Imidacloprid is a systemic insecticide which acts as an insect neurotoxin and belongs to a class of chemicals called the neonicotinoids. Neonicotinoids are a class of insecticides which act on the central nervous system of insects with lower toxicity to mammals. Although it is now off patent, the primary manufacturer of this chemical is Bayer CropScience, (part of Bayer AG). German chemical firm Bayer CropScience. The trade names for imidacloprid include Gaucho, Admire, Merit, Advantage, Confidor, Provado, and Winner. http://en.wikipedia.org/wiki/Imidacloprid Imidacloprid effects on bees - Industry-sponsored studies appear to be inconsistent with those produced by independent scientists. Even after 18 years of use, regulatory agencies still do not have conclusive data to determine the effects of imidacloprid on bee colonies. 
In February 2010, the documentary film Nicotine Bees was released. This film analyzes the possible factors contributing to the large bee die-offs worldwide and concludes that the large use of neonicotinoids is the most probable cause of the recent bee die-offs.
Assessment of the Environmental Exposure of Honeybees to Particulate Matter Containing Neonicotinoid Insecticides Coming from Corn Coated Seeds http://pubs.acs.org/action/doSearch?action=search&searchText=Neonicotinoid+Insecticides+&qsSearchArea=searchText&type=within&publication=40025991
List of (70)crop plants pollinated by bees http://en.wikipedia.org/wiki/List_of_crop_plants_pollinated_by_bees