If everyone adopted the habit of recycling brood combs on a 5 or 6 year
basis then there would be a lot less disease in our hives and
consequently a lot less chemical control.    For all diseases there is a
minimal infective dose which must be reached before a disease will
establish itself.  If you can stay below this thresh hold then a disease
outbreak is highly unlikely.
 
There are two important issues here, the first of course is disease load
or the amount of infectious material trapped in the multiple layers of
cocoon in any brood comb.  Think about the last time you melted down a
brood comb to recover the wax; what was left, a mass of old "disease
containing" cocoon.  Bees deliberately entrap the faeces of developing
brood between these layers of cocoon, if the layers are disturbed then
the infectious material is exposed and so the cycle of infection cycle
continues.  After all, why do we burn beehives and combs after they
become contaminated with AFB spores, to destroy the source of
infection.  Also, ask anyone who has had equipment and combs gamma
radiated to kill AFB spores, after repopulation of the hives, the bees do
extremely well.  The equipment is the same, the only difference is that it
is sterile.  And for those who have expanded a beekeeping business
from a few to hundreds or thousands of hives,  disease wasn't really a
big problem until your business stop expanding (assuming the expansion
was from dividing hives into new equipment and by not buying existing
equipment).  Why ?  Because you continually diluted the disease load in
your hives by placing new foundation in them.
 
The second point worth considering is,  on average how long do feral
colonies inhabit a site ?  Usually only a few years and why because
diseases destroys the colony.  Swarming (by which feral colonies
spread and we breed to suppress) is a wonderful disease control
mechanism, most of the disease load is left behind, only that which exist
on or in the bees is carried to the new colony.  The new colony is then
required to build new comb from scratch, new brood comb not
containing disease harbouring cocoon.
 
If you haven't read between the lines by now, I am a fervent (highly
biased) believer in comb recycling.  It wont cure all your disease
problems but it sure well substantially reduce the impact of disease on
your hives.  And as for the cost of comb replacement.  As hard as
beekeepers try to keep brood combs out of honey supers it inevitably
happens, and without all the connotations associated with this in terms
of  the risk of disease spread, a dark brood comb will send light honey
darker than anything else I know of except heat.  Generally the darker
the honey the lower the price and so by comb replacement you offset
this business loss which means more $/kg or $/lb for your product.
 
Finally, for those who say that antibiotics are cheaper and easier.
Antibiotics like most chemicals an interim measure until the bugs "figure"
out a new strategy and become resistant to the chemicals.  This problem
exists right through all forms of monoculture be it crops, livestock or
bees.  We really aren't protecting our bees from disease we are really
genetically selecting for chemical resistance in the enemy.  We should
adopt the strategy of the disease causing bugs and select for resistance
in our queen breeding programs to restore the balance.  Unfortunately,
it's a fact of life that simply organisms like bacteria usually develop
chemical resistance faster then complex organisms like bees.
 
For those who might disagree with my logic,  my beliefs are based on 22
years of beekeeping in which 10 were spent managing 2000 colonies
and 7,000 mating nucs.
 
Robert Rice.
Apiculture Service Manager (South Island)
Ministry of Agriculture
Lincoln,
New Zealand.