http://en.wikipedia.org/wiki/Imidacloprid_effects_on_bee_populationList of Insecticides harmful to bees:
http://en.wikipedia.org/wiki/Pesticide_toxicity_to_beesWikipedia article of the Insecticide in question (I believe the Wikipedia Article was written by a pro-Bayer person so read it with that understanding):
http://en.wikipedia.org/wiki/Imidacloprid_effects_on_bee_populationPlease note, insecticides may be only one portion of the problem. The other portion is that bees are moved around to pollinate crops and thus intermix extensively throughout the year. This brings with it an increase exposure to mites and other biological problems for each bee hive (i.e. such biological problem is spread faster among bees do to the fact bees are being shipped all over the country).
It is believe this one, two punch (Extensive movement AND the new pesticides) are what is leading to Colony Collapse Disorder (CCD). The best solution would be to ban this type of Chemicals (based to Nicotine) AND put restrictions on the movement of bees. The former is going to be opposed by Farmers who sees this new type of insecticide as necessary to keep lost to insects down, while the latter is going to be opposed by farmers who want to grow only one crop in an area.
Lets remember Bees need various crops to gather pollen with very few exceptions, plants only come into pollen for a few weeks a year. Thus bees can only pollinate that crop for the few weeks it is in pollen. Afterward the bee must find another plant that is coming into pollen. In olden days farmers would plant various crops so that the bees had a different plant coming into pollen throughout the year (including flowers and other plants planted just to give the bees something to pollinate between crops coming into season). With modern huge farms, generally only one crop is grown so the bees must be moved in during the flowering stage and then moved out afterward. This is the reason bees are being moved around do to mono-culture. Bees are surviving in areas where mono-culture is NOT in use, but not elsewhere (Mostly deep woods away from domestic bees that are being moved around, please note "wild" bees are also disappearing but mostly in areas where they come into contact with bees that are being moved around).
A complication in this debate is that the latest insecticide tends to be "ejected" into the ground along with the seed it is suppose to protect. This "Ejection" is believe to cause some of the insecticide to separate from the plant and stay active for up to two years afterward (The "half-life" for the insecticide is given at 90 days, but bees are one of those insects that gather more of this type of insecticide up then other insects, mostly do to moving from flower to flower and each time getting more and more of the insecticide). A further complication may be the the insecticide works by making the insect disorientated, and this disorientation would affect a bee colony at much lower levels then solitary insects.
The solution appears to be one that is unacceptable to farmers. Banning this type of insecticide AND restricting the movement of bees (i.e. restrict such movements to clear farming districts, no East coast to West Coast movement, the great plains are used for grain crops that do NOT depend on bees, just prohibit any movement of bees over the grain belt would be a start.
Please note, they are other insects (Bumble bees for one) that can pollinate these crops, but they are NOT movable like the honey bee and thus NOT an acceptable substitute (The honey crop is minor part of raising bees in the US, China dominates the production of honey and undercuts any domestic production, thus most bee keepers main form of income is moving their bees to pollinate crops).