Losses of managed honey bee colonies nationwide totaled 33.8 percent from all causes from October 2009 to April 2010, according to a survey conducted by the Apiary Inspectors of America (AIA) and the Agricultural Research Service (ARS).
Beekeepers identified starvation, poor weather, and weak colonies going into the winter as the top reasons for mortality in the operations.
This is an increase from overall losses of 29 percent reported from a similar survey covering the winter of 2008-2009, and similar to the 35.8 percent losses for the winter of 2007-2008.
The continued high rate of losses are worrying, especially considering losses occurring over the summer months were not captured, notes Jeffrey Pettis, research leader of ARS' Bee Research Laboratory in Beltsville, Md.
ARS is the U.S. Department of Agriculture's principal intramural scientific research agency.
The survey was conducted by Pettis and past AIA presidents Dennis vanEngelsdorp and Jerry Hayes.
The three researchers said continued losses of this magnitude are not economically sustainable for commercial beekeepers.
The 28 percent of beekeeping operations that reported some colonies perished without dead bees present – a sign of Colony Collapse Disorder (CCD) – lost 44 percent of the colonies.
This compares to 26 percent of beekeepers reporting such dead colonies in the 2008-2009 winter and 32 percent in the 2007-2008 winter. Beekeepers that did not report colonies having CCD lost 25 percent of the colonies.
As this was an interview-based survey, it was not possible to differentiate between verifiable cases of CCD and colonies lost as the result of other causes that share the "absence of dead bees" as a symptom.
The cause of CCD is still unknown.
The survey checked on about 22.4 percent of the country's estimated 2.46 million colonies. The survey reports only winter losses and does not capture colony losses that occur throughout the summer when queens or entire colonies fail and need to be replaced. Summer losses can be significant.
A complete analysis of the survey data will be published later this year. The abstract can be found at http://ento.psu.edu/pollinators/news/losses-2009-10.
More information about CCD is available at www.ars.usda.gov/ccd.