A national survey of managed honey bee colony losses in the USA: results from the Bee Informed Partnership for 2017–18, 2018–19, and 2019–20

Beekeepers in the United States have experienced high losses of managed honey bee (Apis mellifera) colonies for more than a decade. Long-term, multi-year monitoring efforts are crucial to provide a temporal and spatial context to these losses. To document and explain these losses, the Bee Informed Partnership has conducted national surveys on managed honey bee colonies since spring 2011, continuing the work of surveys first commissioned by the Apiary Inspectors of America in spring 2007. Here we present survey results from three years – 2017–18, 2018–19, and 2019–20. Each year, colony loss rates were estimated and compared among three loss periods – summer, winter, and annual – and three beekeeping operation types based on their number of colonies managed – backyard (≤50 colonies), sideline (51-500 colonies), and commercial (>500 colonies). At the national level, we recorded the highest winter colony loss rates (37.7%) in 2018–2019, while 2019 marked the year with the highest summer losses (32.1%). As documented in past surveys, we observed that smaller scale backyard beekeepers experienced the highest winter loss rates when compared to the larger operation types. Similarly, commercial beekeepers experienced higher loss rates during the summer compared to the other operation types. Overall, our results highlight the temporal variability, specifically among loss periods and years, of colony loss rates in the United States, and suggest a strong effect of beekeeping operation size.

十余年来，美国规模化饲养西方蜜蜂（Apis mellifera）蜂群的养蜂从业者持续遭遇严重的蜂群损失。长期、多年度的监测工作对于为此类损失提供时空维度的背景支撑至关重要。为记录并解释此类损失，自2011年春季起，蜜蜂知情伙伴计划（Bee Informed Partnership）针对规模化饲养的西方蜜蜂蜂群开展了全国性调查，该工作延续了2007年春季由美国蜂场检查员协会（Apiary Inspectors of America）首次委托开展的调查项目。本文呈现2017-2018、2018-2019及2019-2020三个年度的调查结果。每年均针对三类损失周期（夏季、冬季及年度总损失），以及按饲养蜂群规模划分的三类养蜂经营模式——散户养蜂户（饲养≤50群）、副业养蜂户（饲养51-500群）、商业养蜂户（饲养>500群）——估算蜂群损失率并开展对比分析。在全国层面，2018-2019年度的冬季蜂群损失率达37.7%，为统计周期内最高；2019年度的夏季蜂群损失率达32.1%，亦为历年峰值。如过往调查所记录的那样，本研究发现相较于规模化经营的养蜂户，散户养蜂户的冬季损失率最高。同理，商业养蜂户的夏季损失率亦高于其他两类经营模式。总体而言，本研究结果凸显了美国蜂群损失率的时间变异性，尤其体现在不同损失周期与年度之间，并表明养蜂经营规模对蜂群损失率存在显著影响。