Hi Allen,
Just a couple of thoughts.

First ETO treatment needs to be done correctly and monitored ( using
biological indicators and sending in samples for confirmation) so you
know if it actually worked of course.  There is some risk but one
beekeeper here burned all AFB colonies last fall - he only had a few
and figured it was the best way to go - trying to nip the problem in
the bud so to speak.  The result?  A major outbreak of AFB in his
outfit this summer.  In this case the source of infection was not
robbing of honey jars but nucs purchased a couple of years ago.  Yes
it took this long for the infection to become apparent but it is in
those used frames that came with the nucs.  Again the main way AFB is
spread is movement of combs.  Yes robbing can spread it but nearly all
spread is from infected combs that we beekeepers move to healthy
hives.

Now a few comments on honey bees resistant to AFB.

Hygienic stock will certainly help but hygienic isn't the only factor
in resistance to AFB as noted on this list before.  In fact, to know
for sure that a stock is resistant to AFB one must do an actual
disease challenge.  Some ( a few) hygienic will get low levels of AFB
when challenge with infected comb but truly resistant lines will not
even show a single cell of AFB.  Not that may be a minor point as the
hygienic susceptible colonies usually eventually contain and even
clear up the infection but just because the bees are hygienic does not
mean they will not get AFB ever.  The other issue is not to expect too
much from any resistant stock.  By that I mean don't buy hygienic
breeder queens, raise production queens from them which are open mated
and expect all the colonies to be hygienic.  The level of hygienic
behavior will increase markedly but it will take 3 to 5 years of
buying those hygienic breeders before your bees will have high levels
of hygienic behavior and brood diseases will be nearly absent from
your bees.  At that time you will find colonies where the bees are
removing pupa which are still white in color and had no identifiable
disease but not disease you can clearly identify.  Of course it is
important that these bees also produce honey, winter well, and are
generally a good productive bee to work with.  Not the same reasoning
applies to the varroa resistant stocks being released - it will take a
number of years for the traits are at high enough levels to result in
varroa resistance in the field of any importance.  Don't try them the
first year and give up on them because if the breeder continues to
purchase resistant breeders in a few years the bees in his outfit will
be more resistant to varroa mites but it will take at least a few
years for this to happen.

Now a little case study on AFB resistance or more accurately hygienic
bees.  There is a beekeeper here ( commercial beekeeper ) who has been
getting hygienic breeder queens from Dr Spivak for at least 3 years.
In those years the incidence of chalkbrood has decreased markedly in
his bees to the point of being nearly completely gone.  In fact brood
disease is gone from his bees.  One will find a few pupae in some
hives which the bees are removing from their cells which are still
white in color and one cannot tell why they are being removed.  It
could be brood disease ( any of the brood diseases ) or varroa mites
but they are being removed before any disease is to the infectious
stage so the colonies have very good brood patterns and nice large
clusters.  His honey production has been up the last two years and he
is pleased with the bees.  So it can help but it took a few years to
get where he is today.  I suspect that if he continues to get the
hygienic breeders he may see continued improvement in the bees but
from a disease standpoint he really can't get much better than he
already is.

Get any disease resistant stock you can and don't expect it to
completely take care of the problem in one year.  This applies to any
resistance either to disease or mites.  Hygienic is one easy way to
screen for colonies with good brood disease resistance and therefore a
good character to look for in breeders.  As a plus it also seems to
help slow the increase in varroa mites in the colonies.

This has gotten rather longer but hope it is helpful.

blane

******************************************
Blane White
MN Dept of Agriculture
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