It's now 10 years on, and we are still struggling to understand Colony Collapse Disorder.
Here's a Spring, 2016 update from a California-based honeybee expert, Elina L. Niño, who is Assistant Extension Apiculturist, University of California, Davis: Deciphering the mysterious decline of honey bees
Unfortunately, despite the article's optimistic title, there is not a lot of deciphering success to report. Parasites, viruses, and pesticides are all believed to play a certain role in the health of the honeybee ecosystem, and none of them are easy to fix.
Parasites are a big problem, literally:
Varroa feeds on hemolymph (the insect “blood”) of adult and developing honey bees. In the process it transmits pathogens and suppresses bees' immune response. They are fairly large relative to bees: for perspective, imagine a parasite the size of a dinner plate feeding on you.
Viruses are harder to study, but clearly important:
For example, deformed wing virus (DWV) causes wing deformities that prevent bees from performing normal work functions such as foraging for food. Viruses have been implicated as an important factor in honey bee health declines, but we are just starting to understand how honey bees' immune systems fight against them.
And pesticides have a significant role to play:
There are many gaps in our knowledge about neonicotinoids and other types of pesticides. We have little understanding about the impacts of pesticide combinations and how they affect developing bees and other pollinators. To fill some of those gaps, our lab is testing combinations of various agriculturally important pesticides on adult worker survival and queen development.
The U.C. Davis lab where Niño works is here: E.L. Niño Bee Lab (It's easy to remember, even if it has nothing directly to do with the movement of bodies of warmer-than-usual water in the Pacific Ocean.)