video: bees removing larvae with varroa

[Stromnessbees]

I found this video which shows bees removing larvae (or should I write pupae?) infected with varroa. The page belongs to a Germany-wide association of beekeepers which work together to breed varroa-tolerant bees. They have very strict selection criteria and isolated mating sites, and they swap queens of successful colonies amongst each other.

http://www.toleranzzucht.de/home/video/

I found it very cunning how the mite still got away! :mad:
It also shows the needle-test which is described on this page (in English):

http://www.beekeeping.com/articles/us/danish_varroa_report/index.htm

Doris

[Jimbo]

Hi Doris,

Great video. I noticed the beekeepers were not wearing any protective clothing. When I went on a visit to beekeepers in Denmark the only people wearing protection were the Scottish visitors. It was after this visit that got me started in trying to improve my bees. I always wanted bees that were gentle and did not sting me. I tried to breed this gentle trait into my colonies for years but soon discovered that it would be difficult with hybrid bees. The bees in Demark and Germany are pure breeds and also bred to be gentle to handle. On a visit to Ireland I also saw gentle Galtee black bees.
Back in 2006 John Tyler from Largs noticed in some of his 70 colonies the varroa had been damaged by his bees. The varroa had cuts and bashed outer shells. He tried to breed from these colonies but I don't know how he got on. The point is how many of us (who have varroa) when doing a varroa count actually check the varroa for signs of damage. It may be we have colonies of bees trying to be varroa resistant but don't actually know it.
There is a BIBBA group I think in Cornwall also looking at varroa resistant bees.

Jimbo

[Jon]

I think Gavin has pictures of varroa damaged by bees.

[Jimbo]

Hi Jon,

I have seen pictures of damaged varroa but can't remember where I saw them (the memory is not as good as it used to be!). If Gavin or anybody else has pictures of damaged varroa it may be of interest to post them on this site for people to know what to look for when counting the varroa.

Jimbo

[gavin]

I'm not sure if I do!

There was this:

http://www.scottishferals.org.uk/

We took it so far, but my attempt to try these bees at my apiary didn't work out. One colony was hygienic (cleared out infested cells) but didn't keep on top of the numbers of Varroa and seemed to drop undamaged mites. Another colony did better, and the one that impressed me most was one of my own stocks that I was using to multiply Varroa for tests - it let them build up but them held them in check. Damaged mites have legs or antennae amputated, or a big hefty dent in the carapace. I know a man who watches his bees doing this.

However the whole business is complex. Hygienic behaviour is part of the picture, grooming is part of the picture, damaging mites is part of it, and there may be other mechanisms too.

Grooming is thought to be a learned or induced behaviour, less directly influenced by genetics but genetics must be a part of it. My feeling is that many colonies can do this. May be the same thing as biting and damaging. The hygienic trait is also there in some colonies, probably the VSH trait discovered by John Harbo and Jeff Harris that Rodger Dewhurst and James Kilty were working on.

Eric in one of his pieces in the latest SB mentions the suppression of mite reproduction. There is no evidence for this and it seems to be just that VSH bees leave sterile mites alone and excavate fertile ones, giving the impression that they have somehow been sterilised.

Definitely scope for selecting partial Varroa tolerance (for those who have enough colonies to do this!).

G.

VSH? Varroa Sensitive Hygiene. Many bees are capable of spotting some problems with brood and removing the affected brood. VSH bees can detect most (>95%) of worker cells that have a reproducing mite in residence within 5 days, or something like that. Normally hygienic bees will get some of them but not all.

Later thought: This VSH trait can work on its own even if adult mites escape. Continual interruption of the brood cycle means that mites can't build up, and eventually the mites run out of steam. However give them some drone brood and things change - discovery and removal of mites is harder and reproduction rate higher. Some A. cerana entomb infested drone by strengthening the cappings, but there is no sign that A. mellifera does this. But couple a strongly VSH colony with a propensity to repeatedly groom and bite parasites and you may have something good enough.

[Stromnessbees]

Hi Gavin


the one that impressed me most was one of my own stocks that I was using to multiply Varroa for tests

... is this by any chance one of your surviving colonies?

Doris

[gavin]

Hi Doris

The colony in that box went queenless and was finally requeened from a sister line. It is now down to one seam of bees. The sister line is still doing well enough.

The high Varroa populations until late summer couldn't have been good for my bees, and for now I think my priorities are going to be breeding healthy bees without Varroa pressure rather than breeding Varroa again.

best wishes

G.

[Neils]

Fascinating video, I've noticed my bees doing something similar during inspections this year though I'd obviously not chalk it down to VSH at this stage. The pin test though is very interesting as it does appear something practical that can be tried out by your average layman (ie me)

[Jimbo]

Hi Nellie,

I have been told that another way to do the test is to freeze the cells in situ which is a lot quicker than pushing a pin into cells 100 times. I have been told if you can get dry ice pellets put them onto the area for a few minutes. As most people will not have access to dry ice you could possibly freeze the area with a spray that plumbers use to freeze pipes. I have also seen a spray in the chemist that freezes warts that might work.
I must add that I have never tried any of the above as I try my hardest to produce brood and not kill it!

Jimbo

[Neils]

Nice Idea Jimbo, I was favouring the pin test as it looked a bit less kerfuffle given the distances involved going to and from the apiary, not to mention cutting out and re-applying the comb to take it home and freeze, I hadn't considered using a wart spray type affair.

I suppose it also wouldn't be too much trouble, once you've made the pattern to use the offcut to make a push in needle widget to do them all at once.

[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?