CCD explained?

[gavin]

Hi John and Jon

Yes, I think that they have basically cracked it. If the virologists at Rothamsted had not been made redundant they may have helped crack it earlier.

No doubt there are lots of subtleties yet to come out, but it seems likely that this virus and this microsporidian pathogen is the explanation. Probably also explains the Spanish losses linked to Nosema ceranae and explains why N. ceranae is not always so pathogenic. Might explain the French troubles. Does Nosema apis also amplify the virus? Not sure.

It doesn't seem to be known yet whether the Apis cerana virus was the same as the CCD one. However an iridovirus was spotted in *Varroa* in colonies of moribund US bees in 1996. Not the US but Peace River in British Colombia, Canada.

See: Scott Camazine, Tsu Peng Liu. JOURNAL OF INVERTEBRATE PATHOLOGY 71, 177–178 (1998) - as discussed on Bee-L.

Even more interesting is the *negative* association of DWV with CCD in Jerry Bromenshenk's study, while IIV was showing that strong positive correlation with CCD. That could mean that the IIV is more pathogenic to Varroa than bees.

Did it come from Apis cerana? Mibbae. Varroa did.

So (hypothesising!):

- IIV could be a pathogen of Varroa that also affects the bee host for Varroa, and this 3-way relationship developed while Varroa was a pathogen of Apis cerana.

- Nosema ceranae makes this a 4-way relationship. A separate pathogen of Apis cerana, it also has the action of amplifying the number of IIV (aka AIV) particles in the bee and rendering otherwise benign pathogens virulent.

- Varroa jumps to Apis mellifera

- perhaps later (perhaps sooner or simultaneously) IIV/AIV jumps to Apis mellifera and the Varroa on it too

- Nosema ceranae makes the jump too (when will we ever learn?!)

- Nosema ceranae promotes the amplification of IIV (aka AIV) in Apis mellifera, giving rise to dramatic collapses in populations in the US, Spain and maybe France too. All after Varroa took hold.

Taking this further on:

- IIV/AIV could, in the absence of Nosema ceranae, provide part of the explanation for that tricky Varroa tolerance seen in some bee stocks yet which can disappear in another location

- It seems that we are currently experiencing a year with low Varroa numbers. Is this due to this virus?

- what about the Isle of Wight disease, Marie Celeste and other disappearing diseases, do we now have a better explanation for them? Has AIV been around for a long time?

OK, time to go and lie down now.

Gavin

[Pete L]

Excellent post Gavin,really interesting the way you have linked these pathogens together....and also about the comments about the isle of wight disease back in history,certainly makes you wonder about that. I think this is even more reason to take nosema detection and control far more seriously than many seem to nowadays,well since the arrival of varroa anyway.

[Rosie]

Pete, what's your take on "take[ing] nosema detection and control far more seriously"? Do we breed nosema-tolerant bees or do we throw chemicals in the hive to kill nosema but at the risk of encouraging susceptible ones? Would it be better to cotrol nosema to delay the spread or entry of IIV into the country (assuming it's not here already) or would it be better to let affected colonies be culled naturally?

I don't expect you to know the answers, by the way, but presumably you have an opinion.

Rosie

[gavin]

Personally I think that the lessons are to take pathogens more seriously all round. The only way I can think of to slow the spread of pathogens which we don't even know about yet is to move bees less - a lot less - from country to country. It seems that a major pathogen has been missed in the States for at least 3-4 years despite all that fuss about CCD, and maybe missed in Europe too.

We are yet to find out what really triggers and predisposes colonies to CCD even if the disease is essentially a disease of two pathogens, and presumably there are lessons there too. Do large apiaries provide opportunities for transmission? Is long-distance transport on trucks one reason for the devastating nature of the disease? There was one prominent organic beekeeper (*very* organic) affected, but she did say that there were migratory beekeepers nearby.

But yes, in the shorter term, controlling Nosema as well as Varroa is a sensible precaution.

Gavin

[Pete L]

Hi Rosie
i believe we would all like bee's that were resistant to nosema,plus other diseases and parasites,indeed some are already more resistant than others. But from my own past experiance of nosema this is not going become widespread any time soon,or without great losses, so yes i believe we need to treat.
I really don't like putting any chemicals into hives,nor does any beekeeper,but i do know that there are better methods of treatment than fumidil, from my own experiance on my own bee's at least. I believe that good nutrition,and using essential oils in syrup make for healthy bee's. I also believe all beekeepers should test,or have the bee's tested for nosema once,preferably twice a year,which used to be done much more before the arrival of varroa.

[Phil McAnespie]

Excellent comments Gavin. Unfortunately for the bees commerce overtakes common sense though.
This is really interesting research and I trust becomes conclusive in time. It would be nice to see science prevailing over conjecture.
I agree with your comments about controlling Nosema, given the recent rise in it's appearance. It's good to keep chemicals out of
the hive, but it is folly to ignore them altogether.
Well done for all the work.

[Jon]

Just to update this thread, Jerry Bromenshenk has another paper due out defending his work on Iridovirus which other researchers did not corroborate.
He made a detailed post about the situation on Bee-L yesterday.

original Bromenshenk paper from 2010

Rebuttal from Tokarz et al, 2011

[The Drone Ranger]

every so often Lidl have microscopes -- Biolux I think for around £50 by all accounts good quality
I a decent one off ebay it had a had a hard life and the stage controls for maneuvering the specimen needed stripped and cleaned
Stain Giemsa was easy to find -- might be harder now there are more rules about posting/transporting chemicals
(Quick Ian Craig 1 Day microscopy course)
You will be kitted out for detection of nosema