> If antibiotics have only a marginal effect, why use them?

Because in beekeeping, the profits are made on the margins.  If one can
reduce colony losses by 5%, or perhaps restore bee productivity or lifespans
to that of healthy no-Nosema levels, and get 20% bigger honey crops, then
the marginal gain is "pure profit", and goes straight to one's bottom line.
>>  the bulk of the evidence still shows N. ceranae as a factor in colony
survival

> ...the above is false.

A responsible regulatory authority, Dr. Medhat Nasr, has offered "it is
clearly not a cut and dried answer to the question as to how nosema is
implicated in colony mortality..."  This was a good definition of the
current consensus as it stands.  Absolute words like "false" seem out of
step with this consensus.

> There are numerous studies showing
> that N. ceranae may have little or no
> effect on colony survival.

But on the other hand, there are multiple studies showing that it is a
factor in survival, and a substantial body of lab work where, under highly
controlled conditions, it sharply impacts bee lifespans.  Note that bee
lifespan cannot be hand-waved away as "not a factor" in colony survival.
Shorter lifespans of bees will certainly kill some colonies that would
otherwise survive winter, as there is a minimum survivable cluster
population for any winter.

> But beyond this, I think we should
> be *leading* the movement away
> from antibiotic use in bees,

And do what?  Practice "Lassie-faire Beekeeping" on the issue of Nosema?  It
would be nice to have an alternate (kinder, gentler, organic) control, but
we don't have one yet.  I agree that antibiotics for AFB still seem to be
used inappropriately, but I think that better understanding of how the
spores move around can fix this, as Tylan has a persistence that is
surprising.  OTC was less of a concern for persistence.

> I just don't see Nosema as a major threat to northern beekeepers

Others would disagree, and they have data from multiple studies to support
them.

> and fumagillin should be reserved
> for human medical use.

This concern is valid for antibiotics in meat, but the specific issue of
persistence of Fumagillin in apiary use has been addressed in this thread,
and the consensus of regulatory authorities is that it rapidly degrades, and
is not known to be present in honey sampling, even at a 10ppb limit of
detection.  It seems a long stretch to claim that any human impact would
result from apiary use of Fumagillin, given the data at hand, as any trace
level below 10ppb seems very unlikely to have any effect on humans, not at
even 100x the average rate of honey consumption.

So, to summarize the position "for" Fumagillin:

(a) N. ceranae truncates individual bee lifespans
(b) N. ceranae seems to impact honeybee colony health
(c) Fumagillin is consistently effective against N. ceranae in the lab
(d) Fumagillin is sometimes effective against N. ceranae in the field
(e) We don't yet know why "field" varies from "lab" in (c) and (d)
(f) Its use in apiaries presents no chance at all of impacting human
antibiotic resistance, so it is "ethical" given the data we have on its lack
of persistence in apiary use, and lack of detectable residues in honey.
(g) It works like a champ against N. apis, and has yet to result in
"resistant strains" despite decades of use, including all possible misuses.

If I understand the case "against" Fumagillin, it is:

(a) that N. ceranae is an irrelevant factor in honeybee health
(b) that Fumagillin is completely ineffective against N. ceranae
(c) therefore, it should not be used because it is an antibiotic
(d) beekeepers should eschew all antibiotics on ethical grounds



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