We can verify Randy's observations. To date, we have more than 1000 samples
from 70+ locations across the U.S.
We often see Nosema ceranae in collapsing colonies, but NOT in all of the
colonies. This may be a correct finding, or it may be a result that is an
artifact of incorrect sampling - having to do with what is termed 'a
representative sample'. In other words, how many bees, of what age, and in what part of
the colony do you need to sample to discover something, if its there.
Defining what is a truly representative sample takes some work.
Based on the findings of the Spanish, conversations with Randy and Eric
Mussen, we've changed our sampling, and put it to the test last week in CA. In
many cases, we got decidedly different results, depending on the age of the
bees that we sampled. As reported by the Spanish investigators, if N. ceranae
was present in these samples, we found that it showed up in the old bees, and
in dead and dying bees in front of the hive, but not necessarily in young
bees. In really bad cases, it was in bees of all ages.
I also recently saw what may be my first observed case of a bee kill from
N. ceranae,. The colonies were doing poorly, dead bees on ground in front
of hive (1-2 bees per square inch, for 1-2 feet out from entrance), dead/dying
bees were of all ages, and they were loaded with N. ceranae - worst case
that we've seen.
In addition, this beekeeper and others who have sent us samples with high
levels of Nosema often report that their colonies aren't making honey.
Since last April, we've been finding N. ceranae in lots of colonies. Like
others, we're having trouble finding any N. apis. From our findings, if a
bee operation has CCD, we will see N. ceranae in at least some of the bee
colonies. I still don't know if its a causal agent or a consequence of some other
pathogen. We are seeing viruses in conjunction with Nosema in CCD colonies.
Clearly, some bee operations have a Nosema ceranae problem, and it by
itself, at the levels we've seen in some of these operations, reportedly is
sufficient to cause major problems. And, we've seen lots of failures of various
treatments in terms of ability to control this pathogen. Simply stated, we lost
90% of our colonies, and they were treated with registered products, at the
doses, etc. on the label.
Eric commented to me that some of the commercial products vary in terms of
concentration of active ingredient, so read the label before making up any
syrup. This reminds me of the days in which TM came in lots of different
concentrations, with little or no labeling that would give you a warning that the
product varied - eventually they started clearly labeling as TM as TM10, 25,
or 100.
Also, according to Eric, Randy pointed out to him that the last registration
for fumagillin that we had in the US was when we were using Fumidil-B. The
Medivet product, Fumagilin-B, is coming into the US from Canada under a
veterinarian memorandum of understanding with the FDA. It is not registered.
IF/when bees go off feed, they won't take any medication in syrup, since
they won't eat. The Spanish drench their bees to treat severe cases of Nosema.
That's NOT according to label in the U.S. I've heard rumors that the drench
method is described on the label of one of the Canadian products - if so,
maybe someone on this list has that information. Note, neither I nor Eric can
recommend use of unregistered products nor off label applications.
I'm not convinced that force feeding (by drenching) of sick bees is going to
work - it may be too late. That said, even in the worst case scenarios, we
found colonies with lots of Nosema in older bees, but the newly emerged bees
were not infected - yet. So, treating these colonies may save these bees.
Just don't expect it to help the old bees - they may be too far gone.
However, like Randy, I don't think Nosema ceranae is the full answer with
respect to CCD. Having seen a case of what appears to be a classic bee kill by
Nosema, as reported by the Spanish - it was NOT the SAME as CCD.
Nosema is of sufficient concern, unto itself, that we've set up to screen
bees and comb for Nosema, with MSU doing PCR confirmations (is it ceranae or
apis), as needed.
So, check for Nosema, but don't blindly treat. Treat if you find it. You
may have to treat now to protect the summer bees, treat again in the fall to
get through the winter - again, according to our colleagues across the pond.
Reportedly, if left untreated, it will begin to show up in bees inside the
hive by mid-summer.
Treating for Nosema twice a year should help, but it doesn't seem to cover
all cases of CCD. DO NOT EXPECT it to protect you against CCD. Nosema may be
a player in terms of CCD, but its not the full answer.
We've re-sampled some operations that have had a long history of poor
performance, as well as having had CCD. Operations with lingering problems (over
months) frequently have Nosema.
To summarize:
We currently think that N. ceranae accounts for some of the poor performance
and bee losses being seen. I think it may be a component of CCD. I don't
think it causes CCD by itself - but this is clearly in the realm of OPINION.
Best advice, start screening for N. ceranae, year round. Treat if needed,
and follow up with Nosema screening to see if the treatment worked.
Keep in mind, we've been finding Nosema all year round.
Jerry
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