In your explorations have you encountered Varroa Sensitive Hygeine and
have you tried googling 'sub-lethal neonicotinoid bees'.-

I used your suggestion and googled them both, The Varroa Sensitive
Hygeine Queen is interesting and maybe quite useful in restoring
populations but again we need to identify and control all the
factors. The however is still believed to be pathogen(s) and
stressor(s).

as for the 'sub-lethal neonicotinoid angle . Do note that the
drunken beeor mad bee syndrome is very similiar, be it caused by
natural fermentation, corn syrup, etc. So perhaps that is one of the
stressor. (loss of inhibition perhaps?) Again there is increased
levels of pesticides ( to include miticides to control the pathogens)
found in all hives and bees to include neonicotinoid. But these are
all found in healthy as well as collapsed hives and this has been
going on for many more years than neonicotinoid has been around.
Again I would have to ask why did it take 5 years for a major kill off
in the FRG? Not logical. But to your specifics concern If you get a
chance read this in its entirety, here is a snippet.

http://www.plosone.org/article/info%...l.pone.0009754

High Levels of Miticides and Agrochemicals in North American Apiaries:
Implications for Honey Bee Health:

"Since 1999, beekeepers in France experiencing bee losses described as
“mad bee disease” have blamed the systemic neonicotinoid pesticide,
imidacloprid [14]. Lab studies confirmed its toxicity to bees,
including impaired learning and memory [10], and field studies found
low levels of imidacloprid in a high percentage of pollen samples
collected from maize, sunflower and canola [7], [8]. Conflicting data
exist for establishing a causal relationship between imidacloprid and
honey bee losses, yet regulatory concerns remain [15]."