A national survey of managed honey bee 2012-2013 annual colony losses in the USA : results from the Bee Informed Partnership

For the past six years in which overwintering mortality of honey bee colonies has been surveyed in the USA, estimates of colony loss have fluctuated around one-third of the national population. Here we report on the losses for the 2012-2013 seasons. We collected data from 6,482 US beekeepers (6,114 backyard, 233 sideline, and 135 commercial beekeepers) to document overwintering mortality rates of honey bee colonies for the USA. Responding beekeepers reported a total 30.6% (95% CI: 30.16-31.13%) loss of US colonies over the winter, with each beekeeper losing on average 44.8% (95% CI: 43.88-45.66%) of their colonies. Total winter losses varied across states (range: 11.0% to 54.7%). The self-reported level of acceptable winter loss was 14.6%, and 73.2% of the respondents had mortality rates greater than this level. The leading self-identified causes of overwintering mortality were different according to the operation type; backyard beekeepers generally self-identified “manageable” factors (e.g., starvation, weak colony in the fall), while commercial beekeepers generally identified non-manageable factors (e.g., queen failure, pesticides) as the main cause of losses. For the first time in this series of surveys, we estimated mortality during the summer (total loss = 25.3% (95% CI: 24.80-25.74%), average loss = 12.5% (95% CI: 11.92-13.06%)). The entire 12-months period between April 2012 and April 2013 yielded a total loss of 45.2% (95% CI: 44.58-45.75%), and an average loss of 49.4% (95% CI: 48.46-50.43%). While we found that commercial beekeepers lost fewer colonies than backyard beekeepers in the winter (30.2% (95% CI: 26.54-33.93% vs 45.4% (44.46-46.32%) respectively), the situation was reversed in the summer where commercial beekeepers reported higher average losses than backyard beekeepers (21.6% (95% CI: 18.4-24.79%) vs 12.1% (11.46-12.65%)). These findings demonstrate the ongoing difficulties of US beekeepers in maintaining overall colony heath and survival.Keywords: Colony losses, Overwinter, USA, 2012-13, Honey bee, Mortalit

A national survey of managed honey bee 2013-2014 annual colony losses in the USA

Honey bee colony losses are a major concern in the USA and across the globe. Long-term data on losses are critical for putting yearly losses in context. US colony loss surveys have been conducted yearly since the winter of 2006–2007. Here, we report the results from the eighth annual survey on winter losses and the second annual survey of summer and annual losses. There were 7425 valid respondents (7123 backyard, 190 sideline, and 112 commercial beekeepers) managing 497,855 colonies, 19 % of the total US colonies. Total losses reported were 19.8% [95% CI 19.3–20.3 %] over the summer, 23.7 % [95% CI 23.3–24.1 %] over the winter, and 34.1 % [95 % CI 33.6–34.6 %] for the whole year. Average losses were 15.1 % [95 % CI 14.5–15.7 %] over the summer, 44.8 % [95 % CI 43.9–45.7 %] over the winter, and 51.1 % [95 % CI 50.2–51.6 %] for the whole year. While total winter loss was one of the lowest reported in 8 years, 66%of all beekeepers had higher losses than they deemed acceptable.Keywords: survey, honey bee, mortality, USA, colony lossesKeywords: survey, honey bee, mortality, USA, colony losse

Winter weather predicts honey bee colony loss at the national scale

Western honey bees (Apis mellifera) have experienced elevated rates of colony loss over the past decade. Past studies have attempted to determine what factors are behind these losses; however, few have considered the effects of environmental variables; key drivers in ecological systems. Existing investigations were conducted at local spatial scales, over small geographic areas, and failed to measure how environmental variables may influence colony loss rates differently across space. Here, we sought to determine the ability of environmental variables to explain honey bee colony winter loss rates across the contiguous U.S. over a nine-year study period, while elucidating how spatial methods produce results which differ from non-spatial approaches. To conduct this study, loss data from stationary beekeepers were obtained from the Bee Informed Partnership’s national Colony Loss and Management Survey for winters spanning from 2011 to 2019 and were aggregated by zip code. Environmental data (i.e., temperature, precipitation, relative humidity, wind speed, elevation) were obtained from PRISM, the Global Wind Atlas, and the U.S. Geological Survey, and averaged by month across the study period. Environmental variables and loss were regressed using linear and geographically weighted regressions. Results demonstrated that effects of environmental variables on colony loss varied across space, indicating that spatial models should be used when studying honey bee colony losses. Additionally, we found that increased winter colony loss rates were linked to lower November mean maximum temperatures and less February mean precipitation, thus, these two variables may be good predictors of observed winter loss rates. Finally, results also revealed that weather conditions during winter months were better predictors of winter colony loss than conditions during other months of the year. Overall, our results illustrate how environmental factors strongly impact managed honey bees and highlight the importance of regionally specific management practices to help prevent losses in the future