Coevolution of Honey Bees and Varroa Mites: A New Paper

[mike bispham]

I have observed there seems to be a size cut-off for being able to go totally treatment free. I cannot tell if it is because of the ability to provide more oversight of the hives or if it is the "too many rats in tha cage" effect. The larger you get, the harder it becomes to stay totally treatment free. It seems to be that way with many animals.

As I understand it John Kefus and his partners have managed this - I think they run several thousand hives. I think operations on that sort of scale are requeening yearly, and I would think it would be necessary to be taking breeding queens (and sourcing drones) from the farmed stock, in order to be managing a process of co-evolution with the mites. But it could be there is just too much horizontal transmission of mites genes to allow the milder, less fecund strains of mites to evolve - something that is I believe key.

It may be too that there are limits to the degree to which you can pack hives and expect them to thrive without throwing chemicals at them. Like battery hens; at a certain size and density its impossible to continue without systematically feeding antibiotics.

In theory at least a large operation could be composed of a number of smaller genetically independent apiaries - in which case any such critical-mass problem shouldn't exist...?

These are just my own thoughts mind...

[mike bispham]

No, I haven't read or experienced Marla Spivak's training or advice. I have used some queens which came from her stock. I shouild look into what you refer to. Any advice on how to go about that? A websearch probably, right?

You could start from here Mark. There may well be more up to date stuff from Marla and her colleagues out there - I haven't looked in a while. There are links to other related documents.

http://www.suttonjoinery.co.uk/CCD/selected%20links.htm

This links to her Bee Lab at the University of Minnesota, from where information on her courses can be found:

http://beelab.umn.edu/

Mike

[Solomon Parker]

But it could be there is just too much horizontal transmission of mites genes to allow the milder, less fecund strains of mites to evolve - something that is I believe key.

I'm not sure I follow you. It's the more virulent mites that must evolve to be less virulent. One prime way that is done is by letting them kill hives and thus remove themselves from contention. At the same time, good bees will be able to deal with any kind of mites, otherwise treatment-free beekeepers would see periodic crashes as once in a while the virulent mites will occasionally get into the system. I don't see these crashes, nor does anyone I am in contact with.

[mike bispham]

I'm not sure I follow you. It's the more virulent mites that must evolve to be less virulent. One prime way that is done is by letting them kill hives and thus remove themselves from contention.

Hi Solomon,

My starting point was the general principle that horizontal transmission tends to encourage virulence, while vertical transmission favours (evolution toward) gentler strains. Virulent mites killing colonies can escape death themselves by moving sideways into other hives. This will occur far more where colonies are closer together, allowing robbing and wholesale movement into new homes of colonies failing because of over-virulent mites.

Where colonies are further apart, and there is thus less opportunity for sideways movement, the only mite strains that will survive are those that don't kill their hosts, and allow them to build sufficiently to swarm. These must be gentler (that probably largely meaning largely less fecund).

Too much horizontal movement thus allows virulent strains to prosper, and I related that to larger outfits where many hives are often close together.

I'm not sure I agree that 'more virulent mites must evolve to be less virulent.' I think its more the case that the more virulent strains who kill their hosts will perish, while the less virulent strains who don't will continue. Again, this process is made harder when wholesale horizontal transmission is available.

At the same time, good bees will be able to deal with any kind of mites, otherwise treatment-free beekeepers would see periodic crashes as once in a while the virulent mites will occasionally get into the system. I don't see these crashes, nor does anyone I am in contact with.

I agree. I don't think that observation is inconsistent with my understanding - but I could be wrong.

I suspect though that bees that do well with reasonably gentle mites might be overwhelmed by a heavy enough attack from highly virulent mites - though it seems that's not likely to happen very often in larger apiaries.

A lot of this is about questions of degree - which makes understanding and discussion harder, but I suspect its important to try to engage with it. It's not just about 'good bees vs bad bees', but about bees that are good enough for the conditions at hand.

Mike

[sqkcrk]

And what about the presence in this Country of two different kinds or strains of mites? Genetically different I believe. Is one more virulent than another? Or is it w/in a kind or strain that degree of virulence is found?

[mike bispham]

And what about the presence in this Country of two different kinds or strains of mites? Genetically different I believe. Is one more virulent than another? Or is it w/in a kind or strain that degree of virulence is found?

I don't know, but I expect the general principles we are discussing apply equally to both. In other words, there's probably no need to know.

[Solomon Parker]

I'm not sure I agree that 'more virulent mites must evolve to be less virulent.' I think its more the case that the more virulent strains who kill their hosts will perish, while the less virulent strains who don't will continue.

They are the same thing. You're making the assumption that more virulent mites cannot evolve to be less virulent and thus will hopefully extinct themselves. However, as is the normal for most species, there is a continuum. It may very well be the case that there is not enough genetic diversity to accomplish the feat, we don't know. But if more virulent mites kill off hives (and thus themselves, there will not always be another hive to move into) then the ones that don't will be the ones that survive.

On the other hand, I feel all this is immaterial. Mites are receiving strong selective pressures from the vast number of commercially kept and treated hives to become more virulent, to survive treatments. It would seem that mite adaptation would be moving in two directions among the two types of populations. However, the commercial population is much more cohesive and pervasive, therefore I conclude that the mites in general are adapting to be more virulent and survive treatments, and at the same time, the bees among the non treated and feral populations are out-adapting the mites, or have reached a tipping point where they have gained the upper hand.

For whatever reason, it absolutely can be done, which was not accepted to be the case a few short years ago. At first there was only Dee Lusby, then Michael Bush, then BeeWeaver, and now small treatment-free producers are popping up all over. I am one and I'm overjoyed to demonstrate the fact that bees can survive and thrive treatment free when a little more than a year ago, I was being told it couldn't be done. Hopefully, I'll get a few more chances to rub it in.

[mike bispham]

They are the same thing. You're making the assumption that more virulent mites cannot evolve to be less virulent and thus will hopefully extinct themselves. However, as is the normal for most species, there is a continuum. It may very well be the case that there is not enough genetic diversity to accomplish the feat, we don't know. But if more virulent mites kill off hives (and thus themselves, there will not always be another hive to move into) then the ones that don't will be the ones that survive.

I agree with this.

On the other hand, I feel all this is immaterial. Mites are receiving strong selective pressures from the vast number of commercially kept and treated hives to become more virulent, to survive treatments.

I think there are two separate kinds of virulence in play here:

First: virulence against the defences of bees (which largely relates, as I understand it, to fecudinity - do the breed so fast they cripple or kill medium-resistant bees?);

Second, resistance to treatments. This might have something to do with fecundity, but it might have nothing to do with it - its simply about being less affected by the treatment.

It would seem that mite adaptation would be moving in two directions among the two types of populations. However, the commercial population is much more cohesive and pervasive, therefore I conclude that the mites in general are adapting to be more virulent and survive treatments, and at the same time, the bees among the non treated and feral populations are out-adapting the mites, or have reached a tipping point where they have gained the upper hand.

I think that my distinction above is relevant here. Mites in the wild, and in non-treating apiaries are encouraged to become less virulent (in the first sense), while the second sense (resistance to treatments) is immaterial - they're not being subjected to any selective pressure vis a vis treatments.

In the wild and non-treating environments mites and bees (and viruses) are co-evolving to states where all can survive and thrive together - because of selective pressures that force that - live together or die together.

In intensive apiaries none of this is occurring, and the system is sick. Evolution toward co-existence is frustrated by treatments, and by the continual import of new non-resistant queens. Meanwhile mites are having theor own little arms race with beekeepers and their treatments.

Do you see what I mean?

For whatever reason, it absolutely can be done, which was not accepted to be the case a few short years ago. At first there was only Dee Lusby, then Michael Bush, then BeeWeaver, and now small treatment-free producers are popping up all over. I am one and I'm overjoyed to demonstrate the fact that bees can survive and thrive treatment free when a little more than a year ago, I was being told it couldn't be done. Hopefully, I'll get a few more chances to rub it in.

I couldn't agree more! I think now we'll soon be turning to questions of what the 'it' it is that can't be done is. Some things can't be done. But small and medium scale treatment free productive beekeeping ain't among them.

Mike

[Solomon Parker]

Do you see what I mean?

I do, and we largely agree. Where we differ is that I take the position that resistance to treatments (be they chemical, physical, whatever) goes hand in hand with virulence. I find it difficult to isolate causes and effects especially when sets of both exist side by side in the same system. I feel that stimulus that causes strength in one area will lead to strength in other areas as well, whether it be fecundity or just the ability to hang on.

Speaking of non-resistant queens, in my first foray into beekeeping, I was given a hive of Kona (Hawaii) stock. They didn't have a chance. At the time, Varroa had been present in my area for almost a decade, and had not existed in Hawaii. And yet, for some reason, people have continued importing queens from Hawaii (and Australia and New Zealand), areas that have had even less time to deal with varroa than we have. I am unable to understand the logic behind this. Interestingly enough, my great uncle had lost more than a hundred of his colonies and had half a dozen still remaining treatment-free in the mid nineties. He didn't seem to be aware of the existence of varroa at all and credited the losses to 'the drouth.' Another thing I never understood was the wholesale destruction of infected colonies when mites first surfaced. When has a program like that ever worked?

[jim lyon]

I do, and we largely agree. Where we differ is that I take the position that resistance to treatments (be they chemical, physical, whatever) goes hand in hand with virulence. I find it difficult to isolate causes and effects especially when sets of both exist side by side in the same system. I feel that stimulus that causes strength in one area will lead to strength in other areas as well, whether it be fecundity or just the ability to hang on.

Speaking of non-resistant queens, in my first foray into beekeeping, I was given a hive of Kona (Hawaii) stock. They didn't have a chance. At the time, Varroa had been present in my area for almost a decade, and had not existed in Hawaii. And yet, for some reason, people have continued importing queens from Hawaii (and Australia and New Zealand), areas that have had even less time to deal with varroa than we have.

Are you aware that the Kona stock was built up by Binford (Bweaver) and Roy S. Jr. (Rweaver) and it was the Weavers who turned the Kona operation into a major queen raising area? Are you also aware that Kona has been constantly improving their stock by importing drone semen from resistant stock years ahead of any mite infestation? I am not going to try to make the case that Kona queens are the best queens around but I have been around their operation enough to know that no one tries harder to furnish a quality product and to do so on a timely basis than Gus and the folks at Kona queen. If you book a queen there you are going to get it and you are going to get it on time, they have been invaluable to the industry for years.

[Solomon Parker]

What I will say is that 16 years ago, a Kona queen didn't have a snowball's chance in a blast furnace without Apistan.

[Ben Franklin]

I picked up two Tree hives this past week. Very Strong hives. The comb inside tells me these are old hives. The owner said they have been there for over five years.
One of the things we noticed is the calmness of these bees. Chain saws going and all and no one got stung. Even after a bumpy ride home they were peaceful.
Now I hope to raise some queens from these feral hives.

[Adam Foster Collins]

I found this paper to be very interesting, and encouraging.

For commercial beekeepers or people who have larger operations, I wonder if there might be an economically viable method of an approach to getting away from treatments. For instance, what if you were to create a small nuc yard, and not treat just those. Say, begin with 20 nucs, or single deeps. Don't treat. Winter those. Graft from survivors. Create more nucs the next season, winter, etc. The idea being to use a relatively small amount of resources through using small colonies from which to make selections.

Nucs are great to have anyway. And if you make the nucs up on the early side, then remove resources to keep them small, you aren't really managing the mites so much through the breaking of the brood cycle (if that works at all).

Is there some managable way to work toward treatment-free while maintaining a commercial enterprise? Is there a way to approach treatment free without risking your whole business?

Adam

[sqkcrk]

You would have to do so much more than replace the bees.

[mike bispham]

Is there some managable way to work toward treatment-free while maintaining a commercial enterprise? Is there a way to approach treatment free without risking your whole business? Adam

Hi Adam,

I don't speak from personal experience - I'm raising a treatment free apiary from feral stock - but Marla Spivak and others advocate a systematic approach of locating 'hygienic' queens through a frozen brood test (search that phrase).

New queens are raised from those that pass, replacing those that failed the test. (Low tech ways of doing the test are possible... don't be put of by talk of liquid nitrogen)

This process should be aided by the normal breeder act of helping the right genes through the male line as well, by keeping large unrestricted brood-nest colonies producing lots of drones around the apiary to help press the right genes forward.

The frozen brood test (or 'assay') allows you find out which queens are 'varroa sensitive hygienic' (VSH) while maintaining treatments - something treatments normally obscure.

Once a sufficient proportion of hives are testing positive you can drop the meds. You must never restart - that will just set you back to square one.

From there on just propagating from the best producers will maintain the hygiene levels, as any mite-vulnerable queens will always tend to be poor producers.

This amounts to simply bringing the characteristic of mite-resistance into a normal selective propagation process - something essential to all kinds of husbandry.

Feral 'survivor' blood will also help, as will bought in hygienic queens.

Again, read up from my link page. Knowing what is happening and why helps a lot.

Best wishes,

Mike

[mike bispham]

I do, and we largely agree. Where we differ is that I take the position that resistance to treatments (be they chemical, physical, whatever) goes hand in hand with virulence. I find it difficult to isolate causes and effects especially when sets of both exist side by side in the same system. I feel that stimulus that causes strength in one area will lead to strength in other areas as well, whether it be fecundity or just the ability to hang on.

Yes, I can see that. I reckon we could talk about a lack of restraint on virulence. Without selection of less virulent strains the more aggressive simply gain the upper hand. In general terms, virulence will allways win through until a restraining factor comes into play. In the case of feral stocks that factor is death of the host, with no opportunity for horizontal transmission. Result: death of (virulent) strain.

Does that make sense?

Speaking of non-resistant queens, in my first foray into beekeeping, I was given a hive of Kona (Hawaii) stock. They didn't have a chance. At the time, Varroa had been present in my area for almost a decade, and had not existed in Hawaii. And yet, for some reason, people have continued importing queens from Hawaii (and Australia and New Zealand), areas that have had even less time to deal with varroa than we have. I am unable to understand the logic behind this.

I raised this issue on Bee-L a couple of years ago. Clang! The censor's doors swung shut!

Another thing I never understood was the wholesale destruction of infected colonies when mites first surfaced. When has a program like that ever worked?

I think it can work. American Foul Brood is controlled here that way. The trick is to destroy the vulnerable hosts, and let the non-vulnerable rise in the population. [1] Of course treatments and/or manipulations defeat any such effort. It is the vulnerability which must be systematically bred out and eradicated.

Mike

[1] From the UK regulator, FERA

"AFB is a notifiable disease under the Bee
Diseases and Pests Control Orders (for England
and Wales) and is subject to official control by a
programme of apiary inspections carried out by
the NBU. Control of the disease is through
compulsory destruction of infected colonies,
which is a very effective measure. This
eradication policy has been highly effective since
the 1940s when first introduced, bringing the
incidence of foul brood down from several
thousand infected colonies per year to less than
100 nowadays. In recent years disease incidence
has been characterized by sporadic but large
outbreaks which have been rapidly brought under
control by the inspectors and beekeepers
working together. Methods of control of AFB
using antibiotics that are used in some overseas
countries are not effective, as they only serve to
suppress signs of the disease without eradicating
it and through frequent use allow the
development of resistant bacterial strains. The
use of antibiotics to control AFB is not
permitted in the UK."

(Note the logic of breeding in the host is not included in this rationale. FERA are idiotic in this respect - they do it because they know it works, not because they understand why it works. MB)

[Adam Foster Collins]

...Marla Spivak and others advocate a systematic approach of locating 'hygienic' queens through a frozen brood test ...
New queens are raised from those that pass, replacing those that failed the test...The frozen brood test (or 'assay') allows you find out which queens are 'varroa sensitive hygienic' (VSH)

This amounts to simply bringing the characteristic of mite-resistance into a normal selective propagation process - something essential to all kinds of husbandry...

Mike,

Interesting. However, consider this portion of the paper:

"...However, since the Gotland population does not demonstrate hygienic behavior (Locke and Fries 2011) nor had significantly high proportions of infertile mites, there is no reason to suspect that they are expressing VSH. Instead, the suppression of mite reproductive success in Gotland may be due to another mechanism, such as pupal volatile compounds that can inhibit the initiation of egg-laying of mites
(Garrido and Rosenkranz 2003; Milani et al. 2004)."

In selecting for VSH, how do we know we're not also selecting against other desirable traits that we don't yet understand. The Gotland population is surviving without apparent VSH traits, but they're not sure how - so this trait cannot yet be selected for. In some ways VSH traits are the most obvious - we can test for and see the traits fairly easily. But what about something like "pupal volatile compounds"? Who's to say that there aren't more common traits that are just as effective, but more difficult for us to see? Who's to say that the bees don't have some other, more readily displayed trait that's just as effective?

For example, someone in the future discovers that if you don't feed bees sugar, their body chemistry changes enough so that they're just that critical bit less nutritious for the mite, and that is the tipping point. Of course, I'm not suggesting that is the case- but just that it is so difficult to understand all the variables. When bees are left to their own, all of the beekeeper-induced variables are soon eliminated. But which needles in that haystack are the important ones to the bees surviving mites?

Is this were the addition of feral genetics might fill the gap? With "wild cards" that add genetic variables we hope will help?

This potential to inadvertently select against important traits is, I think, what Dennis was talking about earlier on this thread. And it is also what I fear in selecting for a specific trait regarding varroa. If one selects based on survival, it allows for things we don't yet grasp. You still select for production, gentleness, etc etc., but survival is first.

Does that make sense? I don't profess to know a bit about this from a breeding standpoint - but these are just questions from a person interested in getting into it.

Adam

[mike bispham]

Mike,


In selecting for VSH, how do we know we're not also selecting against other desirable traits that we don't yet understand. The Gotland population is surviving without apparent VSH traits, but they're not sure how - so this trait cannot yet be selected for. In some ways VSH traits are the most obvious - we can test for and see the traits fairly easily. But what about something like "pupal volatile compounds"? Who's to say that there aren't more common traits that are just as effective, but more difficult for us to see? Who's to say that the bees don't have some other, more readily displayed trait that's just as effective?

I think those are very sound thoughts - I was just outlining what I believe to be Marla Spivak's main method. And yes, adding in feral and bought hygienic strains must help the apiary to find a fuller range of tools. I think moving toward selection based on performance as soon as possible is a good plan (once treatment free), as whatever it is that's working is working best in those colonies. And to guard against losing valuable traits a range of mite -resistant queens (and drones) should be maintained and used. They'll mix in anyway in a free mating environment.

But which needles in that haystack are the important ones to the bees surviving mites?

Those that work best! That's natures way - the ones that thrive get off more swarms, which survive more often, and put up more drones. The weakest drop out altogether. Size and productivity (sans treatments) = 'has what's needed'

This potential to inadvertently select against important traits is, I think, what Dennis was talking about earlier on this thread.

I agree, as much as possible try to broaden the defences - but the frozen brood test might be the best way for larger/commercial operations to make the initial break from treatments. It can be systemized and taught to workers - these things matter.

I think working to keep variation up while insisting on sound mite-managers is the way to start. In general, thinking about these things is very worthwhile, and a sensible course can be found to suit all circumstances.

Mike

[Solomon Parker]

If one selects based on survival, it allows for things we don't yet grasp. You still select for production, gentleness, etc etc., but survival is first.

This is 100% for me. I came to the conclusion based on information I had heard in the past that feral colonies had widely varying rates of VSH. Whatever the bees need to take care of the problem (be it pheromones, hormones, smells, tastes, colors, timings, temperatures etc.) that's what I want them to do. I leave it up to them.

[Adam Foster Collins]

I think I'm with you, Solomon.

Honestly, I think letting them alone in terms of selecting for survival is all any of us are really qualified to do. There are just too many things we don't (and may never understand about the bees).

I think we must continue to select for traditional traits like temperament and production levels, as these are things that are important to our interaction with them. But in terms of survival, I think survival itself is the only trustworthy indicator.

Adam