Oregon State University bee researchers are trying to better understand honeybee health.
Oregon State University bee researchers are trying to better understand honeybee health.

More than 20 percent of Oregon's managed bee colonies did not survive this winter, a loss that is not sustainable.

The figures are similar to those experienced nationally, according to a news release.

Between Oct. 1, 2013, and March 31, the state's beekeepers reported a 21.1 percent loss. That's a slight improvement over the six-year average in the state of 22 percent.

Nationally, commercially beekeepers reported a 23.2 percent decline last winter, according to a collaborative national survey by the Bee Informed Partnership. Overall, an average of 30 percent of colonies have died each winter during the past decade.

"These are challenging times for beekeeping and we have reason to be alarmed," Ramesh Sagili, an entomologist who has conducted honeybee colony loss surveys for the past five years, said in the release. "While 10-15 percent loss of colonies is considered acceptable, current rates of decline could drive professional beekeepers out of business."

No one cause is to blame for the decline. Rather, it's a complex of stressors that include parasitic varroa mites, other parasites, viral and bacterial diseases, poor nutrition, pesticide exposure, genetics and cross-country transportation.

To replace lost colonies, beekeepers typically split healthy hives of 50,000 bees, a process that takes months and adds substantial costs for labor, new queens and equipment.

The United States is home to about 2.6 million managed honeybee colonies, according to the Bee Informed Partnership.