John,
I suggest that you ask the relevant authorities to supply to the
responsible Beekeeping Authorities a copy of :
1. The dossier that Bayer presented to get authorization of their
product relating to each crop that is to be treated, i.e. Maize, Canola,
Sunflower etc.-- including support material.
2. Find out the time period for residual activity of Imidacloprid and
its resulting metabolites. - and find out on what basis it was
calculated.
3. Find out if they have presented documentation "sub lethal effects".on
bees.
4. Check all documentation for dates and places, whether it is truly
independent info. or from people working for Bayer.

If the info. is not given then ask yourself why - to my mind if they are
proud of their product they will not hide the true facts.
Good luck and don't give up!

Peter