(Beyond Pesticides, June 10, 2011) A report released jointly by the U.S. Department of Agriculture‚Äôs (USDA) Agricultural Research Service (ARS) and the Apiary Inspectors of America (AIA) shows that losses of honeybee populations over the 2010/2011 winter remained abnormally high, reflecting continuing damages attributed to colony collapse disorder (CCD). CCD, linked to a range of factors and agricultural chemicals, including systemic pesticides, has devastated bees and beekeepers around the country in recent years. According to the survey, 30% of managed honeybee colonies across the country were lost over the winter. Over the past five years, since the discovery of CCD, annual winter colony losses have hovered near the 30% mark. Similar loss percentages for the previous four years reflect this trend: 34% for the 2009/2010 winter, 29% for 2008/2009, 36% for 2007/2008, and 32% for 2006/2007.
ARS entomologist Jeffrey Pettis, PhD, who helped to conduct the survey and has been the agency‚Äôs lead researcher on CCD heading up the USDA Bee Research Laboratory, said, “The lack of increase in losses is marginally encouraging in the sense that the problem does not appear to be getting worse for honey bees and beekeepers. But continued losses of this size put tremendous pressure on the economic sustainability of commercial beekeeping.”
Dr. Pettis, quoted by Discovery News, says that, ‚ÄúWe averaged 10 percent winter losses before parasitic mites, around 20 percent winter loss when two parasitic mites (Varroa and tracheal mites) arrived in the 1980’s, and now with CCD we are over 30 percent losses in the fall and winter.”
This latest survey, conducted by past AIA presidents Dennis vanEngelsdorp and Jerry Hayes along with Pettis, PhD, had a total of 5,572 respondents, collectively managing an estimated 15% of the country‚Äôs 2.68 million honeybee colonies. 31% of the respondents noted colony losses with the bodies of the dead bees missing from the hives ‚Äď a key indicator of CCD. Beekeepers who noted an absence of dead bees also had significantly higher rates of colony loss, at 61%. Average colony loss for an individual beekeeper’s operation was 38.4 percent.
Average loss by operation represents the percentage of loss in each operation added together and divided by the number of beekeeping operations that responded to the survey. This number is affected more by small beekeeping operations, which may only have 10 or fewer colonies, so a loss of just five colonies in a 10-colony operation would represent a 50 percent loss. Total losses were calculated as all colonies reported lost in the survey divided by the total number of bee colonies reported in the survey. This number is affected more by larger operations, which might have 10,000 or more colonies, so a loss of five colonies in a 10,000-colony operation would equal only a 0.05 percent loss.
The preliminary survey analysis notes that, ‚ÄúThis survey only reports on losses that occur during the winter and does not capture the colony losses that occur throughout the summer as queens or entire colonies fail and need to be replaced. Preliminary data from other survey efforts suggest that these ‚Äėsummer losses‚Äô can also be significant. Beekeepers can replace colonies lost in the summer and winter by splitting the populations of surviving colonies to establish a new hive. This process is expensive, so replacing 30% of the nation‚Äôs colonies annually is not considered sustainable over the long-term.‚ÄĚ
Colony Collapse Disorder is the name given to the mysterious decline of honeybee populations around the world beginning around 2006. Each winter, one-third of the U.S. honeybee population has died off or disappeared (more than twice what is normal). While CCD appears to have multiple interacting causes including pathogens, a range of evidence points to sub-lethal pesticide exposures as important contributing factors. Neonicotinoids are a particularly suspect class of insecticides, especially in combination with the dozens of other pesticides found in honeybee hives. Key symptoms of CCD include: 1) inexplicable disappearance of the hive‚Äôs worker bees; 2) presence of the queen bee and absence of invaders; 3) presence of food stores and a capped brood.
Clothianidin and imidicloprid are members of the neonicotinoid family of systemic pesticides, which are taken up by a plant‚Äôs vascular system and expressed through pollen, nectar and gutation droplets from which bees then forage and drink. Neonicotinoids kill sucking and chewing insects by disrupting their nervous systems. Beginning in the late 1990s, these systemic insecticides began to take over the seed treatment market. Clothianidin is Bayer‚Äôs successor product to imidacloprid, which recently went off patent. Both are known to be toxic to insect pollinators, and are lead suspects as causal factors in CCD. Together, the two products accounted for over a billion dollars in sales for Bayer Crop Science in 2009. Imidacloprid is the company‚Äôs best-selling product and among the most widely used insecticides in the U.S. Starting in about 2004, seed companies in the U.S. began to market seeds treated with a 5-X rate of neonicotinoids (1.25mg/seed, compared with the traditional 0.25 mg/seed).
To hear scientists and professional beekeepers discuss the impact of pesticides on honeybees and other pollinators, see the video of the Pesticides and Pollinators Panel from Beyond Pesticides 29th annual National Pesticide Forum.
Beekeepers reported that, on average, they felt losses of 13% would be economically acceptable. Sixty-one percent of responding beekeepers reported having losses greater than this, reflecting the devastating economic impact of these significant losses on the commercial beekeeping industry. These losses, however, are not only significant for beekeepers and their business, but for all of us. Pollinators serve vitally important roles in agricultural ecosystems, enabling a wide range of crops to grow and provide us with food. If crops are not pollinated, they do not produce fruit and food production declines.