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NickWallingford

AFB control Then & Now

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1 hour ago, kaihoka said:

I was offered some bee gear , boxes queen excluder etc , by a friend who had quit bee keeping 30 yrs ago. It had been in his shed .

I was advised to decline . It was in good condition but he said he never knew what foul brood was .

The gear was burnt .

Did I make the right decision .?


Yes, one of the best pieces of advice we were given was to start with new gear. We have burnt three hives almost brand new hives. Have been hyper vigilant since and don’t keep bees in certain places.
 

I would burn everything again as heartbreaking as it is.

 

We have no access to a dipper, and they are a dangerous piece of kit in the wrong hands.

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Given the value of the woodwork is the Value of what, 3 boxes of honey at the moment?  Why would you risk finding it in Feb? Gone are the days of getting one last sneeky harvest... 

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9 hours ago, CraBee said:

 

@tristan how much residual honey do you think there would need to be in wets to cause an AFB infection?

no idea.

however the more honey there is the more chance its going to be taken back to the hive and fed to the larvae. 

it may take large amounts of spores to infect a hive but only takes a few to infect a lavae.

but also keep in mind dry gear can infect a hive. its not just honey. i would presume that bees come into contact with the spores, they get cleaned off by other bees and then fed to the young.

 

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9 hours ago, NickWallingford said:

 

Back in about 1993, Dr Mark Goodwin did this:  20 supers were collected from hives with a light (est 5 larvae/pupae showing infection).  The honey was extracted, and the next spring the 20 boxes were put on 20 clean hives.  There were another 20 clean hives that did not have the infected supers placed on them in the same apiary.

 

Within 2 days, all hives (even those without the infected supers) tested positive for AFB spores, even though no obvious robbing had occurred when the wets were added.

 

Ultimately only 45% of the hives given the infected gear developed AFB infections.  20% of the hives *without* the AFB infected supers developed infections.

 

Two things catch my eye: the 45% is lower than I might have expected in these circumstances, and I feel the 20% is a high hive infection rate given the situation...

 

45% of hives developed AFB!

And 20% indirectly.

That's useful information and highlights that putting wets out to be robbed is very risky.....

 

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45 minutes ago, CraBee said:

 

45% of hives developed AFB!

And 20% indirectly.

That's useful information and highlights that putting wets out to be robbed is very risky.....

 

Nope. It highlights that putting infected wets back onto an apiary is very risky, both for the hive that goes on and other hives in the apiary.

You could make an assumption from this test that robbing infected wets out is also a risk but whether it is a higher risk or a lower risk can only be ascertained by scientific experiments or perhaps many years of observational data.

There  is a lot about AFB spread that we don't know everything about. 

For instance, I have seen plenty of AFB outbreaks caused by dead, robbed out hives and when these hives are in an apiary you often get quite a few more hives to burn which is what you would expect but if there are other apiarys around you often get a higher percentage of AFB in those apiarys even when they are several kilometres away.

I absolutely agree that any AFB wets are a huge risk factor but I have seen no evidence that robbing them out rather than placing them onto a hive is a greater risk.

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12 hours ago, john berry said:

Nope. It highlights that putting infected wets back onto an apiary is very risky, both for the hive that goes on and other hives in the apiary.

...

I absolutely agree that any AFB wets are a huge risk factor but I have seen no evidence that robbing them out rather than placing them onto a hive is a greater risk.

 

I would agree with John here.  For 'open robbing', if a super had come from an undiagnosed hive, the AFB spore levels would be divided among the hives that rob it out.  The hope/plan/belief is that even *if* an inspection had failed to find the disease before extraction, and *if* (well, when...) spores are brought back to a colony, that the spore level will not be so great as to cause a clinical infection. 

 

I'd still have to express amazement that *only* 45% of the hives that had infected supers placed on them became infected.  As pointed out, these were infected supers placed directly on clean hives - and only 45% broke down.  I would have expected that to be even higher...

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Aah there you are @Emissary ..... how's yer bubble been ?

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15 hours ago, Emissary said:

From the memory banks..... Minimum infective dose is 50,000,000 AFB spores per litre of honey. 

 

This from some of Mark Goodwin's work:

 

Quote

It is quite difficult to infect a colony with American Foulbrood disease (AFB) although some beekeepers seem to be very good at it. Under trial conditions to you need to feed about 5 million AFB spores per litre of sugar or honey to infect a colony.

 

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24 minutes ago, NickWallingford said:

you need to feed about 5 million AFB spores per litre of sugar or honey to infect a colony.

Is AFB transferable in sugar syrup?  I would have thought that was not the case, and would have only been possible if the frame already had AFB in it.  

i.e. enough AFB spores in the frame for infection to exhibit

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15 minutes ago, Maggie James said:

Is AFB transferable in sugar syrup?  I would have thought that was not the case, and would have only been possible if the frame already had AFB in it.  

i.e. enough AFB spores in the frame for infection to exhibit

 

Absolutely transferable in syrup...  But the colony needs to be exposed to 5M spores before larvae and pupae might get infected.  Some spores will be stored in honey.  Some will find their way into the adult bee stomachs.  The overall spore load will decrease when the bees defecate outside the hive. Some spores may be fed to larvae.  But it all depends on how many they get whether there are enough to cause an infection.  We can eliminate clinical cases of AFB, but may never eradicate the organism.  But though the spores might survive damn near forever, unless there are enough of them at one time, the colony doesn't get 'infected'.

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So if I make up syrup, how do the AFB spores get into the syrup?  What is AsureQuality's or an AP1's take on this?

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1 hour ago, NickWallingford said:

 

This from some of Mark Goodwin's work:

 

 

Ahhhh.... "the palest ink is better that the best memory".... some Chinese dude

But then I looked..... the 50 million spores per litre was from one of two papers to have researched this - from 1932.  The other was from 1994 and came up with the 5 million figure but the level of detection available at the time using plating methods was 20 million.  MAF used the 50 million figure when they did their Import Risk Assessment on the importation of Australian honey in 2005.

In a practical sense these are semantics, but of historical interest.  The take home message is - clinical symptoms of AFB mean there are enough spores to make all the honey on the hive infectious.   The implication is that if you are extracting honey from such a hive, the combs will be infectious to any hive you put them back on.  If AFB turns up sporadically in your outfit with no apparent source, then the most likely source is you having extracted from a hive with AFB.
You should inspect the hive for AFB before removing any material that will end up in another hive.    Honey, brood, pollen etc.

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41 minutes ago, Maggie James said:

So if I make up syrup, how do the AFB spores get into the syrup?  What is AsureQuality's or an AP1's take on this?

 

Sorry.  I don't mean to be causing confusion, and I'm certainly not wanting any AFB spores in your syrup!  This was part of Mark Goodwin's earlier work into AFB.  The AFB spores were intentionally mixed into the syrup at a given 'dose'.  Three different doses, as I recall.  From the results, he concluded something along the lines of AFB is not so absolutely contagious as we sometimes feel - he had not been able to cause an infection at the two lower doses...

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