Nature Coast Beek --
Corn seed is coated with systemic insecticide, and talc dust. The talc dust keeps the seeds from clumping and smooths the seed flow through the pneumatic planter hoses. Unfortunately the insecticide also coats the dust, and this dust is likely collected much like pollen by the foraging bees.
Since "Poncho 600" (tradename for the Bayer neonicontinoid Clothlanidin) is toxic at the parts-per-billion level to Bees, the escape of the talc dust is a serious issue.
Randy Oliver is generally skeptical of the overheated campaign against the neonicontinoids, but thinks that the talc dust route of exposure is a serious impact. He also hypothesizes that the drought conditions last year concentrated the NeoNics in the withered plants, rather than diluting them below impact. Read his assessment (cited above, to get a rounded perspective on the issues).