Summer and Winter Mite Falls after Treatment

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RoofTops 

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In a moment of weakness I posted this on the other place yesterday where it has subsequently gathered dust. I'll never learn.

The issue is how a comparison between total mites killed by a late summer treatment compared with the mites killed by a winter OA trickle might suggest the effectiveness or otherwise of the summer treatment. The problem is counting how many mites fall out after treatment does not show how effective that treatment is but a com[parision between two different treatments at different times of the year might be able to give some indication.

There are two enclosed charts.

Varroa Drop Chart shows the number of varroa that fell during thymol treatment which started I think at the very end of August 2005 and then how many fell after an OA treatment on 31 December. The chart might take a little while to understand as the columns are not evenly spread by date, but the tallest column is 17 September. The two on the right are for 1 and 2 Jan. I didn't check after 2 Jan but you can see the rate has already started to drop off.

The chart Varroa Records I got from somewhere else, can't remember where now, but it attempts to show how a relationship between the mite fall after a late summer treatment and a winter treatment can indicate how effective the summer treatment was.

There are two lines drawn on the chart but there could many more added between them. The lines simply show approximate upper and lower boundaries for low and high summer infestations. Medium infestations would lie between these lines. The two lines simply show that for example, in one hive with a high infestation a low summer fall is followed by a high winter drop if the summer treatment was ineffective. Other points on the lines and indeed any other line you might want to draw between them can show how effective your summer treatment was. The point about the lines is you can't tell just from counting a summer fall how effective your treatment was as you don't know how many mites there were in there to begin with. It is only following the winter treatment that you can tell, after counting the mite fall, how effective your summer treatment was.

For example, a summer fall of 300 mites followed by a winter fall of 50 would indicate an effective summer treatment, but if the winter fall was 200 then the summer treatment was not very good.

Taking the data from my Varroa Drop chart, in round numbers about 400 mites were killed in summer and about 100 in the winter, perhaps a few more as I didn't count to the end - it was too cold! However, a total winter drop of about 30% of the summer fall seems OK from the second chart.

There are of course other variables (such as uniting colonies and introducing brood from other hives) but the point of the second chart is taking a single reading on mite fall is not necessarily a reliable way of knowing how good your treatment is. Comparing readings using different treatments at different times of the year can give more information.

It would be useful if anyone who took accurate records of late summer treatment fall this year also did a count after winter OA and let us know the results.
 
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Eyeman 

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Seems to be gathering dust over here as well.
Someone trying to tell you something??
No seriously:
Thanks for the info on mite drop rates. I plan on putting the "insert" in for 2 weeks after oxalic acid treatment so as to get an idea of how many mites were left after summer/autumn treatment.
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I suspect others may be in the same situation as me- I think it looks like an interesting start to a thread, and I'm intending to add my 2d worth; but I'm not treating for at least another week or 2 (depending on when my oxalic arrives) so I haven't got the data to add yet.
 

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OUr varroa researcher Pekka Korpela says that natural winter dead rate of mites is about 50% and it is same as dead rate on wintering bees.

But I do not understand why to compare winter and summer treatment?

How to do it? What is the original mite count and what it is after treatment? How many are still alive?.

All these are carefully researched.
 
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Finman 

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It would be useful if anyone who took accurate records of late summer treatment fall this year also did a count after winter OA and let us know the results.
.............Why? What is the idea to count them?
 

RoofTops 

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Finman, the idea is to work out how effective the summer treatment is by comparing the mites killed by the winter treatment of oxalic acid syrup with the number killed by the summer treatment. If the winter treatment kills 50% of the number killed by the summer treatment it may indicate the summer treatment was not very effective.

My reason for putting this up is people are using all sorts of different varroa treatment regimes in the summer but how do they know if they work? Simply counting varroa is not enough if you don't know how many varroa are in the hive to begin with.

There are other tests (Beltsville) but this method does not require the beekeeper to do anything extra - other than count the mites of course.
 

MJBee 

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I have full records of the Aug/Sept Apiguard treatment and will follow up with an accurate count post OA Dec/Jan.
Rgds Mike
 

Finman 

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Finman, the idea is to work out how effective the summer treatment is by comparing the mites killed by the winter treatment of oxalic acid syrup with the number killed by the summer treatment. If the winter treatment kills 50% of the number killed by the summer treatment it may indicate the summer treatment was not very effective.
EU varroa group has studies these things very carefully during 10 years.
I wonder what are you going to find?

After that Group tens of university group researches have make studies.

When ordinary Eglihsman does his studies, it is vain work because arrangemenst are not what they should be. And real researches need much money. Unversity guys are paid for that.

***********

I cannot understand why you want to have "your own results". What then?

.
 
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Finman 

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When you kill mites and get a fall, how do you know how much mites are alive in the hive?
 

RoofTops 

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When you kill mites and get a fall, how do you know how much mites are alive in the hive?
That is the point of the second chart - comparing mite fall at two different times of the year from two different methods of treatment.
 

Hivemaker. 

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When you kill mites and get a fall, how do you know how much mites are alive in the hive?
You kill all the bee's, and do a big alcohol wash test.

Then drink the vodka,and see twice as many mites.
 
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Statistacily speaking the results of the two treatments may be skewed as there are many vairiables and could not be compared by a say 2 way ANOVA.

As long as varroa mite are being exterminated to bring them to a reasonable level, what else can be asked?... total anhialation would be nice... will put it on my Christmas wish list along with the end to world poverty and a new begining for world peace!
 

MuswellMetro 

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That is the point of the second chart - comparing mite fall at two different times of the year from two different methods of treatment.
So, how do i compare my 6000 mite drop hive over ten weeks with the four others that are less than 500 drop and went down to 2 mites per week in 6 weeks

what winter drop on the 6000 hive would be acceptable on oxalic 25%=1500

i am just hoping it get through winter, then trying a shook swarm and starting apiguard in the first week of August for 8 weeks
 
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Eyeman 

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When you kill mites and get a fall, how do you know how much mites are alive in the hive?
In a broodless colony it is estimated that at least 90% of the mites are killed by a single trickling oxalic acid treatment. If these dead mites all fall on to the insert tray under the OMF then you should be able to count them.
Am I wrong in assuming if 90 mites drop off then there must have been 100 to start with?
 

RoofTops 

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Eyeman, if the colony is broodless then an OA trickle should kill well over 95% of the mites, possibly even as high as around 98%.

MM -the second chart suggests that if the winter fall following OA is around 25% of the fall following a late summer treatment then yes, your summer treatment was effective. A fall nearer 50% suggests the opposite.

For those who still don't get this theory (and it is only a theory) if 100 mites fall out following a treatment in August, on its own this does not tell you if the treatment was effective as you don't know the level of mites to begin with. As OA syrup given in mid-winter is known to be at least 90% effective the relationship between the mites killed in winter and those in summer gives you a better idea how effective your summer treatment was.
 

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So the derivation of efficiency is thus?

Oxalic drop/0.95 will give mite numbers at mid-winter (assuming an oxalic acid efficacy of 95%)

Count back the number of brood cycles since the end of the previous treatment.

Divide the mid-winter mite number by 1.7 (to the power of the number of brood cycles since the last treatment) to give an estimate of the number of residual mites surviving that previous treatment.

Add residual mites to autumn treatment mite drop and then work out the efficacy of that treatment. Efficacy can then be calculated as: {100 - [residual mites*100/(mite drop + residual mites)]} %

Looks to me like the time broodless before oxalic trreatment might make quite a difference to the back-calculated residuals. Three weeks (brood-free) would give an error (on the residual mites) by a factor of x1.7.

Easily calculated accurately for a few colonies, provided, of course, that there were no other factors interfering with those calculations (eg assumed there were no external 'boost' to the mid-winter varroa numbers, due to local collapsing colonies/drifting/robbing, etc.).

And, of course, if one can be bothered to the trouble of accurately counting the varroa drop for each treatment. Or really be that bothered to do it at all.

The mid-winter treatment mite-drop might show that winter oxalic acid treatment was unecessary, of course.

Regards, RAB
 

Eyeman 

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The mid-winter treatment mite-drop might show that winter oxalic acid treatment was unecessary, of course.
That is the point.
I'm still trying to work out which treatments I am applying are effective and more importantly which ones can be omitted.
 
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