This has been posted before. They are having a lot of trouble rendering the fungus into a mode of application. My solution is just to grow grapes and use the fungus from the leaves by putting the leaves inside the inner top. I'll know more on how well this works next fall when I have a full season of expermentation behind me. I'll also be doing the same thing with Oxalic acid from Rhubarb leaves.
If you want to have some fun on Varroa mite control google psuedoscorpions.