Scientists have discovered that a rapidly-mutating, species-jumping virus is contributing to mass honeybee deaths that are threatening the U.S.'s multi-billion-dollar agricultural industry, honey supplies, and (obviously) bees. 

According to a paper published in the American Society for Microbiology's online publication mBio, the tobacco ringspot virus (TRSV) — a virus which transferred from tobacco plants to soy plants and finally to bees — has been linked to the steady annual decrease in the honeybee population, also known as "colony collapse disorder." The researchers write

In the present study, we showed that a plant-pathogenic RNA virus, tobacco ringspot virus (TRSV), could replicate and produce virions in honeybees, Apis mellifera, resulting in infections that were found throughout the entire body. Additionally, we showed that TRSV-infected individuals were continually present in some monitored colonies. While intracellular life cycle, species-level genetic variation, and pathogenesis of the virus in honeybee hosts remain to be determined, the increasing prevalence of TRSV in conjunction with other bee viruses from spring toward winter in infected colonies was associated with gradual decline of host populations and winter colony collapse, suggesting the negative impact of the virus on colony survival. 

RNA viruses are usually a single strand of genetic code, and so are better at mutating to avoid a host's defenses. These types of viruses cause illnesses like AIDS and the flu in humans. TRSV is also a threat because it is the first known virus to infects bees through pollen. The New York Times explains

The virus is found in pollen that bees pick up while foraging, and it may be spread as the bees mix saliva and nectar with pollen to make “bee bread” for larvae to eat. 

And explains some more:

Mites that feed on the bees may also be involved in transmitting the virus, the researchers said.

These "vampire mites" are parasites that are not themselves harmed by the virus, but help spread TRVS throughout bee colonies.

Unfortunately, the discovery does little to explain what exactly has been killing bees off at such a rapid pace since late 2006. In recent years, one-third of U.S. honeybees in commercial colonies have been dying annually from what scientists call "colony collapse disorder," a catch-all term for the cocktail of pathogens, pesticides, and viruses destroying the bees. Biologist and`beekeeper Randy Oliver commented to the Los Angeles Times on the discovery, saying “I'd be hesitant to proclaim that this virus is the cause of colony collapse, but it certainly shows the degree of our lack of understanding of the complexity of bee pathogen interactions." The Israeli Acute Paralysis Virus has also been correlated with increased bee deaths, and some suspect that certain pesticides, and a high-fructose corn syrup diet also weaken the bee population.

In other sad bee news, Vice reports that some worker bees are using plastic to build hives, because we've left so much of it lying around, and proving once again that the planet would, indeed, be better off without us.