The approach of "dipping" equipment in paraffin and other waxes
is a great way to preserve woodenware, but is (to my knowledge)
not considered sufficient to decontaminate AFB-infected equipment
anywhere but in New Zealand and Australia. Ditto for Sodium
Hypochlorite (Clorox bleach).
Even under controlled lab conditions, the results in trying to
kill AFB by heating wax have been mixed (see below).
But regardless of what has been seen when using lab gear, can
anyone assure that any temperature can be achieved and
maintained in a large vat of wax/paraffin? I think that a few
thermocouples on long wires, moved around in a vat might
be a real eye-opener. (Newer volt-ohm meters come with
the ability to directly read thermocouples, which means
that one can try this for well under $200 US)
To attempt this with a wood fire and a vat large enough to hold
beekeeping equipment is clearly not "lab conditions", and there
will clearly be "warmer" and "cooler" areas within the mass of
the heated wax.
As an example of how universal this very basic thermodynamics
issue is, go get a good oven thermometer, and check out the
oven in your kitchen. You will find variations of temperature of
15 - 25 F in an oven set to "350 F", just by moving the thermometer
around on the rack. (This is why bakers use fire-brick lined ovens,
as the larger thermal mass overcomes this inherent problem.)
If an oven with a thermostat and very large heating coil within
mere inches of your thermometer cannot keep the temperature
stable and even, what chance do you have with a wood fire and
a vat bigger than your oven?
Temperature variations can be a problem on the high side, too.
160 C is alarming close to 200 C, a good estimate of the flash
point of paraffin (it can vary from mix to mix). You don't want to
be anywhere near a large tub of paraffin that reaches flash point.
As an aside, water will not extinguish a wax fire. A large amount
of baking soda or sand will, but the usual 1-lb box of baking soda
will not be enough for a fire involving such large amounts of paraffin
or wax. Any of the CO2 or dry chemical (A/B/C) rated fire extinguishers
will, but again, one, even a large one, will not be enough. If I were doing
this, I'd want 6 big ones, lined up in a row. But I'd likely instead attempt
to set a new personal best in my 100 meter sprint time if a fire started. :)
When one slides woodenware into a wax bath, the wood itself is
going to take time to heat up, and one is forced to wonder if the wax
from the dipping tank is going to melt the wax in all the cracks and
crevices where AFB can hide, or if the process simply covers up the
AFB spores with a layer of wax/paraffin that may be "scavenged" at
a later time by the bees, thus exposing the AFB spores.
If one were to do a lye bath, to remove all wax from the woodenware,
and then do the wax dipping, this might improve things a bit, but I just
don't see the value of trying to "save" infected gear.
The only actual part of a hive considered an "asset" by my
beancounters is drawn comb. Everything else (bees and woodenware)
have a "value" that is soon swamped out by costs of "maintenance,
and one ends up with nothing but ongoing annual costs associated
with "bees" and "woodenware", rather than a "value". (Yes, one can
sell either, so they do have a cash value, but an honest man can't show
either as an "asset" on books.)
For all the money a bee club would spend making a "dipping tank", they
could buy two very nice table saws, and start cranking out woodenware
that was much cheaper than the store-bought variety, plus create a
known-working local "standard hive body" to avoid bridge comb.
When facing AFB, if you can't bear to burn the entire hive, consider scorching
the woodenware with a torch. How much scorching is required? Just keep
scorching the inside surface until you reach the point where you stopped
scorching the outside. :)
The published science on the subject of heat and AFB that I
know of is focused on AFB spores in wax, in honey, or alone.
I don't think that anyone has ever tried to study the case of
"on woodenware". (Too many variables.)
Burnside, C.E. 1940. "The thermal resistance of Bacillus larvae."
J. Econ. Entomol. 33:399-405
Calesnick and White "Thermal resistance of Bacillus larvae
spores in honey" Journal of Bacteriology Vol 64 1952 pp 9-15
I have the citations in my notes, but I don't recall ever reading either
of the two above.
Kostecki and Jelinski "Investigations on the sterilization of
beewax for foundation production." Bulletin of the Veterinary
Institute in Pulawy. 1977, 21: 1-2, 6-9; B
"...it is suggested that wax from infected apiaries
should either be extracted with carbon tetrachloride
or sterilized in an autoclave at 121 deg C for 30 min..."
(Note that "an autoclave" is one of the few known
accurate heat chambers one can buy.)
Hansen, Rasmussen, and Ritter "The sensitiveness of the
foulbrood bacterium Bacillus larvae to heat treatment"
Proceedings of the International Symposium on Recent
Research on Bee Pathology, September 5-7, 1990,
Ghent, Belgium. 1991, 146-148; Bd.
"The wax was melted with steam at about 119 C. After melting,
the wax was kept in a container for 15-30 min at about 80 C.
In one of the batches a very light B. larvae infection
was proved. In the remaining batches, B. larvae could not be found."
...but 119 C is a lower temperature.
Machova "Resistance of Bacillus larvae in beeswax"
Apidologie. 1993, 24: 1, 25-31
"The heat resistance of Bacillus larvae spores introduced
artificially into beeswax was studied by exposing the wax to a
temperature of 150 C and testing the viability of the spores at
intervals. The number of viable spores in the wax decreased with time;
initial concentrations in 2 samples of wax of 3X10^5 and 3X10^8 viable
spores/g wax decreased to 0 after 20 and 60 min, respectively."
So just as some AFB infections are worse than others,
some infected equipment might need to be left in longer
than others.
Machova, Skrla, Bacilek, Vesely, and Peroutka "Experiences with
beeswax disinfection by overheating"
"In a test on an industrial scale, 400 kg wax, contaminated with
2.1 X 10^8 spores/g, were heated to 118? over 3 h 15 min, kept at the
temperature for about 10 min, then allowed to cool. No chemical changes
occurred, and all spores were killed."
|
