Introduction
Here we are very close to the winter solstice and the end of the year. It will be good to see more daylight gradually creeping into our days quite soon here in the north. The weather is still variable and yesterday the temperature was around 9°C so all the colonies were active with some bees collecting pollen from mahonia, Mahonia aquifolium. This prickly shrub with a profusion of yellow flowers is also known as Oregon grape.
As we reach the end of 2026, I want to thank everyone who has supported the Beelistener by reading the articles, contributing articles, and donating money to help me cover the site maintenance, security and admin costs.
For this last main blog of the year, I am very pleased to welcome back Bartek from Poland who shares the second part of his excellent guest blog on local bees and varroa resistance. Thank you, Bartek.
Varroa Resistance
And now let’s go a little bit into varroa resistance vs locality of the bee population. I won’t go into much detail in this post because you will find all the necessary information in my book, Beekeeping in Harmony with Nature, the evolutionary solution to the varroa problem (you can buy it from Northern Bee Books – https://www.northernbeebooks.co.uk/products/beekeeping-in-harmony-with-nature-maleta ).
It was noticed in many, many observations, practical trials and scientific experiments, that you cannot transfer varroosis resistance to different localities. When you raise a queen in some population which we could call “resistant”, and transfer it to a different apiary, then most likely you won’t see satisfying resilience and varroa resistance (even if she’s mated with drones from a so-called resistant population). Why is that? There are many hypotheses – most likely it’s because of epigenetic factors (these are the environmental factors that allow genetic adaptations to be “turned on”), and because of different local pressures that the transferred queen (or rather her worker-offspring) are not well adapted to. So, she may carry enough genes and have sufficient varroa resistance to cope in one locality, but that’s not enough to survive and thrive in another. To simplify it even more: she has the genes, but they are not “turned on” and/or her immunological response (or rather her offspring’s) is not enough to cope with local pathogenic flora. Some factors of the new environment are too harmful to the colony, or they prohibit some of its adaptations to be “turned on”.
Behaviours
It was noticed that for some behaviours to occur there might have to be some specific surrounding conditions. I don’t know how well it is documented by science, but there are lots of opinions on that topic which we could call anecdotal evidence. E.g. that bees have to have so-called “storage safety” and plenty honey stores to turn on grooming or VSH behaviours. So, if those opinions were true (and they seem very reasonable, probable and convincing) in industrial beekeeping the bees would rarely turn on their hygienic behaviours as everything is organised so that they are constantly stimulated for growing and gathering crops rather than taking care of themselves (either by methods of management or breeding goals which may exclude the important behaviours – but that’s very different story!)
And so, wherever we hear about bees coping with varroosis – they are always local! Not everywhere they are native, but everywhere they are local! They are never brought there and make a resilient and varroa resistant population from the start! Even if they are brought somewhere in the beginning (like African bees to Brazil, or African genetics to Elgon population near Hallsberg, Sweden) – they have to undergo the process of local selection to surrounding conditions. It is said that to call some population resistant (or specific colonies) it has to live somewhere (self- sustaining) for at least 6 years.
Experiment
In a COLOSS experiment conducted in different countries in Europe, they set some apiaries with local and brought/foreign genetics in each place and left them untreated. After a few years most of the bees died, but the majority of survivors were local – independently of the specific locality and breed of bees. To say it in other words: if you set up an apiary with a local and non-local population, the best probability of survival you’d have is with local bees, and most probably the non-local would die off. No matter where you are, what breed of bees are local for you – you should choose them. With our mixture of bees, it sometimes does not have to mean native, but just local. My opinion is that the best way of starting your local resistance breeding is to get bees from apiaries closest to your place, and on the other hand look for stock bread for resistance to varroosis. Best if the latter are local. But even if You introduce some genes of varroa resistance, you may find Your bees dying regardless of that. E.g. in Poland we have so much mixture of bees, as Polish beekeepers rarely care for their native bees, so it would be best just to get bees from the closest locality to your apiary instead of looking for native populations which may be few hundred kilometres away in some genetic-protection areas. Sometimes people from Poland look for native stock in Scandinavia or British Isles, because there is a bigger probability of getting “pure” A. m. m. bees – a native subspecies.
Let’s take the Hallsberg/Sweden example now. Erik Österlund, a breeder from Hallsberg in the late 80’s went with other beekeepers to Kenya, Africa, to get genetics that proved to be resistant in South America. That time there was no way to know if varroa mite is already in Africa (and where exactly), but it was known that Africanised bees in South America are resistant to varroosis. It was also believed then, that maybe introducing “resistant genetics” and some simple management methods (such as small cell foundation) would be enough to withstand varroosis pressure for the bees. Erik took some genetics of Apis mellifera monticola bees, mixed them with A.m. sahariensis and Buckfast bees and introduced them to his apiary. It was a totally non-local bee that came from that mixture. He then bred those bees for generations without major introduction of foreign genetics. When the varroa mite finally came to his locality all non-treated bees started to die – including his mixture and other local or native bees. Now after years of selection his bees consist of a resistant population. By “resistant population” I don’t mean a population within which all of the colonies are resilient and thriving with varroa mite. Some still die, some still get sick. But the population is completely self-sustaining and coping perfectly with the mite – as a group. It also allows Erik and other local beekeepers to lead successful apiaries with reasonable crops without or with minimal treatments (with only few losses due to varroosis). At least Erik claims so, and I believe him. It’s completely consistent with all that we hear from such similar cases and some different ones, but still close enough so we can compare them. Meanwhile – according to the breeder – some people that are not convinced of his stock and methods lose bees in much bigger numbers, even though they keep native A.m.m. bees (if left untreated or sometimes even with the treatments). Also, right now, after almost 40 years since the mixture was introduced, it is probably much better locally adapted to his conditions, than 99% of bees in Poland, which are constantly mixed.
Losing Bees?
Will you still lose bees regardless of what stock you keep? Yes, you will.
Right now, there are many factors that influence the rather poor condition of the bees. Environmental factors are very important in that. Also, what beekeepers do – introducing foreign unadapted genetics and making mixtures, unreasonable treatments or unsustainable management of keeping bees – contributes significantly to this problem. But the best chance of a long-term solution to varroa problem is to keep locally adapted stock, constantly bred for mite resistance and varroosis tolerance. This proved to be successful in many places all over the world. It’s your choice what you will do. You may be part of the solution or part of what is completely opposite.
It was also noticed (by methods of cubital index on the wings of bees, which is a good assessment, without complicated studies of bees’ genome), that when you keep local stock for generations (regardless of what is the genetic origin of it) bees tend to “clear up” their genetics. It is so because more and more of native-local bees tend to survive, and foreign genetics slowly “disappear”. Besides, – regardless of the genetics – bees and their phenotypes (behaviours and general look) are much closer to the original historical native bees that lived locally where you are. It’s because the environment shapes the phenotype of organisms just like it did in the past. Those that are not adapted well enough will die, and will exclude themselves from the gene pool. Just let that happen naturally in your apiary, by keeping local stock – it’s the best you can do for the bees and for your neighbours so we all can enjoy healthy adapted bees, not the hybrids that you have to constantly care for if we want them to survive.
How to Have The Best Bees.
Bees have to cope with your local environment, and yes, the best adapted stock would be native bees – but only if they are native subspecies and local ecotypes, not introduced from elsewhere. Are there such bees in your neighbourhood? If not, just breed from your local stock – whatever it is now, and stop introducing foreign genetics.
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I’m a sceptic, I don’t believe in Santa. If “varroa resistance” truly exists, it’s alongside a host of other factors. You hypothesise it’s not just genetic but “epigenetic factors” so that varroa resistance is not transferable from one population to another. That’s stretching reasoning, I’ll keep working on general improvements in my locally adapted bees and be ready to treat as necessary. Treatment free is not for me!
Hello davandwrightlivecouk. Thank you for reading the blog and commenting. Here is Bartek’s reply below. Best wishes, Ann.
I’m a sceptic too. And what You write is kind of a misunderstanding of my words. I’m not saying it’s not genetic at all. I’m saying that genes are somehow dependent on the environment – on two levels. First level is that genes are formed/shaped by many factors (in which the environment is probably the most important) in the process of evolution. So You can say that the environment shapes the organism, and so the organism is dependent on the environment. The second level is that genes may be „turned on” and „turned off” depending on environmental factors (also by others) – these are epigenetic factors that I mentioned. For example if You have a thousand year old tree it survived a lot of draughts and floods, and maybe even fires. It’s all in its genes, and its reactions to those environmental pressures are by turning on and off those genes (it’s also in a manner hereditary in its seeds!).
And so if You take an organism to a different location – i.e. different environment its genes may not „work” as they do well in its local environment. The good example are some African subspecies of Apis mellifera that are unable to form a proper winter cluster. If You take such a colony north they may not be able to form a cluster and winter as northern subspecies of bees do. That does not mean they for sure wouldn’t survive the winter. They will just not be able to preserve food storage properly and would have to work much harder to keep warm and if winter prolongs they wouldn’t be able to do cleansing flights etc. and so the probability of their death rises very high.
And so we know that there are some varroa-resistance mechanisms that are gene-dependent. But it’s also the issue of „turning on” those mechanisms and also there are some other factors that the bees’ genes may not be sufficiently adapted to. E.g. If bees are not adapted to some minor local things that are not even connected directly to health/pathogen issues (like digesting honey-dew) they may have it harder to fight diseases as they may have problems with coping with local conditions.
So some mechanisms are easily transferable from one population to another, but that does not mean that thanks to that the organism will cope and survive. This may just not be sufficient. The best chance (which does not mean certainty) is to have the local stock.
I know that treatment free from scratch is not for everyone – perfectly understood here. What I try to convince people to, is to come up with a goal of being treatment free in the future (in 10-15 years), making a plan to get there, implement it and be consistent in it. Because each tool that we need to get there is on the table right now. It’s just a matter of deciding whether to reach for that tool and use it or not. My opinion is that the goal of treatment free is the best future we can have for all of us. Poisons are bad – they are bad for us, for bees, and for bee products. They may be seen as a necessary evil by many right now, but in the long run this evil is not necessary! Best of luck with Your project!
This is an interesting website!
Thanks, Iain.
Another nice piece about VR bees from Bartek. With new evidence coming to light recently I have learned several new things which I wish had been around for longer. It would have increased my confidence to stop treating and probably sped up my decision. After reading almost everything that I could on varroa and varroa resistance in bees over 12 years and being TF for 10 of these I can confidently let people know that the information from Bartek and Steve Riley, which has recently appeared in the Bee Listener, is extremely valuable for anyone looking to attempt to stop treating, or simply to reduce the amount of treatment for mites which makes sense for many reasons apart from reducing the profits from some very large pharma companies.
Primarily, the information in Steve Rileys book The Honey Bee Solution to Varroa has illustrated that, by regular monitoring of the daily mite drop, you can make a very good assessment of how well your bees can adapt to stopping treating and gives exellent reasoning about why this is so (or not). The information here today from Bartek also confirms what I and many of my associates have thought and that is referring to local adaption and the regression of local bees over a period of time to the original honey bee type for the area.
I know that my bees are all pure Amm which originally came from wild or feral swarms and were capable of surviving varroa before they came to me which made things surprisingly easy for me to go treatment free. I also know that they can retain their resillience to varroa when taken a fair distance away but I never sell them as varroa resistant because I also know that, although the trait is generally reckoned to come from the queen, it takes 10 or 20 to tango (in our bees anyway) and so the trait needs drones with similar traits to continue.
I now need to get information from other beekeepers to make an assess ment of how far the queens can travel and retain the traits further down the line. I know that they are successful at 40 to 60 miles away and now need to check on bees 100 to 150 miles away and also to make sure that they are not being hybridised which I think will stop the resillience from being passed on. By getting this information it will also give us a good idea of the drones in other areas and whether the wild/feral bees in the background here have become reistant to varroa in the wild.
PS I have just read Barteks excellent reply to davandwrightlivecouk’s message to the blog and I agree totally with Bartek’s reply. Luckily in my part of Ireland we ahve a high population of wild colonies which have made it easy for me to go TF BUT davandwrightlivecouk will never know how sceptical and nervous I was in the first place.
Hello Alan. Thank you very much for taking the time to write such an informative and reassuring comment following Bartek’s great guest blog. It is useful to hear from someone who has been treatment-free for so long, and particularly so to read about trait retention up to 60 miles from you. Good to know that ongoing studies are being done on how far queens can be moved and offspring will still retain the good traits. Best wishes, Ann.
Thank you Ann, It is nice to be able to pass on information that will hopefully help others to have bees that achieve their goals of treatment free bees or reduced treatment for them. Interestingly I have just started to read the book and, lo and behold, the first chapter discusses the benefit of having survivor bees in your area to back up the TF trait.
Thank you for taking the time to deliver the blog which covers a variety of topics aimed at all levels of beekeeper.
I’ve read the following point a few times and was reminded of it after asking a question at Bob Binnie’s lecture the other day. It is very interesting to hear his views on everything. He has had a ‘resistant’ population that was totally wiped out after another beekeeper set up an apiary with non-resistant bees in a field next door. He brought up the point that the varroa evolve as much as the bees to live in a degree of harmony if that is the right word. In treated bees you are potentially selecting for varroa that reproduce fast to compensate for being wiped out repeatedly. This may explain why resistant bees moved into a different area that doesn’t already have resistant bees don’t cope so well.
Hello Andrew,
thanks for commenting on this guest post. The issue of resistance of bees to varroosis is very complicated and complex, so in the described case there could be many factors. Remember that correlation is not causation. For example they found a correlation between ice consumption and shark attacks – and it’s highly doubtful that there is any causation between the two 🙂 [probably just people swim more and eat ice-cream if it’s hot].
So in this case there could be a causation (the non resistant population brought with itself some factor that could influence the dwindling of the resistant population) but it could be only a correlation (e.g. there was some sub-lethal pesticide spray that influenced the weakening of the “resistant” population of bees which caused their death much later or made it more prone to any disease factor, not especially varroosis).
If there was any causation between the two events (which is quite probable here) in my opinion it is doubtful if the differences between the varroa mite itself caused the die-out of the population. It is said (and proved in many experiments) that varroa mites themselves have very small differences as far as genetics is concerned – it’s very low diversity in them. Some scientists say that there is actually no real difference in the mites and no significant diversity that would influence the bees survival – it’s rather the difference in the bees (the host) and in pathogenic flora. There was an experiment run in Gotland island not only on bees left without treatments but also on varroa mites (mentioned in my book). Even after 10 years of not treating they did not find any real genetic differences in varroa mites (comparing to the control group) – they only found some genetic differences later (of course it’s difficult to say how this change in genetics influenced the behaviour of the mite – so how less virulent it actually was and what could that “lower virulence” in the mite actually mean?)
But remember that the varroosis effect is summed up from such factors:
1. the presence and the population numbers of the mites in the hive;
2. the presence and infestation rate of the pathogenic microflora that mites transmit;3. the level of virulence (the ability to infect and kill) of the pathogens mentioned in point 2.4. the level of tolerance of the bees to pathogens transmitted by the mites (it’s not 1-0, tolerant of not – it’s a spectrum); 5. the level of resistance of bees to varroa mites (ability to control the population of the mites by the bees) – this is also in the spectrum and not 1-0 (fully resistant vs non-resistant)6. (probably some more factors here)
E.g., in Australia they have the mite right now, but they don’t have DWV which is said to be the most virulent killer of the bees. So they have varroa mite, but their “varroosis” is different than our “varroosis”. They have the mite infestation level even up to 100% (statistically there is a mite on each bee), but the bees – at least some of them – can cope with it, as there is no killing virus. Meanwhile in the USA or continental Europe it is said that 1-2% is enough threshold to treat and 8-10% means death of the colony – sometimes more, sometimes less (because of virulent viruses). [so the disease varroosis is not equal to parasite varroa mite]
So in the case You presented (assuming causation) there could be some scenarios. I would say the most probable explanations are:
1. the bees were not actually very resistant – they could cope with some varroa but when the mite pressure grew because of more bee density it was over their ability and the population of mites outgrew the tolerance;2. the bees were resistant enough and tolerant to local pathogens, but the “new” bees brought some pathogens to which the local population was not resistant (like bringing diseases from Europe to America decimated the local Indian populations). 3. more competition for food and resources, more pressure of robbing etc. made bees more stressed with the external factors and they stopped taking care of themselves as they used to before (it’s a living complex organism that reacts to the environment).
There was an experiment run in Germany (it’s mentioned in the footnotes of my book) where they counted mites in the colonies in lower density region (around 2-2,5 colonies per km2) and higher density region (around 4-5 colonies per km2). And the average mite population in the first group was like 200-300 while in the second group it was over 1000. So just increasing the numbers of bee colonies in the regions makes a huge difference in the mite pressure on the bees.
So to sum up – I’d agree that there is some similar adaptive mechanism that You mentioned in the comment, but I believe it’s not based on the mite diversity but rather some tolerance of the bees to the pathogens and the virulence of pathogens.
But of course that is just my opinion and somehow a guess. We may just name the factors that we know of, but they are so complex that it’s very difficult to say which one influenced the most in the specific situation 🙂
Best wishes to You
Bartek