This New York Times article makes me suspect that the problem might be weaknesses developing from attempting to rebuild the common honeybee into a high-priced industrial commodity.

The article says that this kind of thing has happened as far back as the late 1890s, but making bees into a nationwide mobile industry may have taken what used to be a localized natural problem and made it widespread.

It might be an example of taking an agricultural product that used to be robust and turning it into a high-maintenance, fussy genetic sport sensitive to things that old-fashioned crops used to shrug off. Or tossing away healthy genetic variation in favor of one or two more profitable species--that a single disease can wipe out.

Farmers have been wising up to these things over the past years. When my dad worked for Green Giant, genetic diversity and not relying heavily on a few exotic hybrids were important goals. Farmers are also discovering that in some cases, organic is not only better, but can even be more profitable. I'm no bee expert, but maybe similar lessons have to be learned about bees, including localizing the industry, and maybe not breeding the hell out of them.