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There was some off-thread-chatter about Varroa mites losing virulence when TF "let 'em die" management encourages a hypothetical selection for reduced lethality.
Rather than burden that particular thread with actual peer reviewed science, I'm starting an independent thread on the topic.
Ongoing research is looking at the master variant evolution of DWV in the Hawaiian chain. The paper is co-authored by Dr. Stephen Martin, who initially studied virus variants in Hawaii after the introduction of Varroa

The new research finds that a DWV variant "B" which is 1) more infectious, and 2) able to reproduce within Varroa (not just Apis larvae) has rapidly become dominant over an earlier variant "A". The Variant "A" previously replaced a wide assortment of other types immediately after Varroa invaded the naive Hawaiian islands.

The highly infectious and rapidly reproducing variant "B" is present in 1) feral, 2) treated, 3) managed but untreated apiaries. Whether variant "B" is more or less lethal to colonies is undetermined, though the research indicates that colony death is driven by the concentration of virus particles, and infectious and freely reproducing types (such as "B") produce more particles.

Hence: the actual observed trajectory for Varroa mediated virus disease is toward greater and faster lethality whether and irrespective if
an apiary is 1) feral, 2) untreated or 3) varroa managed.
Cite: https://mdpi-res.com/d_attachment/viruses/viruses-13-00969/article_deploy/viruses-13-00969.pdf



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hmm so the bees can evolve, the mites can evolve And now the Virus can also evolve.
does not bode well.
I think even the virus count has increased went from 11 to 14 or something, Maybe they were there and not yet discovered.

More Mite research IMO is a good thing.

GG
 

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Is there any concensus yet on whether hygienic removal can contribute to spread of some infections due to cannibilization and food sharing. It used to be a consideration that the trait could be overdone..
 

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Is there any concensus yet on whether hygienic removal can contribute to spread of some infections due to cannibilization and food sharing. It used to be a consideration that the trait could be overdone..
What was cool about these studies was she had indicated that it wasn't confirmed how the behavior was removing proliferation of the diseases and seems like more speculation than fact that the nurse bees were self-isolating and likely absorbing the diseases through cannibalism and maybe reducing need for trophyllaxis (sp?) because they were full and thus reducing potential spread to the rest of the colony before they walk themselves out the front door.
 

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JW:

Thank you for posting the study- good read.

I was curious if any conclusions had been drawn relative to these findings by Dr. Martin considering his recent 'Parallel Evolution' article.

I contacted him, and he was gracious enough to respond while on location in Hawaii- and he gave me permission to quote him.

'See the attached article- preliminary data suggest that in resistant colonies virus levels of both A and B fall- this is directly due to lack of mites. Increase the mite populations and the colonies will die from either strain A or B.'

So as many of us might have surmised, it appears the only reliable way to minimize hive failure due to DWV is to keep mite population growth low- by whatever internal or external mechanisms available or necessary.

Otherwise, the study itself was interesting in that they directly evaluated treated, untreated and feral colonies, observing:

All the colonies in each group, managed treated (n = 15), managed not-treated (n = 15), and feral (n = 11) had quantifiable amounts of DWV-A and DWV-B. For each group, the genome equivalents of DWV-B were not significantly different, i.e., feral vs. managed untreated (T = −0.43, p = 0.67), feral vs. managed treated (T = −1.59, p = 0.13) and managed untreated vs. managed treated (T = −1.13, p = 0.27). However, the DWV-A load was significantly lower in feral colonies than in managed, untreated colonies (T = −2.41, p = 0.027) or in feral than in managed, treated colonies (T = −2.16, p = 0.042). Managed treated and managed untreated colonies had similar levels of DWV-A (T = 0.04, p = 0.97)

Feral colonies that are able to resist Varroa without treatment had significantly lower DWV-A genome equivalents than treated colonies (Figure S1) but similar DWV-B genome equivalents. The managed untreated colonies had similar DWV-A levels to treated colonies, which were also significantly greater than levels in feral colonies. This is unexpected using the same methodology have found a reduced DWV burden in resistant, not treated, managed populations in South Africa and Brazil [30].


The other thing I found interesting was this little nugget:

A pivotal study in Hawaii found that prior to the spread of Varroa, DWV infections consisted of a diverse array of variants, and post Varroa, this diversity was drastically reduced [9], a finding that was independently found in the UK honey bees [14].

Thanks again for the post.
 

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Here's a study https://www.nature.com/articles/s41598-021-88649-y.pdf

Seems like it can be a problem as the viruses may be able to spread from bee to bee without the mites.
Joebee33:

If you haven't seen it already, Dr. Boncristiani discusses both the Evans et al article and the Wagoner research that @James Lee refers to above:

I noted that Kamon posted this video over in another thread, but I thought it worthwhile to hang it here as well given that he references this video as a counterpoint:


Specifically, at about the 7 minute mark he asks the rhetorical question of, "Is hygienic behavior good or bad for honey bees"?

His answer (and description of the scientific process in general) is insightful in my humble opinion.

The study itself is really interesting- if a more nuanced method of assessing and selecting for VSH based on odor cues becomes available, this could be a real game-changer.
 

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the actual observed trajectory for Varroa mediated virus disease is toward greater and faster lethality
This is an interesting work, I had not come across the different virus strains before so thanks for that. I am not sure that conclusions about the trajectory of the bee-virus interaction can be drawn from it though.

Specifically the paper says "The enhanced replication combined with a reduction in pupal virulence will give DVW-B...." so the relative effects on colony survival of the two strains are not clear cut. The world map of the different strains, if accurate, suggests that some comparison of colony survivability in the presence of one or the other should be possible. The relative abundance of the strains at the margins would also be instructive.

More generally, the virus is adapting to a new host, as is the mite and the bee is adapting to two new pathogens, this will be a dynamic situation, wild swings in population dynamics in all directions are likely and drawing conclusions about longer term outcomes requires caution.

Sel.
 
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