> bees in Thailand ... pluck the mites from the affected bee, and kill it
with
> their mandibles.

This grooming behavior is not unique to Thai bees.  It is another
characteristic present in all populations of bees, more dominant in some
populations, less in others.  I heard Steve Taber in  1997 talk about a
breeder in Germany who noticed this tendency in some of his bees by
observing dead mites with a jewelers glass.  Some of the mites were dented
or dismembered.  The breeder was attempting to strengthen this attribute
through selective breeding.  I don't know the breeder, nor have I heard
updates on his project.  But the propensity for survival IS evident in SOME
bees.  Selective breeding CAN bring such characteristics to the forefront,
and we are currently guessing (probably correctly) that natural populations
are also exhibiting characteristics that allow the to better coexist with
varroa.

It is possibly (probable?) that restocking with bees that have been
artificially kept alive with chemical treatments is contrary to a goal of
breeding varroa tolerant bees.

Aaron Morris - thinking dynamically!