The study, published today in Nature, looks at the "significant decline" of wild bumblebee populations worldwide and blames it on bumblebees catching diseases, probably when they hang out on flowers on which infected honeybees left their germs. Or they get them from invading honeybee hives to steal nectar, which would kind of serve them right.
One of those diseases is Deformed Wing Virus, which "causes ghastly deformities," Science magazine says. "Young bees develop with bloated abdomens and shrunken or crumpled wings, making DWV one of the worst viral diseases in commercial honey bee hives."
According to the study, the same strain of DWV was found in both honey and bumblebees. Infected bees died at 15 days old; their normal lifespan is 21 days. And they live in smaller population than honeybees, so diseases affect them more.
Bumblebees provide $3 billion worth of fruit and flower pollination in the United States, the AP says, compared to $20 billion from honeybees. So while bumblebees don't give us as much as their smaller cousins, their contribution is hardly insignificant.
As the BBC points out, scientists believe another big driver of bumblebee deaths is the loss of their habitats, as humans keep paving over their wildflower meadows.