One of the writers I have been following at the moment is Kim Flottum- here are some articles to check out:
Why the U.S. should stop importing bees from Australia
7 Causes of CCD
And a few others...
Migratory beekeeping and honey bee health
Here's a YouTube video on treatment-free beekeeping. This is something that comes up quite often in beekeeping meetings (from what I've seen)-- Michael Bush (not the football player) is a very intelligent man.