Here are two links to recent news items on the latest research on Colony Colapse Disorder.
The NY Times article states: "A fungus tag-teaming with a virus have apparently interacted to cause the problem, according to a paper by Army scientists in Maryland and bee experts in Montana in the online science journal PLoS One.
"Exactly how that combination kills bees remains uncertain, the scientists said — a subject for the next round of research. But there are solid clues: both the virus and the fungus proliferate in cool, damp weather, and both do their dirty work in the bee gut, suggesting that insect nutrition is somehow compromised."
The scientific study referred to in these articles is here:http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013181
The study concludes: "These findings implicate co-infection by IIV and Nosema with honey bee colony decline, giving credence to older research pointing to IIV, interacting with Nosema and mites, as probable cause of bee losses in the USA, Europe, and Asia. We next need to characterize the IIV and Nosema that we detected and develop management practices to reduce honey bee losses."