By: Maryann Frazier
As beekeepers we disagree about many things (some would say, most things) regarding how best to keep bees healthy and productive. And even the things we agree on, we often have wildly differing views about. However, I believe, nearly all of us would agree that we want more of our honey bee colonies to survive longer (especially through Winter) and we want them to be able to do this with as little (preferably no) chemical intervention as possible. I’ll even go out on a limb here and say that a majority of us believe a key to achieving this objective is dependent on genetics, in other words, the inherited ability of bees to resist or tolerate mites and diseases.
This is possible and has been documented in different honey bee populations around the globe: early work by Walter Rothenbuhler (1964a) and more recent work by Marla Spivak and Gary Rueter (2001) and others in the Spivak lab demonstrated that we can select for hygienic behavior and this can lead to resistance to America foulbrood; Russian bees shown to be varroa mite resistant and brought to the U.S. by the USDA are now being propagated here; in South Africa where Varroa, first identified in 1997, was identified as a major threat to beekeeping on the African continent (Allsopp, 2004 ) but by 2006 was considered an “incidental” pest, (Allsopp) and the wild honey bees of the Arnot forest in New York State now considered “persistent” despite varroa (Seeley,2005).
So we have solid evidence demonstrating that mite and disease resistance is possible in honey bees. But how to bring this about on a broad scale across a large and varied landscape (the whole of the U.S.) made up of beekeepers keeping bees with countless different reasons for doing so and, again, widely if not wildly, differing views on how this is best done, is where things break down. But given that the genetics of a honey bee colony is totally determined by the queen and the drones she mates with, the selecting and breeding of queens for mite and disease resistance should be totally within our grasp. However it is important to remember that there are actually two components to achieving the queens we desire; genetics (inherited qualities like good honey producer, mite resistance, reduced swarming, etc.) and quality (ability to lay a lot of eggs over a long period of time). And it turns out trying to produce large numbers of high quality queens that have the genetics we desire is very difficult.
The Good Queen
The acquisition of a “good” queen is what all beekeepers have desired for as long as there have been beekeepers. We know them when we see them, not necessarily by how they look but by how their colonies look; the ones with most supers, overflowing with bees when opened, frames of brood solid from top to bottom and side-to-side. But now the “good” queen, the “ideal” queen we dream of, needs to be able to withstand the pressures of mites and diseases. We want queens that are mite resistant and/or “survivors”. There have been a number of approaches to acquire these qualities in our queens. One approach advocates for locally reared queens. In the north especially, where winters are long and cold and overwintering losses high, some believe wintering can be improved by using locally reared queens that are perhaps better “adapted” to northern climates as opposed to queens reared in the south with its short, mild Winters.
Honey bee population structure is interesting. In places where honey bees have existed for thousands of years (think Africa and Europe) subspecies or ecotypes have evolved. These are populations adapted to specifi c local conditions, for example, Apis mellifera mellifera, the dark German bee, A. m. ligustica, the yellow Italian bee, A. m. scuttelata, the African savannah bee and. A. m. yemenitica the East African coastal bee. It is worth noting that as our ability to understand the genetic makeup of organisms improves through the use of molecular techniques, some of these long-designated subspecies are being amalgamated, nevertheless sub-species do exist. But honey bees are, of course, new to the Americas and several sub-species have been introduced here, not to mention, the Africans that have invaded from the south. This, in addition to the fact that we have a highly mobile beekeeping industry; queen and package bee rearing in a few locations and shipping to all corners of the country, migratory movement of colonies for pollination and honey production, etc. makes the existence and maintenance of any kind of population structure very unlikely. Still some have argued that bees reared in a place, albeit a large place “the north” are more likely to survive in the north than bees reared in other places, specifically “the south.”
In 2013 we carried out a study to ask the question, “are bees (queens) reared in a northern climate more likely to have higher overwintering success than bees (queens) reared in the south.” We used 60 colonies established from packages and nucs (Russian stock used for one of the Northern groups), to compare four different stocks, two northern and two southern. These were equally divided into three apiaries around State College, PA. It is important to note that all four stocks were from reputable queen breeders and selected for some type of varroa mite resistance. While we carried out this work over a two year period with similar results both years, the newly published study (Döke et al. 2018) focuses only on year two of the study. What we found was that, where the stocks originated from did not affect their overwintering survival but what did significantly influence colony size, weight in Fall, and overwintering success was apiary location (Figure 1). Colonies that were heavier in the fall were more likely to survive the Winter (Figure 2). In addition, colony size, weight in Fall and overwintering success are very likely correlated with floral resources around the apiary (Figure 3).
Another similar study conducted by E. MacGragor- Forbes (2014) in Maine did fi nd evidence that colonies headed by locally reared queens did overwintering better those headed by non-locally reared queens. Similar to our study, she used packages, half of which were re-queened with locally reared queens while the other half, used for comparison, were not requeened. But under these circumstances, the observed increase in overwintering survival of the re-queened versus non requeened colonies could have been due to the act of requeening itself, a difference in quality between the locally bred and package queens, local adaptations of northern bred queens, or some combination of these factors.
Package bees; blessing and a curse.
Thanks to the package bee and commercial queen rearing industries we have virtually unlimited access to bees and queens. Other than perhaps dairy farming, I cannot imagine work more demanding than the production of package bees. The relatively recent increase in demand for bees, created by high annual losses and thousands of new beekeepers, has placed tremendous strain on this relatively small industry. As is the case in most industries, maintaining high quality is challenging when demand for quantity skyrockets practically overnight. It is perhaps not surprising that maintaining queen quality in package bees may be a causality of both the decline of honey bees and the new found popularity of beekeeping.
From 2007-2016 our lab at Penn State conducted research on the impacts, particularly, sub-lethal affects, of pesticides on honey bee health. Queen egg-laying was one of many criteria we measured. To do this we caged queens and some young workers on an open frame for 24 hours and then counted the number of eggs laid. We did this prior to and after pesticide applications. In 2011 we installed 25 packages and assessed the egg-laying rates of their queens. Even before applying pesticides, egg-laying rates ranged from 200-800, averaging slightly over 400 eggs per day. Easy to say, these are not the “good” queens we desire. To address this, in 2012 and 2013 we re-queened all of our packages immediately after installing them with queens from a well-established (southern) queen breeder. Egg-laying rates by these queens, 32 (2012) and 37 (2013), ranged from 185 to 1,500 averaging 1,045 and 137 to 1,684 averaging 1,038, respectively (unpublished data). True, this work was done several years back and we only have one year of data on the packaged bee queens, but queen failure continues to be a problem and is listed among the major reasons for overwintering losses by commercial beekeepers (self identified, Bee Informed Partnership) many of whom now re-queen on an annual basis. And while there may be several different factors contributing to queen failure, the pressure has not let up on the package bee industry to produce ever-increasing numbers of packages and queens.
So what’s a beekeeper to do?
Undoubtedly many of you have your own ideas about this, but I offer my own humble opinion on how we can make progress on improving the health of our own honey bee colonies and the population at large.
Regardless of where your bees live, use the best quality resistant/survivor queens you can get your hands on, regardless of where they come from. Support those breeders who are working to develop resistant/ survivor stock. Buy local if you can get ‘em. This takes some of the pressure off of the large commercial queen rearing outfits and supports local efforts. Who knows, perhaps overtime we can even develop local population structure with bees adapted to local geographic and climatic conditions.
Bees need good real-estate. Apiaries need to be located in close proximity to diverse sources of nectar and pollen that is present throughout the foraging season, hopefully punctuated by intense seasonal nectar flows that allow them to make enough honey for themselves and an excess for you. And this forage needs to be free of pesticides; no small challenge!
Have a mite/disease control plan. Even if that plan is to do “nothing,” allowing the mite-susceptible colonies to die and making splits and/or rear queens from the survivors; that’s a plan. Albeit a plan that requires ownership of a sufficient number of colonies, ideally located in a number of apiaries in order to have enough survivors to split and/or select from for rearing queens.
On the other hand, buying a few packages or nucs, placing them in your yard that is perhaps surrounded by fields of corn and soybeans, or on your rooftop in a golfing community and taking a hands-off approach to mite and disease management with the objective of simply buying more packages/nucs next year when this year’s die off, is not a plan. This approach only counters efforts to establish resistant bee populations by seeding an area with non-resistant genetics. When they die and are robbed out, these colonies are a source of mites for other colonies. In addition, this approach puts undo pressure on package bee and queen producers trying to meet the ever increasing demand for bees.
If we truly want mite resistant and/or survivor bees we must work toward that goal. We can do this by supporting the efforts of those producing high quality, resistant queens, be they local or not. And because we know that using resistant stock alone currently is not likely to keep mites from killing colonies, we can assist these colonies by using other cultural methods that fi t our management objectives and even treating with soft chemicals.
But treating only when mite levels reach a designated threshold that keep them from killing colonies. The goal is to get to the point where we can rely on resistant stock and cultural controls most of the time. This approach, of course, is called Integrated Pest Management (IPM) and it is applicable across agricultural systems. It does not exclude the use of chemical control but makes chemical control the choice of last resort.
Taking this a step further, some in the scientific community are now suggesting an upgrade to IPM to enhance pollinator protection; Integrated Pest and Pollinator Management (Biddinger and Rojotte 2015). IPPM advocates for pest control in cropping systems that also takes into consideration pollinator protection and improving habitat to enhance pollinator populations, especially in crops that are pollinator-dependent. The earnest implementation of IPM in our honey bee colonies and IPPM across agricultural systems can do much to improve the health of our honey bee populations and the environment they, and we, inhabit.
Allsopp, M., 2004. Cape honeybee (Apis mellifera capensis Eshscholtz) and Varroa mite (Varroa destructor Anderson & Trueman) threats to honeybees and beekeeping in Africa. International Journal of Tropical Insect Science Vol. 24, No. 1, pp. 87–94.
Allsopp, M., 2006. Analysis of Varroa destructor infestation of southern African honey bee populations. MS Dissertation. University of Pretoria. Pretoria.
Biddinger, D.J., E.G. Rajotte. 2015. Integrated pest and pollinator management-adding a new dimension to an accepted paradigm
Curr. Opin. Insect Sci., 10 (2015), pp. 204-209
MacGregorForbes, E. 2014. Sustainable Agriculture Research and Education (SARE) Outreach, USDA – National Institute of Food and Agriculture (NIFA) Annual Project (FNE12-756) Report: A comparison of strength and survivability of honeybee colonies started with conventional versus northern re-queened packages. https://projects.sare.org/sare_project/fne12- 756/?ar=2014
Döke, M.A., C.M McGrady, M. Otieno, C.M. Grozinger, M. Frazier. 2018. Colony Size, Rather Than Geographic Origin of Stocks, Predicts Overwintering Success in Honey Bees (Hymenoptera: Apidae) in the Northeastern United States, Journal of Economic Entomology, toy377, https://doi.org/10.1093/jee/toy377
Rothenbuhler W.C. (1964a) Behaviour genetics of nest cleaning in honey bees. I. Responses of four inbred lines to disease-killed brood, Anim. Behav. 12, 578-583.
Seeley, T., 2007. Honey bees of the Arnot Forest: a population of feral colonies persisting with Varroa destructor in the northeastern United States Apidologie, 38 1 (2007) 19-29
Spivak M., Reuter G.S. Resistance to American foulbrood disease by honey bee colonies Apis mellifera bred for hygienic behavior. Apidologie, 32 6 (2001) 555-565