video: bees removing larvae with varroa

[gavin]

Guys

I believe that either the pin-killing or freeze-killing tests will identify 'normally' hygienic stocks. This is a good thing for things like foulbrood and chalkbrood resistance, but only a bit useful for Varroa. 'Varroa Sensitive Hygiene' brings the ability to identify and uncap Varroa-infested cells specifically, so these crude assessments of hygienic behaviour aren't quite good enough for the real thing.

What I intended to do last year was to raise Varroa-infested brood in a heavily infested colony, then transfer freshly-sealed combs to colonies under test. Counts of empty cells before and after a period would give an indication of how good they were at finding infested cells, but the final thing would be to sample some of the remaining cells prior to them hatching so that a true figure could be obtained of '% infested cells uncapped'.

Rodger Dewhurst and James Kilty were talking about more casual opening of patches of sealed brood to look for numbers of sterile vs fertile mites remaining, I think.

Foulbrood happenings took my spare time away, and made it wise to treat my bees for Varroa, so it didn't happen. I did supply a post-graduate in Edinburgh with lots of Varroa-infested comb for her studies. One interesting thing was that after quite a long period of queenlessness the next round of sealed brood had most of the mites inside but the mites were dead! No treatment applied at that time. I guess that they got old.

[Stromnessbees]

Oh, no!
When I opened this thread I didn't intend to start a frenzie of home-experimentation on bees. What the Germans are doing is a highly coordinated and planned programme, and due to an attempt at standardising the tests they have a chance to deliver meaningful results. There is no point in doing this alone at home. For that needle test for example they select an area of sealed brood of a specific age, not just any sealed brood, as this might have an impact on the result.

What we could aim at though, is the level of cooperation they have built up, in order to achieve a very desirable target.

Doris

[GRIZZLY]

What's the life-span of a varroa mite ???.

[Neils]

Oh, no!
When I opened this thread I didn't intend to start a frenzie of home-experimentation on bees.

Sorry if I gave that impression Doris. It looked at face value that what was on show through that site was a mechanism that could be replicated by the "hobbyist" beekeeper to start to examine what level, if any of [Varroa sensitive] Hygenic behaviour might be prevalent in their colonies.

I certainy have no itention of just running out and starting to poke holes in, or deep freezing, my frames and seeing what happens but I'm also very interested in taking a more measurable approach to what is going on in my colonies where varroa is concerned. I seem to have very low levels of varroa especially considering I didn't treat with OA over the winter, is this a good sign for my bees that they might be coping without so much intervention from myself or did I just get lucky? Right now I've absolutely no idea.

[Stromnessbees]

Hi Nellie & Grizzly

I am not sure about the lifespan of the varroa mite. What do the experts say?
But I have seen claims that dark bees might be able to get rid of them through their long break in brood rearing during the winter:

Google-translation (slightly altered)
The Nordic-bee overwinters in strong colonies with the lowest feed intake among all races. The long time affects development of the Varroa mite broodless contrary. It is precisely this property, coupled with the other positive features of this us once native to bee, which is not recognized by all beekeepers, especially by institutions. I am of the belief that nations because of their breeding behavior in winter Varroa mite not offer the Lifeline. Would a reinvasion from neighboring colonies of other races be eliminated, in my view varroa treatmwent could be waived in the dark colonies.

Die lange brutfreie Zeit wirkt der Entwicklung der Varroen entgegen. Gerade diese Eigenschaft, gepaart mit den weiteren positiven Eigenschaften dieser bei uns einst heimischen Biene, wird von nahezu allen Imkern und insbesondere von Instituten nicht erkannt.
Ich bin der Überzeugung, dass Völker der Dunklen Biene wegen ihres Brutverhaltens im Winter den Varroen keine Überlebensbrücke bieten. Wäre eine Reinvasion aus Nachbarvölkern anderer Rassen / Schläge ausgeschlossen, könnte aus meiner Sicht auf Varroenbehandlungen an Dunklen Völkern verzichtet werden.

from: http://www.kvarnhult.de/

Any opinions on this?

Doris

[Neils]

Difficult for me to say, I have proper scraggy mongrels in my colonies. There's another beekeeper with similar and a new guy who's just dumped a new hive on his site but I've no idea where his are coming from at the moment so who knows what the impact of these are likely to be?

I guess common sense tends to suggest that a long winter break in brood raising is going to have some negative impact on the Varroa even if only slowing their numbers down. It would be interesting to know whether that translates outside AMM into other breeds if they're exposed to a long[er]/colder winter? Ie is it unique to AMM/Darker strains or if you subject a.n type of bee to a colder, longer winter, is there a corresponding gap in them starting to raise brood come the spring? I'm not sure whether that point comes off too well, but I guess what I'm trying to say is that is it a trait of AMM itself that it takes a long gap over winter or simply that where there are long winters AMM tends to be more prevalent but if you took my scraggy mongrels to Norway for the winter, would you see a similar increase in the period where there's no brood being raised? I.e. is it a trait of the bee generally or a reaction to encountering a long, cold winter? Does that make sense?

[gavin]

What do the experts say?

I asked this of Dennis Anderson when he came to visit John McLean's bees in 2008, and he didn't know.

The trouble with the Amm literature is that it is sometimes based on wishful thinking. Hard to discriminate fact from supposition. Long brood breaks in winter *might* help with Varroa, but as Nellie says cold winters would have that effect on many bee types. Another Amm trait is a general restraint in brood raising. That ought to be a powerful help with Varroa as it is usually the booming colonies that let Varroa run rampant.

Some of the continental types have a reputation for being hygienic (in the sense of identifying and dealing with sealed brood problems) which, as discussed here somewhere, can be good for Varroa but aren't necessarily that good.

Native Amm might have their own ways of dealing with Varroa which could trace back to adaptation to the pressures they have been under in the past (acarine, maybe?). Maybe the grooming and biting seen in some colonies is this kind of thing, and there are probably other things bees can do which give them the upper hand with Varroa.

I wonder if the Amm we have here is a variable genetic hotchpotch, even without the effect of imports, and carried with it a lot of variation that has been bred out of the traded strains of continental races. That might be one of its great advantages. It may still have a range of traits that are useful for Varroa tolerance.

[Jon]

I have noticed a few colonies uncap cells and remove pupae during Autumn Apiguard/Thymol treatment.
I wonder is this linked to hygienic behaviour or is it just related to an individual colony's reaction to Thymol?
Could hygienic behaviour be triggered by something like Thymol fumes or a smell given off by varroa infested pupae?