>However, if the question was whether making splits such that there is a
>break in the brood cycle (by using either shook bees, queen cells, or
>walkaway splits) has the effect of reducing  varroa level (and virus)
>levels, then the answer would likely be "yes," due to a number of mechanisms
>other than the one which you laboriously described.

Yes.  That has been almost my only control measure for the past few years, split, split, split.  I drizzled some oxalic once a year, too, in the past two, mostly because it made me feel as if I am doing something.

I think that, besides the interruption in brood rearing in splits, the known fact that varroa do more poorly in small clusters than large is a factor.   

The surface of the cluster is a dangerous place for varroa.  They prefer to be close to the brood and that is where to find the majority of them. 

As cluster size decreases in a colony, the ratio of dangerous cluster surface to safe cluster volume increases drastically, and the distance from brood to cluster periphery decreases.  Additionally, the boundary becomes more distinct.  

Mites at the periphery are at risk, particularly in cool weather, so considering these factors, in small clusters phoretic mites are at significantly greater risk.  Wandering varroa are more likely to find themselves at the cluster limit where they are vulnerable to a fall into bee-less space

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