Treatment select for increased reproduction rate

Varroa mites multiply in bee larvae. After they come out of the cell when the bee is fully formed, they sit on the adult bees and suck hemolymph.

It was observed many years ago that during the brood period of the bees, 2/3 of the mites was found in the capped bee brood cells while 1/3 was on the bees.

VarroaBin2 Varroa mites on bees. Many years ago 1/3 of the mites were sitting on bees while 2/3 was found in the capped brood. Today this has changed to 15% and 85%. (Photo: Anders Berg)

If the mites had been sitting longer time on the bees than they did, before they returned into a brood cell, a greater proportion than 1/3 had been found on the bees. If they had been sitting less time there would have been a smaller proportion found on adult bees. The shorter the time the varroa mites are sitting on adult bees, the faster they return into a new brood cell to reproduce. This would increase the speed of varroa reproduction in the bee colony.

It is thus from the beekeeper’s and the bee colony’s point of view desirable that the mites are sitting as long as possible on the bees, resulting in a slower development of the varroa population. So, if the proportion of mites had been ½ on the bees and ½ in capped brood, this would have been better than that found for a number of years ago when varroa mites had arrived.

In early December 2015, two professional beekeepers from the Spanish mainland came to the small island of La Palma, one of the Canary Islands, and lectured on the varroa problem (http://archiv.resistantbees.com/phoretische-varroen). One of them was Manuel Izquierdo Garcia, a biologist at the University of Seville. (Thanks Rüdiger Dietrich who drew my attention to this.)

30 years ago when varroa mites came to Spain, the proportion of mites on the bees was 1/3 and 2/3 in capped brood. During the past 30 years, the mites’ behavior have changed. You could say that during the 30 years of conventional treatment of bees to kill mites, the mites have responded by spending less time on the bees to accelerate their reproduction rate. They have also changed the place on the bees they usually sit, from the abdomen to the middle part of the bee.

The result of this change has resulted in 15% are found on the bees (previously 33%) and 85% in the capped brood (previously 66%).

VarroaYngel2 Mites are sitting shorter time on the adult bees. Thus you find at a given time 15% of the mites on the bees today and 85 % in the brood. This have increased the reproduction rate of the varroa population.

Increased treatment

This change has consequences for beekeeping. It explains why we in Europe have had to increase treatment to kill mites. There are examples of recommendations in several countries where the fight starts in spring and continues throughout the season. And anyway, or should one say, maybe sometimes also because of this, the bees have difficulties to survive.

Powdered sugar

Some types of treatment will also be less effective due to this change. Treating with powdered sugar, only kills the mites sitting on the bees. One must fight very often if powdered sugar should have any effect of relevance.

Oxalic acid

If there are still small areas of capped brood when one uses oxalic acid against the mites, the oxalic woun’t have the effect one wants. This becomes more relevant when climate change means warmer winters, as it will be more common with brood in winter times, the time when oxalic usually are used. It becomes even more important keeping bees that really have brood-free periods during winter, also for treatment free beekeepers.

Treatment is a dead end

It is becoming increasingly clear that it is a dead end using all kinds of chemicals against varroa mites. And it is with the increased reproduction rate of the mites more difficult to select resistant bees and get areas with treatment free bees – which is the solution.

Focus on varroa resistance

All this show how important it is to focus on producing as varroa resistant bees as possible and develop management methods without chemicals. It is important that all beekeepers understand the problem and are involved at least somewhat.

Every beekeeper can at least try to identify which of his or her bee colonies are the least good in resisting varroa mites and replace the queen(s) in those. The simplest way is to just remove the queen in such a colony and let the bees rear a new of their own. It is not the best method, but a start. Then you can make more steps in improving your bees, depending on interest and opportunities.

31 thoughts on “Treatment select for increased reproduction rate

  1. “The simplest way is to just remove the queen in such a colony and let the bees rear a new of their own”
    Simplest, yes, but this raises a new queen who will inherit the characters of the queen you are replacing. Far better to remove the queen, insert a frame with new laid eggs from the best colony you have into the center of the brood nest, and remove all queen cells on other frames. If this is done whenever you replace a poor queen, over time this will improve the genetics of your colonies, but don’t always use the same good colony or you may increase inbreeding..

    • Yes Phil. Your suggestion is far better. I agree. And it isn’t very difficult either.

  2. If this increase of varroa in the capped cells is in fact true, then a method to eliminate the varroa while still in the capped cells would be beneficial. Two methods are available to the beekeeper 1. Mite Away Quick Strips that will kill varroa in capped cells and 2. Drone Capture Frames when the drone cells can be removed at 24 days and varroa destroyed.

    • You are right here Martin. But that’s not the only thing formic acid does. The experiences from Sweden I would say formic is difficult to use correct without any bad effects. When using it correct it works. But I have found thymol is safer to use, also for the health of the bees, and used during three weeks it has high efficiency. Drone capture frames I’m suspicious against as you select for mites preferring worker brood, which isn’t what we want. Actually I’ve found thymol is enough spring and late summer. But I have finally realized that bees can never develop the needed resistance unless at some point you stop treating the bees, at least one apiary at a time, that is enough isolated, which probably is 2-3 miles.

    • Hi Martin,
      in principle your conclusion to concentrate on mite decrease within brood is right, however, the next conclusion to use the “crunch” mite away strips is wrong in my eyes.
      You replace the problem by another and the only benefit within this strategy is that you buy time. However, it is inherent by nature to find an answer to this strips and mites will evolve that will live with the strips.
      This is demonstrated by their ability to adapt on several treatments, e.g. chemicals or others, as Erik highlighted in this blog. My conclusion is, most of our treatment system against varroa focus on selecting a strong mite (or better adapted mite) whereas the bees will be weakened (r better say not allowed to be adapted by taking all stock in the next year by using heavy treatment)
      Moreover, if you come from a broader perspective, you find exactly the same issue in animal farming with antibiotics and pesticides in industrialized agriculture. The point we have arrived here is scaring, if one compares the beginning by starting with low doses of one antibiotic the 60-ies and ending by using high doses of coctails of antibiotics right now. THe current peak is Kentucky fried chicken, who purchase chicken from a chinese mass chicken production, which uses 19!!!! antibiotics in 23 days when a chicken is raised. And stil they are having rawbacks by bacteria. They same issue you have with pesticides, their consumption is inceasing by year, with their devasting effects on nature in general and on bees in special. However, weeds are adapting and I heard that in South America and US framers start to get rid of weeds manually, because weeds can’t be backfighted by pesiticides anymore.
      Having said that, the only alternative in a long term perspective is to get rid of any treatment and allow bees in a long term to adapt on mites as well.
      Hence, I completely support Eriks conclusion, that treatment is a dead end!

  3. All of this debate has left out the most important thing:
    IPM or Integrated Pest Management.

    IF you use one chemical treatment time and again, you will select mites resistant to it. But if you alternate between different treatments (including non chemical like drone trapping), then the mites that are resistant to chemical A will be killed (or the majority of them as no chemical is 100% effective in practice) on the next treatment, as long as it is a different class of chemical. This was the problem in UK when the only two approved treatments (Apistan and Bayvarol) were both synthetic pyrethroids and resistance to one was also resistance to the other!!
    So varroa control is not ‘Oh dear I have got varroa, I’ll have to teat with xxx again!’, but a planned programme of monitoring floor inserts and using different treatments.

    • Shifting treatment types between the years is far better than sticking to one until it fails, also for the bees, generally. But chemical treatment from many areas, including bees, has learnt us in the long run new problems arise all the time. When you use chemicals, which you might do, as I did, to be able to put food on the table, you ought to realize you have to focus on finding ways to finally get rid of the chemicals.
      Now so many beekeepers have succeeded in landing there, that it should inspire and give hope to the rest of us to put more efforts into it.

  4. hello together
    your talks are very interesting because i make same experience with my treatments to bee-hives.especially when i changed a treatment which was not correctly used from my side ,or used a bit later then before i have lost many hives in short time . in the end of all traetments i feal very clear to stop with treatments as soon as possible i can change to small cells collonys.but my carnica-bees cannot build 5,1mm or even 4,9mm it properly right. since many years i do not feed sugar -have my own wax circulation from newbuild honey frames, breading the new queens only in their original quenns cells and let make their married flight at home . i see that bees a getting stronger trugh this work but also have their biggest problems with the big cells(5,4mm) to get rid of varroa in young stadium(vsh) before its ist to much for the healthy hife.
    heartly from pita

    • Pita, you can try plastic frames from Mann Lake to help your bees coming down in cell size. http://www.mannlakeltd.com/beekeeping-supplies/category/page19.html
      A problem can be different frame sizes. But the plastic frames are possible to use a saw and cut them into smaller sizes. It works, even if sometimes on one side the spacers will miss. It’s enough to use 4-6 frames in the middle of a brood box. You will probably have to use them for some years until your bees are well adapted to a smaller cell size. When the bees draw them bad it’s easy to cut the wax down to the foundation and let the bees start from the beginning again. It’s important to roll on liquid wax before putting in the hive. It’s no problem if you use too much of wax. The bees will take care of it.

  5. While its interstiong information, I would love to see some facts. The conclusion is also very troubleing. We here in public are the Ambasadors to beekeeping. getting someone started under the guise of not treating is disengenious at best. While the goal of genetic restince is fantastic, so far 20 years of experince and attempts by many have failed to produce and marketable abilities. Like it or not the current situation is to stay on top with rotating tratments. The dream of varro restiance is being pursued in several areas and by some people who are darn good at it. Until such time there is some real succes, claiming treatments are the problem is the same as trying to live with polio when there is a vaccine.

    • I’d love to see more facts than just trusting the scientists at the university of Seville that reported the changed distribution of the mites. So I’ve aasked for it. We’ll see if we can get them.
      Mites spending shorter time on the adult bees before entering a new brood cell for reproduction give a quicker total reproduction rate of the mites, no doubt.
      Glad you recognize the fact that several beekeepers have succeeded in producing a resistant local stock. Or did I read too much into your writing? Anyway, that’s a fact. And they did it without being darn good, but just good. That’s enough. And if be study how they did it, it’s much easier for us. Then it’s enough to be an ordinary beekeeper.
      What you need is first a quite isolated area, 3-5 km (2-3 miles) to other bees, and not hundreds of bees at that point. Use small cells in major number of brood combs (for example the Mann Lake standard whole plastic frame). Make 1-2 splits every year from the good colonies. Shift queens through queen pupae from the good ones in the apiary. No one of these beekeepers monitored mite levels, but I think it’s good to do it and take some kind of extra action if mite levels rise too high. Don’t bring in package bees or nucs or colonies after you started to see progress. But try out a few queens from beekeepers saying they have good stock. Bring out colonies when you get too many and establish new apiaries nearby. You can do it with 5-10 colonies, like some have done, and some have grown to hundred colonies or more.
      Don’t worry, I don’t promote stopping with treatment whatever situation you are in, that would be foolish. I didn’t. I’d have lost food on table that way.
      Start with trying to get some good queens from somewhere if it’s possible. Otherwise just start recognising the least good colonies and shift queens in them. Monitor mite levels through downfall of mites or alcohol wash with the bee shaker. Get away from the hard chemicals and use if you have to milder like Thymol.
      If you read more on my blog I think you understand me better.

    • Charles,
      what facts do you want to see? Since the start of varroa treatment the treatments become heavier and is not just one as in the beginning, there are several distributed over the season.

      Secondly, it is a matter of fact, that mites adapted on several ways of treatment. I recently read that mites in the beginning of treatment with Apistan are susceptible to 10ppm. After several years of treatment mites need 100000ppm, to be killed. The source is german http://www.voralpenhonig.at/index.html.

      Thirdly, the situation of the bees has become worse and worse, which is because insectizides that are promised to not affect bees of course kill bees as well on the other hand.

      On the other hand, there are several beekeepers that going on with treatment free beekeeping in the US and in Europe for years now.

      Taken together our responsibility is, as Ambassadors is to teach alternative ways of beekeeping that secure the nature and in the end of the day ourselves. And as pointed out these ways are working….:-)

      T

  6. Are You sure, that mites hiding in the capped cells are always reproducing? I mean is the theory of increasing reproduction rate proven. I’m sure that it’s true somehow, but I’m not sure, that 85% of “hiding” varroa mites, means increasing reproduction rates for sure with ALL of these mites.

    What I’ve read about VSH (probably even on Your blog, but I’m not sure of that, maybe on beesource or resistantbees) is that bees uncap ONLY (or mostly) cells where mites reproduce, but skip cells where varroa female is hiding BUT NOT reproduce.

    Wouldn’t that mean (maybe?) that varroa just hide in capped cells? I’m sure they increased reproduction a little, and maybe we made varroa evolve quicker by treatments, but I’m sure varroa mites have their biological cycles, and probably we made them mature somehow earlier, but I’m sure that thay cannot reproduce UNTILL they are fully mature.

    Maybe the “new” ratio (85 – 15 % – which for me is undoubted) only means that we changed mostly habits of varroa (meaning they mature in cells not on the bees), and not neccessary their ablility of reproducing?

    It’s just a thought… (hopefully I made it understandable with my English)

    regards
    Bartek, Poland.

    • Hi Bartek,
      your are right in pointing out that VSH is both hygienic behaviour (uncapping of infested brood where mites are reproducing) and secondly not uncap brood where mites are in but nor reproducing, hence having a low OVR (ovipositioning ratio). Normally, the ratio is 6, which means one non reproducing mite to 6 reproducing mites. VSH stock distinguish by having low OVR ratios 2 or even 1 ore even below one, according to Harbo et al.

      Secondly, if you look at “normal” host parasite interaction, there will be a balance between host and parasite after time, which mean: The parasite (mite) can’t be to infectious, as this will kill the host and finally himself. Hence, all superinfectious parasites kill themselves in the end of the day. On the other hand all susceptible host will be killed as well. This ended up in the mentioned balance, of not too infectious mites and resistant enough stock that build up a coexistence.

      There are enough examples out there, that illustrate this basic biological knowledge. E.g. for Apis cerana in Asia, for this russian type Apis mell. mell. in Sibiria, for the Apis mell. capensis and Apis mell. scutellata in South Africa, for the bees Apis mell. mell? in Arnot forest (US) and for the bees that are not treated in Gotland island. It is all the same story with some variation of course. All of these bees where not treated and left alone to built up their coexistance. In all examples bees find their way to fight back the varroa in the given way and develop resistance.

      On the other side, in all countries where treatments are used, bees become more and more susceptible, treatments become heavier and mites become stronger as pointed out before. I’m not aware of only one example, where these natural principles are disregarded, bees are resistant, even with the sophisticated integrated pest mangement…

      Everybody who has a head on his shoulders can think about these facts and can draw his own conclusions…..
      In case he want to fight against nature the result will be endless treatments and weak bees, as Pita has described as well. He can be as sophisticated he wants to be, this only buys time. But finally he will loose …..

    • Hi Bartek. Interesting speculation, but all investigations of the fertility of mites in brood for bees not selected for Varroa resistance over the years show about the same high fertility. It is probable that that would include the Spanish bees. We only have figures of 85%/15% from Spain, yet. I can’t see any reason for mites now to mature slower, so that they as they usually are ready to lay eggs when they enter a brood cell for the first time. But even if they waited until the second time they entered a cell to lay eggs. That would only be a small slowdown, that soon would be caught up by the growing population of mites.
      Regradless of the distribution of mites in a hive, 85%/15% or different, treatment against mites is a dead end. especially as it is shown to be not very difficult to evolve a resistant stock. The more that are involved the quicker the total solution of the Varroa problem will arrive.

      • I wasn’t saying we should treat. 🙂 My comment wasn’t about that at all. I think I was misunderstood or I understand wrong Your replies to my comment.

        My apiary is treatment free. I did not treat my bees 2014 (I lost them all, though), and I haven’t treated them 2015 (for now they are all alive as far as I know).
        I agree completly we should look for the balance between the parasite and host, and being treatment free is the only way.

        I was just saying that maybe mites don’t reproduce faster, but just changed their habits and hide from us (that is from our treatments). that’s all I ment 🙂 That was just speculation. I know no studies to back it up.

        • Sorry to know you lost all colonies in 2014 Bartek. I should suggest a somewhat different strategy för 2016, if the bees survive, than you used in 2014. Maybe monitor mite levels. Be sure to identify the lest resistant colonies in some way and keep those colonies down by killing the queen and then requeen the colony in some way. Split the best colonies, to multiply them and to keep down the mite populations. If mite populations grow too high you can take out all capped brood twice with a week in between. That’s effective.

          • Thanks for Your suggestions.
            In 2014 in my region (near Kraków, region Małopolska) we had enormous losses – no matter if the bees were treated or not (of course they mostly were treated – as far as I know only mine were not). Thousands of colonies died. Many of my collegues also lost all their apiaries even they were treating. It was said that 2014 was probably the worse year since varroa came to Poland in 1980.

  7. It is always sad, both for the beekeeper but also for the bees, when there are heavy losses of colonies.
    There needs to be a balance between the desire not to use chemicals, and the welfare of the bees.
    Although I have had varroa for many years, I have not had any losses. I treat all colonies with oxalic acid in the winter and sometimes will treat a swarm. I used to trickle, now I use a vapouriser.
    I have floor inserts and monitor mite drop regularly, and treat as necessary, giving preference to non chemical methods. I use the varroa calculator to see if treatment is needed:
    http://www.nationalbeeunit.com/public/BeeDiseases/varroaCalculator.cfm
    There is a link on there to ‘Managing Varroa’ which is a very useful source of information.

    Selecting for varroa sensitive hygeine (VSH) can be done. Leaving the bees to select naturally needs many colonies, as most will die out, as someone has already said. It is better to select by removing a frame, killing a batch of brood (laboratories with liquid nitrogen use that), and replacing the frame, and counting how well the colony removes the dead brood.

    However, VSH is a recessive character, so subsequent generations will lose the trait if the queens mate with non VSH drones. So VSH has only been successful where the beekeeper continually selects, or where all beekeepers in an area have VSH colonies so queens mate with VSH drones. Only where VSH queens are easily available will that be possible.

    • I don’t advocate buying packages or new colonies every second year and let the bees suffer from mites and die. There are alternatives when you don’t want to use chemicals. Oxalic is a chemical as well, and thymol, even if it’s said they’re natural. They’re most often not produced of natural products, and they leave residues too. They are used in concentrations not natural for the bees and disrupt a development of natural resistance. But I understand when the decision is taken to us it, even sometimes concerning chemicals that leave more harmful residues.
      That said, I want to stress the fact that it’s well possible to develop resistant stock, even for hobby beekeepers, without knowing much of science. If you learning some simple principles from that have done it. Darrel Jones in north Alabama and Richard Reid in Virgina are beekeepers that started out small. Jones is still on the smaller scale. Reid has grown to 70 big colonies and 100 nucs (overwintering) and is still growing. Both have their bees at least 3 km (2 miles) from other types of bees. They started with bees that they thought had more resistance than other bees. They make a lot of splits and nucs. After some progress they don’t bring in new packages, nucs or colonies. But try out some new queens now and then. Jones stopped treating in 2004 and now has a daily downfall of mites of 0.3. But he doesn’t monitor mites regularly. Reid began with bees again in 2008 and has never used any treatment. He doesn’t either monitor mite levels. Reid had one big winter loss in winter 2012/13, but otherwise have 10-15%. Earlier it wasn’t uncommon to see wingless bees for him (DWV). Now he never sees any of those any longer.
      VSH is an additive gene allele character according to John Harbo, one of the developers of the VSH breeding method, not a recessive one. In his findings two genes are involved, thus four alleles. If all for alleles are present you have 100% VSH character. If two alleles are present you have about 30%, which is enough to give resistance under favorable circumstances. I though think the picture is somewhat more complicated. There is a general hygienic behavior reacting on every mite, not only those with offspring. And there are maybe different levels of the mite when the trait starts working.
      It’s been found, if I remember correctly, that if a colony is highly hygienic for removing dead brood (what is the way brood hygienic behavior is measured) it shows somewhat VSH trait. It is a week connection that way. If a colony is highly VSH, it is not following as a consequence that the colony is good in removing dead brood. The trait for removing dead brood is a recessive trait, and governed by probably four genes (maybe different number depending on the findings today).
      What I want to stress is that it’s very rewarding for any beekeeper to try to identify the least resistant colonies and in some way shift queens in those. I think it’s good to monitor mite levels. And a method of removing an efficient number of mites without using any type of chemical is to remove all (including worker and drone) capped brood twice, with a week in between.

  8. I think you are correct in more detail about the genetics of VSH, I tried to keep it simple, but I think we are agreed that it is complex.

    My concern is for the bees belonging to beekeepers who think it is simple, can be done with few colonies, and then many colonies of bees die. I have much sympathy for the bees in that case, none for the beekeeper.
    The selection method I mentioned kills a number of eggs and larvae and pupae, but adult bees all survive.

    • I think we have the same concern Phil. And I think you are engaged in resistance selection as well. Varroa resistance is complex and I think the bees develop it the best. We can help them do it. Even with a restricted number of hives, if we are quite isolated from other bees (not 100% is necessary). But to succeed you have to give them right conditions. Better start with bees that already have some kind of resistance. Better start with a low mite level. Better try to keep the mite level under some sort of control. Breaking the brood period by splitting for example. Increase the best genetics by splitting as well. Shift queens in the least good ones.

  9. Very true, good luck with your bees.
    We need more beekeepers who love their bees!

  10. Eric,
    The varroa situation outside its historical range is still very dynamic. We wait hopefully, if not expectantly, for successful isotopes to emerge from the murky pool of mellifera’s genes. Varroa currently has few natural enemies outside of bees and people. If nature follows its usual course, that is likely to change. Viruses, microbes, fungi, other mites, or other natural enemies of varroa will emerge. One of the issues with treatment, and arguably, particularly with rotating treatments, is that we may interrupt or eliminate potential natural enemies of varroa. You mentioned in a recent post that you were going treatment free in one of you apiaries, but you were going to first use a treatment to knock back the mites and give the bees a head start. That treatment could also set back or eliminate natural enemies of varroa that may be beginning to arise. The possible adverse effect of that can be made worse where the apiary is isolated from areas where those potential natural enemies of varroa exist.

    • David
      Your reasoning is logical and good food for thought. One reason for few natural enemies in the form of predators chasing mites or the like (it exists), researched and reported as far as I know, may be that the bees’ ability to adapt and cleanse themselves from mites is strong. A side effect of all kinds of Varroa treatment is bad effect on the micro fauna (and flora, maybe microbes are counted here), in the bee colony. And this at least has no good effect and probably a negative effect on fighting the mite. Also the health of the bee is affected, but that is also the case of side effect of the mite sucking hemolymph. Another bad effect is that the chemical most probably is disrupting the adaptation of the bee to the presence of the mite and to fighting it better.
      So yes, I had that in mind when I thought of the best way to start an apiary treatment free (chemical such of all kind including acids and essential oils). But as the situation now is that the virus level is evidently quite high in the apiaries (which in a way is not only bad as the selection pressure for selecting virus resistance is good). And that is most probably due to a constant little higher varroa level in the apiaries (together with using acaricides makes the bees more susceptible to viruses). (But to be remembered also is that the net result for my beekeeping operation, which includes ability to select for varroa resistance to some degree, is a reasonable loss of hives and a crop, though going totally treatment free and finally coming back to a beekeeping situation like before the arrival of the mite, total stop for treatment at some point is needed.)
      But I also knew that the beekeeper in southern Sweden that went totally treatment free just like that, did so by introducing queens from me in splits from colonies that had been treated with Apistan for maybe 4 years. Then moved those splits to an apiary at least 3 km (2 miles) from other bees into the forest. That’s why I decided to try that alternative, treating with a pyrethroid. We’ll see if what happens this season.

      • Erik,
        Thank you for your thoughtful response. (I confess some awe in corresponding with you in your own right as well as considering your history with Brother Adam.) I appreciate the immediate economic considerations on you, your operations, and, importantly, your research, and, from your position, I would accommodate them as you have. I would however be a voice on your other shoulder to state that successful adaptation will involve genetic selection of not only bees, but also the mites themselves, the viruses they vector, and actual and potential natural enemies of mites, including natural enemies that suppress mites by contributing to conditions within the bee, the mite, or the greater hive that are not conducive to the mite’s growth or reproduction. Arguably, a larger initial pool of genes for each of these creatures in isolated test yards is potentially helpful to that adaptation.
        David

        • David,
          The only genetic selection I make selectively on only one trait is VSH. And that is not made first in the line of selection methods, but rather maybe second in line, maybe third.
          The bees and whatever other ‘playmates’ are involved are allowed to compete and adapt to each other in whatever way they want. That is anyway the intention. What I have discovered is that the way I have worked this intention may have been performed to a degree. But to really let the game be played according to the rules of the involved (except me) is to stop treatment chemicals totally. And that’s what I have started to try to do and still keep some kind of control not letting the mite level rise to high. I do hat through making splits of the colonies that are not bad (good ones) and shift colonies as soon as possible in the bad ones. I may have to reduce the mite level. And I see two alternatives, pulling all capped brood twice with a week in between. Or remove the colony to a ‘hospital’ yard and treat it with thymol. Then shift the queen.
          As you see, I accept it if the involved ‘players’ choose to adapt mites as well as bees, or other members of the micro fauna. I’m looking forward to the final result.

  11. All this ‘ let evolution take its course’ is al very well, but IIRC when varroa hit USA a beekeeper with about 1000 colonies did just tat,and lost al but about 2.
    So if you can stand that rate of loss (financially), and are happy ith many hundreds of bee colonies dying, go ahead!

    I personally don’t have that many colonies and would not be happy to kill (dare I say by negligence, when means of keeping them alive are available) many millions of bees.

    If you want VSH, then either buy VSH queens and requeen, or select for it yourself by accepted means of killing patches of brood and selecting colonies best at removing the dead borod.

    • Phil,
      Read my answer to David. To just buy some colonies from anywhere without checking for eventual resistance traits, and just stop helping the colony against the Varroa is not kind to the bees and a waste of money and work. If you have read my blog I think you realize that I don’t promote such a behavior.
      There are though good strategies that help all beekeepers making their bees more resistant. And many many beekeepers have the resources to help their bees to make it the whole way.

  12. I am not recommending to
    ‘just buy some colonies from anywhere ‘

    I can ony conclude you do not care about your bees, and are happy for millions to die.

    • Read the whole sentence and context please Phil.
      … and just stop helping the colony against the Varroa is not kind to the bees and a waste of money and work.
      So I don’t follow you reasoning to arrive at the conclusion of yours. Your conclusion is not in tune with the line above.
      I think you care for the bees. That’s why you help the bees to survive against he Varroa with the help of drugs. The problem is that the Varroa problem is growing in spite of the use of more and more chemicals more and more often throughout the season in many countries. The only longterm sustainable solution is to help the bees to evolve to fighting the mite with their own abilities. I think this is possible in a way that fewer bees will die than it is with what is sometimes called conventional chemical treatment methods.

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