Winter 2016 honey bee colony losses in New Zealand

Abstract

Estimating winter losses for managed honey bee (Apis mellifera) colonies is critical for understanding hive productivity and health. This study reports estimates of overwinter colony losses in New Zealand, which has seen exponential growth in the number of managed colonies in recent years. Over 35% of all beekeepers, and 50% of all commercial beekeepers in the country responded to the internet-based 2016 New Zealand Colony Loss Survey, providing detailed information on over 275,000 colonies (over 40% of all registered colonies) that entered winter 2016. Using three different methods, we estimate overall winter losses to be below 10%. However, nearly 29% of beekeepers lost more than 15% of their colonies over winter 2016, and nearly 25% of beekeepers lost more than 20%, indicating considerable skewness. These results are subject to strong regional variation, with the highest losses reported in areas with significant mānuka resources. Similarly, non-commercial beekeepers report substantially higher loss rates than commercial beekeepers. Beekeepers who lost colonies over the winter of 2016 most frequently attributed the cause to colony death, queen problems, or wasps. However, varroa and competition for apiary sites were also identified as important areas of concern. In this analysis, we explore variation in both region and operation size for all five of these challenges.