I'm gonna go out on a limb here.
Gotta do it, as out on limbs is where the ripe fruit hangs.
What we have been calling "Nosema ceranae" may or may not be
actual Nosema ceranae. What we have been calling "Nosema apis"
may not be Nosema apis, either. One or both of what we are seeing
may be a variant of "Nosema bombi" that jumped hosts from Bumblebee
to Honey bee.
Why do I speculate so "wildly"? There's a number of reasons:
1) We know exactly how Nosema bombi got to our shores - it came
here on bumblebees imported for greenhouse pollination.
This exotic invasive pathogen has driven at least two
species of US native bumblebees to extinction. See:
http://entomology.ucdavis.edu/news/robbinthorp.html
2) No one seems to have a good story as to how Nosema
ceranae got to our shores, got established, and spread.
3) Light microscopy (normal microscope) methods for
discrimination between Nosema apis and Nosema ceranae
been mistaken for many years by multiple highly competent
people, and yet no one has yet compared all three types
of Nosema (apis, ceranae, bombi) under the same
microscope on the same afternoon.
4) Even the assumed-to-be more accurate molecular methods
of differing between Nosema apis and Nosema ceranae
(based upon RNA - the "16S ribosomal subunit sequence")
may or may not be able to differ between Nosema apis and
ceranea AND bombi. A conclusion is being made upon only
a few hundred bases out of hundreds of millions of bases
in the complete sequence. While these bases were chosen
to differ between Nosema apis and what we are calling
"Nosema ceranae", there is no assurance that either type
of Nosema is being uniquely identified using this method.
"Screening" is never the same as making a firm identification.
5) Eric Mussen of UC Davis confirms that Nosema apis and Nosema
bombi are "very close genetically", while Nosema ceranae is
much more closely related to other types of Nosema, such as
Nosema vespula.
6) No one involved in the CCD work has gotten into the taxonomy
issues, so there is no consensus on HOW to differ between
any of the pathogens at hand, hence the confusion. The
confusion is the same, regardless of the pathogens at
issue, be they Nosema, viruses, or fungii. What is needed
in all cases is some full sequencing, anything less just
won't do.
7) We've had Nosema apis for years and years, but not at "epidemic"
levels. Since we've started to see the new nosema, the one we
are called "ceranae", we've also seen a much more widespread
prevalence of BOTH types of Nosema, and so has Canada. How
the heck did THAT happen? Why does everyone suddenly have so
much Nosema of both types, when in years past, Nosema apis was
one of the ignored problems of beekeeping, and not as universally
widespread.
Just to recap, this is not the first time that the data at hand
did not match the conventional thinking about CCD, yet the data
did not change the thinking as quickly as one might hope it would.
A year ago, I speculated that Colony Collapse Disorder "just had to be"
"a pathogen problem" rather than a pesticide problem or a management
issue.
Why? 'Cause the problem clearly spread like a pathogen. Any pesticide
problem
would have left some bees with "only the shakes" because they would only
get
a "whiff" of the poison, rather than a dose that would do lasting harm.
Any
management issue would have revealed itself in beekeeper surveys.
Last summer and fall, I stated that the actual best "marker" for CCD was
both
kinds of Nosema (apis and ceranae) in the same hives at the same time,
rather
than Ian Lipkin's pet virus.
The consensus and focus of attention has moved from pesticides, to
"fungal infections", to Israeli Acute Paralysis Virus, to (at last)
the suitably more complex mix of both kinds of Nosema, Deformed Wing
Virus, and (after what I am sure was lots of arm-twisting to save face)
IAPV, even though IAPV isn't correlating to CCD cases well at all.
Here's the AIA statement on the newest consensus:
http://home.ezezine.com/1636/1636-2008.04.25.11.04.archive.html
We are left wondering why such a wide range of different levels of
virulence
has been reported for "Nosema ceranae", everything from "kills hives
dead in
3 days" from Europe to "no worse than Nosema apis, but not as seasonal"?
The easy answer is that we are not talking about a single pathogen, or
even
minor variants of the same pathogen. The easy and obvious answer is
that we
are talking about different pathogens, but we haven't bothered to figure
out
which one is what one or what one is who.
So, I'm betting on a taxonomical surprise in the Nosema area.
This matters because we have to "know our enemy" to be able to defeat
it.
I could be completely wrong in the above. Recall that people laughed at
Columbus, they laughed at Fulton, and they laughed at the Wright
Brothers.
But they also laughed at Bozo the Clown. :)
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