Dear Ed:
I hate to make the following recommendation but circumstances require
it.  Because of the proximity to the zone where africanized bees are
located, I would not take any chances with it having africanized traits
in it. Also, sometimes bees have a tendency to become meaner through
inbreeding.   It is both difficult to work with
nasty bees and a liability.  Find the queen. Kill it and replace it with
a known docile
strain.  It is a great pity because from what you say, there is a
possiblity that this particular colony has developed natural resistance
to mites.
Best regards.
Dr. Rodriguez