Understanding colony collapse and the loss of honeybees

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By Master Gardener, Brunswick County Extension

Many of you have heard about the decline in our bee populations and are concerned. You should be concerned. I found this University of Georgia Cooperative Extension article informative. 

Nearly 30 percent of all honeybees literally disappeared last winter, fleeing their hives never to return. Researchers have studied colony collapse disorder since it was identified in 2006. They are now uncovering answers to this problem.

A combination of factors contribute to colony collapse disorder, or CCD, including pesticide exposure, environmental and nutritional stresses, new or reemerging pathogens and a virus that targets the bees’ immune systems, said Keith Delaplane, an entomologist with the University of Georgia College of Agricultural and Environmental Sciences.

Delaplane is the national director of the $4.1 million Managed Pollinator Coordinated Agriculture Project. Funded by the U.S. Department of Agriculture, the consortium of U.S. honeybee scientists and educators is working to reverse honeybee decline. And the varroa mite, an old bee enemy, is emerging as a key to the problem, Delaplane said.

Varroa mites

Honeybees get the parasitic, blood-feeding varroa mite when they co-mingle with other colonies. Once the colony is sick, the brood gets sick. Adults don’t live as long, and the population doesn’t replace itself. The mites spread viruses and activate those already in the bees.

“There seems to be a trigger that when they stress the bees, the viruses the bee has been carrying are suddenly awakened,” Delaplane said. “The mites are both a vector and an activator.”

Pesticides are available to treat bee colonies for the parasites, but recent research has shown these pesticides in conjunction with other chemicals are harmful. 

“One of the most important discoveries by our CAP team has involved toxicology,” he said. “Beekeepers are treating chemically for varroa mites, but when bees leave the hive and encounter agricultural insecticides, we see lethal synergies between the bee hive chemicals and the agricultural chemicals.”

Finding this connection was by chance. 

“We just happened to pick this to test; the potential is there for infinite insidious combinations,” he said. “This evidence is a big motivator to try to get synthetic chemicals out of the beehive through integrated pest management or new remedial technologies such as RNA interference.”

Colleagues at Purdue University are working to identify genes that regulate hygienic behaviors in bees, one of the most important bee behaviors for varroa mite resistance. Genetic research could lead to better breeding programs, simplifying the laborious and time-consuming methods currently used.

For more information about the plants listed above, send your gardening questions or comments to: Brunswick County Master Gardener Column, P.O. Box 109, Bolivia, NC 28422, or call 253-2610. Enclose a self-addressed, stamped, envelope if requesting information or a reply. Answers may be printed in this column. Visit the Brunswick County Center of the North Carolina Cooperative Extension Service website at www.ces.ncsu.edu/brunswick/ or access the site through the Brunswick County Government online website at www.brunsco.net.