# Can varying levels of resistance been seen when using brood breaks to manage varroa?



## Adrian Quiney WI (Sep 14, 2007)

Perhaps, but I have not seen any research on brood breaks and the variation of their application to evaluate resistant stock.


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## Solomon Parker (Dec 21, 2002)

The level of treatment should never be lowered unless to zero. Insufficient dose leads to resistance. Zero dose either leads to death (also eliminating the virulent pathogen selecting for reduced virulence of the pathogen) or not death (indicating no need for treatment).


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## Adrian Quiney WI (Sep 14, 2007)

If one knew that resistance was going to be achieved by the constant pressure of exposing the host to the parasite, then yes maybe you are right.
However, suppose resistance was achieved by a mutation that occurred in one generation. In that case suspension of treatment, or suspension of a method, for a group of colonies would identify that mutation.


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## Solomon Parker (Dec 21, 2002)

That's a hypothesis, but it doesn't fit the evidence. There is no single trait or mutation that results in resistance.

That is generally how resistance is enhanced. Mutations that introduce resistance to parasites are possible but not common. It's in the best interest of the parasite to achieve non-virulence, but also in the interest of the host to achieve a level of resistance, and the more the better to the point of diminishing returns depending on the investment.


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## jonathan (Nov 3, 2009)

The key thing in evaluating mite tolerance is to apply the same treatment (or no treatment) at any given time to all the colonies in the study so as to maintain an even playing field.
This would apply to any artificial brood breaks as well.


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## mike bispham (May 23, 2009)

jonathan said:


> The key thing in evaluating mite tolerance is to apply the same treatment (or no treatment) at any given time to all the colonies in the study so as to maintain an even playing field.
> This would apply to any artificial brood breaks as well.


I agree, hard though it is, an even playing field is more than just helpful with evaluation. 

I'm a bit surprised nobody has volunteered 'mite counts'. Wouldn't a mite count just prior to the break supply the necessary data?

Mike (UK)


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## Oldtimer (Jul 4, 2010)

Mite counts? A good rough guide but that's all. They can be deceptive there are so many variables this is why it's all so hard.

Factors we don't always consider that can affect mite count include is the hive in a position where it collects drifters? if so it will have a higher mite count. Did the hive start the season for some reason maybe beekeeper induced, with a higher mite count? As mite populations increase exponentially it could now have a much higher mite count. What's happening in the broodnest? The state of the broodnest could mean there is a lot of phoretic mites available for counting, or could mean there are very few phoretic mites available for counting.

Me, I don't count mites. Even if it could be done accurately, it still discounts the other factor, which is viral and other infections and ignores we should also be looking for bees with better than average tolerance to that. Because of this and to take all things into consideration, I use the trusty old "eyeball" method. Ie, I look at the brood. If all is perfect, I'm fine. If there is PMS (parasitic mite syndrome) visible, then that demonstrates that the combined effect of mites (whatever their number) and the viruses they are transmitting, is beginning to overwhelm the hive. Light PMS I may allow to continue to see how the hive deals with it. Heavy PMS, battle is over I'll act in some way to save the hive.

Although I currently treat any hive that needs it (heavy PMS), by using the tools described above and breeding from the best I believe my bees are going longer between treatments than they were a few years ago. So this method is making gains, where the cold turkey bond method killed every hive I did it to so no gains were made.


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## BernhardHeuvel (Mar 13, 2013)

mike bispham said:


> brood breaks are the sole varroa control method?


Mike, are you interested in what I want to try this year? It concerns brood breaks. It is a method a master beekeeper developed with multiple queen hives. You need two brood breaks minimum for it to work. But two brood breaks are seriously decreasing bee population. With two or more queens per hive you can do this because of the sheer mass of bees in that hive. I am just about to try this method, since it seems to be well thought out. 

If you are interested, I provide more details.


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## mike bispham (May 23, 2009)

BernhardHeuvel said:


> Mike, are you interested in what I want to try this year? It concerns brood breaks.


I might, if it supplies a good assay method. That's what I'm looking for. Really though my interest is academic at the moment. If I get mite problems that threaten to halve my population I'll look at alternatives, till then the plan is to do nothing except requeen and raise spares.

I really just wondered if anyone had a reliable (ish) method for lifting resistance using only brood breaks. 

No treatment/manipulation gives the best assay of course, but not everyone can or wants to do that. I might not want to if it all goes wrong.

Mike (UK)


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## BernhardHeuvel (Mar 13, 2013)

So this is the plan:

I use 2queen hives, simply because a double brood break would decrease the bee population too much and it would be worthless for honey production. 2 queens = double amount of brood. 

For this is I divide the brood boxes vertically with division boards. The goal is to maximize amount brood per hive/box. I've done this before and it isn't difficult. 

Coming out of winter the 2queen hives are worked and supered as normal. Just before the peak of population, right in the first strong flow, which is May here, when swarms naturally occur, I will pull all the capped brood combs out of the hive. Combs are replaced with emtpy but drawn comb. Open brood is left in the hive. As is the queen. The open brood goes up into the upper brood chamber for easy removal.

The capped comb from different hives is collected into stacked up supers and transported into a distant apiary. If you stack up 5 boxes of capped brood you can use the resulting hive for honey production, too. They get a queen cell that is just before emerging. Until the new queen is mated the mites are starved.

Old hive: About 10-13 days later the now capped brood gets removed again. Most of the remaining mites entered the brood and now can be removed. You either destroy this brood combs or put them into a second split again with a ripe queen cell. Open brood is left again.

In the splits you simply wait until the new queen mated and started laying eggs. Once the first patch of brood is capped, you remove that brood and destroy it. And with it the mites, that starved almost for a month and readily went for the new brood.

Some time later - this is in July where I live, you repeat the process one more time for the old hive.

It sounds like a lot of work, but sure it is less than it seems to be. It only works with multiple queen hives. The inventor of this method is Wolfram Peschetz. The method very much reminded me of the MDA splitter method with the double brood breaks. I will give it a try, since I am doing 2queen hives anyway.


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## Delta Bay (Dec 4, 2009)

> I really just wondered if anyone had a reliable (ish) method for lifting resistance using only brood breaks


You should use the brood breaks as a way for increase or to maintain numbers. Once they have gone through their July brood break and the new queen has started laying you replace that queen with your tested and selected stock.


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## Juhani Lunden (Oct 3, 2013)

mike bispham said:


> When attempting to raise resistance to varroa in an apiary it is necessary to know which hives are more resistant. When treatments are being used the level of treatment can be lowered evenly across the apiary to reveal the spectrum of resistance.
> 
> Can the same thing be done when brood breaks are the sole varroa control method?
> 
> Mike (UK)


I have always thought it this way: brood breaks are good when only one or two hive at a time does it. Then, I suspect, the mites partly go to neighboring hives. I think, I´m not sure, this happens, because otherwise it seems od, that sometimes hives, which have for instance changed their queen, lose 90% of their mites in one year/season. But what about the situation, if all the hives in a bee yard have a brood break, which starts at the same time and has the same duration? It halts the increase of varroa population for a moment. Maybe something like this: without brood break 5 times increase in a summer with brood break 4 times increase. 4 times increase might just be low enough for the hive to survive.

In the process of breeding for varroa resistance it is always good, almost necessary, that bees which are somewhat resistant, also show the ability to withstand high infestation level of mites. These are two different abilities: the ability to reduce the increse of varroa and the ability to withstand high varroa infestation levels. The ability to withstand a high infestation level is probably almost the same as resistance to viruses. This ability to withstand high infestation levels is necessary in the process. The only way to avoid it is very intensive monitoring of the mite levels, which causes a lot of work. 

Brood breaks are hard to handle in short summer environment. But if they help the bees evenly, they can be helpful tool to separate survivors. 

Salomon Parker: There is no evidence that resistance to OA has ever occurred. So diminishing OA treatments is harmful.


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## BernhardHeuvel (Mar 13, 2013)

BernhardHeuvel said:


> ...


Some more details, probably necessary for the understanding.

The first batch of capped comb that is pulled, is taken with attending bees on them. About ten frames of capped brood and 13,000 bees per hive. 

The second batch (after ten days) is about four frames of capped brood. Which gets destroyed.


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## mike bispham (May 23, 2009)

Adrian Quiney WI said:


> If one knew that resistance was going to be achieved by the constant pressure of exposing the host to the parasite, then yes maybe you are right.


Adrian,

It is. And only that. But what that means is exposure over a number of generations, resulting in progressive natural selection of the most tolerant (fittest) strains. Perhaps that's what you meant?

Mike (UK)


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## mike bispham (May 23, 2009)

Juhani Lunden said:


> I have always thought it this way: brood breaks are good when only one or two hive at a time does it.


It isn't clear Juhani, do you mean when the beekeeper does it (artificial brood breaks) or when the bees do it?



Juhani Lunden said:


> Then, I suspect, the mites partly go to neighboring hives. I think, I´m not sure, this happens, because otherwise it seems od, that sometimes hives, which have for instance changed their queen, lose 90% of their mites in one year/season.


Can't that be accounted by natural wastage - once new mites stop coming up?



Juhani Lunden said:


> But what about the situation, if all the hives in a bee yard have a brood break, which starts at the same time and has the same duration? It halts the increase of varroa population for a moment. Maybe something like this: without brood break 5 times increase in a summer with brood break 4 times increase. 4 times increase might just be low enough for the hive to survive.


My point was to say: while using brood breaks as the primary mite control method, can we differentiate reliably between the differing levels of resistance - so as to know which to increase and which to cull/requeen. 



Juhani Lunden said:


> In the process of breeding for varroa resistance it is always good, almost necessary, that bees which are somewhat resistant, also show the ability to withstand high infestation level of mites. These are two different abilities: the ability to reduce the increse of varroa and the ability to withstand high varroa infestation levels. The ability to withstand a high infestation level is probably almost the same as resistance to viruses. This ability to withstand high infestation levels is necessary in the process.


Makes sense... for the moment anyway...



Juhani Lunden said:


> The only way to avoid it is very intensive monitoring of the mite levels, which causes a lot of work.


Again, I'm not clear, avoid what? 



Juhani Lunden said:


> Brood breaks are hard to handle in short summer environment. But if they help the bees evenly, they can be helpful tool to separate survivors.


I can't say I'm entirely convinced that ABBs are as useful a tool as reducing treatments to expose the resistance levels. But if as you say ability to withstand higher levels of mites (poss. viral resistance) is important that method would presumably de-select the better ones! 

Mike (UK)


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## Juhani Lunden (Oct 3, 2013)

Replies to Mike: 

It isn't clear Juhani, do you mean when the beekeeper does it (artificial brood breaks) or when the bees do it?
-I meant what ever brood break, man made or natural. It doesn´t matter, if we think about the increase of varroa population, or does it? Brood break is brood break. 

Can't that be accounted by natural wastage - once new mites stop coming up?
-Do you think 90% of the mites would be gone because of supersedure(changing the queen)? I think it is estimated that about 10% of the mites die in the winter during one months broodless period. You cannot really have more than one month of broodless period during the summer. I don´t know if this is true, but I would from that above winter figure estimate, that supersedure would cause 10% loss in mite numbers. And they sometimes lose 90% of their mites. Why? I cannot think of anything else but drifting to other hives.


My point was to say: while using brood breaks as the primary mite control method, can we differentiate reliably between the differing levels of resistance - so as to know which to increase and which to cull/requeen.
- if the hives can be managed exactly the same way, I would say yes we can. But if for instance one hive, for what ever reason, is not having a brood break, that would make evaluation impossible. This one hive would have effect on the other yards evaluations as well. The other yards must be managed the same way, that is, there must be one hive too, which is not having a brood break. 


Again, I'm not clear, avoid what? 
-Avoid the huge mite pressure caused by the inadequate mite resistance (of most of the hives) in the beginning of the varroa resistance breeding program. It is only in the very late phase of the breeding program, when most of the hives have good resistance, that this phenomena can be avoided.



I can't say I'm entirely convinced that ABBs are as useful a tool as reducing treatments to expose the resistance levels. But if as you say ability to withstand higher levels of mites (poss. viral resistance) is important that method would presumably de-select the better ones! 
-I would not use brood breaks either, but since you asked, I think they could be used and still make right decisions of selection. There might be other factors. For instance I have a feeling that it could be possible that the mites are redistributing themselves during the brood break: After the break, it could be, that there are more mites, in proportion, in those hives where the mites can make more increase. (I even once distributed the term "mite magnetism". Describing the phenomena when mites seem to somehow show up in some hives in wast numbers, and disappear from other hives.)


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## marshmasterpat (Jun 26, 2013)

BernhardHeuvel said:


> So this is the plan:.


If you try this, please start a new post and let us know reports. Too much of it is new to me as a new bee keeper, but if it is successful in a trial, let us know please.


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## honeydrunkapiaries (Oct 16, 2013)

marshmasterpat said:


> If you try this, please start a new post and let us know reports. Too much of it is new to me as a new bee keeper, but if it is successful in a trial, let us know please.


I wouldnt worry too much about stuff like this untill you have a season under your belt, and have the whole of winter to brood over it. If you just started your hives Varroa shouldnt be a huge issue.


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## enjambres (Jun 30, 2013)

How are the mites moving from one hive to another if not on the bodies of the bees?

I know mites can be lively little beasts (I occasionally find a live one on a sticky board and watch it move a bit before dispatching it), but it's hard to imagine they can go large distances on their own. Are there any known max distances or temperature or vegetation characteristics or other dispersion-limiting factors? Given that they are obligate parasites of honey bees (and not so much on other types of wild bees, correct?) and that they can only develop to adulthood within bee-larval cells it seems they'd be pretty well stuck to the hive environs. (And biologcally very vulnerable to a mite-caused or mite-vectored dead out, particularly in the winter in cold climates where the hive space would not be re-occupied for months.) 

(And thinking about that factor: do ordinary beekeeping economics and practices provide a "bridge" between hives when equipment, drawn combs, even frames of honey are moved from one hive to another, play a part in this? Can phoretic mites enter a prolonged resting state - as can some other insects - in the absence of a host and then revivify once they luck out and find themselves re-hived with live bees? They are so tiny that they could enter tiny crevices and easily remain concealed.)

Do bees shed live mites at nector or pollen collection sites that are then able to re-attach themselves to subsequent-visiting bees? How long can phoretic mites survive in the open air if not attached to bees' bodies? 

My winter stand has my hives placed close together (with foam insulation panels betwen hives), but last summer, and particularly in the fall when I was attempting to move them around, they were a couple of hundred feet from each other. My summer plans this year are to move them about 20 feet apart, each on their own stands. I will be dismayed to hear that mites (walk) between hives as one of my hives has historically had almost no mites (and no treatment). Right now, except for drift on the bees' bodies, I doubt mites are strolling around on their own as it's far too cold. But if they do move on their own from hive to hive then I need to think about separating the hives sooner rather than later.

Enj.


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## AR Beekeeper (Sep 25, 2008)

Enjambres; In the lab a varroa can live 5.5 days away from the bees, I doubt they last that long under winter conditions in the bee yard. In summer they die rapidly because of dehydration. 

Varroa is spread by drifting bees, robbing weak colonies and carrying home their mites, and beekeepers exchanging brood that has varroa in the capped cells. It would be possible to exchange a comb that had a varroa or two walking on the comb, but most will be on nurse bees and in capped brood.

Having colonies side by side in pairs will not be a factor in varroa infestations so you are not rushed to move your colonies.


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## mike bispham (May 23, 2009)

Something I've been thinking about recently is the plausible desirability of passing on the right sort of mites. VSH bees tend to 'breed' low-fecundity strains of mite, and that's the bit that really helps - the mites simply don't have an ability to blow up their population quickly. Any more fecund mites that are bought in aren't a problem (as lons there aren't thousands of them) since a) the bees subject them to the same treatment, breeding their fecundity out, and are aided b) by the low fecundity strains already present.

What this means is its better to have a medium low-fecundity mite population than to have none or very few. 

Quite how thought this should condition our understanding and management equations I haven't figured out yet. It does make me wonder if part of the problem of failure of introduced 'resistant queens' in a treating apiaries might be due at least in part to the wrong sort of mites. A new queen should come equipped with a good few of her own mites to help her. 

The same idea might be helpful within non-treatment apiaries, and might have a place in brood-break efforts at control - though how to work that for resistance building still eludes me. 

Mike (UK)


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## Daniel Y (Sep 12, 2011)

Solomon Parker said:


> The level of treatment should never be lowered unless to zero. Insufficient dose leads to resistance. Zero dose either leads to death (also eliminating the virulent pathogen selecting for reduced virulence of the pathogen) or not death (indicating no need for treatment).


Solomon, this would only apply to Antibiotics.


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