Honeybee colonies in the U.S. have suffered massive losses

Honeybees perform a vital task as pollinators. In the United States alone honeybees pollinate $15 billion worth of food crops every year. Yet between April 2018 and April 2019 local beekeepers lost more than 40% of their honeybee colonies, according to a nationwide survey by researchers at the University of Maryland. It was the highest loss ever recorded.

For the 13th time this year a nonprofit called Bee Informed Partnership, which is led by the university’s researchers, examined losses in 319,787 managed honeybee colonies kept by nearly 4,700 beekeepers across the U.S. where a total of 2.69 million managed honey-producing colonies are cultivated around the country. What the researchers found is hardly reassuring.

During the summer of 2018, U.S. beekeepers lost just over 20% of their colonies, as opposed to a rate of 17 the previous summer. Overall, their annual loss amounted to 40.7%, which was a slight increase over the already disconcerting annual average of 38.7%.

Winter months were especially bad last year. During last winter an estimated 37.7% of managed honey bee colonies were lost, which was an increase of 7 percentage points compared to the previous year when the figure was 30.7%. It was an increase of 8.9 percentage points compared to the 13-year average winter colony loss rate of 28.8%.

“These results are very concerning, as high winter losses hit an industry already suffering from a decade of high winter losses,” said Dennis vanEngelsdorp, an associate professor of entomology at the University of Maryland and president for the Bee Informed Partnership.

The continued losses in cultivated honeybee populations across the U.S. are especially alarming because concerted attempts have been underway to reverse the trend, says Geoffrey Williams, an assistant professor of entomology at Auburn University who was a co-author of the survey.

“Just looking at the overall picture and the 10-year trends, it’s disconcerting that we’re still seeing elevated losses after over a decade of survey and quite intense work to try to understand and reduce colony loss,” Williams said. “We don’t seem to be making particularly great progress to reduce overall losses.”

Varroa destructor parasitic mites, which attack honeybees and cause diseases like varroosis in the insects, have been among the main culprits. The mites can spread from colony to colony with relative ease and it can be exceedingly hard to prevent their spread. Despite efforts to eradicate the mites, the problem seems to be getting worse, vanEngelsdorp says.

“But mites are not the only problem,” he stressed. “Land use changes have led to a lack of nutrition-rich pollen sources for bees, causing poor nutrition. Pesticide exposures, environmental factors, and beekeeping practices all play some role as well.”

And worse is likely yet to come as climate change, including extreme weather events, and other manmade causes are expected to wreak havoc with insect populations. Wildfires swept through bee colonies last year and also removed already limited forage in areas where bees are kept. Flash floods, too, destroyed crops and bee colonies.

“A persistent worry among beekeepers nationwide is that there are fewer and fewer favorable places for bees to land, and that is putting increased pressure on beekeepers who are already stretched to their limits to keep their bees alive,” said Karen Rennich, the Bee Informed Partnership’s executive director.