Tomas Mozer wrote:-
 
 
> the oct.1998 issue of american bee journal (v.138,#10,p.738-742) has
> articles on the
> disinfection of afb-contaminated woodenware and testing efficiency of
> disinfecting
> with hot paraffin, by m.del hoyo et al. in argentina, corroborating
> horacio's posting.
 
As luck would have it my copy of the October ABJ turned up today by snail mail.
 
The article was very interesting.  I could see nothing in the article to support Horacio's observation that the paraffin treatment also helped preserve the timber.  As I posted previously, it depends on the natural durability of the timber being used and I notice in the article in the ABJ that one of the timbers they were using was Eucalyptus.  This could have a high natural durability depending on the species.  Here in Australia if radiata pine or plantation hoop pine are used the wax treatment will not preserve these timber.  Radiata pine or plantation hoop pine will rot within a few years even though it is wax treated if the hives are located in  high risk (decay) area.
 
I asked the original question on the temperature relationship as work that I have been involved in showed that at 100 degrees centigrade you needed 5 hours to kill spores of AFB with dry heat and 3 hours at 130 degrees.  If the heat is "wet" then the time is dramatically reduced.
 
We used a powder coating kiln at 130 degrees for 4 hours to heat seeded boxes but we still had about 30% of our sites showing viable spores.  So dry heat in a large commercial situation has not given the desired results.
 
In our trials we used a concentration of 300 million spores per sample which may have been higher than those in the article.
 
The one interesting point of the article was the higher number of viable spores after the longer incubation time.  We also found this.  It raises the point, that whilst they are viable, are these spores virulent?
 
The article is very interesting becuase I had heard anecdotal stories from New Zealand that bees were removing the wax treatment from the boxes, that had been waxed dipped, exposing the AFB spores underneath and the hive was being re-infected.  Looking at the Argentinian work it could be the NZ case that they did not dip for long enough or at a higher enough temperature.
 
All in all it is very interesting work.
 
Trevor Weatherhead
AUSTRALIA