WASHINGTON — Well-meaning home gardeners who buy plants to attract pollinators might be harming honeybees, according to a study that an environmental group released Wednesday.
The Pesticide Research Institute found that seven of 13 types of garden plants purchased at top retailers contained neurotoxic pesticides that could harm or kill bees and other pollinators.
Researchers looked for the presence of such pesticides, known as neonicotinoids, in plants at garden centers in Washington, D.C., the San Francisco Bay Area and Minneapolis. The study was co-authored by the Pesticide Research Institute and the environmental organization Friends of the Earth.
It found neonicotinoids in more than half the bedding plants, tomatoes and squash, said the lead author of the report, Susan Kegley, a California beekeeper who is the CEO of Pesticide Research Institute.
She feared that people who think they're buying pollinator-friendly plants might be doing more harm than good.
"Bees are in trouble already," she said. "What we'd like, as home gardeners, is to have the gardens to be a place of refuge for the bees, and not another area that's poison for them."
The pesticides remain in the plants and soil and can continue to affect pollinators for months, or even years, after the treatment, Kegley said.
Retailers either should insist that their suppliers stop using neonicotinoid pesticides or should label them so consumers can understand the danger their purchase could pose to bees.
Companies that make pesticides have fought back about claims that neonicotinoids are the cause of widespread bee die-offs. They've been particularly vocal about the European Union's move toward banning products that contain neonicotinoids.
When the EU announced the ban last spring, Bayer CropScience said the action distracted attention from issues that the company thought were responsible for the threats to bee populations. More likely causes, the company said, include mite infestations, diseases and viruses, and the need for more nectar-rich habitats.
The company, one of the largest manufacturers of such pesticides, didn't respond to a request for comment before the study was released. It's said previously that banning such pesticides will put at risk farmers' ability to destroy pests that can severely damage crops.
But many scientists and beekeepers are worried that there hasn't been enough research into the cumulative effect of pesticides.
A report last spring by the Environmental Protection Agency and the U.S. Department of Agriculture suggested a complex mix of problems. It blamed parasites and disease, genetics, poor nutrition and pesticide exposure, as well as farming practices that fail to give bees a pesticide-free buffer zone to forage in heavily developed agricultural regions.