My own personal bias here, but based on many observations and numbers,
mostly unpublished....
We can consider the role of colony size, brood production, etc. as a
possible explanation for lower total mite numbers in colonies, but the
bottom line is that if you have no resistance, you will have growth in
mite numbers. All that smaller sizes, swarming, splitting does is
delay the inevitable. Individual bees, including immatures, are not
directly affected by the total number of mites. They are affected by
the density, or the probability of being reared or fed upon by a mite
or its offspring. You can have a very small colony, with low mite
numbers, but if the density of mites is high, it will suffer.
In my years in research, we would see colonies of select VSH lineages
with negligible levels of mites right side by side with unselected
colonies collapsing with incredibly high mite loads. For those low
number colonies, we would often get irritated at having to go through
thousands of brood cells to collect a minimum amount of infested cells
for various evaluations. Now that we just run a few colonies with VSH
background, in a short brood production season, mite numbers stay quite
low, "no treatment needed". As a reality check, just to show that it
is not the environment, we come across colonies kept by friends and
local hobbyists, of unselected origins, collapsing with mites. It
takes longer here at the 38th parallel and 7000 plus feet above sea
level, but it eventually happens.
Is any of this of any value? Perhaps as a proof of concept, pointing
to possibilities. Naysayers say no, that in a commercial go, go
setting none of this is implementable.
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