# Mite count in drone brood as a diagnostic?



## mathesonequip (Jul 9, 2012)

seems valid to me. last summer I was lucky enough to be in some hives with doctor lawrence connor, he told a small group of us to use a comb scratcher to open 10 or 15 drone cells. if we saw 2 or 3 mites, scratch some more and do a shake test. the drone scratch was a quick test to see if more was required...it seems to me that as you go north you can not get away with as much. so my numbers would be lower than a lot of the country, a bit more like Ontario. a lot of the bees in Ontario are south of me.


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## shinbone (Jul 5, 2011)

mathesonequip - Thanks for your input.

Regarding comparing rates of varroa infestation in drone and worker brood, I found this informal comparison in a single hive by Solomon Parker in http://www.beesource.com/forums/sho...atment-Free-Colony&highlight=drone+brood+mite :

"_Of the drone brood, I uncapped 56 drones, finding 15/56 (27%) infested with at least one varroa, and two with two mites for a total of 17 mites. Of the worker brood, I uncapped 73 and found 5 infested with a mite (7%) . . . ._"

It is well known that more varroa will be in the brood than in the phoretic stage ("75% of the varroa is in the brood" is the rough number I have seen quoted in threads here on Beesource, i.e. 4x in brood vs on adults). Further, it is well known that mites prefer drone brood over worker brood (4x in drone brood vs worker brood from Solomon's single count example). Accordingly, there should be about 8x as many mites in the drone brood than found on adult nurse bee from an alcohol wash or sugar roll. Obviously, the "8x" factor is just a rough estimate.

This 8x factor (again, it is just a rough estimate) means counting mites in drone brood is a more sensitive measure for varroa, and thus, can be used as an early indicator of a hive getting into "varroa trouble." In other words, a beek will start seeing significant numbers of varroa in drone brood before an alcohol wash starts detecting significant numbers. The drone brood is the "canary in a coal mine." Meaning, a hive headed to eventual collapse due to varroa can be identified earlier by drone brood counting than with an alcohol wash (or any other method which monitors mites on adults). As such, using drone counting, the mite numbers of a hive headed to varroa-induced collapse may possibly still be small enough that "softer" methods of mite treatment will still save the hive.

Easier to do. Less equipment. Less skill required. Less planning. More sensitive. What's not to like about drone counting?

I am just thinking out loud, here, but this seems like a logical conclusion to me. Anyone got any thoughts to add/share?




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## AHudd (Mar 5, 2015)

Removal of drone brood is the method I plan to use for monitoring mite levels.

Alex


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## shinbone (Jul 5, 2011)

Here's a blogsite with photos showing mites in drone brood. http://curbstonevalley.com/blog/?p=6739

A 2001 paper from the American Bee Juornal with some computer modeling. Wilkinson and G. C. Smith. _Modeling the Efficiency of Sampling and Trapping Varroa Destructor in the Drone Brood of Honey bees (Apis mellifera) .

_A 2009 Virginia Cooperative Extension paper comparing different mite sampling methods_. http://pubs.ext.vt.edu/444/444-103/444-103.html

_


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## shinbone (Jul 5, 2011)

AHudd said:


> Removal of drone brood is the method I plan to use for monitoring mite levels.


In that case, you may want to consider reading the Wilkinson and Smith paper.

And, it would be great to hear how it works for you.


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## crofter (May 5, 2011)

That is the method I used this past season. I had two bee inspectors to my hives in the fall. They looked for good capping pattern and uncapped about 20 drone cells and pulled larvae with tweezers. No mites. Usually you find enough disturbed drone brood between combs on inspection to check and dont feel I am compromising anything. It seems to me it is the least invasive and the least likely to chance messing up the queen. It sure is less fuss than doing a sugar or alcohol shake.


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## AHudd (Mar 5, 2015)

shinbone said:


> In that case, you may want to consider reading the Wilkinson and Smith paper.


I'm not familiar with that paper. I may have read it and just don't remember the authors' names. I googled the names and came up with an investment firm etc. ,etc. Could you give me a little more info?

Thanks, Alex


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## AHudd (Mar 5, 2015)

crofter said:


> That is the method I used this past season. I had two bee inspectors to my hives in the fall. They looked for good capping pattern and uncapped about 20 drone cells and pulled larvae with tweezers. No mites. Usually you find enough disturbed drone brood between combs on inspection to check and dont feel I am compromising anything. It seems to me it is the least invasive and the least likely to chance messing up the queen. It sure is less fuss than doing a sugar or alcohol shake.


I agree.
Alex


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## shinbone (Jul 5, 2011)

Sorry, I should have been more specific - it is the second link in Post #5, above.

And for anyone considering drone culling for varroa control, though the paper is just computer modeling, the authors conclude that drone culling isn't a good method of controlling varroa.


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## shinbone (Jul 5, 2011)

crofter said:


> That is the method I used this past season. I had two bee inspectors to my hives in the fall. They looked for good capping pattern and uncapped about 20 drone cells and pulled larvae with tweezers. No mites.


Crofter - did the inspectors happen to mention what they consider to be the treatment threshold when counting mites by looking at drone brood?

The most relevant numbers I have seen so far, appear to originate from a 1996 British government publication and are: 5% is a light mite load and 25% is a severe load. I did not see in the publication how those number specifically translate into when to treat, though.


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## crofter (May 5, 2011)

We got talking about oxalic acid and treating whenever you see *any* mites. The Canadian Agriculture recommendations for treatment action has been lowered recently from the previous acceptable levels. I did one vaporization spring and fall as preventative. Some people will go on about how horrible an idea that is but I see Snl suggesting a vaporization and stickyboard count as a diagnostic measure. With 3, 8 and six hives it is not very conclusive test but no winter loss for three years makes me a believer. 

I have just barely got into my hives and only two have any drone brood yet so have not pulled any to check for mites. I want to raise queens so am not going to be culling drone hard at least till later in the summer.


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## shinbone (Jul 5, 2011)

crofter said:


> . . . I see Snl suggesting a vaporization and stickyboard count as a diagnostic measure.


I've done this. Do an OAV treatment and then count the dead mites. If you see a lot on the sticky board, do another treatment. Rinse and repeat until you see a minimal mite fall. One of the nice features of the OAV/sticky board is that you know when you are done treating, AND, more importantly, you know when you are not.


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## AHudd (Mar 5, 2015)

shinbone said:


> Sorry, I should have been more specific - it is the second link in Post #5, above.
> 
> And for anyone considering drone culling for varroa control, though the paper is just computer modeling, the authors conclude that drone culling isn't a good method of controlling varroa.


I went back to post #5 and there it was, the authors' names. I just missed it. 

Thanks, Alex


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## AHudd (Mar 5, 2015)

shinbone said:


> In that case, you may want to consider reading the Wilkinson and Smith paper.
> 
> And, it would be great to hear how it works for you.


I had one hive come into Spring very weak. It was a double deep, so I broke it down into a single using the best frames and froze the rest. My suspicion was mites. After pulling more than 100 drones, I found only one mite. So, the problem with this hive was not mites, I hope. I later discovered this hive to be queenless. I gave it two frames of brood and eggs from my strongest hive on the 10th of April. I hope to see eggs on my next inspection. To be clear, my goal is to be treatment free, but I think I need to monitor mite levels to be sure the VSH stock that I purchased is working as advertised. I hope checking drone brood is an effective way to _monitor_ mite levels.

Thanks for the links and your input.
Alex


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## RayMarler (Jun 18, 2008)

shinbone
A nice thread with some very informative links, thanks so much.
I've done drone brood control in the past, and then stopped. I had more losses after stopping. At the very least, it is a way of monitoring varroa levels, but I feel it can also be a way of control. The problem arises when there is no drone brood in the hives. They tend to slow down drone production here in July and pick back up again mid to late September. When they do pick it up in the fall, it is at a much lower rate than they do in the spring. Unfortunately, mid July through mid October are good months to be monitoring and controlling varroa levels here.


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## shinbone (Jul 5, 2011)

Ray - Thanks for the kind words and the input.

Good point and something I hadn't thought of - if the hive isn't making drone, then there is no drone brood to be counting. Maybe this seasonal limitation is the reason drone counting isn't used for mite monitoring?


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## mathesonequip (Jul 9, 2012)

because drone populations vary with the season and local flow conditions, counting mites on drone larvae is an indicator not a monitor that says this is ok or I am in trouble. if the count is high there is a big problem. if nearly none are found, I am in good shape for now. if some are found do a shake test to find a standard measurement, them make management decisions based on facts not guesses.


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## AHudd (Mar 5, 2015)

shinbone said:


> Ray - Thanks for the kind words and the input.
> 
> Good point and something I hadn't thought of - if the hive isn't making drone, then there is no drone brood to be counting. Maybe this seasonal limitation is the reason drone counting isn't used for mite monitoring?


I have seen on the bee suppliers websites, drone foundation for sale, I wonder if that would keep the bees from slowing drone production?

Alex


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## KQ6AR (May 13, 2008)

I use 5 mites on 10 drone pupa as a high end. Then I start cutting out the drone frames instead of letting them emerge.


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## RayMarler (Jun 18, 2008)

AHudd said:


> I have seen on the bee suppliers websites, drone foundation for sale, I wonder if that would keep the bees from slowing drone production?
> 
> Alex


Part of the reason they slow or stop drone production is flow strength or weakness in an area, part of the reason is also from the time of year. Sometimes they will fill the drone comb with nectar instead of using it to raise drones. Drones are raised in great numbers in the spring, slowing or stopping through summer, picking up somewhat in the fall, in my area.


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## AHudd (Mar 5, 2015)

RayMarler said:


> Part of the reason they slow or stop drone production is flow strength or weakness in an area, part of the reason is also from the time of year. Sometimes they will fill the drone comb with nectar instead of using it to raise drones. Drones are raised in great numbers in the spring, slowing or stopping through summer, picking up somewhat in the fall, in my area.


Thanks for reply, Alex


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## Kofu (Jan 26, 2011)

I froze a TBH bar of drone brood a couple of days ago, thawed it, and pulled out about 15 drone brood. Got about 3-4 mites on the bodies of the drone pupae as they came out.

Then I turned the comb over and pulled out a few more drones from the other side. Same ratio. Then I looked on the cookie sheet I had laid the comb on, and there were another 3-4 mites that had fallen out when the emptied drone cells were turned over. Perhaps the mites retreated to the bottom of the cells as it got colder?

I repeated the process a little more carefully. Bopped the bar and shook the comb a bit to get out any stray mites, then did it again with a fresh slate. Same results. About half the mites were not attached to the drone pupae and did not come out with them.

I'm just getting into counting mites more diligently. From live drone brood that I've pulled out or dislodged from the comb, last year in the summer, at times I saw a lot of mites attached to the drones, and moving around when exposed. inch: (The hives did survive the winter.) This year I'll be trying several approaches to monitoring the mite load. And I'm thinking that at least with frozen, it's helpful to shake and bop the frames/bars to get out any mites that might have retreated from the cold.


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## shinbone (Jul 5, 2011)

Kofu - Interesting observations. I'll spend some time looking into the cells I pull drone from when counting mites. Thanks for posting.


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## JRG13 (May 11, 2012)

I did drone removal and checking twice this year already... the first round was disappointing, I did not find a single mite after going at it for 40 minutes or so. The second time I was so happy I found a single mite in one cell and there was another stuck in some honey. I know there should've been more mites in my opinion so I kind of gave up on the idea that removing drones was reliable or that checking drone brood was a good indication of mite levels. These were full frames of drones as well.


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## shinbone (Jul 5, 2011)

JRG13 said:


> I did drone removal and checking twice this year already... the first round was disappointing, I did not find a single mite after going at it for 40 minutes or so. The second time I was so happy I found a single mite in one cell and there was another stuck in some honey. I know there should've been more mites in my opinion so I kind of gave up on the idea that removing drones was reliable or that checking drone brood was a good indication of mite levels. These were full frames of drones as well.


 Mites strongly prefer to reproduce in drone brood. If you are pulling out a bunch of drone pupae from a hive, but not seeing many mites, then it is safe to conclude that that hive's infestation rate is low. What other conclusion is reasonably possible?

How else did you check mite levels in that hive? Is there some other factor that allows you to ignore the low drone-brood mite count and conclude that the hive has a lot of mites? 

I know a properly done OAV in the Fall when the hive is broodless will result in very low mite counts in the Spring. Because I OAV in November, I usually don't bother looking for mites until late Summer/early Fall. As an example, however, this week I have been monitoring a sticky board for a hive that consists of about 25 medium frames of bees, and have not seen any mites on the board in 5 days. This hive got a single OAV treatment just before Thanksgiving of 2014. I know a sticky board is not the most accurate method of mite counting, but, still, 0 mites in 5 days is a pretty clean hive. Not surprising because OAVing a broodless hive is a very effective mite treatment.






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## mathesonequip (Jul 9, 2012)

Right. this rrg13 quote is mixed up, disappointed because not enough mites??


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## JRG13 (May 11, 2012)

When making some splits, there was some random drone brood here and there. I caught one emerging with a mite square between the eyes, and when I pulled him out, he had another 4 mites keeping him company in the cell. I figured I'd find some in that drone brood based on catching that single drone emerging that was fairly infested from that hive. I know it's funny Matheson, but it would be like going through your apiary doing mite washes or sugar drops and not finding a mite... it's good on the bee side of things, but wouldn't you just look back and think what a big waste of time finding absolutely nothing...


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## mathesonequip (Jul 9, 2012)

yeah, unfortunately we all have mites. you get more on drone brood because it is capped longer with a female mite laying an egg a day. the male is tiny, white and usually eaten by mother and daughters by the time the bee emerges from the cell.


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## camero7 (Sep 21, 2009)

I've basically quit pulling drone brood looking for mites. I just cut out the drone brood from my foundationless frame and move on. Since I don't raise queens drones are not valuable and it's a pain to pull and check. Some studies have indicated that around 80% of the mites are on drone brood in the summer, so I figure I'm getting quite a few mites as I go.


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## vdotmatrix (Apr 5, 2014)

http://www.southernoregonbeekeepers.org/how-to/how-to-sample-bees-for-a-varroa-mite-count


shinbone said:


> Rather than doing an alcohol wash or sugar roll of adult bees from the brood nest, etc., what about counting mites in drone brood to determine mite infestation levels?
> 
> I'd rather pull 10 or 20 drone larva/pupa than assembly the equipment for an alcohol wash or sugar roll. Capped drone brood can be pulled anytime the beek feels the need to check mite levels, no need to be schlepping jars and tubs and alcohol/sugar into the apiary. Obviously, the percentages would have to be adjusted to account for the varroa mite's preference for drone brood, but that should be easy enough to do. However, practically no one mentions this as a mite count method. Anyone know why drone-brood mite counts are not used?
> 
> ...


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## Phoebee (Jan 29, 2014)

We just picked up a nuc that had been inspected the day before by a state bee inspector. We were told a drone brood sample was the method used by the state inspector.

I'm not an expert at this, but I've done my own counts of mites on drone brood I'd frozen. From my couple of attempts I'd say that 3 pupae is a horribly inadequate number. I went through about 100 pupae on a frozen green drone frame, writing down the number of mites visible on each pupae. At one point I found no mites on 20 pupae and then the next few were loaded. After noticing this I did some reading up and saw a recommendation that the sample be not less than 200 pupae.

For frozen drones frames, which you do as a mite control measure, sampling the pupae is not killing bees ... you did that already. And if they are still frozen, you will have no problem pulling them from the cells. However, when I've tried this on live pupae, only the purple-eyed pupae pull from the cells reliably. Purple-eyed are the oldest and will have the most visible mites. Earlier stages have immature mites which are white and hard to spot, and fewer of them. And the earlier stages tend to be mushy ... you try to pull them out of the cell and you get goo. To find purple eyes you'll need to open more cells than you intend to sample. Also, look down in the cell after you remove the pupae ... there may be mites left behind.

If you are freezing drone frames, it is a pure waste not to take advantage to count a sample of your victims. Although I do see the point above ... if you don't need the drones and they're varroa bait, well, good bye, guys.

And I have not used this method this year. For some reason, while drone production was rife this spring, the hives are concentrating on workers now, and have put nectar in the drone comb.


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