WASHINGTON, D.C.—In a move to meet President Barack Obama’s National Pollinator Strategy, the U.S. EPA has launched the first of four upcoming risk assessments aimed at determining the effects of neonicotinoid insecticide use on bee populations in the United States.

The subject of the first assessment, imidacloprid, was shown to have potential for a negative effect to beehives when the chemical comes into contact with crops that attract the insects. According to the EPA’s report, “the preliminary risk assessment identified a residue level for imidacloprid of 25 ppb (parts per billion), which sets a threshold above which effects on pollinator hives are likely to be seen, and at that level and below which effects are unlikely.

“These effects include decreases in pollinators as well as less honey produced. For example, data show that citrus and cotton may have residues of the pesticide in pollen and nectar above the threshold level. Other crops such as corn and leafy vegetables either do not produce nectar or have residues below the EPA identified level.

“Additional data is being generated on these and other crops to help EPA evaluate whether imidacloprid poses a risk to hives,” it added.

Once the 60-day public comment period included in the risk assessment concludes, the EPA will decide if revisions to the assessment are needed based on comments and what action, if any, will be taken to reduce its stated risks of imidacloprid.

According to the EPA, those interested in commenting by March 16 or following the progress of the risk assessment should visit the agency’s website at www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2008-0844 and sign up for email alerts.

A webinar will also be held in early February; watch for details at www.epa.gov/pollinator-protection/how-we-assess-risks-pollinators

Imidacloprid is the first chemical to undergo a risk assessment by the EPA as part of the president’s initiative. Additional preliminary risk assessments are scheduled for clothianidin, thiamethoxam and dinotefuran later this year, with public comment periods open in December.

Rick Foster, professor and extension entomologist at Purdue University, explained neonicotinoid insecticides are used in the Midwest, primarily as seed treatments, but imidacloprid use is sparse and typically implemented by growers of specialty crops.

“Bottom line is, the total amount of imidacloprid used in this part of the Midwest is a relatively small amount. It’s used more by specialty crop growers like fruit and vegetable growers than it is by anyone else,” he said, adding that it is a common chemical used in the turf grass industry to control grubs.

Nevertheless, neonicotinoid insecticide use is a major concern for John Benham, past president of the Kentucky State Beekeepers Assoc. “Most of the time, any systemic insecticide is going to kill good insects as well as bad insects,” said Benham, who cited the monarch butterfly as another potential victim of neonicotinoid insecticide use.

In addition to the primary negative effect for bees, Benham said the insecticides’ weakening of their immune systems is putting them at a higher risk from other threats.

“Bees have a problem now with varroa mites. They can generally handle varroa mites, but when their immune systems are weakened by the pesticides that are in the water, dirt, pollen, nectar and everything they touch, it makes it very difficult for the bee to survive.”

Research done by Purdue entomologists shows a decrease in the usage of neonicotinoid insecticides may not leave growers scrambling for an alternative. John Obermeyer, Integrated Pest Management specialist and a member of the Purdue Department of Entomology, cites research completed recently by his colleague Christian Krupke, which found that pests targeted by neonicotinoid insecticides may not do economic damage to the crops.

“Speaking from Krupke’s research and his findings of recent, the neonics are being overused and their benefit to crop health and especially yield are certainly in question,” said Obermeyer. “So the question is, do we need to use so many of them?

“Our research findings are that we are not picking up yield benefits with these.”