How can I improve Varroa resistance?

I use Top Bar Hives. For my first two years I used Apilife Var, oxalic acid etc and basically, there was a varroa problem each year. So at the start of this season I decided to clench my teeth and avoid miticides, since I knew of a few examples of natural beeks developing varroa resistant bees by the Live And Let Die strategy. And there’s been a thriving feral colony in a neighbour’s roof nearby for 5 years. So it’s obviously possible.

So as we near the end of this season, I find the varroa counts are around 50/day and rising, despite a sugar dusting a couple of days before the last count. So I suspect that this strain of bee – originally Buckfast, probably just half Buckfast genes by now – have become used to someone else sorting out the varroa, and will never get the idea that they need to do something themselves. Reading around, the population dynamics of varroa are such that you can get away with non treatment for one season, but if they start off heavily infested next season, the mites will chew through the colony in no time. Unless they develop coping mechanisms, and this lot seem clueless.

This is especially frustrating as the hive 2 feet away contains a cast given me by Gareth, descended from a hive which has not had varroa treatment for 5 years, and it has a drop of one per day. Which shows that it is the bees, not the local area that is the problem.

So I’m wondering what I can do to help these wimps get a handle on the problem. The most obvious is better temperature control. Now the main nectar gathering / evaporation period is done, ventilation isn’t as big a problem, so I have sealed the bottom of the (mesh floored) hive. This might enable them to cook varroa to a point where they stop breeding.

I will sugar dust, but I gather this isn’t really effective, it just knocks phoretic mites off and doesn’t get the ~50% sheltering in cells – and due to some unknown reason, possibly less competition among the remaing mites, their breeding rate is almost unaffected. So sugar dusting is more a cosmetic thing than a practical solution.

I don’t want to lob an essential oil like thymol in there. I reckon just because a chemical is “natural” doesn’t mean it doesn’t upset the hive balance, for example the microbial microfauna. That’s just blind meddling; even though there’s evidence it stimulates chucking out of substandard brood, there’s little research on its other impacts. Anyway, brood laying will be dwindling now.

I would welcome any other ideas about how I can improve the hive environment to maximise this colony’s chances of dealing with the varroa themselves.

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7 Responses to How can I improve Varroa resistance?

  1. johnmkubwa says:

    Paul, I have not used any varroacide since 2008. Colonies seem to have adapted and are coping well. I have lost a few colonies on the way but I also cull weak colonies rather than prop them up.
    Husbandry is key:
    1. Enabling colonies to regulate their own temperature (optimum brood rearing for bees 35/36 degC; for varroa 33 degC. Opening hives cools the brood nest and favours varroa.

    2. Allowing bees to swarm breaks the brood cycle which disrupts varroa in the swarm and the home colony.

    3. Colonies naturally exhibit hygienic behaviour and will eject anything damaged such as deformed drone pupae or bees with deformed wings.

    4. All chemicals damage bees (brood , drones and queens) and also disrupt genetic responses e.g. identifying varroa as a pest and doing something about it.

    5. Hive design has an effect on the above. Open mesh floors cool the hive; varroa do fall through but the pest persists. In a ‘National’ the floor is only 1/4 inch below brood frames. Warrés have solid floors or sumps; often 8 inches from brood combs( fallen varroa cannot easily jump back on and cool draughts are minimised)

    6. Allowing colonies to make their own comb reduces the pollution of foundation ( recycled from dozens of unknown hives which have used a cocktail of chemicals) Making new comb requires temperatures around 40 degC.

    7. Allowing bees to live on their own honey rather than sugar (fed after beeks have taken all the honey)is essential for strong immune systems.

    Some of our group are getting bees from members with adapted bees and we are spreading the community of non treatment and adapted bees. Many are using swarms and not treating; there are successes and failures. But if the Bee is to be self-sustaining we need to start somewhere – with me it was 2008. Buying commercial, treated bees is starting from scratch and risky; Queens are often imported from abroad and not adapted to our climate let alone forage and varroa. Some people have just started introducing an indigenous mite to predate on varroa – early days….

    Lots to think about and worry if you have only one or two colonies. but IMO the Bee can do it – man does mess it up!
    JohnH Stockbridge, Hants

  2. simplebees says:


    You find yourself in the dilemma that many non-treaters face sooner or later: what to do when varroa counts are high? It is to avoid exactly this question that those who make the decision to stop treating often stop counting. I stopped counting when I stopped treating for exactly that reason. The dilemma is always made worse when one has only one or two hives: they become more precious to us. But that preciousness can be exactly what stands in the way of a wider solution.

    The received wisdom is that a hive with counts at the level you report will not make it through the winter. Yet I hear stories of hives with very high counts that do get through and then go on to thrive, coming back from the brink. Whether there is some mechanism that only gets triggered by a very high infection level is an open question.

    As a small example, the hive you gave me in 2012 showed a high fall on the one occasion I sampled it at this time last year (not as high as yours, admittedly, but high enough to be concerning), but it came through the winter and subsequently filled 5 boxes and superceded its queen. If I were a honey-forcer I could have taken perhaps eighty ponds of honey from it this year.

    So your hive might come through and, there again, it might not. As I know you are well aware, the bees overall know what they are doing and we need to have the courage to assist (as John has so clearly set out above), but not interfere. Interference is the easy route, non-interference takes courage.

    It sometimes helps to think of the hive as a complex information processing system with all sorts of algorithms. Every time we interfere we put extraneous input into that system and risk unbalancing the output in ways we cannot possibly predict.

    Gareth, Cotswolds

  3. Paul says:

    Well with such consistent feedback from two of the most eminent practitioners in the field – who have proven their assertions with results in the field – I feel reassured about the non intervention path. Particularly as a related colony seems to be doing fine with Gareth. Perhaps they *do* need a high level to trigger the workers to have a damn good clean out, “and don’t forget the kids’ bedrooms!”
    I already use most of John’s points but I understand you are setting out the whole lot so others reading this will see the whole picture. There is one idea I pick up from there though (apart from laying off the sugar dusting). The entrances to my TBH are a little way up from the floor. This makes it difficult for undertaker workers to haul things out up the vertical drop… at least I assume that’s why the floor is littered with an extraordinary array of rubbish like a teenager’s nest. I actually built a little ramp inside the other hive while it was empty to help them keep it clean! Need to sort that out in the big occupied one. Oh joy. Maybe some plasticene…
    If the big-but-infested hive does fail next year, I’ll just have to man up and replace it with a swarm, rather than Buckfasts (which I now worry are a bit inbred).
    I had a thought which might be worth trying if things go too far next year. Transfer a comb of brood from the varra resistant hive to the failing one. As the new brood mature, they may be able to teach the clueless workers how to deal with varroa by example.
    Thank you for the feedback!

  4. Julia says:

    I am not sure my thoughts count for anything, since I am a total beekeeper beginner. Would it be possible to help your hive, without medicine, to at least pass through the winter, then in the swarming period, hope that the hive swarms. If I understand the theory, the swarm will be healthy and perhaps genetically better prepared for diseases. Then let the original hive die a natural death. This way you select for healthy bees. Whatever you decide, wishing you lots of luck and healthy, happy bees. – Julia, Liguria, Italy

  5. Julia says:

    Thank you John, thank you Gareth, for the clarity of thought. This helps tremendously! I don’t think it can be repeated and brought to public eye too much. Appreciate very much Paul’s questions as they are very helpful to see what others come across. GRAZIE!

  6. George says:

    Great thread! Facing the same dilemma myself near Abergavenny! But I have only one hive. I am a beginner so everyones views are really interesting. I am going to have to keep my fingers crossed that my hive will survive. Interestingly, mine are also buckfasts. I guess the good news for you is that if your hive fails – you can fall back on a small split from your varroa resitant hive – probably a good strategy anyway. Good Luck and thanks.

  7. Paul says:

    Just noticed Julia’s comment about the swarm. What an interesting idea (actually it would be the colony left behind that was a new strain, because the original queen would leave with the swarm). It would be simple to do, because I could put such a swarm back in the other end of the TBH with a divider between them. Typically the swarm would supercede the queen (i.e. kill her once she reared a replacement). Then – optionally – I open the divider and reunite the colonies, which would be simple as their smells would already have mingled (and they’re half sisters anyhow). They can choose which queen the new united colony will use; both will only have half the genetics of the original queen. You are right, this should strengthen the genetics – hybrid vigour. A possible downside might be that the result of crossing Buckfasts with any other strain is said to give a ferociously aggressive crossbreed, but I’m not sure I believe that as I suspect the bees in my big colony are only half Buckfast now and they seem gentle.

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