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Drone comb loaded with mites

26K views 77 replies 23 participants last post by  BeekeepingIsGood 
#1 ·
I checked my back yard top bar hive which was started with a feral swarm. It seems to be doing well, though it has stopped expanding after filling about two thirds of its four foot length. I have harvested about a bar of honey over each of the last two months, and added a bar to the brood nest 4 times. Yesterday I pulled a heavy bar of capped honey--the bottom third was drone comb. I was a little surprised to find 2-4 mites on each of the drone larvae.

I haven't done an alcohol wash. Does the count in drone brood correlate with a dangerous level of varroa indicating need for treatment? How effective is drone comb culling in controlling mites?
 
#44 ·
>>The half that prefer drones.
>A citation to support that exists?

A citation to prove that the ones that, when faced with drone or worker brood, infested the drone brood. That they prefer drones? I'm confused. They sorted themselves out.

>Drone brooding is for a relatively short part of the season, what happens to them when drone brooding ends.

And that is exactly the right question. If they did as they do in cerana, they would do nothing when there was no drone brood.
 
#47 ·
There would only be selective pressure if there is a genetic basis for mites getting into worker brood. If there is no such genetic link, and it is chance that some mites end up in worker brood, then there is no possibility of selecting for mites who prefer worrker brood. I have no idea whether there is a genetic basis for varroa mites selecting worker vs. drone brood, or whether they all genetically prefer drone brood and some just end up in the less desirable worker brood. I don't know if anybody in the world can answer that question.

Also, it does not necessarily follow that selecting for mites that prefer worker brood would be bad, and it could very well be good. Mites don't reproduce as well in worker brood, so maybe it would be good if we could breed a mite that is not attracted to drone brood. For all I know, that could be the silver bullet to Varro mites (although I doubt it). Once again, I don't know if anybody in the world really knows the answer to this question.

Bottom line, I don't think anybody has any actual knowledge about these factors.

There is evidence that drone removal is effective in the short-term, and it is most certainly chemical-free. I do know one top-notch beekeeper who has been removing dronce comb (and breeding resistant bees) for a lot of years now, and he has very healthy bees, with no sign of breeding nastier mites.
 
#51 ·
I think what we need here on the forum is a top notch entomological geneticist who can sift through all this speculation and give a once and for all answer. But something tells me that even then there will be some who think they know more than that person and will disagree.
 
#52 ·
This ultimate arbiter is driven by pressures to publish and obtain funding. Forums are free, but don't pay well, or add to resumes. Fortunately, some knowledgeable folks do post, and those are a real treat, and appreciated.
 
#57 ·
The practial (read lazy) beekeeper would skip culling if the bees can thrive without it. Why not?

On the micro-level, will the bees in your apiary become more hygenic or mite-resistant if you keep culling drone cells? --I guess I don't want to bring up the selective breeding argument again, but this seems logical to me. If they're dieing from mites, maybe they should die. There certainly are bees thriving without treatment/culling. That seems like ideal selective breeding to me.

Lastly, I am convinced by those who say that the bees naturally prefer a certain percentage of drones/drone comb in the hive. I don't want my bees spending all their time/resources building new drone comb because I keep cutting it out making them feel unbalanced.
 
#58 ·
WOW lets remember the Top Bar Hive was attractive as a more "natural" bee driven way to "handle" bees. Overthinking it totally defeats the purpose. If you want to or "have" to save a colony from mites culling the drone brood is by far the best way to DECREASE the "Mite Load" (remember these key terms). WHY because TBH bee handling is suppose to be SIMPLE and FUN. Get back to the basics! Who cares what brood mites prefer.....common sense would dictate and we know they prefer drone brood and some end up in worker brood, again SO WHAT. Its not where they are its the "LOAD" they place on the colony's ability to fight off viruses. Culling drone brood and powdered sugar treatments WORK the best at DECREASING the load and neither one involves harsh chemicals. If its not broke DON'T fix it........NOW my answer is the most effective and selective. Select for STRONGER bees, select to not have the mites........CULL the colony. Just my two cents worth.
 
#60 ·
Never saw it harm the brood. The benefit outweighs the risk exponentially anyway. Again overthinking it would be a shame, it takes all the fun out. Remember for every scientific paper that says one thing there are several that say something different. Here is a simple rule to follow. If you hear about something TRY IT FIRST, do your own experimenting and share, share, share your results so that everyone may benefit. The beauty is in the experience, if you want to read journals go to the library. Want to learn about bees go to the apiary!!!!!!
 
#62 ·
Duncan,

Yeah, but HIVE+ and I have been having a PM discussion about methods, so getting in to the papers from formal studies helps us decide which methods we can actually handle. Maybe I can't evaluate correlation between hygienic behavior and certain volatile compounds emitted by dead pupae, because I don't have GC/MS, but I can certainly build the cages from wood and hardware cloth used in this study by the same guys who did the heavy sugar study above.

"A strategy for using powdered sugar to reduce varroa populations in honey bee colonies"

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1180&context=entomologyfacpub

Determining varroa on capped brood is best done by sacrificing the brood, but that's what you do with the drone brood strategy anyway. Instead of feeding the brood to the chickens, evidently you drown them in alcohol to kill and dislodge mites (at least, that's what these researchers do with samples of adults). A mason jar of moonshine ... uh, I mean denatured alcohol is evidently good enough labware. Hey, drones either get kicked out to starve or die the first time they have sex. Maybe drowning in booze is not a bad option.
 
#64 ·
A perfect example of my point: the whole idea of "heavy" treatments with powdered sugar is a moot point. Experience already tells us powdered sugar is dusted on, Thomas Dowda's method perfected by Dennis Murrell. Always worked for me anywhere there are mites. Why? It removes mites from the colony when a mite count tells you the hive is approaching the economic threshold. Removing mites DECREASES the mite load. This combined with drone culling works anywhere. Brood is usually covered with bees anyway and the benefit exponentially out weighs the risk and as you pointed out drones are a dime a dozen.

Not saying stop reading journals, just don't blanket apply them without observing and adjusting. Environmental differenced require it.
 
#65 ·
Like I said, I'm more interested in the methods. Some of you guys already know these tricks but I'm scrambling to learn. Ferinstance, Mr. Bush mentioned an alcohol wash and I was not familiar with it. But one of the papers used the method, described what they were looking for, and now I know it is not some benevolent way of getting you bees all nice and clean and refreshed. But it gives the ability to count mites accurately on a sample of unfortunate bees, when otherwise you'd hardly spot any by just eyeballing frames.

If I want to study one of these factors that has not been looked at yet, I need to learn these methods.

Whatever I can learn hanging around this forum, or in bee class, or from a soon-to-be-assigned mentor is great as well. Fact is, I'm wallowing in this stuff and can't wait for mid-April when we pick up our nucs. Sorry, Duncan, I can't learn from my bees yet 'cause all I got is a couple of empty 8-frame hives. So instead I'm hitting the books, etc, and getting the stuff ready to go. Really pretty paint job on my supers, though.
 
#67 ·
Looking back, I believe you "mentioned" alcohol wash, but that mention was that you had not done it.

If I freeze drone brood I will have already done the murder ... might as well count the mites. I don't have chickens or a fish pond as some have suggested, and the last time I tried feeding bark beetle larvae to the birds, the ants got 'em first.
 
#70 ·
The section I removed was the only drone comb I saw and there had to be at least 300 mites in that section of about 150 cells with an estimated 90% infestation rate.
I did a count, had 7 mites on 203 nurse bees, 3.5%. These are locally adapted survivors from a swarm trap collected 6 months ago: not too bad to work with, but they were plenty p-o'ed when I brushed off a brood comb. This isn't my only hive, and no monetary risk, seems like a good opportunity to watch and see what happens. Mr. Bush, I look forward to meeting you in Arizona next month, hope you are still coming!
Thanks jfb58 for the numbers. I've been curious to what extend varroa prefers drones. There are summaries of numbers that come up when I do web searches, but I'm digging deeper to find the context for those numbers.

My current situation is similar to yours. Drone production is dwindling right now. I uncapped the small patch of remaining drones and found maybe 50-66% infested, often with multiple foundresses. As drone production dwindles do pretty much all remaining drone cells get infected?

About a month ago I did a full colony sugar dusting after a drone comb emerged and about 35 mites dropped. I sugared them twice since then and got little to no drop. Yesterday, after uncapping the highly infected drones, a full colony sugar dusting yielded 1 mite.

So it's hard for me to correlate any sense of the two measurements without assuming almost all the mites were in the drone comb. Maybe I do have to do a sugar roll of nurse bees, or protect my bottom board from ants, to get a broader picture of the infestation % situation.
 
#75 ·
To answer that, goes like this.

First re drone brood, even in a hive with a natural amount of drone brood, about 40% of mites in brood will be in the drone brood, and about 60% in the worker brood, or at least that's what was found when someone counted them all. Of course the ones in the drone brood produce more offspring due to the longer pupal stage.

But in any average hive around 80% of mites are inside brood cells, and around 20% walking around on bees (phoretic). So if a sugar dust is done, only around 20% of the mites are available to be contacted by the sugar. Of that 20%, only a small % of those, are actually dislodged, and this can be demonstrated by doing an alcohol wash of a bee sample immediately after a sugar dust to see what was missed by the sugar dust.

Because of the way mite populations expand exponentially, often a mite population can be right back, or past where it was, very soon after a sugar dust.

However people still think it works, because they do a sugar dust and find some mites afterwards, so therefore it "worked". Many do not consider that finding 100 mites is not going to do much good if the mite population of a hive is 2000, which it easily can be. A better test than seeing how many mites dropped without knowing the total population, would be to see where the hive is a few months later.
 
#76 · (Edited)
So if a sugar dust is done, only around 20% of the mites are available to be contacted by the sugar. Of that 20%, only a small % of those, are actually dislodged
Randy Oliver seems to feel it might be as high as 40% of the phoretic mites.


However people still think it works, because they do a sugar dust and find some mites afterwards, so therefore it "worked".
In this context, I'm mainly looking at it to provide some indication of overall infestation levels. The problem is on 3 of 4 occasions virtually no mites dropped. Even if we extremely low-balled sugar dusting as only dropping 1% of the phoretic mites(20% of the overall mite pop.), and guess that despite seeing 66% infestation in the drone comb there's only a 9% total infestation, I'd still expect 14 mites drop in a hive of 80 000 bees. If we use Randy's 40% figure then I should being seeing 576 mites drop.

Perhaps there's something else at play here? The reason why I peeked in the drone brood in the first place was because I saw an undeveloped worked getting pulled out of the entrance.

SO if I don't have much drone brood, sugar shake should help get some of the mites out.
A small percent. Those that have found it useful were doing it at high frequencies before a serious mite problem developed, or during broodless periods. These are my notes on sugar dusting varroa.
 
#77 ·
Yes agree. Based on your best case, and worst case calculations, you should have seen minimum 14 mite drop, and maximum 576. But "The problem is on 3 of 4 occasions virtually no mites dropped".

Which demonstrates that sugar dusting is not effective, or at least not reliable. That's the something else that's at play.

Having said all that, if someone wants to sugar dust I have no issues with it, other than it can damage young larvae although they can be quickly replaced with minimal loss to the hive, and don't rely on it to rid your hive of mites.
 
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