Dear Stan,

There has not been many studies that investigate the susceptibility of EFB to gamma irradiation:

Pankiw, P. L. Bailey, T. A. Gochnauer abd H. A. Hamilton.  1970.  Disinfection of honeybee combs by gamma irradiation.  II. European foulbrood disease. J. Apic. Res 9: 165--168.

Hornitzky, M.A.Z.  1982.  Use of gamma irradiation from cobalt 60 in the control of Streptococcus pluton in honey.  J. Apic. Res. 21: 126--127.

Unfortunately, the Pankiw paper is missing from our library, but a summary of the paper states that the study irradiated infected comb with 8kGy of gamma irradiation, and following treatement there were 'sufficient viable organisms... to cause EFB when these combs are placed in healthy colonies.'  The Hornitzky paper that small samples of honey (100ml) could be sterilized when subjected to a dose of 14kGy.

We are running a study looking at the penetration of high velocity electron irradiation through different types of comb (ie with honey, without honey, with crystalized honey) to see how many combs can be sterilized at once.  There is so little EFB out here that we have not set any treatments up, however I was unaware that so little data exists for EFB that maybe we will include it on future runs.

From an old post by Joe Hemmens:

>Many years ago EB Wedmore gave the following:
>
> Destruction of disease germs,
>
> AFB 12 minutes in water at 100C
> EFB 10 minutes in water at 65C
>
> He wrote this in 1932.

Since 1932 there has been some work on looking to decontaminate comb without irradiation or fumigation with ethylene oxide. The work I am familiar with is from NZ, where they investigated various methods of sterilization of more bulky colony wooden ware, such as supers, lids and bottom boards.  All the work is with AFB.  Dipping equipment in hot paraffin wax has been shown to provide excellent decontamination of hive equipment when immersed for 10min at 160C (Goodwin and Haine 1998a). It does not work at lower temperatures or shorter periods of time.  Spores have also been shown to be killed IN THE LAB using the antiseptics sodium hypochorite or Virkon® (Goodwin and Haine 1998a) and adequate decontamination of hive boxes was achieved in the field following treatment with 1% Virkon® (Hansen and Brødsgaard 1999).  Other antiseptics, such as Savlon®, Dettol®, ethanol and methylated spirits are ineffective at killing spores (Goodwin and Haine 1998).

                Goodwin, R. M. and H. M. Haine.  1998a.  Sterilizing beekeeping equipment infected with American foulbrood disease spores.  New Zealand Beekeeper.  5: 13.
Goodwin, R. M. and H. M. Haine.  1998b.  Using paraffin wax and steam chests to sterilize hive parts that have been in contact with American foulbrood disease.  New Zealand Beekeeper.  5: 21.

Given that dipping in 100C paraffin at 10min did not sterilize AFB, I doubt that boiling for 12min would be effective.  As for EFB, I am not sure. If you want to try it, why not set up a small controlled experiment.


Sid Pullinger wrote (also several years ago):

 > I have an old
> freezer I use as a fumigation chest, using acetic acid to fumigate against
> EFB and nosema.

Now, my question is what would be the best methods of treating these frames
(radiation and ethylene dioxide and not options here) in view of the
information above.  Sid, is your acetic acid fumigation for frame treatment
when scale is present, or just for prevention?

<<I have found that scraping the frames back to the permadent and then pressure washing does NOT take off the scale.  Perhaps soaking them first in something would help.

I am glad you tried that because I was also wondering if that would work.  Perhaps sodium hypochorite or Virkon®?  Contact Mark Goodwin or Cliff van Eaton in NZ for better guidance. There is some information in there new book; Elimination of American Foulbrood Without the Use of Drugs.

<If melissococcus pluton is not spore forming, then how long does the scale remain infective?

Correct, it does not form spores.  Why it is not killed by 8kGy of gamma irradition is also a mystery.  Being in spring pollination, I can see why you are concerned, as the disease is typically only a problem where management necessitiates moving colonies from pollen rich spring yards, into stressful, pollen poor pollination yards.  Perhaps pollen patties prior to and going into pollination may help the colony keep pace with the disease?  I am afraid I have not much experience with EFB in the Peace.  Good luck.

Regards,
Adony

Adony Melathopoulos
Apiculture Biotechnologist
Agriculture and Agri-Food Canada
Beaverlodge Research Farm
Box CP 29
Beaverlodge, Alberta CANADA
T0H 0C0

T +1 780 354 5130
F +1 780 354 8171