A Minnesota beekeeper has won a round against the U.S. Environmental Protection Agency (EPA) in a protracted lawsuit over a class of insecticides implicated in the decline of honeybees and other wild insects.

A federal judge in California ruled this week that, in doing a regular review of the pesticides, the EPA failed to consider the potential impact of neonicotinoids on insects on the federal Endangered Species list, as required by law.

"The EPA pretty much admitted that it had failed to do that in this case, so it was pretty hard for the judge to rule in their favor," said Steve Ellis, a Minnesota beekeeper who was a plaintiff in the suit. Ellis has been at the forefront of the fight against widespread use of neonicotinoids and is a member of Minnesota's Governor's Committee on Pollinator Protection.

Judge Maxine Chesney of the U.S. District Court for the Northern District of California held that the EPA had unlawfully issued 59 pesticide registrations between 2007 and 2012 for a wide variety of agricultural, landscaping and ornamental uses.

The lawsuit, filed by the Center for Food Safety, other environmental groups and several beekeepers, challenged the EPA's approval of several neonicotinoid products, a class of insecticides that are the most widely used in the world.

Although honeybees are not on the Endangered Species list, the plaintiffs invoked the law in a broad challenge to the way the EPA reviews pesticides.

"We are using the power of the Endangered Species Act to protect beekeepers as well," said Peter Jenkins, the attorney for the Center for Food Safety.

One of the most common uses for neonicotinoids is to coat seeds for corn, soybeans, and other commodity crops widely planted in Minnesota and other Midwestern states. The compounds are absorbed by the plant as it grows, making it toxic to pests. But they have also been shown to be harmful to honeybees and other insects that feed on pollen or are exposed to it during planting time.

The manufacturers say that no definitive link has been proven between neonicotinoids and the sharp decline in bee populations.

The lawsuit made multiple claims that the EPA failed to follow proper regulatory procedures, but the judge did not agree, which Ellis said was a disappointment. "We had hoped … they would be taken off the market until proven safe," he said. "But hopefully this will be part of improving the overall picture."

However, the judge did agree that the EPA failed to consult the U.S. Fish and Wildlife Service on the impact of two neonicotinoids on endangered species. The wildlife service has recently cited exposure to neonicotinoids as a contributing factor in the perilous decline in some wild bees and butterflies. That includes the Rusty Patched Bumblebee, the first bee to be included on the list, which was once common in Minnesota and other Midwestern states.

Jenkins said a final resolution that will include an agreement on a remedy will likely take several months.

Josephine Marcotty • 612-673-7394