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.
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.
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.
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.
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.
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…
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.
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.
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.
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.