This week, Minnesota's Department of Agriculture compensated two beekeepers after investigators found that neonicotinoid-filled dust from a neighboring cornfield damaged their hives last spring.
Although research linking neonicotinoids and declines in pollinator health has been growing, most studies have not been able to show such a direct cause-and-effect relationship between neonicotinoid seed treatments and bee deaths.
The Minnesota case comes after a law banning the sale of neonicotinoids for consumer use was passed by the Maryland state Senate and is now under review by the House. In another case, The Center for Food Safety and its attorneys are spearheading a case filed with other environmental groups and beekeepers from California, South Dakota and Pennsylvania, as well as farmers from Pennsylvania and Kansas. The groups, which filed the case in the Northern District of California in San Francisco, want the EPA to require neonicotinoid seed treatment registrations under the Federal Insecticide, Fungicide, and Rodenticide Act, or FIFRA.
Through it all, the EPA is continuing its registration review of all neonicotinoids on the market, with a special focus on their alleged role in the declining health of pollinators and colony collapse disorder.
Neonicotinoids are often used as seed treatments to control soil pests and sucking insects. USDA estimates that 150 million acres were planted annually with seeds coated by the chemicals.
Brand names of commonly used neonicotinoids include Poncho and Gaucho (Bayer/imidacloprid) and Cruiser (Syngenta/ thiamethoxam). The insecticides are often included in combination with fungicides such as in Valent's Intego Suite Soybeans (clothianidin), Monsanto's Acceleron or Pioneer's Premium Seed Treatment. Corn seed generally comes pretreated with some level of neonicotinoid seed treatment, although growers have some choice in the rate of protection offered. Soybean growers have more flexibility in choosing whether to have seed treated since soybean seed treatments are generally treated down-stream from the seed supplier.
DUST DANGER REINFORCED
The Minnesota case was a prime example of the "dust-off" phenomenon that can occur with neonicotinoid-coated seeds used with talc seed lubricants. Small amounts of the insecticide can mix with the lubricant coating and contaminate the lubricant dust that blows out of the planter as it is dropping seeds. In this form, the chemicals can drift off target onto flowering plants and trees nearby, for example. When bees visit these flowers, they carry the contaminated pollen back to the hive.
Neonicotinoids, which are highly soluble, can also leach off seeds into groundwater and nearby streams, according to a 2014 USGS study.
One of the Minnesota beekeepers told the Minneapolis Star Tribune that the contamination occurred very directly -- the dust blew from her neighbor's corn planter toward her hives. Two days later, MDA investigators documented "acute levels of the toxins" in the bodies of dead bees, according to the Tribune story.
The beekeepers were reimbursed under a state law established in 2014 to compensate beekeepers in the case of proven acute pesticide poisoning.