Beekeepers lost 44 percent of their colonies in the year ending on April 1, the second-highest rate since surveys began in 2006, said the Bee Informed Partnership on Monday. The high annual rate was driven by severe losses last summer among commercial beekeepers, who lost one-third of their colonies.
The nonprofit partnership said the results for 2019/20 highlighted the cyclical nature of honey bee turnover. The highest-ever summer loss rate of 32 percent among backyard, sideline and commercial beekeepers was followed by winter losses of 22 percent, the second-lowest ever.
High losses during the summer period of April 1-Oct 1, 2019, may have been a carryover from the preceding and particularly poor winter of 2018/19, when 38 percent of colonies were lost, the highest winter rate on record. Colonies are counted as lost when bees die or hives are combined.
Commercial honey bees pollinate $15 billion of food annually so their health is important to the food supply, said Bee Informed.
Surveys of beekeepers began last decade after dramatic and seemingly inexplicable losses were observed by keepers, later called colony collapse disorder. Researchers and the industry hope to learn the causes and develop practices to reduce loss rates. Losses have been blamed on disease, parasites, pesticides and poor nutrition.
When surveys began, winter loss was the focus because of challenges posed by weather. After a few years, summer loss was added to the survey and “we had the numbers to show that loss occurs throughout the year and that summers are not insignificant for beekeeper losses,” said assistant entomology professor Geoffrey Williams of Auburn University.
“This year, summer loss was actually the highest we’ve ever recorded, even higher than winter losses, which is only the second time we’ve seen that, and it’s mostly commercial beekeepers that are driving that loss number, which is unusual,” says Nathalie Steinhauer of the University of Maryland, the science coordinator of the partnership.