> It sticks in my mind that researchers stumbled
> onto the discovery that terramycin has an
> effect on deformed wing virus.
Wow, if there is ever a Beekeeping Edition of Trivial Pursuit, remind me to
not bet against your answers!
I remember this one... it was a wacky little idea to wrap your head around.
(Some people collect stamps or baseball cards. I collect wacky papers.)
Before anyone gets worked up, let me state that the OTC in this case was,
once again, being used to cure a diagnosed bacterial disease/infection.
And before anyone starts feeding their hives OTC, let me emphasize that this
little idea is no longer suggested at all.
Long story short, OTC kills bacteria, which was thought (at that time) to
enhance the spread of DWV. So, OTC kills the bacteria, and as a result, you
don't have as much DWV, even with varroa infestation. Although this theory
was widely circulated at the time, it has since been carefully excised from
all documents, for reasons that are not clear, but are assumed to be
summarized as "it was wrong".
Long story long, it started with a MAAREC handout I was including in my
novice course back then. The claims have since been edited out of the
handout. Here's a link to the pdf of that outdated handout on "The Internet
Archive":
http://web.archive.org/web/20060103163646/http://www.ento.psu.edu/MAAREC/pdf
s/Varroa_Mites_PMP1.pdf
or
http://tinyurl.com/mxnlmmm
The text that raised my eyebrow was:
"Although we do not understand why, treating varroa-infested colonies with
an antibiotic such as oxytetracycline (Terramycin) seems to help them
survive and perform better. Antibiotics are effective in treating bacterial
diseases, such as European foulbrood, but are unlikely to have a direct
effect on the virus infections common with mite infestations. Even so,
oxytetracycline treatments seem to offer some advantage to colonies with
varroa infestations."
This seemed a very strange thing to say in light of the usual varroa-virus
scenario we had been taught circa 1999, and stranger still given that
antibiotics were something to use sparingly in agriculture, so as VA was a
dues-paying member of MAAREC, I followed up with Penn State, which at the
time was producing 90% of the MAAREC handouts.
I was told of the work and sent some data that eventually resulted in the
paper below:
"Impact of an ectoparasite on the immunity and pathology of an invertebrate:
Evidence for host immunosuppression and viral amplification"
Yang and Cox-Foster
PNAS May 24, 2005
doi:
http://dx.doi.org/10.1073/pnas.0501860102
or
http://www.pnas.org/content/102/21/7470.long
or
http://tinyurl.com/md7ztgr
It gave an explanation that seemed plausible:
"The replication of DWV in honey bees provides another example that a
bacterial factor stimulates replication of some viruses... The increased
replication of DWV in honey bees needs two components, varroa mite
parasitization and exposure to a bacterial factor. This microbial challenge
may naturally exist, because bacterial colonies are found on the varroa
feeding sites in some bee pupae... DWV may rapidly replicate in these
mite-parasitized, bacteria-exposed pupae, causing them to develop into DW
bees. This requirement of a microbial factor for DWV replication may also
help explain the results of a statewide extensive survey in Pennsylvania
(10) and experiments in South America (49), where bee colonies treated with
antibiotics survived significantly better than the untreated colonies. The
antibiotics might have controlled the bacteria in the bee colonies, and as a
result, one of the components for DWV replication may have been removed or
depressed."
I have no idea if the OTC idea has been since found to be "overtly wrong",
or if the effect of the OTC was negligible "in the field". I suspect the
first, given the lack of any field trial report.
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