I'm an experienced beekeeper, having kept colonies for thirty or forty years now, and in my opinion the real problem with the bees today is simply excessive overmanagement of colonies.
THE way to make money with bees in the USA, for nearly a century now, is not what's considered "traditional" beekeeping. What's being done is to sell pollination services, honey or beeswax is a bonus item, not the main item you have for sale. In the days prior to 1970, this was easy and possible, you took the bees to Florida for the winter and they pollinated oranges. You moved north with the colonies, and pollinated apples, then peaches and pears and so forth, following the crops around as they bloomed. There's a lot of money in that, large farmers have contracts for this service and you can make a small fortune that way. This is the problem with the "bee wrecks" you hear about every so often, where bees are all over a highway, that's some beekeeper who just lost it with a load of bee colonies on the way to an orchard or field.
Ok, in the 70's, we got hit with the tracheal mite. If not for a monk in Britain, European honeybees would be about as common as leprachauns. He bred a bee that could live with the mites, while they are called "resistant", it's my understanding that the mites are still present, they just don't do the kind of damage that would kill the bees now.http://www.beekeeping.org/articles/us/adam.htm
In the 80's, the varroa mite made itself known, and it killed off at least half the commercially raised bees in the world.
Now, we also have the small hive beetle from south africa. (Apparently they came to the USA on a load of half rotten cantalopes. Never could see why anyone would import rotten cantalopes.) I am, in fact, the beekeeper who alerted the state agricultural dept that small hive beetle was now in Tennessee, and they could not believe it until I sent them samples preserved in alcohol, as it was not expected they would come in from the western side of the state.
Added to these beauties we also have the traditional problems, Nosema, American Foulbrood, European Foulbrood and Wax Moth, along with bears, mice and other creatures that regard bees as a tasty treat.
And that's the issue in a nutshell. Bees being moved around for pollination are under heavy stress already, plus being an invasive species in North America. Add in small hive beetles, varroa mites and the ever present tracheal mite, and they just can't take it.
Yes, there are treatments for purging mites and such from the colonies. They are very stressful, in and of themselves. Imagine pure menthol dissolved in steam being pumped throughout a bee colony, keeping in mind the colony is held together and controlled by pheromones - scent in other words. That is a recommended treatment for tracheal mites. There are others, some so nasty that any trace of the material in question in honey renders it unfit for sale. If you read a few hundred words on the subject, you'll rapidly figure out there is some considerable desperation here.http://website.lineone.net/~dave.cushma ... tment.html
Bees are fully capable of living with these pests, if they are not stressed. The only treatment my bees get is feeding of essential oils in the spring. They thrive. Since I'm not there to manage them (being in Iraq), they will swarm, and have increased my colonies by swarming into old bee hives I had stored on the place. I have not as yet lost a hive to colony collapse. In fact, they swarmed again yesterday, a sad thing, as a swarm in August has no chance of making it though the winter. If they also settle in old hives, my wife is going to feed them up on sugar syrup doped with oil of spearmint and oil of lemongrass to try to get them up to making it through the cold part of the year.
But the real problem with honeybees is that they simply cannot be stressed without limit. My bees are under little stress, and they do very well with pretty minimal treatment. People who drag their colonies all over the US are stressing them past the limit, and they will die.