# Varroa calculator



## Morris (Oct 12, 2004)

Not long ago, someone had posted a link to a handy Varroa calculator. Unfortunately I did not save it. Anyone out there remember where it is?


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## Tia (Nov 19, 2003)

Here ya go, Morris: http://www.csl.gov.uk/science/organ/environ/bee/diseases/varroa/varroacalculator.cfm


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## Morris (Oct 12, 2004)

Tia,

Thanks, that's it.

No wonder this is my favorite web site.


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## George Fergusson (May 19, 2005)

I question the accuracy of that calculator though I have no real basis for saying so other than "it just don't seem quite right". It's a seat of the pants thing. It seems to be based on too simple a model and I suspect it underestimates the varroa population, or at least, the potential varroa population (which is what you really want to know).

It also doesn't seem like it takes into account the month of the observation quite right i.e., I get the same "results" (and the same "advice") whether I enter May, or August when in fact, it makes a big difference. Counting 10 mites a day in August is nothing to write home about but counting 10 mites a day in May is something to be very concerned about.

I'd like to know more about the model.

George-


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## Morris (Oct 12, 2004)

George, You make a good point. Perhaps a good observation would be to actually open caped brood cells, and compare what you see with the results of the calculator.

Morris


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## George Fergusson (May 19, 2005)

The ratio of fallen (dead) mites to the total number of mites in the hive varies drastically depending on whether there is sealed brood or not and how much i.e., the time of the year. Other conditions also effect mite drop- temperature, humidity, grooming behavior, etc. However, the natural drop is largely dependent on the total number of mites period, more or less irrespective of the total number of bees.

During periods of brood rearing, it is estimated that as much as 65% of the mites in a colony are in sealed brood so uncapping brood and counting mites can be used as a method of estimating total mite population IF you can accurately estimate the total amount of sealed brood in your hive.

One study I've read indicates that the total mite population can be estimated by multiplying the mite drop by 250-500 during periods of broodlessness or 20-40 during period when there is brood present i.e., if you count 10 mites a day in June, your total mite population would be between 200 and 400 mites. If you counted 10 mites per day during the winter when the hive is broodless, your total mite population would be between 2500 and 5000. That's quite a range, but with so many factors affecting mite drop, that's to be expected. This is also why monitoring drop over time is so important- if you're inclined to do that kind of thing.

Then again, I'm still trying to sort this mite-thing out. I reserve the right to be wrong and change my mind.

George-


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## Michael Bush (Aug 2, 2002)

>the total mite population can be estimated by multiplying the mite drop by 250-500 during periods of broodlessness or 20-40 during period when there is brood present i.e., if you count 10 mites a day in June, your total mite population would be between 200 and 400 mites. If you counted 10 mites per day during the winter when the hive is broodless, your total mite population would be between 2500 and 5000. 

This seems backwards to me. I would expect that a drop of 10 mites per day in June would mean that there are many more mites hiding in the cells that are not succeptable to being groomed off. While 10 mites per day in the middle of winter would mean significantly less mites, since none are hiding in the cells where they can't be groomed off, than when I see the same number in June.

I'm just using your numbers here and don't mean these to be exact numbers, but I'd guess 10 mites in the winter would be more likely to mean about 250 to 500 mites total (all outside the cells) and 10 mites in JUNE would mean about 250 to 500 mites OUTSIDE the cells and another 500 to 1000 mites INSIDE the cells.


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## Dave W (Aug 3, 2002)

George Fergusson . . .
>One study I've read indicates that the total mite population can be estimated by multiplying the mite drop by 250-500 during periods of broodlessness or 20-40 during period when there is brood present i.e.

Do you have a "source" for this? (Just for my records







On another thread, you gave me some sound advice, "independently verified" and "reputable sources".) 

thanx

[ November 09, 2005, 02:08 PM: Message edited by: Dave W ]


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## George Fergusson (May 19, 2005)

Absolutely Dave, I'm glad someone asked! I've been looking over a varroa population model:

http://www.culturaapicola.com.ar/apuntes/sanidad/ecol%20monogr.pdf

I have not independently verified all this and I probably won't bother though I'm continuing to dig into it. Some of the assertions I've seen elsewhere, and the paper itself sites results and data from similar studies of varroa populations.

George-


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## George Fergusson (May 19, 2005)

>>This seems backwards to me.

I'm glad I'm not the only one Michael- it is totally counter-intuitive and I really had to ponder it for a while before I understood what they were talking about, and I use the term "understood" loosely, and by so doing I am not defending this model, merely understanding it.. Have I hedged enough?

The numbers are based on the "daily mite mortality rate" which varies considerably depending on the presence of brood. For reasons that I haven't fully grasped, the model says the daily mite mortality rate during periods when there is no brood (i.e. winter) varies from 0.002 to 0.004 (multiplier of 200 to 500) and from 0.3 to 0.5 (multiplier of 20 to 40) during periods when there is brood (i.e. summer).

I think a lot of my confusion came from thinking that the natural mite drop is due largely to phoretic mites falling off bees, or being groomed off and that mites in cells are relatively "safe". According to this study/model, that is not the case. Most of the mites that end up on the bottom board either died in the cell (and the more mites entering a cell, the higher the mortality rate) and were hauled out by the bees or they dropped or were groomed off upon emergence. Also more mites die/drop when raised in worker brood than in drone brood (dunno why). The model figures 20% of emergent mites (from worker and drone brood) end up dropping. When all the mites are phoretic the daily mite mortality rate actually drops.

In a sense, all this makes sense.. one thing I've been wondering for a while is if all (or most all) of the mites are phoretic for 5-6 months during the winter and NOT breeding, and they continue to drop at roughly comparable rates as during the summer, why don't their numbers dwindle more? Why does it take 2-3 years for a colony to crash if the mite population is set back to square one each winter?

George-


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## George Fergusson (May 19, 2005)

Dave W- I've been looking (again) at your 2005 mite counts:

http://www.beesource.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000568

Can you estimate the dates when brood rearing started/stopped? It would be interesting to plug some of your numbers into this model I've been pondering and see what develops.

George-


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## Dave W (Aug 3, 2002)

George Fergusson . . .

>estimate the dates when brood rearing started/stopped . . .
Looking at my 2005 mite counts (topic;f=3;t=000568), I first noted "white" (immature) mites on Feb 4. On Nov 4th I was still finding (7) white mites on my sticky board.

Please let us know what "develops"


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## Dave W (Aug 3, 2002)

Some misc comments . . .

>mite population can be estimated by multiplying the mite drop by 250-500 during periods of broodlessness . . .
Looking at my 2005 mite counts . . . on Jan 7th my count was 15, multiplied by 500, would mean my hive had 7500 mite in January. I dont think so!!

>20-40 during period when there is brood present . . .
Last year on July 7, 2004, my natural drop was 108. Multiplying this by 40 produces a number of 4320. 

On July 12 I applied Apistan, in first 24 hrs I counted 1,444 dead mites. For the next 12 days my AVERAGE drop was 879/24hrs. After 44 days of treatment, I removed (and counted) a total of 15,341 mites.

>20% of emergent mites (from worker and drone brood) end up dropping . . .
1,444 / 108 is not 20%
15,341 / 108 is NOT 20%

>if all (or most all) of the mites are phoretic for 5-6 months during the winter . . .
I dont think this is accurate









>if the mite population is set back to square one each winter . . .
My mite drop has NEVER been zero during winter. I think a "slightly" increasing population (winter and summer) may have an impact on when a hive crashes. Looking at my mite drop numbers over a couple of years, I see up-and-downs during the year and a steady overall increase in TOTAL mites over the years.


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## George Fergusson (May 19, 2005)

>>Looking at my 2005 mite counts . . . on Jan 7th my count was 15, multiplied by 500, would mean my hive had 7500 mite in January. I dont think so!!

You think you had less? More? Why? The multiplier is a range, 250-500, and a wide one at that. How's 3750 mites sound?

>>>20-40 during period when there is brood present . . .
>>Last year on July 7, 2004, my natural drop was 108. Multiplying this by 40 produces a number of 4320. 

Reasonable number.. I suppose?

>>On July 12 I applied Apistan, in first 24 hrs I counted 1,444 dead mites. For the next 12 days my AVERAGE drop was 879/24hrs. After 44 days of treatment, I removed (and counted) a total of 15,341 mites.

Lotta mites. The thing to remember is that at any given time, assuming there is brood, up to 65% of the mites can be in cells, reproducing. Estimating 4320 mites on 7/7 and counting 15K dead mites after 44 days of treating means those mites were really reproducing.. not that the 4320 figure was correct.

>20% of emergent mites (from worker and drone brood) end up dropping . . .
1,444 / 108 is not 20%
15,341 / 108 is NOT 20%

I'm not sure what you're trying to calculate there! The estimated 20% of emergent mites dropping is "natural" drop but it doesn't account for ALL the natural drop, and you can't treat with Apistan and consider your subsequent drop anything like "natural".

>>if all (or most all) of the mites are phoretic >>for 5-6 months during the winter . . .
I dont think this is accurate 

For however long your hive is broodless, so then are your mites phoretic. The common opinion is that winter is hard on mites. My opinion is it's not hard enough on them. Clearly, mite populations don't get wiped out come winter.

So anyways, you don't seem to like the factors, multipliers, and percentages I tossed up for target practice which is fine- I've got no vested interest in them being right anyways, but I am interested in getting a better handle on mite population dynamics. You seem to think that suggesting you might have 7500 mites in your hive in January (or 3750 even) is wrong but then 6 months later you document 15,341 mites dead in 44 days. Where they all coming from? How fast are they reproducing? How is the mite population varying over time?

You're the one counting all the mites. What do you think is going on?

George-


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## Michael Bush (Aug 2, 2002)

>>if all (or most all) of the mites are phoretic for 5-6 months during the winter . . .
>I dont think this is accurate 

I agree with Dave. The last of the brood in the fall emerges at about the end of September. A lot of my hives start brood rearing in January. Most have some brood in February. All have a lot of brood in March. That's three to four months broodless here and I'm kind of far North (the Minnesotan's and Canadians are laughing) That's a lot less than five or six months.


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## George Fergusson (May 19, 2005)

I admit my original "5-6 months broodless" statement was an exaggeration. Winter may last that long, but broodlessness doesn't last that long. Drones are not raised for quite a while so reproducing mites are left with utilizing less desirable worker brood for their nefarious purposes until early spring when general brood rearing starts up in earnest. They seem to manage.

I guess the point is that mite populations aren't decimated during the winter, which was always my own misconception.

George-


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## Michael Bush (Aug 2, 2002)

The varroa seem to have the same ability as the bees to live longer in a dormant winter period.


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## Dave W (Aug 3, 2002)

>think you had less? 
Yes, much less!

>Why?
At this time, only "Gut feeling".

>Estimating 4320 mites on 7/7 and counting 15K dead mites after 44 days of treating means those mites were really reproducing.. not that the 4320 figure was correct.
The mites were NOT reproducing ANY FASTER during the 44 days. The increase STARTED about 59 days prior to July 7's 108 count.

>means those mites were really reproducing.. not that the 4320 figure was correct.
The hive had a LOT MORE mites than 4320 on July 7.

>20% of emergent mites . . .
Is it possible to use 1,444 (first days KILL) or 15,341 TOTAL KILL and determine that the NATURAL FALL of 108 does NOT equate to a 20% mite fall?

>For however long your hive is broodless, so then are your mites phoretic . . .
Yes. And some are phoretic DURING period WITH brood.

>common opinion is that winter is hard on mites . . .
Not "common". Where did this originate?

>mite populations don't get wiped out come winter.
True. That part of the mite "build-up" problem.

>you don't seem to like the factors, multipliers, and percentages . . .
Not true. I would LOOOVE to have some that WORKS!!!

>I've got no vested interest in them being right . . .
When we "vest interest" in them and they are wrong, what do we have?

> am interested in getting a better handle on mite population dynamics . . .
Please keep us informed.

>suggesting you might have 7500 mites in your hive in January (or 3750 even) is wrong but then 6 months later you document 15,341 mites dead in 44 days . . .
Starting w/ 7500 (or even 3750) mites in January and a few (less than 100) cells of WORKER brood, then about March, 1000+ cells of worker and a few drone cells will produce a lot MORE mites than 15,341. (and a dead hive!)

>Where they all coming from? 
??? please explain "all".

>How fast are they reproducing . . .
Look at my mite numbers.

>How is the mite population varying over time?
Look at my mite numbers.
I have numers from 2003 and 2004 from this hive also, if your interested.









>You're the one counting all the mites.
And counting, and counting, and counting.
Do you have any NUMBERS to share?


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## George Fergusson (May 19, 2005)

>>20% of emergent mites . . .
>Is it possible to use 1,444 (first days KILL) or 15,341 TOTAL KILL and determine that the NATURAL FALL of 108 does NOT equate to a 20% mite fall?

Forget the 20% figure. That's just the average percentage of emerging mites that one group of researches figured are born dead ("brood mortality") or for some other reason end up on the bottom board upon emergence and do not become part of the free (phoretic) mite population. It's just a contribution to the natural drop but apparently a significant portion of it- one reason why natural drop counts go down during the winter- there's less brood rearing going on. Another reason I think there's less drop in the winter is the bees are clustered and hence move around less- the chances of a mite falling off a bee and not landing on another bee are less.

So your natural drop is going to be roughly 20% of the emerging mites (a hard to pin down figure in itself) PLUS some number of mites dropping for other reasons- old age, grooming, etc.

>How is the mite population varying over time?
>Look at my mite numbers. I have numers from 2003 and 2004 from this hive also, if your interested.

The problem is Dave, you keep killing your mites! That makes it harder to figure out what's going on







And I would be interested in more data from previous years.

>common opinion is that winter is hard on mites . . .
>Not "common". Where did this originate?

MY misconception based on what I've heard. Probably stemming from the fact that if the bees aren't raising brood, the mites aren't breeding either so populations should shrink due to attrition. Obviously not the case.

>>Starting w/ 7500 (or even 3750) mites in January and a few (less than 100) cells of WORKER brood, then about March, 1000+ cells of worker and a few drone cells will produce a lot MORE mites than 15,341. (and a dead hive!)

I'd say you're right. Yet Another frequently mentioned figure is you can see a 12-fold increase in mites during a single brood rearing season- if you start with a 1000 mites in say January, you could conceivably end up with 12,000 give or take some, come November. Woof. In areas where brood rearing goes on pretty much all year, 12-fold is out the window.

Frankly, when someone says "multiply your counts by 200-500" my first reaction is "You don't have a very good handle on this do you?" My second reaction is "Oh. My. There must be a lotta variables at play here.."

>You're the one counting all the mites.
>And counting, and counting, and counting.
Do you have any NUMBERS to share? 

Nothing to compare with yours  I have some, I probably did counts on all my hives once, many of them twice, and some (4-5 hives) 4 or 5 times. With 25 hives and only 5 with SBB's (and they didn't have appreciable mites anyways...) finding the time to count mites wasn't easy. 

I'll be happy to share my data for what it's worth- but your's is so much more valuable because it covers a long period of time on one hive. Mine covers a short period of time on a lot of hives.


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## George Fergusson (May 19, 2005)

I thought I'd take a break from bloviating in this thread awhile and read some of the historical stuff on this site on varroa population dynamics and such. There's been some really good questions asked and stuff written, I particularly like Jim Fischer's assertion that the failure of the research community to suitably address the varroa "problem" is "deplorable and inexcusable" (or something to that effect) and I'd have to agree. I'd also suggest that there's been a lot of research done that hasn't been made readily available to the beekeeping public, for whatever reasons, which I also find deplorable and inexcusable.

It's also clear that nothing really NEW has come to light in this, the most recent thread on Varroa, so far. It's all been said before







but that's to be expected and it's not to say we can't derive some benefit from continued discussion, even if we end up rehashing a lot of old information. Some of us (me in particular) have to come up to speed so to speak, and there's a lot we don't know yet about varroa and how they impact our hives. So we better keep talking.

George-


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## Dave W (Aug 3, 2002)

George Fergusson . . .

>Forget the 20% figure . . .
Sorry, for some (unclear) reason, I thought that you were saying that my (108) natural drop was 20% of the mites in the hive. Guess both agree thats not true.









>I would be interested in more data from previous years.
I have added my 2003 & 2004 mite counts to my original "Mite Count", please see:

http://www.beesource.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000568

>if the bees aren't raising brood, the mites aren't breeding either so populations should shrink due to attrition . . .
True, mite population DOES shrink (some), but NOT to zero.

>"You don't have a very good handle on this do you?" . . .
This may be a bit harsh









>"Oh. My. There must be a lotta variables at play here.." . . .
And NO ONE knows all the answers!









>Nothing to compare with yours . . .
Get busy!!!!







I need some help! A good cross-referance would be very helpful.

>It's also clear that nothing really NEW has come to light in this, the most recent thread on Varroa, . . .
May I point out the follwoing:
1) The mite calculator mentioned above does not reflect MY actual numbers.
2) Winter mite polulation does not decline to zero.
3) Natural mite fall does NOT represent 20% of total mites in hive.

>Some of us (me in particular) have to come up to speed . . .
"me" too!


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## George Fergusson (May 19, 2005)

>>Forget the 20% figure . . .
>Sorry, for some (unclear) reason, I thought that you were saying that my (108) natural drop was 20% of the mites in the hive. Guess both agree thats not true.

Yup. It's a good figure to remember though. More mites die in the process of breeding than during their phoretic phase, and more mites die (or fail to mature, depends on how you look at it) in worker cells than drone cells- hence the estimate of 1.4 mites emerging from worker brood and 2.7 mites emerging from drone brood. Also, mite mortality goes UP when multiple mites enter the same cell to breed (presumably due to competition for the feeding site). The 20% figure is for 1 mite breeding in a drone cell- it's closer to 30% for mites in worker brood.

This also serves to explain at least partly why mite drop counts often escalate in late summer and early fall, as if you all of a sudden had more mites (where'd they come from!!) when in fact you've got the same growing population and they're breeding at the same rate, they're just dropping faster because the queen is slowing down- there's no (or little) drone brood and less worker brood and the infestation grade (# of mites per cell) increases. There might also be immigration of mites due to increased robbing in the fall. Dunno about that, I'm speculating now.

>I have added my 2003 & 2004 mite counts

Awesome









>>It's also clear that nothing really NEW has come to light in this, the most recent thread on Varroa, . . .
>May I point out the follwoing:

Didn't mean to imply this thread was useless, just somewhat redundant. I've sure learned a lot.

>Get busy!!!!

Aye aye Captain! I don't expect to be doing any mite counts till spring, though I've got a few hives on SBB's and will likely do some drop counts over the winter. I did review my mite counts (they're really pathetic compared to yours) and will post a relevant synopsis in a while. For now, there's this:

8/07/05 Hive #15 had a 24 hour drop of 45 mites. I only did one test on this hive, prefering to concentrate on other hives with MUCH higher counts; At the time, the hive seemed strong and populous- it had been one of my stronger hives this summer. I did notice in late August and early September some chalk brood, and some dead brood being hauled out. They took some feed, but did not take it with relish. Finally stopped taking it though the hive was still light.

Yesterday 11/14 I pronounced hive #15 effectively dead. Barely a single frame of bees in the top deep which was largely full of honey. I'd estimate maybe 2000 bees tops. Virtually empty bottom deep except for a little uncapped honey. No brood obviously, but a couple of center frames showed evidence I've learned to associate with heavy mite infestation: evidence of DWV including dead emerging brood with their tongues sticking out (I removed a few and they had deformed wings), uncapped dead larvae, and a few mummies (chalk); there was a small pile (maybe 1/2 cup) of dead bees in the center of the bottom board and some "greasy" dead bees scattered around as well.

Mites got `em.

George-


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## db_land (Aug 29, 2003)

Dave W: Thanks for the 2003, 2004 counts. Seems to me you had/have fluvalinate resistant mites (based on the numbers after Apistan treatment). Don't know why your OA vapor didn't work but you should try it again.

George: No treatments at all? How are the hives doing that had higher counts?


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## Dave W (Aug 3, 2002)

George . . .

>Aye aye Captain!
Thats "Aye aye Captain, SIR!!!"









In two paragraphs (8/07/05 Hive #15 . . . and Yesterday 11/14) you have described PERFECTLY the single most-often used "excuse" AND the classic "results" most often seen by beekeepers. 


db_land . . .

>Thanks for the 2003, 2004 counts . . .
You are welcome. Hope they are helpful(somehow) .

>Seems to me you had/have fluvalinate resistant mites . . .
Is "resistant mites" the only reason?

>OA vapor didn't work . . .
The numers show that it DID work. Just not very effectively.


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## George Fergusson (May 19, 2005)

>No treatments at all? How are the hives doing that had higher counts?

Oh, I treated, and they're largely OK. Initially I tried powdered sugar on a few hives. The process was incredibly labor intensive and time consuming and it disturbed the bees big time, and the results were unsatisfactory. I chose not to do it again. I tried FGMO, but that too was ineffective- I suspect my infestation was way beyond what fogging could handle.

I finally resorted to OA vapor, giving 4 treatments a week apart starting in mid August I think. That helped a lot, judging from the few drop counts I've been able to do since then (too busy feeding and working).

The majority of my hives seem to be in pretty good shape, even the ones with higher mite counts. I've combined some of the weaker ones, just split a few and divied up the stores, and requeened a few. All in all I "vanished" 5 hives, and the other hives assimilated them.

Just this past Monday I "dribbled" my hives with OA-laced syrup, which is how I discovered the all-but-dead hive.

George-


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## George Fergusson (May 19, 2005)

>Thats "Aye aye Captain, SIR!!!"

Delusions of grandeur? Nah...

>you have described PERFECTLY...

Yup. Ironically, it's often your strongest hives that gave you the most honey that crash when your back is turned, and usually in the fall... It happened to some friends of mine with their 2 hives last month. Their hives were both populous and productive 3-year old colonies, all but wiped out over the course of a little over a month. DWV, probably Kashmir virus, classic PMS, the same thing I saw in my hive. They've written them off.

BTW, I've got some bad news for you Sir! I've been playing with VarroaPop, and I plugged your colony data in, and according to the model, your hive died last March. My condolences!










Actually, I *have* been playing with VarroaPop, and I *did* plug in your colony data and "seeded" it with 1049 varroa mites (1% infestation level) and your hive didn't die last spring, it will die next spring







The results, for what they're worth, are at:

http://www.sweettimeapiary.com/pics/davew.txt

And a graph:

http://www.sweettimeapiary.com/pics/dw.bmp

The simulation starts 4/12/03 with the installation of a 3# package (10500 bees) with a mite infestation level of 1% (1049). The model uses 1.5 mites emerging from worker brood and 2.7 mites emerging from drone brood, both with a 90% survival factor. There was no brood or eggs at the time. Your first year was pretty good, the colony did well. The second year wasn't quite so good, but still not bad. This year, you requeened on 4/30/05 in an attempt to bolster your hives failing population, and it helped. You went into winter with a reasonably good looking colony, but the mite population was exploding. Winter was hard on the bees. Come spring 2006, things didn't look good at all. You tried to requeen again in late April, but your hive just never recovered.

RIP....

OK. First, I'm NOT representing this model as reality. It isn't. VarroaPop has a lot of quirks and foibles not the least of which is it doesn't accurately factor in all the effects that high mite infestation levels can have on a hive i.e., vectoring in disease and stressing the colony. In other words, the model can show a happy colony with a mite load that staggers the imagination. Also, you've been treating your hive, and there are no treatments factored into this model though in the case of your Apistan treatment, that's not too far from reality  VarroaPop does support factoring in treatments, but I haven't tried it yet. That said, if the model has ANYTHING to do with reality, I'd say your treatments are the reason you still HAVE a colony.

What's a bit scary is how the mite population seems to fit (sort of) your drop counts using the ballpark multipliers of 20-40 for brood periods and 200-500 for broodless periods. Humor me here, Sir! For example, your Oct 21st count this year is 152. The model says you have 76,520 mites in your hive on that date. Divide that by 500 (broodless drop multiplier) and you get 153. Yes, I know your hive wasn't likely broodless.. Coincidence I'm sure. Do you really have 76 thousand mites in your hive? Dunno. On Jan 7th this year, your drop count was 15. Multiply that by 300 and you get 4500, the model gives 3944, a difference of 556 mites. 200 * 15 is 3000 mites.

So. I dunno. You should take a look at the data and tell me what you think. I'm not done playing with it, this is just a first-pass and probably not a very good one at that. I've got a lot of problems with it, and I'm still figuring out the quirks of VarroaPop. I'm not even sure it's entirely suitable for it's intended purpose!

The column headings should be pretty obvious. Free Mites are phoretic mites, Total Mites = (Free Mites + Mites in Drone Brood + Mites in Worker Brood). Requeening is *necessary* or the colony dwindles. Requeening starts 4/30/05 and every year thereafter at the same time. There's a 10 day break in brood rearing during requeening. Your weather is typical midwest weather.. ADrns and AWkrs are adult drones and workers. Any other questions, holler.

George-


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## db_land (Aug 29, 2003)

The colony size prejections don't make sense. The model has the bee pop peaking in Sept - probably would actually peak in May/June/July. The hive would have swarmed in about July if it had the projected population. On 5/20/06 each bee would be carrying around about 4 phoretic mites - not likely. 12/30/06 every bee is a forager and every forager is carrying 20 mites! Hope there's a better model than this. Thanx,


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## George Fergusson (May 19, 2005)

>The colony size prejections don't make sense.

The postjections don't either!

Sorry, couldn't resist. Glad you took the time to look over the numbers. I also have looked at the colony size figures with some skepticism but I'm not prepared to dismiss them out of hand just because they don't fit what I think they ought to fit. For one thing, I'm a total neophyte, something you should remember in case you're confusing me with someone who knows all there is to know about bees







You may also be confusing the data with reality. Don't do that! It's a model. Aspects of it *may* accurately reflect reality. Other aspects won't even be close. My general approach seems to be to look at it and say "What's wrong with this picture?"

For another thing, VarroaPop was developed at the Carl Hayden Bee Research Center in Arizona. I have a concept of what bee populations look like in the Northeast, I have no idea what to expect in the Southwest- for all I know, Arizona bees don't even get started until September. In my own hives, I've seen bee populations staying rather high well into the fall. Maybe someone with beekeeping experience in the southwest could add some insight here.

VarroaPop doesn't do swarms. It does do requeening, and in fact, if you don't implement requeening in the model, your colony will dwindle and die in 3 years even without any varroa pressure. One neat thing about the requeening function is you can specify how long (in days) brood rearing is interrupted, which allows you to play with scenarios involving caging the queen i.e., what impact does caging the queen for 30 days have on the varroa population?

Take a look at this online honeybee population model "WebBeePop" (also developed at the above mentioned research center):

http://gears.tucson.ars.ag.gov/beepop/

FWIW, WebBeePop also shows the bee population peaking in mid-October. Go figure.

>Hope there's a better model than this.

Sorry, it's all I've found to play with so far  

George-


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## Dave W (Aug 3, 2002)

George Fergusson . . . 

First, I would like to thank you for all your "personal attention". THANK YOU.

In the future, I shall always address YOU as SIR! (without "Delusions of grandeur"







)

>your hive died last March . . .
That may be "more true" than you think.

Your "model" is scarrrry! (accuracy is awesome). A lot of the bee population numbers are EXACTLY as I have (otherwise) estimated. Only requeening (I know of) occured before 3/25/05 when I first sighted an unmarked queen. 

>Oct 21st count this year is 152 . . . Do you really have 76 thousand mites in your hive?

Better ask the maker of Suckercide that question.

If there are 76,000 or 3944 why are "present" counts low? Where did the mites go? When did they leave (show me numbers)?


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## Dave W (Aug 3, 2002)

As if we dont have enough to think about . . . here's somthing interesting (at least to me







)

Since my sticky board was "in hive" all year (except for a minute or two while changing contact paper), we can add up all the mites that have died. 

That figure is 22,687 as of 10/14. All were never alive at the same time, but thats sill a lot of mites that HAVE BEEN in the hive.


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## George Fergusson (May 19, 2005)

>First, I would like to thank you for all your "personal attention".

Aw shucks, I thought you'd think I was picking on you. FWIW, this is as much a learning experience for me as anyone.

>>your hive died last March . . .
>That may be "more true" than you think.

Why do you say that?

>Your "model" is scarrrry! (accuracy is awesome).

First, it's Not My Model







Apparently, db_land wasn't too impressed with the bee population numbers peaking in mid-October, but now Tim Vaughan has started a thread "November Honey" so obviously, what you're going to see for bee population dynamics is going to vary considerably from region to region. Tim's talking honey where he lives and the temperature hasn't gotten above freezing where I live..

I was really interested in what YOU thought of the model.

>If there are 76,000 or 3944 why are "present" counts low? Where did the mites go?

I can't answer that. I have no idea. You've obviously killed some, but my seat-o-pants feeling from your numbers is that you haven't killed enough. Your 9 (?) Suckercide treatments do not seem to have had a serious impact on the mites. The increased drop in late summer and early fall could just be evidence of reduced brood rearing (higher mite mortality) combined with an increasing mite population and not have much or anything to do with the Suckercide treatments. I do know that when hives are broodless and all the mites are phoretic, natural drop counts shrink considerably because a lot of natural drop is due to mite mortality in the cell. I think as brood rearing drops off you're likely to see an explosion in mite drop as multiple mites are entering cells- mite mortality rises in this case. It's probably too simplistic to just say "multiply your drop by 20 to 40 when you have brood, and 200 to 500 when you don't".

In other words, expecting to know exactly what a given drop figure means and what it translates to in terms of total mite population at any given point in time is probably expecting too much... at least given what we (I) know now. Mite drop isn't totally linear but it does appear to be largely *static* for discrete periods of time, neglecting variations due to temperature, etc. One count isn't helpful. Lots of counts is helpful. Figure out the factors influencing drop would appear to be the key.

Remember that in an "average" brood rearing season, "schmaat" experienced researchers say that mite populations can increase 12-fold or more. Start with 1000 mites, end up with 12,000 mites...

I've also mentioned this before... your treatments just complicate the process of interpreting the numbers









On another note, it turns out VarroaPop allows you to specify infestation level as a fractional percentage. Just for the halibut, I seeded your 3# package with 2 mites (an infestation level of 0.02% on 10500 bees) and the results are not significantly different from starting with 1049 mites.

Also, when configuring requeening, you can specify the period that egg laying stops. I requeened your hive in late April 2004 (and each year thereafter) and "halted" egg laying for 30 days (i.e., think "caging the queen"...): Your varroa population was all but wiped out. I need to ponder them numbers for a while to see what happened...... I'll post `em if you want.

George-


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## Dave W (Aug 3, 2002)

>>>your hive died last March . . .
>>That may be "more true" than you think.
>Why do you say that?

My gut feeling is a dead hive starts "dying" long before "it dead". Wish I knew when my began. Im not sure what (if anything) Ive done right, OR WRONG!

>I've also mentioned this before... your treatments just complicate the process of interpreting the numbers . . .
I didnt understand the first time, now that you said it again (must be important?), I must ask, "Please explain".

I have been playing w/ VarroaPop. Guess you need to know the answers BEFORE you hit the "run" button.









If you could "get me started", I would like to duplicate the numbers (about my hive) you have posted.

Listed below are the "blanks" I need to fill-in.

Data Needed for VarroaPop  Varroa Mite Population Model, Version 2.1.0 Feb 15, 2002.

From Main Screen click on view, select MODEL PARAMETERS or click yellow comb (Init Cond) button.

MODEL PARAMETERS  Find three tabs*
*Select Colony Data Tab
Colony Name davew
Eggs: Worker ? Drone ? 
Larvae: Worker ? Drone ?
Capped Brood: Worker ? Drone ?
Adult Bees: Worker ? Drone ?
Offspring/mite: Worker ? Drone ?
% Varroa in Capped Brood: Worker ? Drone ?
% Varroa on Adult Bees: Worker ? Drone ?
Mite Survivorship %: Worker ? Drone ?
Forager Lifespan ?
Queen Strength ?

*Select Weather Tab
Weather File ?

*Select Actions Tab
Re-Queening: Enable ? Scheduled ? Auto ?
New Queen Strength ?
Egg Laying Delay ?
Re-Queen Date ? This Date Only ? Annually ?
Varroa Treatment: Enable ?
Start Treatment ?
Treat for ?
% Mortality ?
% Resistant ?


From Main Screen click on view, select PLOT DATA SELECTION or click on Graph (Select Graph) button.

SELECT PARAMETERS TO PLOT
Foragers ?
Colony Size ?
Adult Workers ?
Adult Drones ?
Worker Brood ?
Drone Brood ?
Worker Larvae ?
Drone Larvae ?

Worker Eggs ?
Drone Eggs ?

Total Mites ?
Free Mites ?
Mites in Worker Brood ?
Mites in Drone Brood ?
Mites per Worker Brood Cell ?
Mites per Drone Brood Cell ?
Proportion Resistant Free Mites
Immigrating Mites


From Main Screen click on view, select 
Weekly Data ? or Daily Data ?
Drone Comb Removal Enable ?
Date ? Percent ?


From Main Screen 
Immigration: Enable ? Disable ?
Setup:
Immigration Profile ?
Number of Mites Immigrating ?
Percent Resistant to Miticide ?
Immigration Start Date ? End Date ?

Simulation Period: Start ? Stop ?

I know its a lot to ask









thanx

[ November 21, 2005, 01:31 PM: Message edited by: Dave W ]


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## George Fergusson (May 19, 2005)

>>I've also mentioned this before... your treatments just complicate the process of interpreting the numbers . . .
>I didnt understand the first time, now that you said it again (must be important?), I must ask, "Please explain".

Sorry, it was largely tongue in cheek- with you treating, it makes it hard to compare your drop counts with a normal "untreated" hive. I don't expect you to just count mites and let your hive crash in the interests of science









>If you could "get me started", I would like to duplicate the numbers (about my hive) you have posted.
>
>Listed below are the "blanks" I need to fill-in.

I'm glad you're playing with VarroaPop, it's got more going for it than first meets the eye. I'll do you one better Dave- I just posted the davew.vrp and davew.col files along with the weather file I booger rigged to get things working right:

http://www.sweettimeapiary.com/pics/

You can download `em. I'll also add a few more comments here.

The weather file... I started with the midwest5yr.wth file that came with VarroaPop; it turns out however that the date ranges available within the program are tied to the date ranges of the weather data in the weather file so I expanded the file by copying the last year in the stock file a few times and search/replaced the dates so it now runs from 1/1/99 to 12/31/2006. The last 3 years are therefore indentical.. anyways, this allowed me to start your simulation on 4/12/03 when you installed your package and run it through 12/30/2006. You can't go to 12/31/2006 because the graphs get foobar'd....

Ideally, one should use REAL weather data for your area if you really expect to get the most out of the program.

You started with a 3# package so I figured that was 10500 adult bees and 0 eggs, 0 brood. I've been using 1% for infestation of adult workers. A mite infestation level of 0.01 starts you out with 1 mite.. i.e., 1% of 10500 is 1 whole mite.. Since there are no drones to start with, and no brood, I left those fields at 0.

For mite survivorship I've been using 90% for both worker and drone. I'm not sure exactly what this field is but I think it's what percentage of mites "survive" breeding in each kind of cell.

Queen strength: It turned out that the maximum setting for queen strength correlated to her laying 3000 eggs a day... I thought that was a bit much. "Half strength" is about 2000 eggs a day, which is still a lot of eggs... I've heard the average "good" queen lays 1500 eggs a day.

Requeening: I set you up to requeen on 4/30/05 and every year thereafter, with queen strength at 1/2. If you don't requeen at all, your hive dwindles without varroa in about 3 years.

Forager lifespan... the maximum is 16 days, the minimum is 4. I've had that set at maximum and at that, it seems kinda short.

Mite bionomics- offspring per mite in worker and drone brood: I've been using 1.5 for worker and 2.7 for drone.

I haven't implemented the drone comb removal, mite imigration, or treatments.

As for the data, one column to really keep an eye on is Mites/Worker Brood (the last one over). According to the researchers that developed VarroaPop, when multiple mites enter worker brood, your hive is in serious hot water. As long as they stay in drone brood, the impact on the colony is minimal. Their reasoning for this is that multiple mites in worker cells impact the longevity and health of the workers- they emerge tired and don't live as long. In the fall when drone brood is absent, they invade the worker cells and the resulting bees are not likely to live long enough to make it through the winter. In cases of severe infestation, on top of weakened workers you're likely to get virii and other problems associated with PMS- deformed wing virus, Kashmir virus, etc. When these symptoms show up, almost invariably in the fall, your hive is likely toast.

Once you get your model up and running, you can play with various fields- I recommend changing 1 thing at a time. As to what to plot.. probably simpler to plot LESS data per graphic, and look at more graphics.

Rumor has it they're working on an update to VarroaPop that includes estimated drop counts and some other features. Apparently there have been a series of articles in recent ABJ issues about VarroaPop. I don't get it  

http://www.dadant.com/journal/toc/AugustContents_000.htm

I may try to round up some back issues, AND subscribe.

Lemme know how it goes.

George-


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## Dave W (Aug 3, 2002)

>normal "untreated" hive . . .
Is there such? I WANT ONE (or 2, or a few)









>let your hive crash . . .
Hey! Watch IT!









>davew.vrp and davew.col . . .
Found them, Kinda, this computer wont open. But, thanks. Your "few more comments here" gives me a start.

>foobar'd









>there have been a series of articles in recent ABJ issues about VarroaPop. I don't get it 
>I may try to round up some back issues, AND subscribe.
I have '05 issues. Both articles are about "when" (time of year) to treat, according to VarroaPop. 

>Lemme know how it goes . . .
This may take a while, hope you dont tired of waiting . . . youve been a lot of help.

thanx


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## George Fergusson (May 19, 2005)

>>davew.vrp and davew.col . . .
>Found them, Kinda, this computer wont open.

Just save `em to disk. The file types are unrecognized, but VarroaPop will know what to do.

George-


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## George Fergusson (May 19, 2005)

>>let your hive crash . . .
Hey! Watch IT!

Nothing personal Dave...

>I have '05 issues. Both articles are about "when" (time of year) to treat, according to VarroaPop.

Sigh. I figured as much. I am going to inquire as to any program updates coming anytime soon.

George-


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## db_land (Aug 29, 2003)

"1% of 10500 is 1 whole mite"

George - for the record 1% of 10500 is 105 whole mites.


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## George Fergusson (May 19, 2005)

>George - for the record 1% of 10500 is 105 whole mites.

Hah! You were paying attention. I was testing you... For the record, 0.01% of 10500 is one whole mite.


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