Think long and hard about which pesticides you use, there is anecdotal
evidence to suggest the compound found in Merit a common turfgrass
pesticide (imidacloprid) may be a causative factor in colony collapse.
If I am not mistaken this was banned in France after beekeepers there
suffered tremendous losses.

Use the search terms "Gaucho bees" if you wish to read a bit more.

Here is a quote from one article that shows some of the economics of
the situation.
This url is the source.-
http://www.newmediaexplorer.org/sepp..._dead_bayers_g
aucho_blamed.htm

The pesticide GAUCHO (containing the active substance Imidacloprid) is
produced by the German BAYER-group. With an annual turnover of more
than 500 million Euro this is the group´s top selling agricultural
agent. Critics assume that the high sales figures are the reason why
the company is contesting a ban on its use.