Colony Collapse Disorder

In 2006, many colonies were lost in the United States that exhibited unusual symptoms.  The bees in the colonies dwindled rapidly so that there were few bees left, and no dead bees around the hives.  Many hives still had a lot of brood, there but no bees to care for it.  This syndrome was called “colony collapse disorder” or CCD.  The cause of CCD is unknown.  There have been a number of new parasites and pathogens of honey bees that appeared in our country within the past 20 years.  High colony losses have been experienced periodically during the past 18 years.  Here are some important new pests of bees in the U.S. - Varroa mites (which cause parasitic mite syndrome – perhaps the worst problem beekeepers face), Tracheal mites, Nosema ceranae (dysentery disease), and several virus diseases.

The Apiary Inspectors of America (AIA) commissioned a survey to estimate colony loses across the country between September 2007 and 2008. The USDA-ARS Beltsville Honey Bee Lab conducted a similar survey of beekeepers pollinating almonds in California in February 2008.   In total nearly 18% of the country’s estimated 2.44 million colonies were surveyed. A total loss of 35.2% of managed honey bee colonies was recorded.  
 
Forty two percent of surveyed beekeepers reported having higher than normal losses. Those reporting abnormally high losses reported having a total loss of 43.7%, while those reporting normal losses reported a 22.9% loss.  In other words, beekeepers believed that loosing close to one quarter of their operation over the winter was “normal.”

 The AIA survey did not differentiate between true cases of CCD and colonies lost due to causes that share the “absence of dead bees” symptom.  However, the 36% of operations that reported having at least some of their colonies die with this symptom lost 41.3% of their colonies. This compares to the 17.5% colony loss reported by beekeepers that did not see these symptoms.  
 
CCD may have multiple causes.  Likely culprits are Nosema ceranae, stress of migratory beekeeping, Varroa mites, viruses and pesticides.  We are participating in a coordinated national project that will address these issues during the next four years, if funding is approved.