Our local Association has been using french  chalk  (talc),  icing
sugar and lactic acid on a low-key investigative basis.
 
The two powders are reputed (and appear  to)  interfere  with  the
mites  ability  to  grip  it's host^H^H^H^H victim, resulting in a
physical knock-down of adult mites.  Dust all comb-sides 'til  the
bees are all dusty.
 
Lactic acid is a soft/natural pesticide of sorts, I'm not sure  of
the  mechanism  but  it  seems  reasonably  effective (5% solution
sprayed directly over the bees for a few seconds per comb-side)
 
All of these require repeat treatments every four  days  for  four
treatments. All of them *can* get the bees pretty buzzy.
 
I'm unaware of any adverse effects these treatments  may  have  on
the bees or brood.
 
At present, I personally use drone-comb trapping & Bayvarol.
 
--
Gordon Scott          [log in to unmask]   Compuserve 100332,3310
Basingstoke Beekeeper [log in to unmask]