Beekeeper James Doan, owner and operator of Doan Family Farms in Hamlin, N.Y., wants to know what is killing his honeybees. In May, Doan witnessed his apiary’s largest bee kill since 1987. Back then, the organophosphorus pesticide methyl parathion was to blame, he says. This time, Doan suspects the cause is dust contaminated with clothianidin, a neonicotinoid pesticide used to treat corn seeds.
Doan is not alone in facing staggering honeybee losses. Declines in honeybees and other pollinator species have been reported by numerous authorities around the world. Data from the Department of Agriculture, the lead federal agency investigating pollinator declines in the U.S., indicate that the number of commercial honeybee colonies in the U.S. dropped from about 5.9 million in the late 1940s to about 2.5 million in 2011.
The Environmental Protection Agency acknowledges that honeybees are in decline, but the agency isn’t convinced that clothianidin or any other pesticide is the only factor responsible. In July, EPA rejected a petition from a coalition of advocacy groups and beekeepers to immediately suspend the use of clothianidin, citing a lack of evidence linking the pesticide to a decline in honeybee populations.
“Available science suggests that pollinator declines are the result of multiple factors, which may be acting in various combinations,” says Thomas Moriarty, a team leader in EPA’s Pesticide Re-Evaluation Division. USDA suggests that losses of honeybee colonies are caused by parasitic mites, poor bee management, inadequate nutrition, and pesticides, all of which make honeybees more susceptible to disease.
To get a better handle on the role of pesticides in pollinator declines, EPA, along with the Canadian Pest Management Regulatory Agency and the California Department of Pesticide Regulation, has been developing a quantitative framework for assessing the risks of pesticides to bees.
The framework involves a tiered approach, starting with a simple screening assessment designed to quickly rule out pesticides that pose little or no risk to bees. The screening assessment relies on high-end estimates of exposure and considers effects measured on individual honeybees in laboratory toxicity studies. The second and third tiers involve increasing information requirements, such as field studies, and they consider effects at the colony level.
EPA released the proposed framework in August and had its pesticide scientific advisory panel critique it at a four-day public meeting last month. Panel members pointed out several limitations with the process, including the lack of data on pesticides in pollen and nectar, inadequate data on the extent and distribution of pollinator declines, failure to incorporate some important routes of exposure, and the lack of validated larval assays.
Throughout the meeting, panelists brought up the lack of data on pesticides in pollen and nectar as a major weakness. EPA used a model derived from pesticide residues on tall grass to estimate bee exposure to pesticides via nectar and pollen consumption. The model appears to be conservative, meaning it leans toward high risk, but “we have a paucity of data—actual residue measurements on nectar and pollen—with which to compare to this estimate,” stressed Thomas L. Potter, a research chemist with USDA’s Agricultural Research Service.
It is unclear, however, who would be responsible for getting such data and who would pay for the analyses. Currently, beekeepers have to foot the bill to find out what chemicals are in their bee and pollen samples, Doan told the advisory panel.
Doan explained how difficult it was for him to get his samples analyzed. When he witnessed large numbers of bees dying in May, he first called the local office of New York State’s Department of Environmental Conservation.
The office told Doan there was no money in the department’s budget to investigate bee kills. So he turned to the New York State Apiary Inspection Program, which has been investigating a parasitic infection in bees called nosema. An inspector came out, took samples of Doan’s bees, and analyzed them for mites and nosema. Neither one was present at a high enough level to be of concern, Doan said.
Not satisfied with the results, Doan then called Maryann Frazier, an entomologist at Pennsylvania State University. Frazier sent Doan’s samples to a USDA bee lab in Gastonia, N.C. Doan had to pay for that analysis himself.
The results showed high levels of clothianidin in both the pollen and the bees, Doan noted. The analysis also detected a few other chemicals, but nothing stood out like clothianidin, particularly in the bees, he said.
Doan believes he is not alone in his struggles to get samples of dead bees and pollen analyzed. “I’ve talked to people from all across the country that had difficult times trying to get somebody from their state to come out and pull samples. I have talked to Canadian beekeepers, and they are telling me similar stories,” he told the panel.
Another problem is that EPA lacks data on the extent and distribution of pollinator declines, several panel members pointed out. USDA has been collecting data on the number of commercial honeybee colonies in the U.S. since the 1940s, but those data follow trends in honey prices, pointed out Jeffery S. Pettis, a research leader with USDA’s Bee Research Laboratory in Beltsville, Md. In addition, the data exclude honey producers with fewer than five hives, who represent an important sector of the industry.
USDA’s National Agricultural Statistics Service considered conducting a large study to determine the rate of decline of honeybee colonies in the U.S., but no funding for such a study ever surfaced, Pettis noted. Instead, USDA has been sending out questionnaires to beekeepers for the past six years to survey honeybee losses. “It is not the best data set, but it is the best data set we have,” Pettis said.
The lack of reliable data on honeybee losses concerned some panel members. “It doesn’t sound like we have the numbers in hand to really assess the real risk to pollinators,” stressed James McManaman, a professor of reproductive sciences at the University of Colorado, Denver.
“We need to do some sort of pattern analysis,” suggested William G. Kelly Jr., an attorney with the Center for Regulatory Effectiveness, an advocacy group that questions the cost-effectiveness of regulations. Such an analysis could show “where this problem is occurring, the extent of it, and whether it is really associated with pesticide use in those areas,” he said.
In developing the risk-assessment framework, EPA relied on bee-kill incident data from its Ecological Incident Information System (EIIS). But that database does not include many incidents that have been reported elsewhere, pointed out Peter Jenkins, an attorney and policy analyst with the Center for Food Safety, the lead advocacy group that petitioned EPA to ban clothianidin earlier this year.
“It is well accepted across numerous stakeholders, especially beekeepers, that EIIS does a very poor job of collecting national bee-kill data,” Jenkins said. In contrast, the system used by Canada’s Pest Management Regulatory Agency captures more incidents and is well regarded, he noted.
Jenkins pointed out that EPA’s database does not include at least 14 bee-kill incidents that occurred in the U.S. in 2012 and 120 incidents reported in Canada. Those incidents were all associated with dust from neonicotinoid seed treatments, he claimed.
EPA acknowledges that exposure of bees to dust from pesticide-treated seeds is the focus of numerous ecological incident reports. However, the agency did not include contaminated dust as a route of exposure in its framework because methods for predicting pesticide exposure from seed coat dust are not yet available for regulatory applications, noted Keith Sappington, a senior scientist with the Environmental Fate & Effects Division of EPA’s pesticide office. In addition, “the agency is currently working to mitigate this exposure pathway based on modifications of seed treatment methods, seed planting equipment, and associated practices,” he said.
But Jenkins and other stakeholders urged EPA to revise the exposure model to include dust from pesticide-treated seeds. “This contaminated dust exposure route and its impact on honeybees has led to Germany, Italy, Slovenia, and to some extent France prohibiting various neonicotinoid seed treatments in the last four years,” Jenkins noted.
Several stakeholders also encouraged EPA to consider guttation fluid—droplets of sap that form on the edges or tips of leaves of some plants—as an important route of exposure. EPA acknowledged that such fluid may contain high levels of pesticides, “but the degree to which honeybees rely on this source of water and nutrients has proven difficult to quantify,” Sappington noted.
Representatives from the pesticide industry, on the other hand, said EPA’s exposure estimates are too conservative. A lot of chemicals that pose little or no risk to bees will fail the screening assessment and be subject to unnecessary higher-tier testing, said David Fischer, an ecotoxicologist with Bayer CropScience, which markets clothianidin.
Other people at the meeting, including several panel members, were concerned about the lack of validated assays for determining the toxicity of pesticides on honeybee larvae, the failure of EPA to consider sublethal effects of pesticides on bees, and the use of honeybees as a surrogate for other pollinator species.
Despite the limitations of the proposed framework, EPA’s effort to improve its process for assessing the risks of pesticides to bees has garnered support. Honeybees and other pollinator species are vital for successful agriculture, but so are pesticides, noted Ray McAllister, senior director of regulatory policy at CropLife America, a trade group representing the pesticide industry. “Improving the quality and rigor of risk assessments will ensure that crop protection tools can be used in a manner compatible with pollinator health.” ◾