In a first, federal review finds widely used pesticide can damage pollinator colonies.

RENÉE JONES SCHNEIDER • reneejones@startribune.com The decline of bees like this one, on a milkweed plant in Minnesota, has generated concern, as honeybees pollinate about a third of the food in the nation’s grocery aisles.

Bees won a victory Wednesday as federal regulators said for the first time that one of the most widely used and controversial pesticides in agriculture is harmful to pollinators when used on some crops.

The U.S. Environmental Protection Agency (EPA) issued the finding as part of its first scientific risk assessment of a much-debated class of pesticides called neonicotinoids and how they affect colonies, not just individual honeybees.

But even as the EPA was releasing its findings, the ongoing war over pesticides and pollinators continued to escalate. Environmental groups and beekeepers, including two in Minnesota and South Dakota, sued the agency, alleging that it failed to properly regulate neonicotinoids used as seed coatings on corn and other crops.

Honeybees pollinate roughly a third of the food in the nation’s grocery aisles, which has amplified global concern over their decline.

In its new analysis, the EPA found that one type of pesticide, imidacloprid, showed clear damage to hives and honey production even when used appropriately on citrus and cotton crops. The risk with other crops is not as clear or is still under study, the EPA said.

The pesticide’s maker, Bayer Crop Science, immediately issued a statement criticizing the analysis.

“At first glance it appears to overestimate the potential for harmful exposures in certain crops, such as citrus and cotton, while ignoring the important benefits these products provide and management practices to protect bees,” the company said.

Environmental groups said the EPA is not acting fast enough to outlaw pesticides it knows to be harmful.

“The EPA over the last year has been gradually admitting that neonicotinoids pose a serious threat to bees,” said Lex Horan, spokesperson for the Pesticide Action Network of North America (PANNA). “It’s high time. But this piecemeal approach is not enough to solve the magnitude of the problem.”

Neonicotinoids have received wide attention, along with diseases, parasites and an increasingly flowerless landscape, as factors in the decline of honeybees worldwide. While largely harmless to humans and mammals, the compounds are a neurotoxin for insects. They can be used as sprays, as granular applications in soil or as seed coatings, which grow along with the plant and make it poisonous to pests and perhaps other insects, including bees and butterflies.

The manufacturers and the EPA have said that if used properly, the insecticides are not lethal to honeybees. But many scientists and beekeepers say that even the lower doses found in farm fields can cause neural damage to the insects and interfere with their complex navigational abilities and reproduction.

The rising concern has prompted the EPA to halt approvals of new pesticides that use neonicotinoids, and to launch a lengthy safety review of products already on the market, now expected to be completed by 2018. The preliminary review of imidacloprid, which is the oldest neonicotinoid and is now used on about 30 million acres nationally, was the first of four.

Fewer bees, less honey

The EPA analysis, conducted with the state of California and Canada, found that damage to bees started to emerge when pesticide concentrations in flower nectar reached 25 parts per billion or more.

“There’s a significant effect,” said Jim Jones, EPA’s assistant administrator for chemical safety and pollution prevention. That included fewer bees, less honey and “a less robust hive,” he said.

Some crops showed higher concentrations than others. Cotton and citrus fruit, for example, had harmful levels. But corn, which is almost universally planted with neonicotinoid seed coatings, showed no effect, largely because it does not produce nectar.

Beekeepers and environmental groups said Wednesday that the analysis failed to consider one of the primary ways pollinators are exposed to neonicotinoids — toxic dust that floats in the air after corn seed is planted in the spring. That’s long been a contentious issue for beekeepers and is the crux of the lawsuit filed in California on Wednesday by the Center for Food Safety, PANNA and others.

Brett Adee, whose family runs the country’s largest honey-producing operation, near Brookings, S.D, joined the lawsuit after more than 6,000 hives were damaged last spring during corn planting. He said a state investigation found his bees were poisoned by a type of neonicotinoid that was used on the seeds being planted by his neighbors at the time.

“None of my neighbors had done anything wrong,” he said. “But a defective product is being marketed. It’s blowing all over the willows and dandelions and not staying on the seeds.”

Peter Jenkins, an attorney with the Center for Food Safety, said the EPA exempted pesticides used in seed coatings from standard regulations. Unlike pesticides used as sprays or granular applications, those used as seed coatings carry no restrictions or mandatory safety measures when farmers and others handle them. It’s a critical oversight, Jenkins said, because the vast majority of neonicotinoids are used in that format. The EPA, Bayer and others are developing new ways to reduce dust from planting, but the environmental groups say regulations are necessary.

“If a beekeeper has a kill from dust off … corn or soybean, there is no enforcement,” Jenkins. “The situation is unacceptable for beekeepers.”

This story contains material from the Associated Press.

Josephine Marcotty • 612-673-7394