In this article in the NY Times it says that the cause of colony collapse is the result of a fungus or two. What this article disregards is that there are all kinds of environmental factors that contribute to the demise of a species, most of these created by human beings. There was a Native prophecy that stated that when the honeybee begins to die off the culture will go along with it. We are farming Italian bees and Russian queens and we continually fail to see that if we set up healthy conditions on our land, the “native” bees will do all the pollination that we could possibly need. The lack of healthy soil and plant and animal diversity continues to constrain the possibilities for increased yield, not in number but in nutrients for us and all other creatures.
http://www.nytimes.com/2010/10/07/science/07bees.html?_r=1&hp