This is a most interesting discussion guys! I might be a little out of my
league here, so please excuse me if I'm just plain off-base.

I'm taking a look at the graph cited. I'm wondering what collection and/or
assessment method was used to count the Varroa population for that study?
Please excuse me as I am a little confused about the whole matter. I wonder
if the 'ether roll' was used, or perhaps the entire colony was killed and
rolled or whatever? 


James mentioned:
>"Well, one can spray pure water on bees and see what appears
>to be an impressive "result" in terms of mite fall.  The
>question has to be about the results of passive ("natural")
>mite fall a week after the treatment, and the impact (if any)
>on the slope of the curve of the varroa population growth."

I would suggest that a person probably doesn't want to "spray...water on the
bees" but if a person should want to take this approach it could work!
[probably not though]. Whatever approach is used, it shouldn't significantly
impact the colony itself (my opinion).

I think that whatever approach one might take to controlling Varroa
population a few steps MUST be taken:

1) Count the mite population (somehow) - however you do it, do it
consistently so that you have a basis for your observations. No method of
assessment/observation is foolproof, but SOME method is better than NO
method, no?.

2) Identify a method of killing Varroa that works for you (semantically,
practically and economically, etc). Mite population growth does seem to
reach a point where "exponential growth" occurs - I think the trick is to
reduce and/or control population counts to prevent that critical threshold
from being reached. And here is the fly in the ointment: WHAT is that
critical threshold for your bees/setting/methods? I can only discover my
bees 'threshold' (if you will) by assessing the condition of my colonies.
[see #1] ...or waiting for the dead-out (ain't gonna do that!).


>"The question has to be about the results of passive ("natural")
> mite fall a week after the treatment, and the impact (if any) 
>on the slope of the curve of the varroa >population growth."

My choice of 'treatment' involves dusting w. powdered sugar. I'm sticking
with this choice until a more suitable technique is discovered (suitable for
me that is). I repeat this technique at regular intervals. It's sort-of like
checking the oil in my engine... Is there enough oil? Is there any oil? Do I
need to put more oil in? Do I need to rebuild the engine???

>"I'm pretty certain you can't make any conclusions from the
>mere number of mites dislodged by the treatment itself."

You might have a point there, but is it not safe to assume that if a mite
isn't around to lay eggs then that mite can't reproduce -> vis-à-vis a
direct reduction in Varroa population?

When a mite ends up on my sticky board and not on a larval bee, then I know
that this is an indication of direct mite population reduction. I know for a
fact that Varroa has a phoretic stage between parasitism and reproduction.
Mite on stickyboard = mite that can't reproduce further! Also keep in mind
that mites have a very limited amount of reproductive capacity - they must
'wash-rinse-repeat' in order to have a shot at reproducing exponentially. I
recall a figure that states a mite can only produce a finite amount of
offspring per parasitism/emergence/phoretic/re-parasitism cycle (2 or 3
maybe?). This is a KEY point that is easily overlooked.


Anyhow here's a little thought experiment:
Imagine I have a 'normal' colony of bees. Somehow I can make an EXACT copy
of that very colony (I have a magic ray-gun, don't worry about the details
for now). So now I take these two IDENTICAL colonies and I use powdered
sugar dusting to asses or count the number of Varroa destructor mites in
each colony. What assurance do I have that both *Identical* colonies will
provide the same mite counts? In other words, what is the degree of variance
between these two counts? Is it possible that the 'powdered-sugar' technique
could have enough variance between applications/scenarios to cause me to
believe that my mite counts are dropping when in fact the only thing
changing is the dusting itself (or how many mites got hit this time around)?
In my mind the answer is "NO". I imagine that even if I have as much as a
30% error between various counts, by using the stated approach I would know
that something was wrong, eventually (trending anyone?). I think that the
dreaded 'exponential population curve' that always looms on the horizon
seems to take care of any possibility that count error could mask
insufficient results.

I'm curious to know what others think.


My head hurts,

- Mike
Sacramento, Ca

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