From: "T & M Weatherhead" <queenbee@gil.com.au>
Date: Sun, 2 Sep 2001 11:43:15 +1000
To: <BiologicalBeekeeping@yahoogroups.com>
Subject: Killing AFB spores

I have been reading the recent contributions re temperatures needed to kill
AFB spores etc.

Research that I was involved in showed that in a laboratory, AFB spores are
killed at 110 degrees celcius after 5 hours exposure to dry heat and 3 hours
after exposure to dry heat at 130 degrees celcius. Remember this is dry
heat with next to no mositure.

When we went to a large drying facility, firstly a timber drying kiln at 110
degrees and a powder coating kiln at 130 degrees we did not get a 100% kill
when using 100's of boxes at a time. We spiked the supers with spores and
then sampled from these spots after treatment. There were spores able to be cultured on a plate but whether they are viable or not was not pursued.

We know from the literature that moisture will aid in shortening the time
necessary to kill AFB spores. This is still currently being finalised.

Research out of Argentina (I think) showed the temperature time relationship to kill AFB spores using wax treatments. It was published in either the ABJ or Bee Culture about a year ago.

Some comments which are not based on research but seem logical to me. I
cannot agree with the premise that changing bees onto larger cells has
caused bees to be more susceptible to AFB. AFB was a problem long before
large celled foundation came into being. I know that you can say it is a
bigger problem now than in earlier years but I can say that during the
second world war 99% of soldiers killed had pants on so pants can be lethal.

In the USA antibiotic feeding has been the norm and antibiotics do not rid a
hive of AFB. Research shows that hives treated here in Australia with 1g
active of oxytetracycline will mask AFB but the clinical signs will show up
again, sometimes up to 15 months later. This was a once only treatment.

If you are spreading AFB infected combs from hive to hive, you must have an increased incidence no matter what size comb you are using. If you want to compare practices now against the "old times" I believe you will see reasons why AFB has become the problem it is today.

There are beekeepers who do not have a problem with AFB because they are
good observant beekeepers. Their only problem are beekeepers who do not
keep hives properly, I call them bee havers and not beekeepers, who can
infect a good beekeeper.

Dr. Marla Spivak has shown that you can breed bees that will be "resistant"
to AFB but unfortunately they do not have the same "resistance" to EFB. To
date, no one can explain why.

I noted points about using caustic soda (lye) to kill AFB spores. Can
anyone quote a reference for this or it is just speculation?

Trevor Weatherhead
AUSTRALIA