Editor's note: According to a new story in Fortune, the lead author of the research paper described below received a grant within the last few years from Bayer Crop Science, a distributor of pesticides. As pesticides are one of the contenders for the cause of CCD, this constitutes a potential conflict of interest that was not noted in the original research paper. So, consume the news along with the appropriate grains of salt.

Bee colonies are still dying off at high rates, but researchers have uncovered some new information that may help save them. A study published in PLoS One this week checked several bee colonies in various states of collapse for over a hundred suspect microbes, and found that bees infected with one combination of two different pathogens were at the highest risk of suddenly collapsing.

Colony collapse disorder (CCD), wherein entire bee colonies die suddenly for unknown reasons, has been a concern for scientists and beekeepers since 2006. CCD swept bee colonies throughout the world, killing them off in no discernible pattern and generally freaking everyone out. Naturally, some people blamed cellphones.

While a lot of research has been done to try and sort out the cause, some of the conclusions have been contradictory—for instance, researchers in Spain pinpointed the fungus Nosema ceranae as the cause, while a study in the US found no correlation between the two.

In this new study, researchers looked at bee colonies that had died off due to CCD, or were in the process of failing, and compared them to a few that had no history of the problem. They couldn't pin down a single pathogen as the problem—however, they could pin down two.

According to the paper, "virtually all" of the CCD colonies were infected by two things: the Nosema fungus that researchers had previously suspected, and a DNA-virus called invertebrate iridescent virus (IIV). IIV is fairly prevalent in bee colonies (75 percent of healthy ones also had it) but its combination with Nosema seemed to spell doom for the bees.

The authors are still reluctant to call this combination of infections the actual cause of CCD, but note that the relationship seems worth further study, and fast. In the meantime, they suggest that treatments for Nosema infections may be in order to stave off sudden collapse.

PLoS One, 2010. DOI: 10.1371/journal.pone.0013181 (About DOIs).