On the other hand, the evidence for neonicotinoids' effects on honeybees is less convincing. Honeybee hives are larger than those of bumblebees and may be better able to compensate for impaired individuals. "It might be very difficult to show the effect in honeybees," says Nigel Raine, a Royal Holloway University of London entomologist who conducted the bumblebee field study suggesting that treated hives were more likely to fail.
Beyond neonicotinoids, research groups have started to find that other pesticides affect learning and population abundance in other bee species. At the 2013 International Conference on Pollinator Biology, Health and Policy, held at The Pennsylvania State University in August, one study found blue orchard bees and alfalfa leaf-cutter bees had trouble finding their own nests after foraging in outdoor fields that researchers sprayed with the fungicides iprodione, pyraclostrobin and boscalid. (Researchers covered the fields with dense mesh cubes, six meters at a side, to keep the bees from foraging elsewhere.) Another study found apple orchards treated more heavily with any type of pesticides had severalfold fewer wild bee visitors than more lightly treated orchards.
Applying research to regulations
What does all this research mean for laws regarding pesticide use? Are any regulatory agencies using these studies as a basis for changing how many pesticides bees are exposed to in the real world?
In the European Union officials have used studies from universities as well as their own reviews as the basis of a two-year moratorium on many uses of three neonicotinoids called clothianidin, imidacloprid and thiamethoxam. The ban is controversial, even among researchers. It's also not clear what its fate will be, as neonicotinoid-makers Bayer CropScience and Syngenta Crop Protection have sued against the ban, saying there's not enough evidence to merit regulatory change.
In the U.S. the Environmental Protection Agency depends mostly on its own six-year research plan to make regulatory decisions, agency spokesperson Catherine Milbourn wrote in an e-mail. The agency is reviewing six neonicotinoids: in addition to clothianidin, imidacloprid and thiamethoxam it is studying acetamiprid, dinotefuran and thiacloprid. The review is part of a program designed to regularly reexamine active ingredients in all pesticides approved for use in the U.S. The agency expects to finish its work by 2019. The reason it will take several years is to give pesticide companies the chance to acquire the data the EPA requested.
The EPA also considers studies by university researchers, but such studies often aren't designed to meet the agency's particular needs for addressing legal uncertainties for regulation, according to Milbourn. "We feel the studies that are currently underway at EPA's request are the most important for our regulatory purposes, since they were designed to answer specific uncertainties that we currently have and also to fully comply with federal laws and regulations," she wrote in an e-mail.
When asked for examples of how recent studies don't fill the bill, the agency declined to review others' work that way. Instead, Milbourn and other officials pointed to a proposal from 2012 that describes a method for regulators to determine pesticides' risks to honeybees in greater detail than the EPA had ever previously required before approving a pesticide.