I have prepared for and selected for varroaresistance for quite some years. Last year I learned how to test a colony for VSH, a simplified method described by John Harbo, easy for everyone to use.
DWV-bees on the hardboard
Before that I just allowed a mite pressure in the colonies until they showed virus problems. That meant in practice appearance of wingless bees, DWV-bees, either on the comb, but still easier, on a hardboard in front of the entrance. (Bees with very little resistance are though not quick in throwing out of the hive DWV-bees, or other virus-troubled bees.) You have to visit the apiary every 10 days or so, but a quick look will tell you, plus a look in the hive after opening the inner cover to check how the colony develops. No need to check down in broodnest unless you register something seems to be wrong.
Breeder candidates
Those colonies that keep going and develop normally without any symptoms, during which time no treatment has been done, they are of course then candidates for being breeders, especially coming spring.
First breeder
In autumn 2011 I had three colonies that had been big colonies (not newly started splits during that year) without treatment for the whole season with no signs of varroa or virus. The winter and coming spring would tell which one, if any, or all, would be able to be used as breeder in 2012. That happened to be only one, H157.
Good to remember is that varroa first began to be a problem in 2008 with first bad winter in 2008-09 and 50% losses. Next winters no such losses.
Next years 5 breeders with VSH as most important
In autumn 2012 I had 11 breeder candidates. In spring 2013 I had at least 5 I judged I could breed from, but that year focused most on VSH. I had just learned to know I could.
I learned about VSH testing that spring in 2013 and did VSH-testing on three colonies.
S120
One was a swarm that looked promising and nice. The mother colony was a feral colony in the wall of the dogtraining center, well within the area of my type of bees. The swarm showed 50 % VSH, half of the pupae with mites had mites without offspring. So even if this colony hadn’t been going for a whole season plus another winter without treatment I used it as a breeder in 2013. I named it S120.
K25
The second I VSH-tested colony had been a very small the year before and not really a production colony then. But it was in an environment with big colonies which needed thymol so I decided to test it and it showed 40 % VSH (4 pupae with mites had no mite offspring of the 10 pupae with mites found). K25 it was named. But it was quite aggressive. I decided though that varroa resistance in this stage was more valuable.
R137
The third VSH-tested colony was a walk away-split from a colony that hadn’t been treated for two years. It wintered with such a tiny cluster and still developed so promising and had such a good pedigree background I choose to VSH test it. Well, it wasn’t possible to get any VSH value as it hadn’t any mites in the brood. I was so amazed I decided to breed from it. And I named it R137, as I decided it was resistant, instead of H137. It must have had a good resistance behavior, but resistance is complicated…
H109
The mother of R137, H109, of course also was used as a breeder due to its history, but she was old and layed 50 % drones in worker cells. Couldn’t really make any VSH test I decided. I grafted one time and killed her.
M176
The fifth I used showed itself to be very old as well and fell off the comb and died just after taking her home in a small split. No VSH-test. That colony I had thought had a new queen that had past the test. But this colony with this the old queen, though good, had been treated every second year with 10 grams of thymol (very little actually relatively) during four years. M176.
Some observations
Why do I tell you all these details? To come to the point for my situation, soon, be patient.
Late in season 2013, S120 showed a couple of wingless bees and got 10 grams of thymol. K25 which really hadn’t had a real production season before it was choosen swarmed thee times in July in 2013! I have never experienced that before, ever. R137 has some peculiar traits. It supercedes its queen every year it seems. And some daughters do too. This year a few wingless bees were seen and it got 10 grams of thymol.
I never do regular swarm controls in my colonies. Usually about 5 % of my colonies swarm. This year many daughters from two breeders from last year 2013 swarmed, from S120 and K25. And almost all daughters from these breeders needed thymol. Some of the daughters of K25 were very aggressive. Remember all queens are mated naturally in the apiaries. The apiaries together form an area with only my type of bees.
Breeder candidates for 2015
BUT maybe it was worth it using the breeders that disappointed me. I must have genetic diversity in my stock. I can’t make queens from just one line (H157).
I have one daughter of S120 and one of K25 that are really outstanding in resistance, honeycrop (more than 150 kg (300 pounds)), very good temper and no swarming tendency. H109 has more than one good daughter. M176 as well. And then there are walk away splits with heritage from the first breeder chosen for resistance H157, which are breeder candidates for 2015. Maybe I will use as well the three breeder used this year, or two of them.
Breeders used 2014
The autumn of 2013 I had 36 breeder candidates. I could have bred from more, but I choose to breed from three this year 2014, of which two are sisters, daughters of H157. These are H112 and H105. H157 had quite some daughters worthy of breeding from. The third breeder this year was L242. After using these three, in the middle of July I made the VSH test on them. In all three the infestation rate in the brood was about 5 %. H112 had a VSH value of 80 %. H105 – 67 % and L242 had 33 %. No treatment was needed for this year either for H112 and H105. L242 got 10 gram thymol late in season. L242 came from a quite isolated apiary with small reinvasion and was moved to my home apiary and probably got more reinvasion here. But all three are wintered very strong.
Maybe I will use H112 and H105 in 2015 as well, we’ll see.
Selection parameters
Now to my point. It seems under my conditions it’s better to focus in first hand on one whole season as big colonies during which no treatment should have been needed (including winter and coming spring), to select breeders. BUT then use VSH testing to tell you which one probably are the best among them, and get confirmation of their status. Of course the breeders must be good in other respects, good honeycrop, good temper and low swarming tendency.
VSH is a good tool for selecting for Varroa resistance, especially when there are difficulties using anything else, but also as a complement when other methods are used. I’m glad I can make VSH tests, in addition to the DWV-test I use.
My first statement to your recent blog is, that both – your early activities to anchor varroa resistance as a breeding criteria and moreover your openess to share your experiences in that field with the community – derserves respect and recognition.I still think that too less professional bee breeders taking care of varroa or disease resistance in their breeding programm.
I learned that your look at both – overall stock performance in the first year and then looking at VSH factor – to choose your breeders.
Now coming to my points: You certainly have tackled this topic already in former years but I’m not aware of this, so my question is: why hit varroa your hardly in 2008 first and not earlier? You was active with your Elgon bee many years before. Why starts the story in 2008? Is the virus load becoming more serious and a new era starts in 2008?
My second question focuses on selection stringency. You described that you have a limit, at which you start anti varroa treatment, which not consider very strong selection pressure. And you pointed out the motivation of this was a loss of 50% of your hives in 2008 which was dramatic, from a business point of view, which is understandable.
On the other hand, if you put a strong selection pressure on hives you get rid of non survivors and focus on suitable candidates. I think Juhani Lunden is doing that consequently….
As bees and insects are very elastic creatures, losses could be compensated quickly and 50% or in good years even 25% survivors could make up to 100% in the end of the year easily. Of course, you need enough surviving candidates to allow for gross selection. My question is, in order to balance the previous point with business aspects, have you ever considered and tried to work with survivor apiaries? That means to leave a part of your colonies without treatment at all? The idea behind is, that a big selection pressure will not alter the genetic, but maybe the epigenetic? Is this a wrong thinking and what are your pros and cons on this topic?
Thanks for your comment Rüdiger
Why varroa hit 2008 and not earlier? It was discovered in 2007 in my home apiary probably arrived some years earlier. Quite normal scenario. Though my activities for resistant bees started already in 1989 with going to Kenya for breeding material and cooperating with beekeepers that had the mite. Varroa arrived to Sweden (the island Gotland in the Baltic in 1987).
You say wingless bees do not indicate severe varroa problems. On the contrary. Aprofessor said recently in an interview to media that when a bee colony show wingless bees it doesn’t take long before it is dead. That’s of course wrong. But it’s occurring enough often to get even a professor to make such a conclusion. But it’s more to this question. It’s not varroa that kills the colony, it’s viruses. But that’s another article.
Why I didn’t let more bees die like Juhani? I don’t have the money. I estimate I have lost income in the range of 50.000 USD anyway due to my selection criteria. And with 90 % losses my stock would have gone and the dominance of my bees in the area, small cell drones and the selection I hade done (or the resistance the bees had anyway). There was an Elgon apiary established in a varroa area in 1995 on large cells without any treatment. It’s still going. How come? In first place no reinvasion. Another reason, due to epigentics that takes place during about the first 5 years, the true genetic (DNA-code resource) capacity is not going to show up in the first years, but it takes another article to clearify that.
Yes. I have considered working with survivor apiaries. Now after the first 5 years with varroa causing problems and thus epigenetic and genetic adaption during difficult circumstances (high density of hives though Elgons causing much reinvasion) maybe is the time come. It seems after 5 years with varroa the bees have adapted more or less into their genetic capacity, dependant also to managment, treatement chemicals, food, agricultural chemicals, etc. After 5 years average varroa population decreases. But now almost no virgin areas for varroa are left to experience this. It took 5 years about for resistance to take place in South America, and also in South Africa, for Apis mellifera (not the original host of the mite).
After reading your comment and my comment from yesterday evening, I think I was a bit unprecise and hasty yesterday evening with the selection stringency topic. Hence to clarify that, I not intended to give the impression that strong selection in terms of varroa resistance is always good, nor that I prefer the way nature or Juhani go and that colonies that can’t survive without varroa treatment have to die.
As you pointed out as well you have to control the number of suriving stocks in order to have a sufficient number of stocks, that maintain genetic variety needed. Hence, therefore I like the term – gross selection – as it describes the above statements with one (2) word(s).
Secondly, I use the criteria of 3-5 wingless bees to start anti varroa actions, as well. This seems to be a good working compromise and has to be practical proven. If one goes beyond that, the trigger for bees to act against varroa will becomes bigger, but the risk of loosing the stock as well.
Reporting from my own evidence, the bee hives that I have, start to express VSH, which is visible by the opened cells with larvae inside, after the mite load becomes obvious. Furthermore, it seems to me that with proceeding time and constant mite load the VSH becomes more frequent. But maybe not that frequent to get rid of all mites easily. Consequently my conclusion was, that these bees still oversee enough infected cells, that allow the mites to keep their number or even to increase their population. Of course I have reinvasion and it’s difficult to differentiate in between.
On the other hand I noticed on my LC bees, that one colony that had >7 wingless bees (I have to apologize I don’t visited that apiary often enough) displayed a high frequency of VSH. Of course still not enough to fight against varroa efficiently and probably they oversee enough infected cells as well. But at least I considered that high mite pressure can result in higher expressed anti mite activities as VSH for instance.
Moreover, others report that they established a kind of isolated “hospital” apiary, which are covered with the affected hives and very often with combined hives to allow for a high number bees/hive. Interestingly, here some stocks survive and these show good anti mite behaviour, by apparently putting this behaviour, which was genetically present before, on a higher importance level. Or with other words epigenetic regulation takes places.
Hence the question is, how helpful is this approach and if so how to manage efficiently. One approach in this direction is to use feral bees, which underwent natural selection totally, what you already do.
But this is probably another article as you have stated already.
BTW, I like your comparison with the 5 years and South Africa and South America. I will think about this and this topic is probably another good article…:-)
Interesting comments. A question and a few comments.
You see VSH. Have you actually in these cases you mention dragged out pupae and put pupae with mites that have offspring in one heap and pupae with mites without offspring in another heap. When he latter heap is bigger that’s showing good VSH. I get the impression you just see cleaning out pupae, most probably with mites. You see the bees cleaning out pupae. That’s not necessarily showing good VSH, but identification of capped brood with mites followed by cleaning out. Of course also mostly a good reaction by the bees. WIth VSH the bees ignore the pupae with mites where the mites don’t have offspring. With enough high mite load for the bees to react on the mite load, can be different with different bees, all bees sooner or later start cleaning out infested brood cells, with good or less good success and result. Varroa susceptible bees start too late reacting on the mite load…
I have combined varroa and virus affected colonies, but it has always resulted finally that the combined colony has died anyway.
Feral bees certainly are good bees to use. But maybe are not resistant enough in a tougher situation with high density of colonies, no break of the brood production the yearly swarming gives and eventual other negative effects in the hands of a beekeeper. But can be a very good source of bees for further breeding.
Hello Erik,
thanks for your fast response.
You are correct to point on a low OVR (ovipositioning ratio – quotient of number of infected cells with ovipositioning mites and number of infected cells with non ovipositioning mites) as a VSH feature as well, to distinguish between other hygienic behaviour. To give you the honest answer, I haven’t measured.
I simply anticipated, when the mothers have considerable amount of VSH and some of the drones as well, there must be some VSH in the daughter queens, but still not expressed enough???….
But I could measure the OVR at least. The number should be below 3 if I remember correctly.
Hello Rüdiger
That’s what John Harbo called VSH (nothing else), and that’s why I call it VSH.
If there is a threshold concerning the number of mites in the colony when it starts to show this trait I don’t know. It seems it’s not investigated. But there are indications the strength of VSH, or what I call VSH index may differ during the season. But that can have a number of reasons. I tend to lean to the explanation which can be described through a scenario where a colony have got a lot of mites through reinfestation, for example robbed a crashing colony. Immediately bees start to clean out mites with offspring, the VSH index is low. Mites survive the cleaning out of pupae and enter new larvae, get cleaned out again, enter new larvae. But now the mites have layed eggs so many times they have lost the ability to lay eggs and arre ignored by the bees. Those pupa are not cleaned out (but may still induce virus problem as the mite may be well filled with virus and the virus may well have multiplied in the mite. Now the VSH index will be higher.
Concerning the number of wingless bees on the hardboard as a criteria for deciding when to treat with for example thymol. 3-5 may be a good number when you have somewhat resistance in your stock and is prepared to loose some colonies and get some colonies that will not give any honey next season.
If you have bees with very little resistance for varroa maybe already just one wingless be is better if you are not prepared to loose quite a number of colonies. If the colony has very little of resistance – when a wingless bee appears on the hardboard there are higher number of them inside the colony walking around spreading virus, than in a colony with better resistance. In the latter case the bees have a higher tendency treating virus affected bees as trash and throw them out of the colony.
Also when your stock is getting quite good in resistance it may be a good economic reason to accept just one wingless bee before treating as you have more good breeder candidates anyway, more colonies not needing treatment. And you will lower the mite pressure still more and you will lower the losses and increase the crop still more – and soon enough anyway you will be able to stop treating altogether.
Hello Erik,
it’s better to stick to Harbo’s definition, otherwise confusion becomes to high….
Your explanation why the OVR is becoming higher for resistant colonies is a good and plausible one. My thinking was that there is someting (chemical?) within the stock what makes the mites unfertile. Although this scenario has been described by Rinderer et al who noticed that combs used by Primorski bees display a higher infertility of mites compared to combas of Italian bees, your explanation sounds more plasubile.
In principle Harris described 3 ways for resistance selection – see http://www.extension.org/pages/30984/selecting-for-varroa-sensitive-hygiene#.VEC6Jcmuk6t. But I prefer the first one to measure the infertility as well. In principle you can combine the first with the third, if you found 0-3 old capped cells and 7-10 days old capped cells in sufficient numbers on the same comb. This is not entirely scientific, because it considers that mite load was constant of the past 10 days or so, but gives you a feeling about the hygienic behaviour in general. But a good pragmmatic approach.
I will do that assay tomorrow and let you know what I found….
And thanks again for your patience to answer my questions….-:)
Well, I find it a good discussion that could be of interest for more than just the two of us.
It wouldn’t surprise me if there are more than one parameter working here. Chemicals are forming the life of insects, so it’s well possible different beestocks put different chemicals in their wax, that have impact on different things, for example resistance to pests. Another reason why to avoid residues in the wax from different sources, and renew the combs regularly. I remember when we were in Kenya 1989 and I had brought small pieces of Swedish wax foundation for starters in the small Apidea combs for the apideas in which we held the queens we got hold of. The native bees just didn’t touch it. (Of course large cell imprints that could also have influenced.) I had to cut pieces of combs from the native colony and fit with rubberband. Then the bees worked them.
The extension.org article is almost old by now and I find the VSH selection harder by their method than by Harbo’s. That’s why I use this two-step method I described in the post. it’s least work for me with still acceptable economic outcome and quite fast progress in resistance keeping the genetic diversity.