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Date: | Tue, 26 Feb 2019 16:45:11 -0800 |
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> Has it been clearly shown that they reproduce in bees? How is that shown?
Sorry Pete, I don't understand what "they" are. Are you asking whether DWV
has been shown to reproduce in bees? If that's what you're asking, then
yes, as evidenced by it's presence in a number of bee tissues, as well as
negative strand virus RNA also being present in those tissues. Only
Campbell claims to have identified DWV in only a single tissue type in
varroa, whereas several others have been unable to do so, or to find other
indicators that the virus does so. Ditto for VDV-1 aka DWV-B.
> How is DWV transmitted between the bees?
- DWV can be transmitted transovarially (virions have been shown to
adhere to the egg casing as the egg passes down the queen's oviduct.
- Viruses can also be transmitted via the jelly fed to larvae, and by
trophallaxis between adults, as well as via transmission via flowers, or
even by inhalation of virions. Most larvae in hives today contract DWV,
but then keep it in a latent (covert) state.
- Varroa can transmit DWV, but a DWV-positive (whole-body extract)
foundress mite may or may not transmit the virus to the pupa upon which she
feeds. Unless the pupa then gets infected, the mother mite's offspring
don't get infected either. There is evidence that there is no direct
vertical transmission of DWV from mite mothers to their offspring.
> I assume that each Varroa infected bee with high DWV virus load will
spread more of it.
Not necessarily, transmission via oral contact appears to be poor. Unless
varroa is present as a mechanical vector, DWV tends to disappear.
--
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com
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