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Pesticide News Story: EPA Acts to Protect Bees
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For Release: July 1, 2008 (updated July 14, 2011)
The EPA has received a number of inquiries since 2008 about bee deaths in Germany associated with the use of the pesticide clothianidin and whether this incident might be related to Colony Collapse Disorder. Based on discussions with German authorities, we believe this incident is not related to CCD. Although pesticide exposure is one of four theoretical factors associated with CCD that the United States Department of Agriculture is researching, the facts in this case are not consistent with what we know about CCD.
CCD is characterized by a relatively rapid decline in the adult bee population of a hive; typically only the queen, a few nurse bees and brood remain in the CCD-affected hive. Reported incidents of CCD have detected few if any dead adult bees. The 2008 incident in Germany, however, was associated with large numbers of dead adult bees in and around the hives. Additionally, testing showed clothianidin residues in the dead bees and their hives.
According to German authorities, the May 2008 incident resulted from inadvertent exposure of the bees to clothianidin, an insecticide used for corn seed treatment, resulting from a combination of factors. These factors include the specific formulation of the pesticide used, weather conditions and type of application equipment:
- The formulation of the pesticide clothianidin used to protect seed corn from corn root worm in Germany did not include a polymer seed coating known as a "sticker." This coating makes the pesticide product stick to the seed. Although the formulation used in the United States also does not require a “sticker” on corn seed, the major seed suppliers and distributors, agricultural industry groups, and clothianidin’s registrant have confirmed that it is typical practice to use “stickers” on corn seed in the United States.
- Normally, corn is planted before canola blooms and attracts bees. Because early, heavy rains delayed the corn planting in Germany in 2008, the seeds were sown later than usual when nearby canola crops were in bloom and bees were present.
- A particular type of air-driven equipment used to sow the seeds apparently blew clothianidin-laden dust off the seeds and into the air as the seeds were ejected from the machine and into the ground.
- Finally, dry and windy conditions at the time of planting blew the dust into the neighboring canola fields that were in bloom and where honey bees were foraging.
Together, these factors helped create the circumstances under which this incident occurred. It is worth noting, however, that though clothianidin was the particular chemical involved in the 2008 incident in Germany, a similar result would be expected if a large amount of any chemical that is toxic to bees was blown into the air on a dry, windy day next to blooming canola fields for which thousands of hives were providing pollination services. An additional noteworthy point is that the primary purpose of “sticker” is efficacy; if the pesticide falls off the seed before or during planting, it won’t protect the plant as it grows. Therefore, it benefits both bees and farmers to use the sticking agent.
While the 2008 incident in Germany is not related to CCD and only coincidentally related to clothianidin, the EPA is examining its practices with respect to label requirements for seed treatment pesticides and will revise them as necessary to prevent the types of exposure that led to the bee deaths. Our initial focus will be on seed treatment pesticides that we know can be toxic to bees and whether the use of stickers or coatings should be required. In many situations, the use of pesticide-treated seeds results in less human and environmental exposure than would the use of the pesticide later, in a spray or dust formulation, after the crop is growing. We want to make sure that seed treatment is done according to best practices that minimize human and environmental exposure.