In April 2003, the EPA decided to give Bayer conditional registration for the use of clothianidin on corn. Bayer could sell the product and seed processors could freely use it, with the proviso that Bayer complete a life cycle study of clothianidin on corn by December 2004. The U.S. bee population didn't start dying off until 2005, says David Hackenberg, the beekeeper who first discovered Colony Collapse Disorder (CCD). "We started seeing problems where bees were disappearing in the fall. We blamed it on mites, viruses and a lot of other stuff because we didn't know what to blame it on." But soon Hackenberg made the connection: bee die-off seemed to follow corn crop plantings so much that "you can follow the trail of this stuff to where bees are collapsing," says Hackenberg. EPA is continuing to allow the sale of clothiandin, even though the study that the agency based its decision on proved to be invalid. An EPA official recently told Hackenberg that clothiandin is still on the market in part because of fears that Bayer would sue the agency if it is removed.
Source: Fast Company, December 14, 2010
Because corn is wind pollinated it must produce pollen in abundance and bees exploit this rich protein source, bringing in more than their daily need and storing large surpluses for later use. Many commercial honeybees also feed on corn syrup over the winter. Corn covers 88 million acres of U.S. farmland. Despite the fact that honeybees aren’t used to pollinate corn, by virtue of its sheer prevalence, this crop accounts for a large portion of honeybee nutrition and exposure, and nearly all U.S. corn is treated with systemic insecticides.
Further information on clothianidin & CCD: