Beekeepers across the United States have reported higher than average overwintering losses since at least 2006. Scientists are investigating various pathogens, parasites, environmental stresses – including the impacts of pesticides – and management issues as likely contributors to the widespread die-offs. While scientists and beekeepers have been puzzling over the cocktail of factors that could be driving the die-offs, Colorado beekeeper Tom Theobald suspects that a group of pesticides called neonicotinoids, which attack insects’ central nervous systems, paralyzing and killing them, play a key role. To date, much of the research into the potential effects of neonicotinoids on honeybees has focused on clothianidin’s cousin and Bayer’s top selling seed treatment, imidacloprid – sold under the trade name Gaucho – which works in a similar way. Attached is an article on the influence of Bayer Cropscience on Dutch policy makers (which appeared the magazine "Vrij Nederland" on April 4, 2012).
Last year a team of French scientists published a study that shows imidacloprid working in concert with a common bee pathogen, Nosema, to significantly weaken bees’ health. The researchers fed bees the chemical and exposed them to the pathogen. The bees infected with the pathogen and exposed to the insecticide at concentrations that would generally be encountered in the environment showed the highest death rate, according to the researchers. Jeff Pettis, research leader at the USDA’s Agricultural Research Services Bee Research Laboratory in Beltsville, Maryland, performed a small but similar lab study, which was published in 2012 (attached). In a telephone interview Pettis said the study is very much supportive of the French study. Dr. Henk Tennekes, a Dutch cancer researcher and toxicologist, has written a book that raises concerns about the long-term, cumulative effects of neonicotinoids on insects and the birds that feed on them. In an interview on the Organic View radio show he said there may be no safe level of exposure to these insecticides because of their potential to accumulate within animals. “New research has shown that tiny doses of these insecticides are capable of producing a breakdown of the immune system of honeybees,” he said during the interview. “Very small quantities of neonicotinoid insecticides are sufficient to cause collapse of bee colonies in the long run.” On scientific grounds, the chemicals should be banned immediately, he said.
In a statement released by Beyond Pesticides, an organization dedicated to eliminating toxic pesticides, James Frazier, professor of entomology at Penn State’s College of Agricultural Sciences, said: “Among the neonicotinoids, clothianidin is among those most toxic for honeybees; and this combined with its systemic movement in plants has produced a troubling mix of scientific results pointing to its potential risk for honeybees through current agricultural practices.” “Our own research indicates that systemic pesticides occur in pollen and nectar in much greater quantities than has been previously thought, and that interactions among pesticides occurs often and should be of wide concern,” he said. With regards to clothianidin, vanEngelsdorp said he doesn’t think there is enough evidence to warrant removing the insecticide from the market. “I think it’s growing. I think we have laboratory data that’s suggestive, but laboratory data doesn’t always translate into field data,” he said. “I think we have more data to show that fungicides have a negative effect than this right now.”
An EPA memo dated September 28, 2005 (attached) summarizes the Environmental Fate and Effects Division’s (EFED) screening-level Environmental Risk Assessment for Clothianidin:
- Clothianidin is expected to dissipate very slowly under terrestrial field conditions, based on the results of five bare ground field experiments conducted in the US and Canada. Half-lives of clothianidin, based on residues in the 0-15 cm soil depth, were 277 days (Wisconsin sand soil, incorporated), 315 days (Ohio silt loam soil, not incorporated), 365 days (Ontario silt loam soil, incorporated), and 1,386 days (North Dakota clay loam soil, not incorporated), and could not be determined at a fifth site due to limited dissipation during the 25-month study (Saskatchewan silty clay loam soil, incorporated). Incorporation did not appear to be a significant factor in determining the rate of dissipation. Clothianidin was generally not detected below the 45 cm soil depth except at one site, where it moved into the 45-60 cm depth. No degradates were detected at >10% of the applied, and degradates were generally only detected in the 0-15 cm soil layer. However, in many cases most of the parent remained untransformed at the close of the study; further accumulation of degradates could have occurred. Two studies were conducted to investigate leaching of clothianidin under field conditions. These studies were conducted in the Federal Republic of Germany and were apparently designed to fulfill certain European regulatory requirements. In these monolith lysimeter studies, 42 to 59% of the applied remained in the soil approximately 3 to 4 years following the first of two applications, and residues were primarily undegraded clothianidin.
- Direct contact and dietary exposure studies of honeybees indicate that clothianidin is highly toxic to honeybees (acute contact LD50 = 0.0439 µg/bee and acute oral LD50 = 0.0037 µg/bee). There is the potential for toxic exposure to honeybees, as well as other nontarget pollinators, through the translocation of clothianidin residues in nectar and pollen. In addition, studies indicate that clothianidin residues may affect foraging behavior. Data from studies determining the toxicity of residues on foliage indicate that clothianidin should not be applied to blooming, pollinating or nectar producing parts of plants because clothianidin will remain toxic to bees for days after a spray application. In honey bees, the effects of this toxic exposure may include lethal and/or sub-lethal effects in the larvae and reproductive effects to the queen. The field study EFED is requesting should resolve uncertainties dealing with clothianidin’s affects on bees. Clothianidin’s major risk concern is to nontarget insects (that is, honey bees). EFED expects adverse effects to bees if clothianidin is allowed to be sprayed on blooming, pollen-shedding, or nectar producing parts of plants. Although EFED does not conduct a risk quotient based risk assessment on non target insects, information from standard tests and field studies, as well as incident reports involving other neonicotinoids insecticides (e.g., imidacloprid) also suggest the potential for long term toxic risk to honey bees and other beneficial insects. Further studies may be needed to determine toxicity to honeybees from granular, seed treatment or foliar spray applications.
- The available data on clothianidin shows that the compound is relatively persistent to very persistent under most circumstances. Clothianidin is stable to hydrolysis at all pH's at environmental temperatures, moderately to highly stable under aerobic soil metabolism conditions (half lives range from 148 to 6,900 days).....Certain degradates appeared to accumulate in some soils under some conditions; over the very long term significant contamination of soil and water with these products might occur. The terrestrial field dissipation studies confirm the findings in the laboratory studies. Clothianidin was found to be persistent in the field (half lives of 277 days, 1,400 days, and too high to calculate).
- The Agency acknowledges that pesticides have the potential to exert indirect effects upon the listed organisms by, for example, perturbing forage or prey availability, altering the extent of nesting habitat, and creating gaps in the food chain
Source: By Brendon Bosworth, New West Feature, 3-15-11 (article attached)
http://www.newwest.net/topic/article/are_regulators_doing_enough_to_pre…
Watch this Youtube video:
http://discounts.savingmoneysaver.com/general/dead-birds-bees-fish-expl…
Article in The Ecologist on January 3, 2011:
http://www.theecologist.org/News/news_round_up/708990/leaked_document_e…
The EPA characterised clothianidin in 2003 (when conditional registration was granted) as follows: "Clothianidin is highly toxic to honey bees on an acute contact basis. It has the potential for toxic chronic exposure to honey bees, as well as other nontarget pollinators, through the translocation of clothianidin residues in nectar and pollen. In honey bees, the effects of this toxic chronic exposure may include lethal and/or sub-lethal effects in the larvae and reproductive effects in the queen. The fate and disposition of clothianidin in the environment suggest a compound that is a systemic insecticide that is persistent and mobile, stable to hydrolysis, and has potential to leach to ground water, as well as runoff to surface waters. "
The data gaps identified by the EPA in 2003 (when conditional registration was granted) were:
Toxicology:
• Developmental immunotoxicity study
• Additional analysis of test materials used in mutagenicity studies
Residue Chemistry:
• Rotational crop residue field trials with mature soybeans
Environmental Fate Data:
• Aerobic aquatic metabolism
• Seed leaching study
Ecological Effects Data:
• Whole sediment acute toxicity to freshwater invertebrates
• Field test for pollinators
Source: EPA Factsheet on Clothianidin of May 30, 2003:
http://www.epa.gov/opprd001/factsheets/clothianidin.pdf
Dan Rather Report:
http://vimeo.com/29419200
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Insecticides taking toll on honeybees
When I first wrote about the mysterious epidemic of honeybee mortality in early 2007, the phenomenon had just been termed colony collapse disorder, or CCD. Scientists were at a loss to explain why bees were wandering away from hives and not returning. Commercial beekeepers have seen average population losses of about 30 percent each year since 2006, and mounting evidence indicates a class of insecticides known as neonicotinoids might be at least partially responsible for the phenomenon.
Because they are systemic insecticides, vascular systems of both plants treated with the product and those that grow from seeds treated with neonicotinoids are suffused with it, which means the insecticide is "expressed" in all parts of the plant, from its roots, stem and leaves to its nectar and pollen. These pesticides act as neurotoxins, and insects that dine on any part of treated plants are subject to paralysis and death.
According to the U.S. Environmental Protection Agency, the agency responsible for the regulation of pesticides, neonicotinoids account for more than 20 percent of the worldwide insecticide market.
In late 2010, a document prepared by the EPA in response to a request by the parent company of the neonicotinoid clothianidin — originally approved in 2003 — that it be approved for use on some additional crops was leaked to a Colorado beekeeper.
The EPA report said "clothianidin's major risk concern is to nontarget insects (that is, honeybees)." It went on to say, "Acute toxicity studies to honey bees show that clothianidin is highly toxic on both a contact and an oral basis. Standard tests and field studies, as well as incident reports involving other neonicotinoids insecticides (e.g., imidacloprid) suggest the potential for long-term toxic risk to honey bees and other beneficial insects."
The report also outlined the potential toxic impact to aquatic species upon entrance into waterways and said: "The proposed application rates and uses also pose an acute and chronic risk to small birds and mammals when clothianidin treated seeds are applied with low efficiency or no incorporation methods."
In response, six national groups affiliated with beekeeping and what I'll call pesticide nonproliferation wrote to the EPA demanding a "stop-use order" on clothianidin. And even though its own scientists' findings questioned its use, the EPA's patronizing response refused to budge, saying a review is planned in the near future, though several conflicting dates for the scheduling of that study exist.
In January 2012, Purdue University released findings from research on the routes of pesticide exposure that supports the role of neonicotinoids in honeybee deaths.
The U.S. Department of Agriculture estimates the seed corn used to plant virtually the entire U.S. corn crop — more than 90 million acres — is treated with neonicotinoids such as clothianidin and thiamethoxam. About half of soybean seeds also are treated.
These insecticide coatings are sticky, and talc is mixed with the seeds to keep them flowing freely. The study found that the large amounts of insecticide-laced talc being released into the environment in the process is more toxic — up to about 700,000 times the lethal contact dose for a bee — than what the little pollinators pick up from corn pollen.
"This material is so concentrated that even small amounts landing on flowering plants around a field can kill foragers or be transported to the hive in contaminated pollen," said Christian Krupke, associate professor of entomology at Purdue and a co-author of the findings.
Bees that do not die from the insecticide might still suffer from the cumulative sublethal effects from exposure that directly correspond to the symptoms of CCD: a loss of homing ability and neurobehavioral and immune system disruptions.
The problem is exacerbated by the fact clothianidin has a soil half-life of as long as 19 years in heavy soils and more than a year in lighter soils, so plants that grow there will continue to express the insecticide.
Clothianidin was banned in Germany, the country of its origin, in 2008 and also in France, Italy and Slovenia. The release of the Purdue study has beekeepers, honey producers and environmental groups again calling on the EPA to ban it.
Source: Columbia Daily Tribune, by Jan Wiese-Fales, February 19, 2012
http://www.columbiatribune.com/news/2012/feb/19/insecticides-taking-tol…