TOTAL losses of managed honeybee colonies from all causes were 23.2% nationwide for the 2013-14 winter, according to an annual survey conducted by the Bee Informed Partnership and the U.S. Department of Agriculture.
This represents a noticeable drop in mortality compared to the 30.5% loss reported for the winter of 2012-13 and the eight-year average of 29.6% for winter losses. Previous surveys found total colony losses of 21.9% in 2011-12, 30% in 2010-11, 33.8% in 2009-10, about 29% in 2008-09, 36% in 2007-08 and 32% in 2006-07, USDA said.
The survey results are based on information self-reported by beekeepers.
Still, losses remain above the level beekeepers consider economically sustainable. This year, almost two-thirds of the beekeepers responding to the survey reported losses greater than the 18.9% level they say is acceptable.
"Pollinators, such as bees, birds and other insects, are essential partners for farmers and ranchers and help produce much of our food supply. Healthy pollinator populations are critical to the continued economic well-being of agricultural producers," Agriculture Secretary Tom Vilsack said. "While we're glad to see improvement this year, losses are still too high, and there is still much more work to be done to stabilize bee populations."
The winter survey covers the period from October 2013 through April 2014.
"Yearly fluctuations in the rate of losses like these only demonstrate how complicated the whole issue of honeybee heath has become, with factors such as viruses and other pathogens, parasites like varroa mites, problems of nutrition from lack of diversity in pollen sources and even sublethal effects of pesticides combining to weaken and kill bee colonies," said Jeff Pettis, co-author of the survey and research leader of the Agricultural Research Service (ARS) Bee Research Laboratory in Beltsville, Md.
There currently is no way to tell why the bees did better this year, according to both Pettis and Dennis vanEngelsdorp, a University of Maryland assistant professor and director of the Bee Informed Partnership who led the survey.
Among the leading causes of colony losses reported by beekeepers in past annual surveys are queen failure, poor wintering conditions and damage by varroa mites. There is a growing consensus among researchers that one of the largest contributors to poor colony health and colony losses is the varroa mite, an Asian bee parasite first found in the U.S. in 1987.
"What is clear from all of our efforts is that varroa is a persistent and often unexpected problem," vanEngelsdorp said. "Every beekeeper needs to have an aggressive varroa management plan in place. Without one, they should not be surprised if they suffer large losses every other year or so. Unfortunately, many small-scale beekeepers are not treating and are losing many colonies. Even beekeepers who do treat for mites often don't treat frequently enough or at the right time. If all beekeepers were to aggressively control mites, we would have many fewer losses."
ARS and other USDA agencies, university programs and the Bee Informed Partnership are working hard to develop best management practices to help beekeepers in the short term and are carrying out research to solve critical problems for pollinators in the long term.
About 7,200 beekeepers who managed 564,522 colonies in October 2013, representing 21.7% of the country's estimated 2.6 million colonies, responded to the survey. In the survey of bee losses for the winter of 2012-13, more than 6,000 beekeepers responded, representing 22% of the country's colonies.
A complete analysis of the survey data will be published later this year. The abstract of the analysis is at http://beeinformed.org/results-categories/winter-loss-2013-2014/.
USDA also announced that it will hold a summit Oct. 20-21 in Washington, D.C., aimed at addressing the nutrition and forage needs of pollinators. The summit will be attended by a consortium of public, private and non-governmental organizations that will discuss the most recent research related to pollinator loss and work to identify solutions.
In March, Vilsack created a Pollinator Working Group, under the leadership of USDA deputy secretary Krysta Harden, to better coordinate efforts, leverage resources and increase the focus on pollinator issues across USDA agencies. Personnel from 10 USDA agencies meet regularly to coordinate and evaluate efforts on improving pollinator health.
Furthermore, USDA earlier this year made $3 million available to help agricultural producers in five states provide floral forage habitats to benefit pollinating species on working lands. The Honey Bee Pollinator Effort is intended to encourage farmers and ranchers to grow alfalfa, clover and other flowering habitat for bees and other pollinators.
More information about ARS honeybee health research and colony collapse disorder can be found at www.ars.usda.gov/ccd.