Drone Culling for Varroa Control

[BaconWizard]

I have obviously failed with my search terms, because I doubt that there aren't already threads about it somewhere here. Please feel free to link any I have missed, but I have looked.

So, my question isn't hugely specific but I have picked-up the occasional opinion on other threads that some members at least, regard the killing of drone larvae to control mite numbers as ineffectual.

On the other hand, in the USA if not in this country, it does seem like a LOT of people do it.

I am eager to learn more about it. I understand the theory of doing it: Mites prefer drone brood x3 therefore encouraging drone brood in one place at a particular time, followed by culling it = a decent percentage of the next generation of mites failing to breed. Sort of like a partial brood-break.

On the other hand, especially if we have a good queen, we want her to spread those genes I assume, and would like our neighbours to do the same.

So what gives? Cull or no cull?

 

[Ian123]

Don’t bother waste of time and whilst you can get good whole sections/frames drawn all of the same age they often become mixed meaning some is capped some is open. Get a decent varroa control system worked out organic or chemical and in the vast majority of case you’ll have no issues or work during the main part of the season.

 

[Ian123]

I should also add don’t start watch and you tube on shook swarms

 

[blackcloud]

I sawed off the lugs of old frame top bars and nailed them between the sidebars of brood frames and drilled through to install bamboo skewers.
Installed one in every hive.
Lots of small windows then created- bees duly obliged and drone comb created which could be arbitrarily chopped out one chunk at a time as it was capped.

Just out of interest I started uncapping sealed brood and found not one instance of infestation.
Ever.
Ever.

As Ian intimates it was a complete waste of time and effort -both of mine and of my bees.
I suppose we all succumb to doing the circus tricks as a part of the learning curve.

 

[JamezF]

David Evans (theapiarist.org) posted some interesting thoughts on drone culling a while back. If I recall correctly he's in favour, but only if it's done very early in the season. He also appears to be using a lot of foundationless frames with two vertical bamboo skewers for support and his experience appears to be that the bees will often draw out one of the three "panels" of comb as drones in such a frame, making them easy to remove.

Personally I've always felt uneasy about drone culling. The number of people talking about poorly-mated queens seems to be ever-increasing and I can't help feeling that drone culling may not be helping with that. The bees have presumably evolved to know what proportion of drones they ideally need and it may be that having beekeepers remove them really isn't doing them any favours. I've no evidence for this, but I just feel that I need a better understanding of how drone removal affects the workings of the colony before doing it.

I think this is the page on theapiarist.org:

Droning on - The Apiarist

James

 

[jenkinsbrynmair]

David Evans (theapiarist.org) posted some interesting thoughts on drone culling a while back. If I recall correctly he's in favour

he's in the minority then, there have been numerous studies on this subject, but if you winnow out the dross from yootoob you will find that the majority opinion is that it's an ineffective and wasteful exercise, it has only a brief and momentary effect on reducing the mite numbers, has a negative impact on the colony 'balance' and causes needless extra work for the bees. There is also widespread opinion that the constant culling of drones must have a negative impact on queen mating.

 

[JamezF]

he's in the minority then, there have been numerous studies on this subject, but if you winnow out the dross from yootoob you will find that the majority opinion is that it's an ineffective and wasteful exercise, it has only a brief and momentary effect on reducing the mite numbers, has a negative impact on the colony 'balance' and causes needless extra work for the bees. There is also widespread opinion that the constant culling of drones must have a negative impact on queen mating.

Yes, that's pretty much consistent with the view I had come to.

However I have the impression from the page linked above that he's against continuous culling, preferring to cull only the very earliest drones once only. Perhaps around 500 drones at most estimating from his photos. That may well be quite a small proportion of the total drone numbers in a healthy colony that isn't constrained by trying to fit them in around worker comb. I seem to recall reading that as much as 20% of the colony might be drones in those allowed to build as much drone comb as they wish. I assume he's suggesting the approach because kicking the mites when they're already down after winter treatments and a lack of brood is more effective than when numbers have built back up.

I wonder if it might be possible to modify his approach if you can be confident that the majority of the drone cells will be in one place (as he suggests is the case with his frames). Perhaps a selection of the drone cells could be opened up and inspected for varroa, removing the block of 500 (or whatever) only if there are quite a few present.

I might have to re-read the article and see if it makes me feel I should do more investigation.

James

 

[Erichalfbee]

James. Has David Evans counted the mites in that first cull ?

 

[jenkinsbrynmair]

I have the impression from the page linked above that he's against continuous culling, preferring to cull only the very earliest drones once only

which again, is pretty pontless, the only way it can have any lasting impact is by a large scale and continuous (more often than weekly)culling of drones which I would have thought most would agree is a foolhardy exercise - almost as bad as annual shook swarming.

 

[JamezF]

James. Has David Evans counted the mites in that first cull ?

He doesn't say, but you could certainly ask. He seems pretty good at responding to stuff like that.

James

 

[drex]

I have a shallow frame in each brood box. Under this they always build drone comb. I occasionally uncap it in order to monitor mite load. I do not cull to try to control varroa
This is the only monitoring I do. My bees get treatment every autumn and early winter

 

[Erichalfbee]

I have a shallow frame in each brood box. Under this they always build drone comb. I occasionally uncap it in order to monitor mite load. I do not cull to try to control varroa
This is the only monitoring I do. My bees get treatment every autumn and early winter

Uncapping it culls it’s though?
What sort of counts are you getting?

 

[BaconWizard]

He doesn't say, but you could certainly ask. He seems pretty good at responding to stuff like that.

James

I've just emailed him to ask. Can't hurt.

I was just thinking that a formic-acid treatment at that time would surely have a similar if-not better effect? But then again, it seems like drones are pretty delicate and can be made sterile by some chemical treatments. Unsure if FA is one of them, but I don't think my neighbours would thank me for badly mated queens. These f-ing mites really HAVE buggered it all up, haven't they?

 

[Erichalfbee]

I've just emailed him to ask. Can't hurt.

I was just thinking that a formic-acid treatment at that time would surely have a similar if-not better effect? But then again, it seems like drones are pretty delicate and can be made sterile by some chemical treatments. Unsure if FA is one of them, but I don't think my neighbours would thank me for badly mated queens. These f-ing mites really HAVE buggered it all up, haven't they?

Even if that were the case sterile drones at the end of the season isn’t really a problem?

 

[JamezF]

which again, is pretty pontless, the only way it can have any lasting impact is by a large scale and continuous (more often than weekly)culling of drones which I would have thought most would agree is a foolhardy exercise - almost as bad as annual shook swarming.

Personally I just don't know. I think there's an argument to be made that it may have a lasting impact if you do it early enough because of the way that mite numbers build up exponentially. I think that's really the key -- if you can get rid of a reasonable proportion of the mites early on then in a system where their numbers increase exponentially then you should end up with far smaller numbers after the same number of generations. Whether the argument actually stands up of course is a different matter

If you have time to read the article though, I'd certainly be interested in hearing specifically where you think his reasoning is flawed. Or if you have references specifically suggesting that early drone culling (presumably at pre-existing low mite levels) is ineffective I'd be pleased to see them. As you suggested, it's hard to find useful information from people who actually understand the science amongst all the youtube (and other) dross. David Evans is at least a scientist, though not specifically one who researches varroa as I understand it. I'd hope therefore that he's less likely just to make wild assumptions than many, but I can't know that either.

James

 

[JamezF]

These f-ing mites really HAVE buggered it all up, haven't they?

Well, mites are probably just doing what they've always done. It's perhaps the process by which the mites got into places they weren't expected to be that's really what's buggered things up.

James

 

[Sutty]

Anyone know how long formic acid takes to work?
If it's only a few minutes it would be possible to have a couple of frames drawn out from drone foundation in the brood nest, every few inspections transfer them without bees into a separate insulated box with formic acid for a while, then transfer back. Could use a higher acid dose than normal.

 

[mbc]

Drone culling definitely upsets colonies and any benefits are far outweighed by this imho

 

[BaconWizard]

Anyone know how long formic acid takes to work?
If it's only a few minutes it would be possible to have a couple of frames drawn out from drone foundation in the brood nest, every few inspections transfer them without bees into a separate insulated box with formic acid for a while, then transfer back. Could use a higher acid dose than normal.

Isn't that the same regime as drone-culling then? Admittedly you keep the drones, but if culling them doesn't help appreciably with varroa then treating only capped drones should theoretically provide the same result or worse, no?

Edit: I guess if this particular regimen of drone culling works, but you want to leave them alive, then it's a thought...

 

[BaconWizard]

Drone culling definitely upsets colonies and any benefits are far outweighed by this imho

I have seen this said before. I don't doubt it, but upset how?