A type of pesticide that's a focal point in the controversy over endangered honeybees has turned up in garden-store plants sampled by Friends of the Earth. Other bee experts say the pilot study on neonicotinoids adds an important twist to the plight of the bees—but stress that more rigorous research needs to be done.

The study, co-authored with the Pesticide Research Institute and titled "Gardeners Beware," reported finding traces of neonicotinoid pesticides, or neonics, in seven of 13 plants purchased from garden stores in California's San Francisco Bay area; the Washington, D.C. area; and Minnesota's Twin Cities. The plants included tomatoes, squash, salvia and flowers that would be attractive to pollinators.