http://roomfordebate.blogs.nytimes.com/2009/09/02/saving-bees-what-we-know-now/
This is an article from The New York Times (9/2/09) about the Colony Collapse Disorder (CCD)and what has been learned or not learned in the past three years. From what I've read, it's a combination of many, many things and not just one as was previously thought.