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Wed, 16 Oct 1996 09:25:37 +0100 |
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<Pine.SOL.3.93.961015163023.24551A-100000@pbr322> |
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In message <Pine.SOL.3.93.961015163023.24551A-100000@pbr322>, Miguel
Corona <[log in to unmask]> writes
> Does somebody has any information or comments about mortality of
>bee colonies caused by viruses associated with varroa? .
I have been writing about this for my local beekeepers after attending
an IBRA conference. Some of the work covered your interest. I can find
the references or summary paper if thats a help. Here is an extract.
<snip>
For years the anecdotal experience of Varroa has been confusing. Some
treated colonies died out while other untreated colonies appeared to be
resistant...... Brenda Ball from the Insect Pathology Section at
Rothamstead Experimental Station has shown that the cause of the
colonys death is not as simple as first thought and not entirely due to
the mite.....
<snip>
The work at Rothampstead has shown that the main cause of death in
Varroa infested colonies has been virus infections. These have all been
associated with bee colonies before but the mite has provided a new
route for the viral particles entry and acts as a vector spreading the
infection both within the colony and between colonies. It is highly
probable that the variation in the response to Varroa infestations is
due to the presence or absence of different types of viral pathogens.
It is also possible to detect the viral infection after the Varroa mites
have been removed and once established it will remain still causing the
death of the colony. The first treatment programmes allowed a mite
population to build and then attacked it with a single treatment. At the
time it was thought that it was the large population of mites feeding
on the bees that was causing the damage. However the direct effect of
the mite feeding on the bees haemolymph seems minimal and future
methods will have to limit the population of mites so that viral
infections cant become established. The symptoms of a viral infection
are not clear but death of all stages of brood in midsummer has been
noted. These infections are also responsible for the deformed wings and
so on that appear in emerged bees. Testing mites for viruses can give an
early indication of trouble as they can be detected in the mite as much
as three months before they appear in bees.
<snip>
--
Dave Black
Blacks Bee Gardens,
Guildford, GU1 4RN. UK.
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