Of the many factors contributing to the worrisome decline in bee populations, scientists are increasingly certain that a certain class of pesticides, known as neonicotinoids, are contributing to the problem. At the beginning of this week, a task force set up by the International Union for Conservation of Nature released the results of a four-year meta-analysis finding what it says is "conclusive" evidence that the pesticides are "a key factor in the decline of bees" -- and are responsible for a host of other environmental problems to boot. One scientist with the task force called the chemicals the "new DDT" -- except worse, because they wipe out the bottom of the food chain, and they're 5,000 to 10,000 times more toxic. By now, the only people who don't think there's any link between the pesticides and bee die-offs are, predictably enough, the people who manufacture them.
Frustrating as it is to watch evidence of a problem build without enough being done to counteract that problem, bee advocates insist that planting bee-friendly gardens can go a long way toward helping the struggling insects thrive. But the Pesticide Research Institute and environmental group Friends of the Earth just dropped this bombshell: More than half of the purportedly "bee-friendly" plants sold at Home Depot, Lowe’s and Wal-Mart garden centers across the U.S. and Canada actually contain neonicotinoids -- meaning gardens planted to save the bees, or even just planted under the assumption that they aren't contributing to the die-offs, instead may be killing the pollinators.
Wired took an in-depth look at the report, which it calls "one of the most comprehensive investigations yet of an often-overlooked source of neonicotinoids in the environment: gardens and the built landscape":
The researchers purchased 71 bee-friendly plants—including daisies, lavender, marigolds, asters and primrose—at 18 Lowe’s, Walmart and Home Depot outlets across the United States and Canada. For more than half of the plants, the researchers measured neonicotinoid residues in the flowers at levels between 2 and 748 parts per billion.
According to ecotoxicologist Vera Krischik of the University of Minnesota, who was not involved in the study but reviewed it in detail, the data is solid and troubling. A dose of 192 parts per billion is enough to kill a honeybee, she says, and dozens of studies have found impairments in bee navigation, memory and foraging ability at between 4 and 30 parts per billion.
These exposures may pose an especially grave threat to wild pollinators. While problems with domesticated honeybee hives are well-publicized, many populations of wild bees and butterflies are also in precipitous but comparatively ignored declines. The life cycle of wild bees leaves them highly vulnerable, says Krischik: While domesticated honeybee hives contain thousands of workers, and can handle some losses, many wild bees live in small hives containing perhaps several dozen workers.
We're still waiting on the U.S. to make like the EU and ban the most toxic neonicotinoids, at least temporarily. In the meantime, Friends of the Earth is calling on consumers to put pressure on retailers to take initiative to ditch the pesticides themselves.
“Most gardeners have no idea that their gardens may be a source of harm to bees," said Lisa Archer, director of the Food & Technology program at Friends of the Earth, in a statement. "We’re calling on retailers to get neonicotinoid pesticides out of their plants and off their shelves as soon as possible. Until then, gardeners should buy organic plants to ensure the safety of bees.”