Bees with resistance to varroa mites

[SDM]

This goes some way to explaining tolerance of mite mediated immune suppression

http://www.saskatraz.com/files/Front...Biology(2).htm

[Mike Cox]

No ... it's also not clear why Type B predominates in the Hoskins bees and not elsewhere. Geographic isolation, instrumental insemination ?? What is the fate of these bees when moved elsewhere ... ?

This is something that Ron is in the process of investigating. One thing that is certain is that it does not depend on isolation; Ron estimates that there are around 100 beekeepers within 10 miles of him. Instrumental insemination is not a factor either; his queens are open mated. Ron argues along the lines that, through his strategy he is selecting for fitter bees, but is also simultaneously selecting for less virulent mites, and less virulent viruses. He believes that this new equilibrium is a natural product of a system that is allowed to stabilise without interference. This is a line supported by theories of epidemiology (of which I am no expert).

Some trials that are on the cards:
- newspaper combining two colonies, one with DWV TypeA and one with TypeB. Test to see which viral type wins.
- transfering colonies with TypeB to a treatment regimen with a varroa intolerant queen.

While Ron thinks the TypeB virus has been in his colonies for around 10 years he was not aware of its significance until recently, and had no means of verifying what he had until last year when the paper on his bees was published. The whole study of TypeB is very, very new.

There's a disconnect between the presence of the Type B virus and the importance or otherwise of the mite fall/mite nibbling/VSH hygiene RH has been working on for years ... which is it? Are the bees hygienic and able to rid themselves of mites, or is this irrelevant because the Type B virus is present ... ?

There is no disconnect at all here. TypeB provides another mechanism through which his bees are able to survive. However Ron is adamant that TypeB alone would not be sufficient to prevent colony losses due to varroa. The physical damage to both adult and larval bees caused by mites feeding on their haemolymph in a colony with unrestricted varroa reproduction is sufficient in itself to cause a colony to collapse. The hygienic behaviour of his bees suppresses the varroa levels to the equivalent of treated hives, and the added bonus of the TypeB reduces his winter losses even further.

He claims to have not lost a hive due to a varroa/viral related problem in 10 years.

Just as there is no one direct cause of colony loss, more a multitude of factors to do with mites, virus and general pressures on colonies, there are multiple factors that can work to protect colonies. The synergy of mites and virulent virus contributed to very high losses when varroa arrived. The synergy of VSH/grooming traits and TypeB virus is contributing to very low losses in Ron's hives. There is no one magic bullet that will protect hives, but stacking the desk in their favour through multiple factors can.

[fatshark]

Aren't typeB infected bees immunised from other types ? So presumably they'd manage fine out of area.

Presumably. Surely this is known?

You could be on to something.

I'm not

[SDM]

Presumably. Surely this is known?

It is

https://www.google.co.uk/url?sa=t&so...SjOadGvLvb2d3Q

[Mike Cox]

The immunisation theory has been tested and so far seems to hold, but there is not yet enough evidence from its deployment in the field to know how well it holds up.

Issues with using it as a "treatment" of sorts are problematic as it is not clear exactly how it is vectored from bee to bee. Possible routes:

The queen lays eggs which already have the virus. The larvae develop already immunised. This would be ideal as you could simply requeen colonies to get the TypeB

The larvae are inoculated when they are fed by infected nurse bees. Making splits then becomes the best way to propagate, dividing the existing population of nurse bees to maintain the viral transfer to the next generation. Making up mini-colonies might be a way to stretch this using mating nucs, so that you can get more colonies from one parent hive. It may be possible to spread the virus by then combining the small colony with the larger one. This combine approach is as yet unverified.

The adult bees or larvae are only infected when they are bitten by a mite. This would be challenging as it becomes harder to transfer from colony to colony, especially at low mite levels. I suspect that this is not the only path for viral infection however, as in Ron's hive with very low mite levels he still has successful transfer of TypeB to all bees in the hive. If mites are the primary mechanism for transferring the TypeB the you could potentially harvest mites from a colony and deliberately transfer them to another.

I have another question - how do we know that this TypeB is confined to Ron's hives? Ron is super-vigilant in his hive monitoring, which is how he managed to progress his breeding so far. Is it not reasonable to speculate that this typeB might actually be out there, unrecognised in the wider bee population? Would it even be recognised in most hives, or would low incidence of DWV be merely put down to a "successful treatment regimen"?

All of these are interesting potential lines of research.

[SDM]

I can save him some time the newspaper type A,B uniting is a waste of time. B wins.

[SDM]

The queen lays eggs which already have the virus. The larvae develop already immunised. This would be ideal as you could simply requeen colonies to get the TypeB

.

Immunised against type A but infected with B and therefore a mutation factory with wings. This is not a vaccination where the bees immune system learns to combat the virus it's simply already infected and can't catch it again.

[Mike Cox]

I can save him some time the newspaper type A,B uniting is a waste of time. B wins.

"Has done a few times in the past" might be a better way of putting it. I don't think it is shown it will ALWAYS work. In particular, will it work if you combine a very small colony (ie a mini-mating nuc) over a larger one? If so there is a potentially resource cheap mechanism to use, rather than merging, for example, full sized nucs.

[Mike Cox]

Immunised against type A but infected with B and therefore a mutation factory with wings

I'm really not convinced by this argument. Are you proposing that your bees which do not display the most grotesque external signs of DWV are actually totally virus free? I'm fairly certain it has been shown that all bees carry viruses all the time, pretty much as we do. A virally "empty" bee is a niche waiting to be filled - I really don't see how it can be possible.

If you have evidence for claiming that TypeB is more likely to cause mutations I'd like to see that, as I'd also like to see evidence that your bees have NO viruses present.

[fatshark]

I can save him some time the newspaper type A,B uniting is a waste of time. B wins.

Eh ... ? If this were the case, Type B should predominate globally. I don't think the ISME J. paper describes taking a type B colony (colonies) and parking them in a region with a 'normal' distribution of Type A and C (and D - Z?), and the varroa that transmit them, and seeing what happens.