On 14/08/2013 8:37 AM, Peter L Borst wrote:
> PLB wrote: "Tylosin, when properly applied, can be used to treat hives
> infected with AFB."

Apparently he also said this:
> That may be so (it would be illegal here in the UK) but will do nothing
> to eliminate the spores which can remain viable for up to half a
> century, so I suspect it is a remedy recommended by the chemical
> companies looking to sell more.
>
> However, some bees do have hygienic traits that enable them to deal
> with AFB and prevent it becoming a problem.  Roger Morse once told me
> that he had colonies of bees that he found impossible to infect with
> AFB!

Anyhow, mishandled quotes notwithstanding, we have been over and over 
this topic for decades here on BEE-L and nothing never seems to change 
except that after two decades of 'conscious raising' and missionary work 
with breeders and queen suppliers as well as some academic work, we do 
indeed have a lot more strains that resist AFB breakdown in varying 
degrees from not-so-well to (apparently) completely immune.

This characteristic (AFB resistance) has bled into the general North 
American (NA) bee population to the point where, when inspecting, I have 
not seen or heard of an entire yard breaking down with severe AFB for 
three decades.  I have seen a large outfit with a few cells of ongoing 
AFB in hives scattered throughout the operation, though.  Whether this 
was the initial phase of a disaster or just hives handling AFB, I don't 
know, but I do know that decades ago, the outbreak would not have been 
so minor or easily treatable.  Several Tylosin treatments in fall will 
likley restore those thousands of hives to where AFB is never seen. 
(OTC works, but is pretty lame and unreliable by comparison).

Of course AFB spores will still be in the hives, but they always are in 
a commercial operation.  Almost no one in North America with more than a 
few yards operates in a region where there is no likelihood of another 
beekeeper having or bringing in infected equipment and failing to 
recognize or manage a breakdown.

Consequently, we all have to assume we have AFB spores in out hives, 
whether we see AFB or not and decide which strategy to employ when an 
isolated case is found or we see a few infected cells in a number of hives.

Basically, in this day and age, AFB is one more thing to blame on the 
queen, so requeening is in order, as is questioning the ancestry of all 
the bees in the outfit and considering switching to better stock.

Then the question is whether to destroy or treat, or both, and whether 
to attempt to totally eradicate every last AFB spore or to live with and 
manage the risk. I choose to treat and be vigilant.

If only one frame or hive is involved, destruction makes sense, but if 
tens, hundreds or thousands of hives are involved, requeening, treatment 
and improved management makes more sense to me.

IMO, no matter how draconian the measures taken, no one can be 
absolutely certain that no AFB remains or that the source has been 
discovered and can be eliminated.

It has been demonstrated that several sequential treatments with Tylosin 
at recommended doses and timing can control AFB to the point where 
recurrence is very infrequent.  So infrequent in fact, that the 
likelihood of breakdown is quite comparable to the likelihood of 
breakdown in new hives in many regions of NA.  We know that there are 
still spores there, but good bee stock is not bothered by them.

Yards with virtually 100% of the hives broken down with severe AFB were 
common in the '70s when beekeepers bought packages with sister queens 
and installed a whole yard or where a beekeeper raised thousands of 
queens from one poorly selected mother queen. At that time, package 
producers had not yet learned to select for AFB resistance

I think we have Marla to thank for much of this raised awareness and for 
showing that the trait can be fixed in bees that are not mean and for 
her personal missionary work with bee suppliers, although Steve Tabor, 
Jerry and others deserve credit for promoting the idea earlier on.

So, as with most beekeeping questions, there is no one right answer. 
The solution is a question of economics.  The cost of one approach must 
be weighed against the others, as is the probability of success and the 
consequences of failure.  (What is the worst thing that could happen and 
how likely is it).

If you know you are not diligent and able to spot AFB, then, by all 
means, burn.  (Actually, get right out of bees, please).

If you are diligent and able to make decisions, and have a large 
investment to save, then consider treating and learn how.  Then decide 
based on a careful consideration of the options open to you.

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