of 29 scientists that reviewed 800 separate studies on neonicotinoids and wildlife. The task force found that neonicotinoids were killing off not just agricultural pests but also insects, earthworms, aquatic invertebrates, and even fish and lizards. These effects happened even when the products were used according to manufacturer guidelines.
Neonicotinoid use, the task force wrote, is "likely to have a wide range of negative biological and ecological impacts."
Dutch researcher Ruud Foppen said he sees a parallel between the new study and the seminal 1962 environmental book Silent Spring, by Rachel Carson. Carson's book, which is viewed as highly influential in launching the modern environmental movement, warned that organophosphate pesticides such as DDT were devastating bird populations.
"In this way, we can compare it to what happened decades ago," Foppen said. "And if you look at it from that side, we didn't learn our lessons."
Sources for this article include:
http://news.nationalgeographic.com
http://www.nature.com
http://www.weather.com
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