> It is possibly (probable?) that restocking with bees that have been
> artificially kept alive with chemical treatments is contrary to a goal of
> breeding varroa tolerant bees.

This statement is true, however there are ways to have the best of both worlds,
that is to treat bees -- and reap the benefits -- and still select just as
quickly and effectively for desirable traits that lead to less dependence on
chemical intervention.

Currently the costs of not treating -- in terms of attrition -- are very high.
Too high for most of us.  Consequently most of us are looking to bees that need
*fewer* treatments and hoping that ultimately we will ultimately arrive at bees
that need no treatment, without losing too may desirable characteristics or too
much of the gene pool in the process.

Here's how we can select and breed without going 'cold turkey':
Where all hives in an operation are treated routinely without measurement and
observation first, artificial tests are necessary to find desirable survival
traits in those bees and these tests which simulate the real situation may not
be comprehensive enough to identify and select for all the attributes that
contribute to a low mite load.

However, if the same hives are sampled for disease and pests before -- or at the
time of periodic treatment -- then we can measure and select using the results
of real world challenges and still reap the benefits of treatment, namely
survival and profit.

In this latter case,  after the treatment we still know which hives have promise
and use them for another round of breeding and/or eliminate obvious losers from
our breeding yards.

This trick is simple with conditions that are easily, quickly and cheaply
observed like varroa and sacbrood or chalkbrood, but a bit harder for subtler
things like AFB and tracheal mites.  For AFB, we usually prefer a surrogate
selection technique due to the unpleasant permanent effects of inoculating hives
with AFB.  For tracheal, after a successful treatment we sometimes have to wait
a year or more before mites return to reliably measurable levels.  That makes
tracheal resistance selection a bit more elusive, and inoculation of test hives
or bees is often used.

Let me explain further:
If we want bees that do not develop many varroa mites, then we know there may a
number of mechanisms that explain why one hive may have fewer mites than the one
beside it.  Some may relate to unique hive conditions (phenotype) such as queen
fecundity or periods of queenlessness or broodlessness, others to genetic
(genotype) characteristics such as attractiveness to mites, SMR or hygienic
properties, grooming, or mite destruction.  No matter. If we put a sticky board
into every hive when we add the Apistan (or whatever) and return within a day or
two and take a glance, we can see that some (many) hives have fewer mites than
the hives next to them.  Whatever the explanation, these hives are more likely
to have some resistance mechanism or mechanisms at work.  In our experience, we
see hives with no obvious mite drop next to hives with hundreds.  No need to
count.  Just mark the best of the hives with no obvious mites and consider them
for breeding, and carry on.

If we want hives that are not much bothered by AFB, then, to select we should
use the hygienic test that was first promoted by Steve Taber, then improved by
Jerry Bromenshank and more recently popularized by Marla Spivak et al.  We can
medicate the bees -- or not -- and apparently not affect the selection, since
this test seems to be a pretty good surrogate for an actual challenge with AFB.

Other than that, for diseases like EFB, sacbrood, and chalkbrood, the simple
solution is to immediately reject any hive from breeding that shows any symptoms
whatsoever.

allen

http://www.internode.net/HoneyBee/
---
"Time's fun when you're having flies." -- Kermit the Frog