At Bee Care Tour in Oregon, David Fischer addressed varroa gate.  It's in testing now - so its not a teaser.  But one can't just toss a new pesticide system for use in/on beehives into the market place - it has to pass all of the registration hurdles, etc.
 
As per mites in fall - we developed a mite model with Gloria at Tucson years ago.  I remember finding that the model clearly indicated that the window of time for mites to successfully reproduce was really tight.   Slight changes in the bee population dynamics in terms of growth and brood development time or in mite establishment, reproduction, and development time had major consequences. Simply stated, its a wonder mites don't over-run colonies all of the time.  It appears that its a bit of a race - when bee populations really cranking out brood, tightly thermoregulating, etc. - they tend to outpace the mites - who if even the least bit slow, lose the race.  But, in the fall, when honey supers are pulled, the remaining  bee population is pushed down into the brood nest, the brood rearing slows down in terms of numbers eggs laid, etc. leading to a higher percentage of infected cells compared to the total, and we've seen thermoregulation loosen as the bees wind down for the winter - which leads to slightly longer development times for bees.  Even a day or two longer is the window of opportunity that the mites really need for success.

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