A collaborative, long-term study has identified a little-understood disease as the best indicator that a bee colony will die.
The study evaluated the health of 80 commercial honey bee colonies in the Eastern United States over a 10-month period, according to a news release.
About 56 percent of the colonies died during the study.
The researchers found that colonies affected by idiopathic brood disease syndrome were 3.2 times more likely to die than other colonies.
IBDS, as the disease is called, kills off bee larvae without large-scale infestations of parasitic mites.
Although IBDS was the greatest risk factor, the reserachers said the "queen event" was a close second.
The queen event occurs when the colony tries to drive out the current queen and replace her with a new one.
The researchers also identified several other risk factors, reinforcing the theory that multiple and interrelated factors cause colony mortality.
Involved in the study were researchers from North Carolina State University, the University of Maryland, Pennsylvania State University and the U.S. Department of Agriculture.
They published their findings in the February issue of Preventive Veterinary Medicine.