sept-oct-2020

IN YOUR ORCHARD THE BEE BOX Unusual Times; The Bee Informed Partnership National Survey State Specific Colony Losses These past months have been unusual in so many ways. A few examples range from beekeepers having to work without crew help for months to many reporting difficulties finding sugar. Another example comes from the 2019–20 Bee Informed Partnership (BIP) Colony Loss Survey results. If you’ve read this year’s 2019–2020 Honey Bee Colony Losses in the United States: Preliminary Results or watched the news, you already know that we recently reported that beekeepers experienced the highest honey bee colony summer losses on record last year (2019). It was one of those rare times when beekeepers experienced higher losses in the summer compared to the winter. Similar to previous years, summer losses were driven by commercial beekeepers (managing 500-plus colonies) who lost more colonies compared to sideliner and backyard beekeepers (managing 50 to 500 and 1 to 50 colonies, respectively). However, Summer 2019 seemed to have hit commercial beekeepers particularly hard. Given all the “unusuals” of the past year, we stuck to the traditional BIP colony loss map to present state-specific results for annual, summer and winter colony losses for the 2019–2020 season. As in previous years, we present both Total and Average Loss for each region and season; individual loss rates are aggregated by either summing up each operation’s losses according to the number of colonies they owned or not. Here’s a quick explanation of the two types of losses: • Total Loss = every colony is treated equally. Thus, Total Loss is more representative of commercial beekeepers who are managing most of the honey bee colonies in the country. • Average Loss = every beekeeper is treated the same, no matter how many colonies they manage. Therefore, Average Loss is more representative of backyard beekeepers since they make up the majority of the U.S. beekeepers. Depending on the number of respondents for each state and the variability in their responses we can be more or less confident in state-level loss rates. As a measure of confidence, we are using “confidence intervals” which reveal the range of plausible loss estimates. The narrower the confidence interval, the better! It means that we have a good idea of what the actual state loss rate was. Broad confidence intervals — when we don’t have a good idea of the actual state loss rate — occur when states have low participation rates or extremely high variability in beekeeper responses. There is an elegant way to account for this though: A statistical tool called “bootstrapping.” For example, instead of calculating the Total Loss for Alabama just once, this tool is doing it thousands of times! It shuffles the 68 state-specific respondents like cards and keeping some out every time, thereby reducing the variability in the calculated estimates. Figure 1: 2019–2020 Summer Colony Loss Map by States. 2 8 A L M O N D F A C T S