>>Therefore, I don't know if complete broodlessness is critical.

I don't mind a patch of two of sealed brood when I trickle.  OA acts 
for a few weeks (I am thinking at least 3 weeks) and the last sealed 
brood will emerge in a few days.  My criterion is no eggs and no open 
brood.

>>My money is on a medly of low-kill mechanisms to keep
the mites from evolving resistance to any.

And I want to have the bees exposed to some mites and viruses they 
vector as this helps weed out the weaker colonies.  Ironically, this 
is an unintended benefit of varroa.

Waldemar

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