Europe’s top food safety agency may be closer to nailing three old suspects for a mystery that goes back almost a decade: what’s been killing off honeybees? But there is still work to do. For now, the European Food Safety Authority (EFDA) has concluded that three neonicotinoid class insecticides pose unacceptable hazards to bees. The three include clothianidin, imidacloprid and thiamethoxam. The three insecticides — approved for use in the United States — are said to damage bees by contaminating dust and collecting as residue on nectar and pollen, the new EFSA report says. Since “colony collapse” began, scientists on both sides of the Atlantic have worked on the mystery. As recently as a couple years ago, a fungus acting in concert with a virus was the focus of research by U.S. Army scientists working with civilians researchers a the University of Montana. Despite what the name might imply, the phenomenon of colony collapse doesn’t mean bees aren’t dying in their hives, but rather that they’re flying off in different directions and dying alone. This makes even collecting dead bees for study a costly challenge for entomologists. Clothianidin and imidacloprid are manufactured by German company Bayer AG and thiamethoxam is made by Swiss company Syngenta AG. EFSA says the way the three insecticides are being used on cereals, cotton, rapeseed, corn, and sunflowers presents a “high acute risk” to bees. The European Commission asked EFSA to assess the risks associated with the three insecticides in seed treatment or granules with particular regard to their acute and chronic effects on bee colony survival. Bee deaths have decimated colony populations, reducing them by 40 percent or more. “Given the importance of bees in the ecosystem and the food chain and given the multiple services they provide to humans, their protection is essential,” EFSA says. “With a mandate to improve EU food safety and to ensure a high level of consumer protection, EFSA has an important role to play in ensuring their survival.” Clothianidin and thiamethoxam were approved for use in Europe before EFSA was involved in the process. The agency was involved in the approval of imidacloprid. In that 2008 review it raised concerns about the high risk to bees, birds, and mammals, aquatic and soil-dwelling organisms from the insecticide. The neonicotinoids class of insecticide affects the central nervous system of insects, causing paralysis and death. EFSA says other studies have shown that the class has significant effects on bee health and colonies. Still, EFSA scientists say there is not enough data to conclude that bee colonies are definitely collapsing from the three insecticides. More information from the companies and more studies are going to be necessary, the food safety agency says. As for the two companies involved, a Syngenta executive told the Wall Street Journal that EFSA was “under political pressure” to produce a hurried risk assessment. “This report is unworthy of EFSA and its scientists,” he told the newspaper. The U.S. Environmental Protection Agency (EPA) has declined requests from activist groups to remove the neonicotinoids class of insecticides from the American market. “The EFSA report confirms what we have been asking EPA to recognize. Clothianidin and other neonicotinoids are highly toxic to bees, and should be banned by EPA and removed from the environment,” said Jay Feldman, who heads the activist group “Beyond Pesticides.” The group claims clothianidin is of particular concern as the “vast majority” of corn grown in the U.S. is treated with the chemical, which is taken up by the plant’s vascular system and expressed through pollen, nectar and guttation droplets from which bees then forage and drink. Neonicotinoids have cumulative, sublethal effects on insect pollinators that correspond to “colony collapse” symptoms – namely, neurobehavioral and immune system disruptions, the environmental group says. Beyond Pesticides, the Pesticide Action Network North America, and the Center for Food Safety are sponsors of a petition to EPA asking for the insecticides to be removed from the market. They have collected more than one million signatures.