I prefer chemicals but perhaps there are some good organic alternatives I am not aware of.
What you mean with organic?
Organic chemicals "Thymol pillow " is working well.
I have Elgon bees which can identify and eliminate varroa, but I do not like them because they give stings and they are not so good in honey work than Italians. It is easier to give anti varroa chemicals, because it take one minute to hadle the colony.
My bees have now apistan resistant varroas after 15 yeards handling.