RE: foulbrood prevention and treatment

There is a world of difference between these two. The idea with
prevention is that the hives never really get foulbrood. The spores
may be present in numbers sufficient to initiate the infection but as
soon as they germinate, the TM present in the larva's mid gut kills
the vegetative stage before it can produce spores of its own. This is
effective in preventing infection due to spores introduced via robbing
etc.

Once the colony starts to break down, it is a different matter. If the
colony has AFB so bad you can smell it, putting TM on it is probably a
very bad idea because the infection will appear to go away but there
is just so much contaminated material that it is unlikely that hive
will ever really be clean.

Now, in the middle is a problematic area. Some people (not me) will
advocate treating what they call a "mild infection". The problem is,
how do you determine what is treatable? Some will say "if you only
find a few cells". I have seen many hives where only a few cells were
visible. However, if you take your hive tool and rake it across the
brood, you begin to realize that there may be many more dead larvae
which the bees haven't uncapped. Furthermore, as shown in the
pictures, the early stage is white, and looks just like a larva dead
from other causes. So, I prefer to go with the old rule: they have it
or they don't. If they have it, get rid of it.

If they don't, well that depends on the potential for infection and
your policy on antibiotics. If you live in an area with a low
incidence of AFB, probably TM is a waste of time. If you are around a
lot of it, you may avoid getting it by spring and fall TM dosing. If
you cannot or will not learn to inspect properly, this might be a good
plan.

One of the things that I hear a lot when I do an inspection is that
they have never seen a hive opened up so carefully and checked so
thoroughly. Many beekeepers just glance at the brood on the way to
putting it in a nuc or whatever. There is a heck of a lot they don't
see. If your doctor did a 30 second checkup on you once a year, you'd
be wondering if you were getting your money's worth. Some people even
make splits without looking at the brood at all. That is an easy way
to make a bunch of sick ones out of a few.

Resistance to foulbrood

L. Bailey writes:

The process of removing dead larvae from sealed cells has been resolved
into two components of behaviour of adult bees which may be controlled
by two independent, recessive characters, one for uncapping
the cells and the other for removing the larvae, homozygosity for both
being required for the greatest expression of these traits and hence resistance.
Aggressiveness of bees was associated with resistance in these experiments
but the two characters probably depend on different genetic
bases because they assorted independently in crosses between susceptible
and resistant strains of bees.

The efficiency of these hereditary qualities of resistance is affected by
other circumstances; young bees of strains selected for resistance are most
efficient at removing dead larvae, but when they are a few weeks old they
remove dead larvae only when nectar is being gathered abundantly by foraging
bees. This may explain the spontaneous recovery of some diseased
colonies that has been noticed when bees have been collecting large
quantities of nectar.




Peter L Borst
Danby, NY USA
42.35, -76.50
http://picasaweb.google.com/peterlborst

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