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Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
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Fri, 23 Dec 2011 11:09:05 -0500
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>>If your treatment actually had an effect (forget your fanciful
>>calculations), then that baseline should have clearly dropped down stepwise
>>after each treatment, and by the end should have been near zero (not 4,
>>since that is not that far from the baseline).

We are further down the road now and the drops have  tended towards zero,
however Randy's comments about temperature are pertinent.  We see more drops
on warm days and fewer on cold, largely, I imagine due to the fact that the 
mites have to drop through two boxes to hit the screen and drop board and 
when the bees are in tight clusters, there is little activity to brush the mites on 
down.

At this point, too, it is clear that some controls would have been nice in that they 
would establish that the mite drops don't drop to almost  zero on their own 
in an Alberta winter.   Maybe  someone has done that work.  If so, I have not 
seen it.

>>... that's as far as I think that you
>>can legitimately go as far as conclusions, unless you do either a cleanup
>>treatment or in-hive alcohol wash and brood sample to confirm the actual
>>amount of mites still happily residing in the comfort of your tall, warm,
>>styrofoam-insulated varroa hotels.

As for a finishing treatment, I have a little Apivar here and have considered 
using it and also am considering another oxalic evaporation on the two hives 
which are still dropping mites in significant numbers.

I am not aware as to how effective Apivar is on bees clustered fro winter, so 
would appreciate any input on that question.

As for oxalic evaporation, I am beginning to have new questions about the method 
that have arisen from my experience and observations as well and they are 
summarized further down here.

>>I'm waiting to see what  happens to the natural drops after this is all over 
>>in another week or two.

That time has now passed and a trend is apparent, particularly if the data is  
plotted  logarithmically as it is in one of the charts at 
http://www.honeybeeworld.com/diary/files/drop.htm

Here are my current  thoughts  as posted in my daily commentary at 
http://www.honeybeeworld.com/diary/
---

At this point in time, I don't really know what to make of the drop results.  

It seems apparent that the temperature fluctuations are having a major effect 
on drops and possibly on the efficacy of the treatments.

I'm beginning to think that temperatures close to zero (freezing) are poor for 
treatment because the bees tend to be clustered too tightly and that either 
they must be disturbed before treatment or that treatment has to take place 
at higher ambient temperatures.  That is not always easy to accomplish this late. 

Broodlessness is the other essential condition for high efficacy.  The two don't 
often come together at the same time.

I'm also thinking that the overnight temperatures may be a consideration, 
too, and that, ideally, the weather should be a few degrees above zero for 
a day or more before and after treatment.  This is possible in Alberta, but
these treatment windows are rare at the time of year when the hives are 
also broodless.

Another thing I've been overlooking and ignoring, largely because the fan-type
machine proponents don't emphasize it is closing the hive for ten or more minutes 
as recommended by the Varrox and Heilyser people.

From the Varrox instructions: 
"Sealing up the hive Seal the whole entrance (or diagnosis drawer) around the 
handle of the VARROX-vaporiser using strips of foam or cloth. Open floors should 
be shut tightly on the whole surface. ...After the hive is sealed up, the vaporiser 
should be switched on for 2 ½ minutes. .... After switching off the 
VARROX-vaporiser, wait for about 2 minutes before the appliance is pulled out, 
so that the oxalic acid-vapour can settle down. Once removed, ensure that the 
entrance of the hive is shut tightly again and left shut for another 15 minutes.

From Heilyser:
"Seal the hive for at least 10 minutes after application using a foam strip. 
The treatment with JB200 Electric Vaporizer can be applied 12 months of the 
year as long as the temperature are 3-5 degrees above freezing point.

Several things are apparent here.  
For one thing, the temperature recommended does not in either case mention 
if the temperature must not go below the recommended temperature for some 
time after treatment.  In our case, we assumed that that referred to the 
temperature at time of treatment and we treated at the end of the day.  
The temperatures dropped afterwards as night fell
(see charts at http://www.honeybeeworld.com/diary/files/drop.htm).

For another, consider what happens if we seal up a hive of bees after a 
disturbance.  They rapidly warm up and use a lot of air.  It is possible to suffocate 
a hive by closing it up, and in fact, that is the easiest way to kill a hive of bees. 
A plastic bag or tape on a hive can kill it quickly.  First, the bees get active, then 
panic and generate a lot of heat and CO2, then they pass out as CO2 is an 
anesthetic for bees, after which they die in a gooey mess as they regurgitate 
their stomach contents.

What is being recommended here?  Is the closing of the hive intended to ensure 
the vapours do not escape, as we tend to assume, or is it intended to create a 
state of panic in the hive that ensures heat, bees milling about, and maximum 
distribution??? 

If so, I totally missed that concept.

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