Chris
Dr. Robb Cramer at MSU in Bozeman has been working with us on this issue.
Robb can do PCR for Nosema - and we can provide that service to beekeepers,
working with him.
We are taking samples, splitting them among our lab and others for various
assays as requested by the beekeeper.
All of the results go into a national database, so that we can look for
trends and patterns.
For any sample, we typically look for tracheal and varroa mites and both
nosemas, Robb does PCR for nosema verifications, etc. as needed, Dave Wick of
BVS runs viral surveys, and Army ECBC will do a complete analysis for all known
viruses and most other bee pathogens. We can get pesticides and other
analysis done, and we do our own HMF, as well as testing for about 400 volatile
chemicals. However, I'm getting off the subject.
The main reasons to use PCR are: 1) to positively ID the Nosema (which is
important to any research on this pest, including evaluations of materials used
to try to control) , and MORE importantly, because PCR is more likely to
review emerging infections (Robb sees both Nosemas in samples that we looked at
under the microscope and didn't find).
The latter is a sampling problem - how much time, how many spots on the
slide, and how many bees does one have to look at to get a given probability of
detection - 50%, 75%, etc. From this perspective, PCR wins over visual
inspection.
However, visual inspection may be sufficient if you just want to know if you
have a nosema problem.
Randy Oliver, the investigators in Spain, and some in Argentina claim to be
able to discriminate by the 'look' of the spores. I expect that they can,
but they're not typical observers.
It seems that IF you have BOTH species, you might see a difference. IF
you've looked at lots of samples - as the aforementioned folks have, you MIGHT
see a difference. But, if you've only one Nosema species, I doubt that most
people could tell the difference based on visible characteristics. Certainly,
we at Bee Alert don't feel that we can make that call with any confidence -
and we've looked at lots of samples.
Now, some say that Nosema apis has more or less disappeared from U.S. bees.
Not so, although Robb wondered about this for some time - since he went some
months without seeing N. apis. As always, we and he see N. apis in bee from
some geographical areas, in the spring. Just like we'd expect.
IF you see a NOSEMA at any other time of the year, its almost certainly N.
ceranae. Chance of it being N. apis are VERY LOW according to Robbs data from
the last year and half.
And, in the spring, you can find bees with BOTH nosemas.
If you've got Nosema now, good bet that its ceranae.
Jerry
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