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From the article:

"The elimination of Sacbrood and Black Queencell virus leaves just Deformed Wing Virus, which does not kill the bees."

So DWV does not kill honey bees?

From the article:

"'The prevailing wisdom is that the mite selects for very virulent strains of the virus,' said Professor Madeleine Beekman from the School of Life and Environmental Sciences at the University of Sydney."

Is that really the prevailing wisdom? That has never been my understanding. I have never even heard that theory proferred. It has always been my understanding that the virulence of the mites can far exceed the virulence levels of the bees they are infecting. Therefore the mite can be a vectoring agent that harbors high levels of viruses that can incubate within the mites that are residents of the hive.

Is anyone else aware of this theory that varroa actually SELECTS the more virulent strains of viruses?
 

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Brettella, Martin 2017 Oldest Varroa tolerant honey bee population provides insight into the origins of the global decline of honey bees
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5385554/
The mechanism underlying the Varroa induced transformation of DWV infection in bees from a genetically variable and low titre inconsequential virus to a deadly virus dominated by a virulent genotype has until now been unknown. The data from this study, along with data from Ryabov et al.13, which showed that the decrease in viral variation occurred in the bee rather than the mite, suggests that in order for a virulent variant to become established it must first become an overt infection within a bee (pupae or adult). This then allows Varroa to then transmit sufficient amounts of this virulent variant throughout the population. Although RNA viruses exhibit high mutation rates and no proof reading activity leading to extremely fast evolution of their quasispecies30 amplification of a lethal DWV variant, which goes on to kill a colony is a rare occurrence. Under natural conditions, without Varroa to spread the virus, the overt infection would likely go unnoticed as the colony would quickly die without spreading the virus further. Pre-Varroa, isolated colony deaths associated with overt infections of DWV were reported in Hawaii5, UK and South Africa24 and Belize (Brenda Ball, personal communication). It has now been shown13 that the appearance of a virulent DWV-variant occurs within the bee, not the mite, which appears to be acting only as a mechanical vector. However, the conditions required for the sudden amplification of the type A variant within the bee remains unknown. Although once present in the honey bee population it is vectored very efficiently by the mites.
Long story short pre Varroa there was very little virulent DWV as if it killed a hive it was mostly at a dead end, with no way to spread
But infected mites from colasping hives attaching on to robbers gave it a very effective way to spread. Now killing the host was not a problem, in fact it was to the virus advantage causing a rise to prominence a few years after mite introduction.
 

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Ok. So I have been educated by msl and a PM that there is, in fact, a prevailing theory that a selection process may be occurring. It seems that this study indicates that this prevailing theory is incorrect. Since I am only now understanding the prevailing theory, I will just recess into some reading and drop that issue for now.


The other "zinger" for me in the article was the assertion that DWV "does not kill the bees." Can anyone help me wrap my head around that? Is this statement true?
 

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My experience is that I have had very few DWV infected bees. Not sure what point the researchers are trying to prove. The other viruses are plenty bad that are transmitted by mites and you still need to keep the mites under control.
 

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The other "zinger" for me in the article was the assertion that DWV "does not kill the bees." Can anyone help me wrap my head around that? Is this statement true?
Fatshark is the bloke to talk to about DWV, as such viruses are 'his day job'. Even if DWV doesn't actually 'kill' the bee right away, it will render it quite incapable of playing any useful role in the life of the colony - and so with enough infected bees the colony will simply be unable to survive. At that point, ALL the bees are dead - dead as a result of DWV.
LJ
 

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Fatshark is the bloke to talk to about DWV, as such viruses are 'his day job'. Even if DWV doesn't actually 'kill' the bee right away, it will render it quite incapable of playing any useful role in the life of the colony - and so with enough infected bees the colony will simply be unable to survive. At that point, ALL the bees are dead - dead as a result of DWV.
LJ
If we are to think of the colony as a superorganism, DWV most certainly "kills bees." Isn't that an accurate statement?

Jonsl: DWV is the most predominate virus in my hives. I have the Beltsville lab report to show it.
 

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The other "zinger" for me in the article was the assertion that DWV "does not kill the bees." Can anyone help me wrap my head around that?
I think the key to such things is to go read the study for you self and not to rely on a journalists unquoted, and often under informed interpretation
https://royalsocietypublishing.org/doi/10.1098/rspb.2018.2452

The conucltion they seem to come to is the more virulent virus such as BCQV and SVB became so bad under the change in vector the hive collapses super fast and it dosen't spread...(but they weren't using mites) thus mainly leaving DWV as it kills slowenuff to spread
they do make the statement " injecting high levels of DWV strain A into pupae did not result in the death of the pupae, indicating that this strain of DWV does not kill developing brood despite" witch may be were the author gets the idea it doesn't kill bees, while it may not kill them out right, we know as beekeepers it will kill the hive.(As LJ points out)

Honestly I question mite research done with out mites, in a mite free country
 

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If we are to think of the colony as a superorganism, DWV most certainly "kills bees." Isn't that an accurate statement?
An accurate 'stand-alone' statement really needs the time element to be included - something along the lines of: " ... kills bees in a matter of weeks." or something similar to that. Just like having your liver and kidneys removed - which won't kill you on the day, but will most certainly seal your fate, as you'll be stone dead by the end of the month.

When you look at a hive infected with DWV, it clearly doesn't kill the bees immediately, as such bees can often be seen wandering aimlessly around. But they can't take cleansing flights, they can't forage, and they certainly can't swarm - to use a popular expression, they're "dead men walking".

MSL's approach - to go to source and read the exact wording (in it's context) is by far the best way of resolving any ambiguity.
'best,
LJ
 

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Excellent point.
I too had no significant viruses prior to the mites arrival.

One of my thoughts is that the viruses, (or is it the treatments?), eventually get the queen although I've yet to see a queen with viruses.

But what has happened is I have a hive loaded with bees, making honey, everything looks fine, and then they take a hit. Look at the bottom box of these hives, there are frames of pollen not being utilized. IMO it's not that there storing it up; rather it is the queen is no longer viable. And then, where I'm located, the hive beetles finish the hive off lickedty split, shall we way.

The last couple of years the bees seem less effected by viruses, but then the mite bomb gets them if they are not treated heavily. IOW, in an area with too densely populated with bees located way too close together, the mites are brought home from around the area. Thus the mite bomb.

I read with interest the VRH stuff about Hawaii...but I wonder what happens with those bees when they bring home loads of mite from outside the yard. I have my doubts as to whether they can handle it any better than my bees handle it.
 

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Fascinating! So the viruses themselves can compete for access to replication "equipment" in the pupae?

And survival of the pupae after exposure to DWV does not mean the health of the colony is spared. Two different levels of inquiry...and maybe a red herring.

I have observed a hive slowly losing ground to some sort of varroa-virus killing - the hive was at nuc sized in fall, then by spring was no longer sending out foragers. Not dead yet! So there is a slower pathway for killing the superorganism...which is what I would assume a virus would do - slowly wear down the numbers of effective bees until there are too few left.

But I have also seen a hive taken down in about 6 weeks over winter - from low mite counts (and later little/no mite frass observed) in October to robbing in November to dead in January. I saw them go robbing, didn't realize the danger. When I opened the dead hive, there was a mite on the queen. There were unbelievable numbers of mites on the dead bees.

So.... here is where selection of _virus_ virulence can be acting on the hive superorganism. How can a virus that kills a hive - so virulent that the bees AND THEN the in-hive varroa die - spread widely? Whereas a virus that was less virulent will just weaken the hive - like DWV is supposed to do - and then be spread faster by robbing etc.

So this experiment injected the pupae by hand with virus, mimicking the varroa infecting the pupae. OK... but I have seen hives die without the pupae EVER being infected.

I would agree it is the mite, not the virus.... but I'm being literal, and I think the OP meant things metaphorically.... When the defining feature of varroa kill is to go from full strength to dead, potentially due to infection post-capped brood in the fall, I question the role of a virus in those deaths.

But I learned so much from the article! Thanks!
 

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Trish
It may have been a different story when they injected the larva with dwv if they had also reduced a big part of the fat body immune system of said larva that the mite lives off of while doing the infecting.
Cheers
gww
 

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DWV kills bees.
You can feed larvae a stock of DWV and they cope just fine, with no developmental abnormalities, deformed wings, or elevated virus levels in the resulting eclosed adults.
However, inject the very same virus stock - using a syringe - and you get either dead pupae, or eclosed adults with the full gamut of deformed wings, shortened abdomens etc. In both cases, virus loads in the injected bees are orders of magnitude higher than those in bees fed the virus.
This experiment recapitulates what Varroa does - it injects the virus and (probably) bypasses gut immune responses that control or restrict the virus. That's a guess, but a reasonable one. It's the same thing that happens with us. We can eat all sorts of pathogenic microbes that - injected - would cause untold harm.
Varroa-free bees (e.g. Colonsay) still have DWV. Low levels. No symptoms.

Disclaimer ... I've not (yet) read the paper cited in the first post. It's add odds with most stuff published and sounds like nonsense ... what's all this about Sacbrood suppressing DWV?!
 

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Discussion Starter · #16 ·
I came across this article and figured I'd bring it here for discussion. I just placed it without comment in hopes that others would take an interest, and only titled it with what the article seemed to be saying. I did find it odd to be more or less a study on mites while coming from Australia, but then again, they do have access to good "control" samples I suppose.
 

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If it was just the mites, then thesholds for hive death would be more consistent In stats we are told that if a factor doesn't explain the variation, then look for other factors.
 

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If it was just the mites, then thesholds for hive death would be more consistent In stats we are told that if a factor doesn't explain the variation, then look for other factors.
I'm convinced that viruses enabled by mites make queens infertile. Had to check my definitions and correct this.:)
 
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