Cheers,
Aaron Morris

> My thoughts are that this may work in the same way as the
> sugar roll to get the mites to drop.

It is unclear why the powdered sugar makes the mites drop.  It was
discovered a few years ago that talcum powder had the same effect.
Speculation for powdered sugar covers two angles.  Perhaps it impares the
mites' ability to hold onto the bees. (Varroa mites have little "sticky
pads" on the bottom of their feet which they use to "glue" themselves to the
bee.  Perhaps the confectioners sugar coats the "glue" and the mites fall
off.  The other angle is that perhaps the powdered sugar causes the mites
discomfort and they simply let go.  Why iy works is unknown.  That it works
is beyond doubt.

I don't know if a sugar spray will have the same effect.  However, it seems
to me that the stickyness of the solution and the surface tension of the
water would have an opposite effect, that it would make the mites more
likely to adhere to the bees rather than fall off.  But this is only
speculation on my part.  I'll be interested in the outcome of your
experiments!

> Depending on the state of the brood nest there are times when
> the majority of mites are on adult bees. Once brood production gets going
> treatments that rely on drop should be less effective in controlling the
mite
> population, and will result in the mite population continuing to grow.

Well, yes and no.  ANYTHING that takes mites out of the hive environment is
a good thing.  Treatments that rely on mite drop remain consistently effect.
Mites that drop out of a hive enviroment are no longer able to add to the
exponential growth rate of Varroa populations.  It's the exponential growth
rate that is the key.  Say you start with 3 mites and none drop out.  After
two generations the 3 mites have 81 grandchildren (exponentially, the 3
beget 9 and the 9 beget 81).  However, if one of the three mites drop out
then in two generations you'll have only 9 grandchildren (3 less 1 leaves 2
which beget 4, one drops out leaving 3 mites to beget 9).  The mite
population still increase , but the RATE of increase is reduced by a VERY
SIGNIFICANT factor.  In this very simple example, two mites drop out of the
hive, by 72 mites are removed from the population!!!!

Now, do mite populations follow such simple arithmetic?  Obviously not.  But
the dynamics aproximate the example.  Drop out methods do not control mite
populations, they simply slow the rate of population increase.  Screened
bottom boards still require other methods of control, chemicals are an
important part of Integrated Pest Management.  However, the impact of drop
out methods can impact mite population growth dynamics such that the
reliance on chemical treatments can be significantly reduced.

Aaron Morris - thinking math rules!
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