Of relevance to everyone

[B+.]

Not sure I follow your logic, every population that's developed natural resistance to varroa has at least partly done so with swarming, aka brood breaks. We know longer winters with longer brood breaks also adversely affect varroa (I can't remember the paper but I'm sure I've read that) so even if the 'phoretic' varroa has munched the fat reserves of its host bee it seems the brood break is more damaging to the varroa population in a colony than to the bees.

Perhaps I should have been clearer in what I meant. I think Ramsey et al showed that varroa is not phoretic during its period on an adult bee. It continues to feed. So, I think a brood break by itself wouldn't really help. It would also depend on the level of infestation how many adult bees were compromised. They could probably survive a low infestation if there were enough unaffected nurse bees to rear the next generation of bees, but, I think a heavy infestation would cause more difficulties and make their survival less certain.
It may be that other defence mechanisms are employed in addition to swarming that helps manage the varroa on adult bees. It is pretty new so we'll have to wait and see what else comes up.

 

[Beefriendly]

The importance of brood breaks and long winters is that varroa cannot increase in numbers as no brood cells with larvae for them. There will be a natural decline in the overall population just by old age/brushed off bees etc.

 

[B+.]

The importance of brood breaks and long winters is that varroa cannot increase in numbers as no brood cells with larvae for them. There will be a natural decline in the overall population just by old age/brushed off bees etc.

I agree...but, if you look at winters recently, how many of them have been long/cold enough for the colony to be brood-free? The value of this new research is that we now know that the adult bees are vulnerable too. This makes it more important than ever to control your mite numbers going into winter.

 

[Beefriendly]

I agree...but, if you look at winters recently, how many of them have been long/cold enough for the colony to be brood-free? The value of this new research is that we now know that the adult bees are vulnerable too. This makes it more important than ever to control your mite numbers going into winter.

B+ we knew the value of treating for varroa before winter long before this research came to light. Whether we erroneously thought they were feeding on hemolymph or fat bodies the adult bees have always been thought of as vulnerable to varroa.
Whilst it's interesting to know what is happening I'm not sure how you target any drugs to the fat reserves. Or how do viruses carried by varroa cross the fat bodies into the bee...although I understand some of the neonicotinoids are fat soluble /puts tin hat on and retreats quickly /

 

[B+.]

B+ we knew the value of treating for varroa before winter long before this research came to light. Whether we erroneously thought they were feeding on hemolymph or fat bodies the adult bees have always been thought of as vulnerable to varroa.
Whilst it's interesting to know what is happening I'm not sure how you target any drugs to the fat reserves. Or how do viruses carried by varroa cross the fat bodies into the bee...although I understand some of the neonicotinoids are fat soluble /puts tin hat on and retreats quickly /

Really? If the mites were phoretic, that wouldn't have been the case.
In any case, I think it's an important contribution to our knowledge and I think he certainly deserved his Phd (he is now fund-raising to continue looking at Tropilaelaps in Thailand).

 

[Beefriendly]

The clue about what most people thought varroa did to adult bees is in the title and the abstract...
"Varroa destructor feeds primarily on honey bee fat body tissue and not hemolymph"

"For five decades, we have believed that these mites consume hemolymph like a tick consumes blood, and that Varroa cause harm primarily by vectoring viruses."

That's what I thought until I read the research. And that is what the authors of the paper thought people thought before they published the research. And that is why most beekeepers thought lowering varroa numbers before winter was important long before the research was published.

We was right but for the wrong reasons....but we were still killing them

 

[B+.]

The clue about what most people thought varroa did to adult bees is in the title and the abstract...
"Varroa destructor feeds primarily on honey bee fat body tissue and not hemolymph"

"For five decades, we have believed that these mites consume hemolymph like a tick consumes blood, and that Varroa cause harm primarily by vectoring viruses."

That's what I thought until I read the research. And that is what the authors of the paper thought people thought before they published the research. And that is why most beekeepers thought lowering varroa numbers before winter was important long before the research was published.

We was right but for the wrong reasons....but we were still killing them

OK.
I understood that they fed on the haemolymph of pupating bees but were phoretic on adults. I have even referred to phoretic mites myself many times.
The "harm" can now also be seen to occur in the fat bodies of the nurse bees which makes them less able to perform other functions (which he lists towards the end of the video). The fat bodies of "winter bees" should be well stocked for the months that they have to survive inside the hive, then brood rearing....but this would not be the case in adult bees during an induced brood break so I think this is potentially more risky for the colony.

 

[Erichalfbee]

I've watched the whole video now
He is an excellent speaker
Thanks for posting the link B+

As far as I can make out if varroa numbers are kept low then a brood break is nowhere near as harmful as one where the colony has a high load. So if we keep the mite numbers down and make sure our winter bees are as varroa free as we can realistically get them we should be on top of things.

Some excellent research and pictures

 

[Swarm]

I've watched the whole video now
He is an excellent speaker
Thanks for posting the link B+

As far as I can make out if varroa numbers are kept low then a brood break is nowhere near as harmful as one where the colony has a high load. So if we keep the mite numbers down and make sure our winter bees are as varroa free as we can realistically get them we should be on top of things.

Some excellent research and pictures

But isn't that what we've been doing, though? At least responsible beeks. I can honestly say I've never spoken to a beek who thought varroa clinging to bees were not parasitizing the adult bee, just not reproducing.

 

[B+.]

But isn't that what we've been doing, though? At least responsible beeks. I can honestly say I've never spoken to a beek who thought varroa clinging to bees were not parasitizing the adult bee, just not reproducing.

Perhaps it sounds like nit-picking but it's about the meaning of the word "phoretic". This means that the host is merely transporting the varroa mite and is not harmed by it. We now know that the adult bee is harmed (so it is not phoresis). We also know the effect of the varroa mite feeding on the fat body of the adult bee.
If your contacts referred to the varroa on an adult bee to be a parasite, that would have been wrong because we had no evidence to support it before this (only that the varroa parasitised bee pupae).

One thing that I am not clear about is how different adult bees after a swarm/induced brood break are compared to winter bees. I believe them to be very different and that is why I am calling this out as a risk

 

[Beefriendly]

I've always thought phoretic was a very bad word to describe the adult part of a varroa life cycle. Most scientific descriptions say something along the lines of
"Adult females undergo two phases in their life cycle, the phoretic and reproductive phases. During the phoretic phase, female Varroa feed on adult bees and are passed from bee to bee as bees walk past one another in the colony. During phoresy, the female Varroa live on adult bees and usually can be found between the abdominal segments of the bees. Varroa puncture the soft tissue between the segments and feed on bee hemolymph through the punctures."
http://entnemdept.ufl.edu/creatures/misc/bees/varroa_mite.htm
This is what I've always undertood.
How else would they endure a brood break if nothing to feed on, they would starve to death and be easy to control.

 

[For want of a better word]

Perhaps it sounds like nit-picking

Very good... well I got it in one!
The rhubarb in the pollytunnel is just beginning to sprout!

Chons da

 

[Swarm]

Perhaps it sounds like nit-picking but it's about the meaning of the word "phoretic". This means that the host is merely transporting the varroa mite and is not harmed by it. We now know that the adult bee is harmed (so it is not phoresis). We also know the effect of the varroa mite feeding on the fat body of the adult bee.
If your contacts referred to the varroa on an adult bee to be a parasite, that would have been wrong because we had no evidence to support it before this (only that the varroa parasitised bee pupae).

One thing that I am not clear about is how different adult bees after a swarm/induced brood break are compared to winter bees. I believe them to be very different and that is why I am calling this out as a risk

I would argue that they were right and now it's been confirmed.

 

[B+.]

I've always thought phoretic was a very bad word to describe the adult part of a varroa life cycle. Most scientific descriptions say something along the lines of
"Adult females undergo two phases in their life cycle, the phoretic and reproductive phases. During the phoretic phase, female Varroa feed on adult bees and are passed from bee to bee as bees walk past one another in the colony. During phoresy, the female Varroa live on adult bees and usually can be found between the abdominal segments of the bees. Varroa puncture the soft tissue between the segments and feed on bee hemolymph through the punctures."
http://entnemdept.ufl.edu/creatures/misc/bees/varroa_mite.htm
This is what I've always undertood.
How else would they endure a brood break if nothing to feed on, they would starve to death and be easy to control.

In fact, varroa have more than two phases: the egg, larva, nymph (protonymph and deutonymph), then the adult. Most people only see the reddish brown adult but there is a lot more going on inside the cell. What you describe is more along the lines of amensalism/parasitism as we now know that the bee is harmed.

 

[B+.]

I would argue that they were right and now it's been confirmed.

Its called a lucky guess ;-)

 

[Beefriendly]

In fact, varroa have more than two phases: the egg, larva, nymph (protonymph and deutonymph), then the adult. Most people only see the reddish brown adult but there is a lot more going on inside the cell. What you describe is more along the lines of amensalism/parasitism as we now know that the bee is harmed.

Yes B+ I'm well aware of all the different varroa life cycles and can even explain why in Cerana it's only multiplies in drone cells and not worker cells (apoptosis).
Definitions of phoresis can include parastism as long as the transport occurs, which we know it does.

I'm more surprised you weren't aware of it feeding on adults before this 2019 paper. As the common long held scientific and laymans view has always been that it does feed on the adult bee during it's phoretic phase.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4838260/

"Varroa destructor is a parasitic mite of the honeybee that causes thousands of colony losses worldwide. The parasite cycle is composed of a phoretic and a reproductive phase. During the former, mites stay on adult bees, mostly on nurses, to feed on hemolymph. During the latter, the parasites enter brood cells and reproduce. "

 

[Swarm]

Its called a lucky guess ;-)

Seeing that the mites are dug in, I'd call it common sense but I guess you would require a paper to confirm that as well.
I can't believe that any beekeeper seriously thought varroa on bees were only getting a lift.

 

[gmonag]

It seems to me that a brood break is not the pancea that it was thought be. Sure, it interrupts the Varroa brood cycle and so controls their increase but now it is evident that whilst the mites are in a forced "phoretic" phase they are still damaging the adult bees more than we realised. This then, has implications for their ability to raise the next generation of brood, which may well be the winter bees.

I now think the way to get the best results is to cause a brood break 3 weeks before harvest (say, early August) as suggested by Ralph Buchler, by caging the queen and then immediately treating with oxalic acid vapourisation at 5-day intervals for the next 25 days.

This will halt the reproduction of the mites and make them vulnerable to the oxalic acid as they emerge from the capped brood. This ensures that the "phoretic" mites cannot damage the adult bees as they will be instantly killed by the OA. After 25 days, there will be a 97+% mite kill and the nurse bees will be healthy. Plus, as a result of not having to rear brood for 4 weeks they will be stronger and "younger" than they would naturally be, when the queen is released to begin laying the winter bees.

Does that make sense?

 

[charlievictorbravo]

First of all , thanks B+ for providing the link to the excellent talk by Dr Samual Ramsey.

As a result of something I’d read, I Googled "phoretic" a couple of weeks ago and found it referred to transportation of one organism by another but did not involve parasitism. The phoretic phase of a Varroa destructor was always thought by most beekeepers to be the phase outside the brood cells so phoretic is clearly the wrong word to describe that phase. I must admit, I had not given much thought to whether the mite fed during this “phoretic” phase but Dr Ramsey makes it clear that this parasitic phase of its existence is probably more damaging to honey bees than its parasitic reproductive phase in the brood cells.

According to his presentation, it appears that there is a true phoretic phase but it only occurs when a mite moves from its feeding location to the top of the thorax of the host bee so that it’s in a position to move to another host. What would we call the phase where it’s feeding on a honey bee’ abdomen? Well, I suppose it’s an “extra cellular feeding phase” i.e it’s feeding outside the brood cells.

The big mystery that remains about the Varroa destructor is how does Oxalic Acid kill it? From the slides in Ramsey’s presentation, I could not see how OA micro crystals from vaporisation or OA syrup from trickling could get to the feet or mouth parts of the mites. We need a study to find out how OA kills the mites. Any thoughts?

CVB

 

[mbc]

I've always described the harm varroa do as akin to having only a handful of needles in a city full of junkies, seems the needles now need to perform liposuction while they're at their dastardly task.
Interesting as it is though, this research makes not a jot of difference to varroa management plans.