Through the years of systematically documenting colony mortality rates, the survey brought important insights. First it dispelled the notion that honey bee colonies are only dying in the winter. Though winter still remains the principal period in which colonies die, summer losses are not trivial, and in some rare cases, can exceed winter losses. Commercial beekeepers in particular, seem to lose as many colonies in the winter season as the summer season, maybe due to their practices to “take their losses in the fall” and more active management throughout the summer. It also confirmed that professional beekeepers are experiencing lower annual mortality rates than small scale beekeepers, despite often being criticized for putting their colonies under stress by frequent moves and intense management. Finally, it became clear that loss rates are not steadily increasing over time, but follow a cycle of higher and (somewhat) lower losses, though remaining consistently higher than what beekeepers identify as acceptable levels. Although the total number of honey bee colonies in the country has remained relatively stable over the last 20 years (~2.6 million colonies according to the USDA NASS Honey Reports), loss rates remain high, indicating that beekeepers are under substantial pressure to offset losses by creating new colonies every year. For more information about the Bee Informed Partnership’s annual National Colony Loss and Management Survey, visit: beeinformed.org/citizen-science/loss-and- management-survey/ and find the complete preliminary result release on: beeinformed.org/2021/06/21/united- states-honey-bee-colony-losses-2020-2021-preliminary- results/.
sideliners). In contrast, commercial beekeepers, as they have reported in previous years, experienced loss rates that were similar in summer and winter (30.9% vs 32.9%; Fig. 2). Survey respondents were asked to identify the top three causes of colony loss in their operations over the summer and winter seasons. Varroa mites were the most frequently cited causes of colony loss in the winter (by 33% of small scale beekeepers, and 65% of commercial beekeepers), and tied first for commercial beekeepers in the summer (70% of commercial beekeepers). Queen issues were the most frequently cited causes of colony loss in the summer by small scale beekeepers (20%), and first tied for commercial beekeepers (70%). A total of 3,347 beekeepers from the United States, that collectively managed 192,384 colonies on 1 October 2020, answered the survey. This corresponds to about 7% of the managed honey-producing colonies in the country (compared to 2.71 million estimated by USDA NASS, 2021). Fig. 2: Managed honey bee colony loss rates estimated from different beekeeper operation types in the United States during the survey periods – summer (1 April – 1 October), winter (1 October – 1 April) and annual (1 April – 1 April). The average loss rates (translucent bars) over the last 10 to 13 years, depending on the season, are presented alongside loss rates reported in 2020-21 (opaque bars). Figure credit: Bee Informed Partnership.
Nathalie Steinhauer, Science Coordinator Bee Informed Partnership
41
J U L Y – A U G U S T 2 0 2 1
Made with FlippingBook - Online Brochure Maker