> Prior to varroa mites, most or all colonies may have had adequate levels
> of heritable resistance to a number of fairly common and ubiquitous
> viruses.  Only with some inbreeding did susceptibility to the common
> viruses surface in a few lines.   So at that level there must be heritable
> mechanisms that come into play to keep infections low, or at least prevent
> epidemics.
>

True. But Varroa, as you noted, changed that. There is a numbers problem
(lots of them); a wound problem (feeding on the bee); and transport of
virus problem.

So you get a weakened bee injected with virus by one or more mites. The bee
does not stand a chance no matter how robust its immune system.

Obviously the solution is to control Varroa. Then you have " adequate
levels of heritable resistance to a number of fairly common and ubiquitous
viruses".

Virus are an issue but generally only when coupled with mites.  Many of the
current problem virus were in colonies pre-Varroa.

So, for me, the issue is not to kick up the bees' immune system since it
will be overwhelmed, but concentrate on the mite. What can we do to control
its numbers?

Bill Truesdell
Bath, Maine

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