I dont treat with anything. If you go without treating you will normally have higher losses starting out. Over time make splits from strong hives that are showing signs of dealing with the mites. Within a few years you will find you have no worse loses than those that treat. And you got extra cash in the pocket. I havent had much luck buying nucs or bees from people who treat and then not treat them. Most of the hives I got that thrive not being treated are from swarms and cutouts of ferral hives. In short I compare treating a hive for mites to putting a flea color in a jar of honey. :-o I know thats a little extreme but putting insecticide in with insects never much made since to me.
We lost most our feral colonies over a period of time when the mites first spread in the USA. If it wasnt for keeps treating hives which allowed them to grow and swarm. We probably would not have any feral hives. The researchers discovered over time the feral colonies started to rebound and grow in numbers. I have heard this is why russian bees are noted for there mite resistance. They was allowed to deal with and adapt to mite problems without our intervention
optimally frankh you would want to monitor mite loads first and then think about what kind (or if) mite treatment you might want to employ. sugar dusting is likely a good place to start but likely only represent a very short term remedy to the problem. reapplication (possible several time) is likely essential for even intermediate term success.
the next alternative is sucromid spray (not so fun to apply but is biologically safe). it effect is also short term in nature.
from there the choices get progressively nasty for either the bees or bee keeper or for both.
my take on the mite problem is pretty much as riverrat has described above.