Managing Winter Colony Losses: A Reason for Optimism

Dick Rogers, Bayer Bee Care Program, Principal Scientist/Entomologist of Bee Health and Integrated Apiculture Research

Anyone who knows me will not be shocked to learn that I am not a gambler. Just the thought of placing a bet on a high stakes game in Las Vegas is enough to make me break out in a cold sweat. This probably has less to do with my being a spendthrift (although some might wish to argue that point) and more to do with my discomfort in being unable to predict the unpredictable. After all, relying on random chance is not a good prerequisite for any scientist, particularly one involved in honey bee research.

And yet, like a gambler with one chip left to play, here I go again: trying to guess what beekeepers can expect from their honey bee colonies following this year’s winter season. Although my track record in predicting the magnitude of winter colony losses over the years has been pretty reliable, I know there are plenty of variables that can have a major influence on whether the news is good or bad.

After looking over a number of factors, I believe beekeepers have a reason for optimism in 2017. Let’s take a look back and then examine a few of these factors to better understand why I think this is so.

Looking Back at Previous Winter Colony Losses

Colony losses over the winter can happen and are often expected. In fact, most bee experts consider losses up to 15 percent to be tolerable. Surveys conducted by the Bee Informed Partnership (BIP) in collaboration with the Apiary Inspectors of America, and funded by the U.S. Department of Agriculture (USDA), found that the winter colony losses were averaging more than 30 percent in the first seven years since these surveys began in 2006. Things improved slightly in some years as beekeepers worked hard to resolve this problem and average losses dropped below 25 percent.

Unfortunately, the spring of 2016 revealed an entirely different situation. In the BIP/USDA survey, beekeepers reported an average colony loss of more than 28 percent – not as high as some of the earlier years, but significantly higher than the two previous ones. What happened?

As I wrote in a blog last year, the higher winter losses seen in 2016 was entirely predictable. At that time, we were finding extraordinarily high infestations of the invasive Varroa mite (Varroa destructor) in the fall samples of bees collected from our research apiaries. Also, across the country, our survey samples and those of independent experts were reporting autumn mite populations at levels that were three-to-four times above what is known to be harmful to colonies. While there are many factors that affect the health of honey bees, perhaps none is more harmful than this parasite. Its lethality has been well-documented by many researchers and, if not properly managed, mite infestations can result in a complete loss of the colony.

Looking Ahead: 2017 and Beyond

While there is always considerable variability in any biological system, I’m hoping we won’t see the same level of losses this year that were reported in 2016. That doesn’t mean we won’t see extreme losses in some apiaries, because autumn mite counts were still far too high in many areas. However, I do expect that we will see modest improvements on average across most colonies and here’s why:

  • Mite Surveys – Mite counts were lower in our research and surveyed apiaries compared to last year. While this decline was modest (about 16 percent), predicted losses based on hives exceeding mite damage thresholds were notably lower and a step in the right direction.
  • Winter/Early Spring – Casual reports from beekeepers suggest that bees survived the winter and adjusted fairly well to the relatively warm spring, especially in the southeast, which allowed colonies to be built up quickly. This could lead to increased swarming and mite problems later on, but for now colony losses appear to be lower.
  • Colony Strength – The rule of thumb says that Varroa does best in strong bee colonies, but there is a difference between strong numbers of bees and strong colony health. After last year’s high losses, I was pleased to see the industry’s emphasis on monitoring and treatment. Efforts by the BIP, the Honey Bee Health Coalition (HBHC), Bayer and university extension offices seem to be making real inroads in helping beekeepers better manage Varroa.
  • Bee "Buzz" – I’ve heard few reports of high winter losses where colonies were able to be opened and properly inspected. While it is impossible to check colonies that were still in deep winter weather, this anecdotal observation was certainly different from last year.

Over the past few years, most professional beekeepers have adjusted to a “new normal” when it comes to protecting their colonies. Most of them agree that it is far more difficult to be successful today than it was prior to the introduction and spread of Varroa three decades ago this year. And yet this pest is only one of many factors that can contribute to colony health. The fact that some beekeepers have been able to keep their losses below 10 percent (below even what is considered to be tolerable) is a testament to their adoption of best management practices in apiculture.

Finding new solutions to the problem of varroa mites and other factors affecting honey bee health remains a focus of Bayer's Bee Care Program and that of many other researchers and organizations. For example, a $1 million collaborative research effort funded by Bayer and administered by Project Apis m., is seeking to find tangible ways to improve the health of honey bee colonies in the United States by the year 2020. Until then, I strongly encourage all beekeepers to read the Honey Bee Health Coalition’s Varroa Management Guide, which provides practical tips for monitoring and controlling this parasite. You can also use the Healthy Colony Checklist for an easy-to-use, fast and thorough method to monitor your colonies on a more frequent basis.

While it’s too soon to expect a sudden and dramatic turnaround, I’m encouraged by the steps our industry is taking to improve the winter survival of U.S. honey bee colonies. Whether we like it or not, Varroa is here to stay. The sooner we learn to manage our colonies more effectively to get ahead of this pest, the better off we’ll all be. And so will our honey bees.

Now that’s a bet I’m willing to take.