US Beekeepers report over 40% annual loss in the Bee Informed Partnership's 2017-2018 survey. This survey, now in it's 12th year, highlights the continued struggles of beekeepers nationwide and reflects the large time and financial investments that are needed to maintain a pollinator force for our agricultural system. The value of this study is to document and examine long term trends in honey bee health. We appreciate all beekeepers who participated and added to the understanding of these critical metrics.
Prior to 2006, there was no regular, standardized survey to quantify and document honey bee colony losses in U.S. operations. At the height of Colony Collapse Disorder (CCD) in 2006 and 2007, the Apiary Inspectors of America took it upon themselves to survey as many commercial operations as they could by phone. In total, 384 operations were contacted and the annual winter loss survey was born. The survey continued in that phone format for several years until the 2009/2010 survey. At that time, the basic winter loss questions were available in an online survey. In 2011, the Bee Informed Partnership was granted funds to expand and create an online survey of convenience for all U.S. beekeepers. This initial online survey took place in 2011 and we began to include questions beyond the degree and extent of losses. We also began to link, and continue to do so, management practices associated with increased survivorship. These management practices include treatments, supplemental feeds, and timing and dosage of such, but also asks what crops are nearby, if the operation engaged in pollination services, how much honey the average colony makes and many other factors. Furthermore, the survey now also looks at summer losses, building on the initial winter and annual losses. With this survey, we are able to track differences in losses between commercial, sideliner and backyard beekeepers as well as stationary and migratory. Before this effort to record losses, there were no other numbers to compare what “normal” losses are for beekeepers and what is considered excessive.
This year, 4,794 beekeepers, collectively managing 175,923 colonies in October 2017, provided validated survey responses. This represents 6.6 percent of the nation’s estimated 2.67 million colonies (USDA NASS Honey Report 2018).During the Winter 2017/18 season (October 1, 2017 – April 1, 2018), an estimated 30.7 percent of managed colonies in the United States were lost (Fig. 1). This represents an increase of 9.5 percentage points compared to last year, and an increase of 2.8 percentage points compared to the 10-year average total winter loss rate of 27.9 percent.
Similar to previous years, Backyard Beekeepers lost more colonies during winter (46.3%) compared to Sideline (38.0%) or Commercial (26.4%) Beekeepers. Backyard, Sideline, and Commercial Beekeepers are defined as those managing 50 or fewer, 51 – 500, and 501 or more, colonies, respectively.
Interestingly, the self-reported level of acceptable winter loss increased from 20.6% to 18.7% this last year. Whether this is due to beekeepers becoming more pessimistic (or realistic) is too soon to tell; however, 69% of participating beekeepers lost more than was deemed acceptable.
During the Summer 2017 season (April 1 – October 1, 2017), an estimated 17.1% percent of managed colonies were lost in the country. This level is on par with the summer lost estimate of the previous year.
For the entire period (April 1, 2017 – April 1, 2018), U.S. beekeepers lost an estimated 40.1 percent of managed honey bee colonies; this is an intermediate annual rate of loss recorded since 2010-2011, the year that these data began to be recorded.
Fig 1. Total winter colony loss rate in the United States across years of the Bee Informed Partnership’s National Honey Bee Colony Loss Survey (yellow bars; 1 October – 1 April). Total annual loss estimates (orange bars) include total winter and summer (1 April – 1 October) losses; the latter has been estimated since 2010-11 only. The acceptable winter loss rate (grey bars) is the average percentage of acceptable winter colony loss declared by the survey participants in each year of the survey.
How do we explain these higher losses this year? It is important to know that the Loss Survey’s objective is to document trends, not determine their cause(s). Also, there are a lot of different factors that affect honey bee health, and ultimately, colony loss. But we venture a few opinions.
In the past, we have looked at the Varroa mite infestation loads in the fall from an independent National Survey (APHIS National Honey Bee Disease Survey) and noticed an association with colony mortality in the winter at the state level. States with higher Varroa loads in September also presented higher mortalities that winter. We did not find this surprising: Varroa mites are the number one (and likely numbers 2 and 3 and maybe 4) cause of colony mortality in our books. It is tricky however, to demonstrate the causality link in the field, even more so when dealing with a social organism made off tens of thousands of smaller organisms. Working with real-life conditions in the field also means having to make adjustments, for example, recognizing that “autumn” and Mother Nature don’t really care what month it is, and that the period of time when honey bees rear winter bees and brood area contracts really occurs over a moving period that varies considerably by region. September in Florida looks very different, weather wise, then September in Maine. So our next step is to add some of those factors in our modelling efforts.
In addition, as many of us remember, last year was an anomalous year for floods, wildfires, hurricanes, severe heat and drought. There is no doubt that extreme climatic conditions challenged honey bees and beekeepers alike. Also, many of the Varroa mite treatments can only be applied during a narrow temperature window and any temperatures outside of that window voids the efficacy of the product or creates dangerous conditions for the bees. So those factors might have affected the loss observed this winter. Finally, we also think we are still on the cusp of getting beekeepers to monitor frequently (monthly) and treat by need rather than prophylactically or by the calendar. This are still misconceptions and barriers to adoption for Varroa mites’ treatments, especially by backyard beekeepers.
Queen with deformed wings. Deformed Wing virus is one such diseases vectored by Varroa mites. Varroa mites are arguably the largest driver of colony loss in the US. Photo courtesy of the Bee Informed Partnership, Inc.
Long term studies such as this one are critical to understand the trends affecting honey bee health. Though the total number of honey bee colonies has been relatively stable in the last 20 years at the national level, the high turnover rate of colonies reported in this survey is indicative of the struggles of commercial operations and the high investment in time and energy required to maintain healthy colonies in the U.S.