Beekeepers lost one-third of their colonies in the year ending in March, down 6 percent from the previous year and the lowest loss rate since 2011-12, when less than 29 percent of colonies were lost, says the Bee Informed Partnership of university researchers. Assistant entomology professor Dennis vanEngelsdorp, of the University of Maryland, said the decline in losses was encouraging but added, “It’s hard to imagine any other agricultural sector being able to stay in business with such consistently high losses.”
Large population declines among honeybee colonies have vexed beekeepers and scientists for more than a decade. Bees are valuable pollinators, with production of crops such as almonds, berries, fruits and vegetables reliant on them. “About one mouthful in three of our diet directly or indirectly comes from honeybee pollination,” says the USDA’s Agricultural Research Service. The bees pollinate an estimated $15 billion worth of crops each year.
Keepers suffer losses during the harsh winter months and during warm weather. Winter losses of around 15 percent are considered tolerable but loss rates have been as high as 36 percent in the 11 years that winter losses have been tracked. Year-round losses have been surveyed for seven years.
In 2014-15 and 2015-16, losses topped 40 percent annually. Parasites, disease, poor nutrition and exposure to pesticide are considered the leading causes. The varroa mite was the most commonly mentioned “stressor” in a USDA survey of beekeepers published last year. USDA is to issue a new Honey Bee Colonies report Aug. 1.
The No. 1 culprit in colony loss is the varroa mite, a lethal parasite that can easily spread between colonies, says a University of Maryland release. Infestations are a particular concern in the fall, when colonies prepare for winter. Mite levels were noticeably lower in most beekeeping states last fall. The Bee Informed group said the decrease was likely the result of increased scrutiny by beekeepers, wider availability of mite control products and a relatively mild fall that resulted in longer life for mite control chemicals.
“Bees are good indicators of the health of the landscape as a whole,” said Maryland graduate student Nathalie Steinhauer, who led the data collection effort for the survey.”
“Honeybees are strongly affected by the quality of their environment, including flower diversity, contaminants and pests.”
Some environmentalists want to restrict use of neonicotinoids, a widely used insecticide that can affect bees. A two-year, multi-state study found no yield benefit from planting soybean seeds coated with neonicotinoid insecticide compared to untreated seed, according to researchers.
Nearly 5,000 beekeepers managing roughly 364,000 of the nation’s 2.78 million colonies took part in the annual Bee Informed survey of losses.