Talk by Norman Carreck

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Jun 20, 2009
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Kingsbridge, South Devon
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0 - Now in beeless retirement!
I went to a talk yesterday given by Norman Carreck who is a pretty well known writer on bees and especially diseases etc.

I suspect some of the things he said will not be agreed with by all on this Forum but I found him a convincing speaker so here goes:

CCD. He explained there is now a group of scientist from around the world who are getting together to try and sort out just what is meant by the term CCD, as what the French think is different to say the German or US view. His own thoughts about what has happened in the US is that the level of pathogens in certain bee populations had built up to such a high level that infection was being spread from bee to bee, without the need for varroa as a vector. The situation is complex as in-breeding may also be a factor. Elsewhere in the world pesticides (the French view) and nosema (Portugal) were seen as factors in CCD.

Varroa. This is the one that might inflame a few passions. He explained work on trying to selectively breed bees which can remove varroa had been going on for about 15 years but so far the results were not very convincing. Evidence now suggests that varroa which are found below a hive with a dent in the caraprice are actually just exhibiting a natural characteristic which happens as the dead mite dries out. Other marks of chewing may well be due to other creatures wandering around the varroa tray. He mentioned the so called "Russian" bees which are sold in the US and claimed to be varroa tolerant but said there was no independent evidence to support this claim.

"Bond" Experiments*. Some years ago 200 colonies were marooned on a remote Swedish island and left to fend for themselves for 5 years. At the end of this period about 40 colonies were left alive. There seemed to be two mechanisms at work to explain the survivors. Firstly, some tolerance by the bees but the most significant factor was the bees which survived had varroa which bred at a lower rate. In other words, the fast breeding varroa killed off their colony and therefore themselves. There are apparently at least two different strains of varroa destructor and one is much more virulent than the other. There is also variation within the strains. Recognition of this is causing some earlier work on varroa to be re-assessed.

What all this means is those who claim to keep bees without treating for varroa may well have selectively bred bees with improved traits of grooming but the major factor will be they have selectively bred their varroa as well. This explains why queens from such bees do not do well when moved to another area. Their offspring cannot cope with the varroa. This is not to condem such work but it means if you want to keep bees without chemicals you need to breed/select them yourself and don't import colonies from outside, which will bring in new varroa.

He also explained the level of mites which kill a colony is very dependent on the level of viruses present. When varroa first hit the UK the "lethal" level of mites could well be ten or twelve thousand mites in a hive, but then as the mites spread viruses this level quickly fell to about two thousand. This may explain why some colonies, possibly in more remotes parts of the country, are surviving despite a high mite load - they simply don't have the virus yet.

Varroa remains probably the major fact behind colony losses in the UK at the moment. A big issue is the lack of effective varroa treatment especially in the north where the lower temperatures and especially when bees have been taken to heather, make thymol treatment less effective.

Hygienic Bees. The major work NC is doing at Sussex University is to breed a line of hygienic bees. They are working with native black bees which came from the Peak District. The aim is to build up 200 colonies but they were worried about in-breeding so were planning to get some new bees from Ireland next year. The reason for choosing native bees was they needed a pure strain otherwise interpreting the results would have been very difficult. They could have chosen any pure bee strain from around the world but decided to go for the British bee. Interestingly, he felt the main benefit of hygienic behaviour was resistance to AFB and chalk brood etc. He was not convinced hygienic bees (which uncap dead cells) did much for varroa. His argument was if the varroa kill the bee they die themselves but if the bees remove the corpse they release the varroa. This is seen in apis cerana, although this does involve a different species of varroa. With apis cerana the varroa only really breed in drone brood and as the bees cannot uncap drone brood if the varroa do too much damage to the drone (by breeding too fast) they will be terminated. This helps the bees and varroa to live in some sort of balance, plus of course the other mechanisms apis cerana has.

* Live and Let Die
Interesting read, thanks RT

Clearly lots going on around the world.
Very interesting stuff. Thanks for the posting.

There seem to be lots of variables, which must make repeatability and 'cause and effect' a nightmare.

How can we apply the 'Bond' method ourselves, in smaller (non island!) apiaries? Could we have a number, say 10, normal hives which get all the love and attention normally applied, and another, say 20, 'candidate hives' of Warré design that just get left to their own devices and repopulated if needed with old feral colonies that are removed from e.g. buildings and are a few years old?

It seems clear that whenever we are harsh to varroa and coddling to the bees, we just make stronger varroa and weaker bees! Some care scheme that allows weaker/less adapted colonies to actually die out, whilst maintaining enough colonies to keep some genetic variance, seems to be what's needed. I think it's more than just the queen-line, as you pointed out, it's the combination of queen/colony genetics, the location, the genetics of the mites, the local virus population and also maybe the type of hive and processes used to care for them.

It may be that beekeepers who are after maximum honey/nucs, or have too much invested in their colonies to risk pushing them to survive aren't going to be the best people to help with this. I'm interested in beekeeping as a hobby, and to try new things - being part of a large group of beekeepers working together in some way to achieve a honey bee which can live in better balance with varroa (+ its virus load) would be perfect for me. If things go too far and I have to start again from zero a few times, that wouldn't be a disaster.

Any thoughts for a good plan?
He mentioned the so called "Russian" bees which are sold in the US and claimed to be varroa tolerant but said there was no independent evidence to support this claim.

Hi John

Thanks for the detailed account of the DARG talk, and it good to hear some of the detail of what they are doing in Sussex.

If Norman (I should say that I know Norman, but that doesn't mean that I'm not going to be critical) is speaking in public as an authority on these topics he really should pay attention to what is happening out there!

Some believe that the resurgence in feral colonies in some parts of the States is due to the widely traded Varroa-tolerant stock, both SMR and 'Russian', the latter originating from Primorski where people took bees East to a region with Varroa and let them fight it out for decades.

The bees that you can read about below don't always survive Varroa without help, but the highly productive nature of American bee forage means that their very large colonies breed large Varroa populations. Bear in mind that the reason Tom Rinderer brought in these bees to the States was because it was already demonstrated that they were surviving Varroa in their own region.

all the best



Comparison of parasitic mites in Russian-Hybrid and Italian honey bee (Hymenoptera : Apidae) colonies across three different locations in north Carolina

Author(s): Tarpy DR (Tarpy, David R.), Summers J (Summers, Joshua), Keller JJ (Keller, Jennifer J.)
Source: JOURNAL OF ECONOMIC ENTOMOLOGY Volume: 100 Issue: 2 Pages: 258-266 Published: APR 2007

Abstract: The most economically important parasites of honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies are the parasitic mites Varroa destructor Anderson & Trueman and Acarapis woodi (Rennie). Research has shown that mite-tolerant stocks are effective means to reduce mite infestations within colonies, but it is unclear whether the stocks available commercially are viable means of mite control because they are likely to be genetic hybrids. We compared colonies of a standard commercial stock ("Italian") with those of a commercially purchased mite-tolerant stock ("Russian") for their levels of varroa and "tracheal" mites (A. woodi) over the course of 2 yr in three different geographic locations. We were unable to detect significant infestations of tracheal mites; thus, we were unable to adequately compare the stocks for their tolerance. In contrast, we found significant differences in the levels of varroa mites within and among colonies located across the three different study sites for both years. By the end of the first year, we found statistically significant differences between the stocks in varroa mite intensity (mites per adult bee), such that Russian-hybrid colonies tended to have a significantly lower proportion of parasitized adult bees than Italian colonies. In the second year, we found statistically significant differences between the stocks in varroa mite load (daily mite drop), such that Russian-hybrid colonies tended to have lower total numbers of mites than Italian colonies. These findings suggest that beekeepers may benefit by incorporating commercially purchased mite-tolerant stocks into their existing integrated pest management programs.

Varroa resistance of hybrid ARS Russian honey bees.

Author(s): Harris, J. W.; Rinderer, T. E.
Source: American Bee Journal Volume: 144 Issue: 10 Pages: 797-800 Published: 2004

Abstract: The varroa (Varroa destructor) resistance of several genetic crosses utilizing ARS Russian honey bees was tested in Alabama, USA in 2001. Bee stocks included pure ARS Russian (Russian queens * Russian drones), commercial (commercial queens * commercial drones), Russian hybrids (commercial queens * Russian drones), and SMR-Russian hybrids ((queens bred for the suppression of mite reproduction trait) * Russian drones). The varroa resistance of Russian hybrids was intermediate to that of pure ARS Russian and commercial stocks. This suggests that Russian hybrids may offer some varroa resistance, but pure ARS Russian stock should be used to achieve the maximum varroa resistance that is currently available in Russian bees. The lowest growth of mite populations occurred in the SMR-Russian hybrids. This may suggest that resistance genes from the two parental types combine in an additive manner, but we cannot be sure because pure SMR bees (SMR queens * SMR drones) were not included in the study.
Gavin, I'm with HP in being an non-scientific oik, so I am just reporting what he said. But as I understood it the whole argument is whether these bees are surviving the varroa or is it to some extent the other way round. Russia was where varroa was first reported on AM I think, in 1930 something or other, so perhaps there both the bees and the varroa have had longer to come to terms? Perhaps the research you refer to is also one of those that needs looking at again in the light of the discovery of different strains of varroa. Unless the researchers know what sort of varroa they have they cannot really interpret their results.

And as Gavin has mentioned DARG we have a website now It was reported at the AGM yesterday members seem to be dying off quicker than they are joining - so some new blood would be welcome!
Can we have a link back from the website? I notice the BBKA have one..
Perhaps the research you refer to is also one of those that needs looking at again in the light of the discovery of different strains of varroa. Unless the researchers know what sort of varroa they have they cannot really interpret their results.

Beekeeping oiks are definitely to be encouraged, as are DARG's efforts. So are questions of those who think of themselves as authoritative!

Those K and J forms of Varroa (Korean and Japanese). I think that you can assume that the researchers in the papers I cited actually did know what they were doing and sourced Varroa from the same place. However both are present in America, but the K type appears to be displacing the J type where they were both found previously. We have only the K type in Europe. Can you guess which is 'far more virulent' according to this paper below?!

Yup, the virulent K type is displacing the J type. Which rather negates the hypothesis that less virulent mites would be more successful in the long run.

But surely the way in which the less virulent strain of Varroa would win is for those colonies infested by the more virulent strain to actually die and take those mites with them (as their host vanishes)? If there are very few true feral colonies left, and therefore most colonies are being treated by good beekeepers with Thymol and Oxalic acid etc and kept alive, it could be US that are preventing the weaker mite strain from winning out . . .
Quite right! Question everything, including me :-(

Suddenly I'm feeling on shaky ground .... but still not convinced!

In a forest where less virulent mites abound, the bees and mites are surrounded by bees with more virulent mites kept virulent by treatments that knock down the populations of mites in managed hives. What happens then?

Some virulent mites have to make it into the forest, you can't stop them. They encounter colonies with less virulent mites, and they take over as they reproduce faster. The colony eventually dies, but not before a large dose of mites on absconding bees infect surrounding feral colonies. They do the same thing. A spreading wave of more virulent mites.

Can you see a way for a pure colony of less virulent mites to survive in this case? Or why the more virulent type should not take over, colony by colony?

All I can see is the steady demise of the feral bees as the more aggressive mites take over, with or without man's interference. Unless, of course, the bees themselves know how to fight back to some extent, and the small cavities mean that swarming is regular and the brood break that brings keeps mite numbers low, or some of the other possibilities that will help feral bees. Which is presumably what happened.

That's my opinion anyway - could be wrong.

I agree that the more virulent mites should always win the day if:

1) they can travel from colony to colony (at least a bit) before their host colony gets wiped out;

2) all colonies are connected in a net that is fully traversable by bees (i.e there aren't any 'islands' of colonies - either real islands or habitats that are isolated in some other way);

In reality, there is only a finite number of these 'islands' and we are rapidly reducing their number: importing queens from Australia, general international freight and travel, the speed of car/lorry transport within each bigger country/island . . .

I guess, if there are a number of separate islands (some big, like the USA!) where the two mite populations fight it out, the virulent ones may well conquer the sissy ones in a particular island; shortly afterwards, all the bee colonies die out - IF meddling beekeepers don't stop it happening :) IF the island became bee-free (and mite-free), there are only two things that can happen next:

1) a sissy mite (and some bees) gets introduced;
2) a virulent mite (and some bees) gets introduced;

If (1), we get a population that grows and achieves stability until a virulent mite turns up;

If (2), the bee population doesn't grow and we revert to a desert again.

So we need to do two things to achieve lasting bee populations (in this model):

1) keep islands as separate as possible and as numerous as possible (make them small and not connectable);

2) kill off or let die all colonies in each island when an over-virulent strain of mites arrives.

There's a horrible nightmare parallel to this argument with humans and virus strains such as Ebola Zaire, but let's not get depressed thinking about that ;-)

What do you think?
Hi Firegazer

If everything is driven by mites being virulent or less-virulent, then I'd agree with what you say. However, I don't think that mite virulence is the big factor, and that's where I'd argue with Norman.

Feral bees might have some advantages. That propensity to swarm, with no beekeeper to keep giving them space. A full colony emitting a swarm has a period of broodlessness in the swarm itself, and maybe an even longer period in the parent colony as new queens in prosperous colonies often take a long time to come into lay. I saw that myself last summer in a colony I was using to try to multiply Varroa for the purposes of testing other colonies. The mites left after the long broodless period usually died in their cells, and the colony (not one I had suspected of being resistant) had largely cleared itself of mites by late summer.

Feral colonies might also have advantages of a deep floor which doesn't let fallen mites back up. Maybe also the shortage of space means that bees have more time on their hands, and they use that to groom themselves.

It could be that natural predators of the mites are more abundant in the forest, or the bees can self-medicate somehow using forest plants. Another possibility is that it is the bees themselves that are different, but somehow that difference declines when they are out of the forest.

I think that there are factors affecting mite numbers that we just don't understand. So although Tom Seeley thought that the less virulent mite hypothesis was the best one to explain his obersvations, he clearly wasn't sure and that explanation doesn't have to be right.

Ebola?! Well, so far it seems to be a contagion that is just too infectious for its own good, and epidemics are self-limiting. Still very scary of course. New forms of influenza are just as scary. We seem to have been lucky that the current swine flu isn't very dangerous (though obviously it is for some people, and that is very sad).

all the best

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Another possibility is that it is the bees themselves that are different, but somehow that difference declines when they are out of the forest.

Maybe it is the nastiest bees (or with another unwanted trait) which are the most advantaged in this respect - and we, as beekeepers, keep that trait, when breeding queens, well away from what we aim for as 'acceptable' queens!

So maybe it is sissy queens that is the problem.

Regards, RAB
When varroa have arrived in some country, first it kills feral colonies almost all. But nowhere it has killed beekeeping. Beekeepers have had allway tools to save their hives. Remember that varroa came from east to Europe. 30 years ago.
Antivarroa bee breeders keep loud mouth when they try to get money to beeding and then to sell queens. But results are difficult to achieve.

One thing is that bees may keep low varroa but not under economical level.
Russian bee destroyes its brood in some stage and then it will become lack of bees. Swarming is one way to avoid varroa in nature. That is why Russian is easy to swarm.

In Britain , that is my opinion, proplem is that even if we have good methods to handle varroa, British beekeepers do not accept methods. YOu have advices what to do but they are so difficult to understand.

And you have those "anti chemical •brigades" which do not understand about chemistry much and they deliver their humbut advices. But it is same in Finland. Oxalic acid is something so horrible. "Essentials oils" are something fine.
It is better to understand that varroa breed itself too against controlling methods. It is a flexible creature. And losses for varroa become bigger and bigger.

If you read what happened to feral colonies in New Zealand, it puts "natural methods" in right figure.

Colonies robbed dyig hives and got huge load of mites. Then robber hive collapsed in few months.

I have seen in my yard that a big hive collapsed in one moth. Only explanation is that it robbed some mite hive in late August.
This is a fascinating subject and full of very subtle, complex, points that are the bane of simple scientific experiments.

Thanks for all the ideas so far.

Has everyone seen the Ian Rumsey paper about the size and alignment of the cells (horizontal rows or vertical rows) making a difference to the mite's chances of being found and evicted by workers? In the same paper he suggests that brood nest shape and alignment (circle or horizontal/vertical ellipse) will change the average time it takes for a mite to get to the brood cell just before it is capped and also the chance of it falling off by grooming on the way. I'll post a link if it isn't old news.

I like Gavin's idea that the bees are more likely to groom when in close proximity and with no telly to watch :)

Top marks have to go to the FinDude, though, for the word 'humbut' which I plan to use today at work: it perfectly describes some of the stuff I hear from suppliers :)
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And I'm going to carry an image in my head today of Finman's big hive collapsing into one moth!

Are you talking about Housel? Or maybe Ian Rumsey? Feel free to post a link, I haven't seen that stuff for a while.

all the best

f everything is driven by mites being virulent or less-virulent, then I'd agree with what you say. However, I don't think that mite virulence is the big factor, and that's where I'd argue with Norman.

I think that everything is driven by viruses! One thinks Professor James Lovelock here.

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