Blane White wrote

>  There is some risk but one
> beekeeper here burned all AFB colonies last fall - he only had a few
> and figured it was the best way to go - trying to nip the problem in
> the bud so to speak.  The result?  A major outbreak of AFB in his
> outfit this summer.  In this case the source of infection was not
> robbing of honey jars but nucs purchased a couple of years ago.  Yes
> it took this long for the infection to become apparent but it is in
> those used frames that came with the nucs.  Again the main way AFB is
> spread is movement of combs.  Yes robbing can spread it but nearly all
> spread is from infected combs that we beekeepers move to healthy
> hives.

There has been research carried out in Australia to look at the effect of antibiotic treatment on AFB.  Hives showing symptoms of AFB, and having been diagnosed in a laboratory as such, were treated with oxytetracycline hydrochloride (OTC).  It was found that the clinical signs disappeared initially but that the AFB came back again in between 3 and 15 months.

This was what had been expected.  We have been told that OTC does not actually kill all the AFB but stops it from multiplying so that the bees can then get on top of the AFB.  So, while OTC gave the hive some temporary relief, it did not cure the hive of AFB.

This is one of the main reasons why Australia does not support the use of OTC to control AFB.  This experiment showed that OTC does not stop a hive from breaking down with AFB at a later date.  If you use these chemicals, then you are spreading around infected material between hives and is exactly as described by Blane.

The use of hygenic bees is one aspect being looked at here in Australia but as Blane and others have described, the problem is that the hygenic behaviour is associated with recessive genes.  Whilst we can bred quens from stock that is hygenic, and we do have them in Australia, the mating is unontrollable and unless you get mating with some drones that carry the hygenic behaviour, then the progeny will not exhibit the hygenic behaviour.  However it is not a lost cause, just a big challenge which we are facing up to.

In Australia one method that we are encouraging is the use of barrier systems to limit any damage that may be caused by AFB and also allow for immediate trace back to identify any hive material that may be infected.  The infected material is either burnt or irradiated.  We are making much use of irradiation as this allows for the material to be used straight away after irradiation.

There are many types of barrier systems and each beekeeper is encouraged to look at the systems in use and then adopt a system that will gel with their own operation.  This is a non chemical system and, used in conjunction with testing honey for the presence of AFB spores, is an effective method of AFB control.

Trevor Weatherhead
AUSTRALIA