Breeding Resistance

I started long before the mite arrived to focus on increasing the varroa resistance in my stock. 1989 I went to the mountains of Kenya to get genetic material that were more related to the resistant bees in South America than we had in Europe. You can read somewhat more about this on the following two links:

Today I realize I probably hadn't needed to do that. Maybe it made it easier to develop resistance. But it wasn't easy to go to Africa either and make a new combination breed. Anyway here I am with what I call Elgon bees. I don't want any other bees today. I have also tried some new strains in combination with Elgon. They may have contributed somewhat to the Elgon stock.

Initial tests with Monticola crosses done by Dr. Bert Thrybom, one of the team members who went to Kenya, showed that Monticola had shorter development time of brood and that what we today call VSH (Varroa Sensistive Hygien) was present to some extent. The other team members were Michael van der Zee, Erik Bjorklund and myself, Erik Osterlund.

As soon as I realized in the beginning of 1990:s that the Monticola-Buckfast crosses were of no threat to beekeeping I sent some queens for testing to areas in Sweden with Varroa mites. These tests were encouraging and made varroa resistance selection possible. I got pieces of combs with young larvae and eggs back for grafting.

Treatment free Elgon beekeepers

When the mites finally reached my apiaries there were beekeepers with Elgons in Denmark (Poul-Erik Karlsen), Finland (Sven-Olof Ohlsson), Norway (Hans-Otto Johnsen) and southern part of Sweden (Leif Hjalmarsson, one apiary) and finally just 100 km from me (Thore Härnkloo) who hadn't used any treatments at all for more than 10 years (including drone brood removal. The bees did it all by themselves, fought the mites.

These beekeepers had one thing in common. Their bees were quite isolated from other bees. Four of them were on small cell (two of these on 5.1 mm cell size, one on 5.1 and 4.9 and one on 4.9). One was on large cells, 5.4 mm

My preparations

I also took my bees down on small cell, 4.9 mm. I did everything I could to prepare for the arrival of the mite. I guess I hoped it was enough to escape the need for treatments without having any losses but a few due to the mite.

I was wrong. All of us seem to have to go through some kind of purgatory, longer or shorter in time. I didn't want to use pesticides like Apistan as residues of it builds up in wax and propolis. And I didn't want to use acids because of the risks for myself, as well as for the bees. So I was left with thymol to use if I decided the bees needed it.

Thymol

I didn't know how to use thymol and I didn't know how resistant my bees would be towards the mite. I wasn't aware of the initial adaptation period after the arrival of the mite, evidently an epigenetical adaptation period.

If you choose to use thymol to treat against Varroa mites, the easiest is to buy a thymol product on the market. I made my own thymol pads by drenching pieces of dish cloth in liquid warm thymol. It melts at 50 Celcius (= 120 Fahrenheit) but smells awfully at that temperature. By weighing pieces of cloth before and after I knew how much thymol the pieces contained. Today I add a very small amount of alcohol. It lowers the melting point substantially so I don't need a breathing mask when making the thymol pads. But I use a pair of gloves.

1. Original Wettex dish cloth approx. 1 mm thick, 200 x 175 mm large, is cut into 12 pieces, about 58 x 50 mm in size. If you use 125 grams of thymol for a lot, you need more than 2 wettex discs of 200 x 175 mm. You get about 25 pieces with about 5 grams of thymol.

2. A digital scale that can be reset, including the weight of a small saucepan, so you directly get the weight of the thymol crystals when you pour them into the saucepan.

3. After filling up with the desired amount of thymol crystals, pour into a very small amount of rubbing alcohol (technical alcohol), a pair of capsules, to 125 grams of thymol.

4. Heat it a bit, not much, stir it a little until you have a clear solution. You can remove the pan from the cooktop to avoid excessive warming and harsh odors.

5. Then pour in almost all 25 pieces (if you used 125 g crystals). Take some kind of pliers and dip a piece at a time to make it completely wet and let it drop off somewhat.

6. Then place the pieces on a plate or similar to dry and cool off a little.

7. A baking tray or the like works well.

8. Even before the wet pieces have dried completely from the alcohol and got hard, when they are still somewhat wet and soft, they can be placed (15-20 pcs) in a plastic bag with plastic zipper. Then put it in a second similar plastic ziplock bag. Then these bags are put in for example a plastic toolbox. It can be brought along ready for use when working the bees.

125 grams of thymol (gives about 25 pieces of thymol pads with about 5 grams of thymol) + less than 1/4 deciliter of rubbing alcohol (technical alcohol) -> heat gently until the solution is clear. The reason for using a little alcohol is that the solution gets clear at a lower temperature. Then the smell will not be so uncomfortably strong at the time it's clear. Do not use more alchohol, then the pieces will take longer time to dry and the bees seem to like the pads less if they contain more alcohol.

1. A weaker colony gets one thymol pad between the middle top bars towards the back, to avoid getting close to the brood that can be close to the top of the middle of the cluster. If it's weak in spring it may be due to viruses because of a high varroa infestation, or that the colony had a tough winter because it wasn't so strong in autumn.
After 10 days the thymol pad is replaced with a new. After another 10 days this piece is also removed.

2. If the colony is strong and it's middle of or late in season it gets two pads. They can be placed above a queen excluder avoiding the center somewhat. A reason for treatment could be a varroa level above 3%. In spring even a strong colony gets only one piece not to lower brood production. After 10 days the treatment is repeated and after another 10 days removed. The thymol fumes are better ventilated with the increased space that this excluder is creating. In hot weather use half the normal treatment and replace the pieces more often, with the total treatment time being three weeks.

3. In the case of sugar feeding at the same time as treating, in preparing for winter in August, the two pads can be placed far from the entrance up to the sugar solution in the feeder. In this case this entrance is on the farther side of the hive. Therefore the pads are placed on the opposite side on the top bars between comb gates. Bees can avoid going up to the sugar solution if the tymol pads are placed right at this entrance. 10 days later, the pieces are replaced by the same number. After a another 10 days, these pieces are removed and treatment ends.

If you can't do selection work among your bees and you choose to treat with thymol my experience tells me the safest way to keep the number of hives and not loose any or very few is to use thymol both in spring and before winterfeed, two applications per occasions. With home made thymol pads of 5 grams of thymol in each one, one plus one (with 10 days in between) is used in spring and two plus two (with ten days in between) in August. That would make a total of 30 grams of thymol a year. Altogether no more than 3 weeks treatment at each occasion.

As little as possible for me

As I'm focused on selecting resistant bees, I treat as little as possible. In 2008 I fumbled forward to know the how to and how much my bees needed. I hoped for nothing. I realised I had to start already in spring due to quite some crippled winged bees in some colonies. The thymol worked a miracle. But I tried to find out when I needed to apply it. I concluded I wouldn't have time to count mites or do any drone brood cutting in my then 200 colonies so I decided to look for the presence of crippled winged bees.

DWV-virus is closely connected to the precense of Varroa mites in a bee colony. Crippled winged bees normally indicates many mites, but not always. Some odd wingless bees can show up especially in spring anyway. In the beginning of when Varroa came to my colonies DWV-bees like the one to the left in the picture above was the normal appearance of them. Today when I see such bees they look moore like normal bees (without the abnormal small abdomen), but with small ragged wings, like the three ones to the right. It's invaluabe to have a hard board, 0.5 x 0.5 m, in front of the hive to see what ends up there from inside the hive.

The first strategy

After a couple of years I came up with a system that seemed to work well.

1. When I saw more than a few crippled winged bees in front of the hive or on brood combs AND
2. the strength of the hive was not what could be expected

I gave the colony one or two pads with 5 grams each of thymol, depending on the strength of the colony. This was repeated 10 days later when the piece(s) were replaced with new one(s). And after another 10 days removed altogether.

If the colony was very weak it got half a piece with maybe 2 grams.
As I found it most important to help the bees survive I gave thymol whenever they needed it, even during summer with supers on. Wasn't that bad for the honey? Actually not so bad as one may think. Thymol is not water soluble but fat soluble, so it gets into the wax, not much in honey. And it was not needed to use thymol on many colonies during a flow, just a few. I wanted to save these colonies from dying, but most of all eliminate reinvasion sources for mites to my healthier colonies. There are some references in the middle of the page of this site: "Fighting Varroa":

Thymol is highly volatile. As soon as you have pulled out the piece with what is left of thymol, it doesn't take long until the amount has decreased a lot in the hive. And the small rest that is left in honey is nontoxic, it is even smaller amount than in Thyme, the spice. It's not possible to feel the taste of it. Some honeys can contain quite some thymol naturally, for example thyme and lime honeys. And to remember, thymol in in these amounts is healthy.

I recommend though to avoid using thymol during a nectar flow very close to harvesting.
If a comb smells of thymol the best place to get rid of the smell is in the hive where ventilation is good and the very most of thymol will go away in a couple of weeks.

Better Varroa resistance

This strategy of mine using thymol when virus problems occurred have made my stock more Varroa resistant. But I have realized that it has also caused an ongoing reinvasion of mites keeping the mite pressure higher than wanted in the apiaries. The use of chemicals seems to help viruses to multiply better, both in bees and mites. So today you need smaller populations of mites to get virus problems, even if my bees probably have become more resistant even to viruses, I think that also the virus pressure in my hives have been higher than if I had used an effective miticide regularly.

New Strategies

I decided to change my strategy and try some new strategies after taking into account the below listed

SIX POINTS

VSH. A good way to control the degree of VSH. Pull out pupae with tweezers and look for mites, mite feces and mite offspring.

1. VSH (Varroa Sensitive Hygiene)

In spring 2013 I listened to John Harbo and checked my most promising colonies that year.
The one with the highest VSH value, 50%, was a swarm from a feral colony in a wall of the dog training center in the midst of "Elgon land".
Click on the links below and you can read more about VSH testing:

This colony had some typical Monticola traits, short development time and black thorax for example. Of course I bred from it. One colony in an apiary at the edge of the "Elgon land" quite far from other bees got a ripe queen cell and the virgin mated there. I call it S241. Early in 2014 the colony superseded its queen.

In 2014 I measured the most promising colonies again for their VSH value. I found one with VSH 80% and of course bred from it. I got very good feedback concerning daughters from this colony from other beekeepers in 2015. But daughters in my own operation were among the first to show deformed winged bees, bees with DWV-virus (DWV – Deformed Wing Virus).

In 2015 I was still mainly following the strategy to treat a colony when it showed DWV-bees so the virus level in the colonies was most probably higher than if I had treated regularly each year with an effective miticide. Maybe a very intense selection of hight VSH might come along with some unwanted trait, as higher susceptibility for viruses?

There are more traits than VSH for the bees to use to fight mites. Maybe VSH 50% is a good choice in a resistance mix of traits, as the feral colony ended up with that.

2. Feral colonies

In many places where a population of honey bee colonies has developed resistance to the Varroa mite, feral colonies are part of the success. They contribute apparently. And why not, no one manage them and they have to make it on their own. Though their circumstances are not exactly the same as for a managed colony. But their adaptation is not disturbed by miticide chemicals, and many times not but agro chemicals either.

This is the entrance to a feral swarm that has lived in this unheated house in a remote little village for many years at one edge of the Elgon area where there hasn't been any managed bee colonies for quite some time. But now a couple of more Elgon apiaries have been established a couple of km away (about a mile and a half).

In 2014 I caught another swarm from a second feral colony not far from the apiary in which S241 was placed. The mother feral colony to that swarm had been living in a wall of an old unheated house for many years. I placed this swarm in the same apiary as S241 and called it C243. Check these links. Tee third link is to a third feral swarm at the edge of the Elgon area in another direction, to confirm we have feral bees in Sweden.

I learned later that not far from this apiary where I placed C243 and this house there are this old village with very old ash trees and other old houses. (The third link above is about a feral colony in an old ash tree at another locality.) So hopefully there are more feral colonies around this place.

S241 might then have been mated for two generations, at least with some feral drones. That might explain why this was the colony that was outstsanding concerning very few mites and other good traits in the very difficult year of 2015. I tried to make a VSH test early in 2015 with S241 but I found only one mite in a brood cell and it had no offspring. Not statistically significant, but a good hint. The colony had not been treated in 2014, or in 2015.

I bred mostly from S241 in 2015. And somewhat from C243 and another colony. C243 also showed VSH 50%!
2015 was difficult for the bees because the spring and summer was wet and chilly. Especially in spring there were few possibilities to gather fresh pollen for the bees, which they need for a strong immune system.

3. Isolation with 3 km distance to other bees

Especially in the difficult year of 2015 I thought about the experiences of a number of beekeepers with Elgon bees, beekeepers that hadn't been treating against Varroa for 10 or more years, with small problems from the mite. They had in common that they were isolated from other bees or/and dominated their area heavily with their bees.

Leif Hjalmarsson at his 3 km isolated apiary with Elgon colonies since established in 1998. Here he kept 5-7 colonies without treatment until he died in 2016.

POUL ERIK KARLSEN on the island Bornholm in the Baltic, he used 5.1 mm cell size. He is now retired and just have a few colonies left, after many years being a relatively big beekeeper on the island.

SVEN-OLOF OHLSSON in western Finland with around 200 colonies at the most. Now closer to 100 colonies as he is retiring and going down in number. He uses mainly 5.1 mm cell size, but also some 4.9.

THORE HARNKLOO in the "deep" forest some 100 to the south of me. He is now retired and has sold his bees.

HANS-OTTO JOHNSEN in western Norway with several hundreds of colonies. He hasn't been treating for about 15 years. He uses 4.9 cell size since many years. He also makes his own wax foundation with a commercial set up. He is now getting funding from the government to find out the important parts in his operation to help other beekeepers. Officials have found the varroa level is very low in his bees, and in the bees of his beekeeper friend Terje Reinhertsen who he has been cooperating with.

LEIF HJALMARSSON in the southern part of Sweden, in one of his apiaries. He used 5.4 mm cell size. Another difference with him and the others was that his Elgon bees didn't have any problems with the mite from the start. The mite had arrived in his operation some 5 years before he received 5 queens from me. He had all the time treated all the bees in all his apiaries with Apistan, an effective miticide.
Leif started his Elgon colonies with very low levels of mites. After introduction of the queens in their colonies he moved them to an isolated spot in the forest more than 3 km from other bees. He didn't treat his Elgons for more than 15 years. He got some new queens from me when he needed. But many colonies just superseded their queen. Unfortunately he grew old as we all do and got a stroke. He passed away early in 2016. He was a good friend and a good beekeeper.

With isolation of about 3 km you avoid reinvasion of mites through so called silent robbing (you don't recognize the bees are being robbed). Silent robbing will take place when mite population is big enough to irritate the bees so they woun't defend their hive good enough. The varroa level probably has to be higher than 3-5 %. Silent robbing in first place takes place in times of nectar drought, which mostly occurs when varroa population is growing at the end of the season and the amount of brood is going down.

4. Minimize moving bees

One big stress factor for bees are moving them to new places. It enhances drifting and mixing of bees and mites. Harmony takes time to get back, time during which defense systems woun't function to 100%. Maybe also some combo adaptation between mites and bees are disturbed by heavily mixing of mites.

Chris Baldwin moves about 1000 of his 1500 colonies to different pollination services in the United States, such as the almond trees in California in February. He is one of the few, perhaps the only beekeeper of this size moving bees for pollination missions who hasn't been treating against the Varroa mite for many years. Moving them stresses his bees, but he has an operation system that copes with that. He makes a lot of splits. See the link:

I also glanced at how Dee and Ed Lusby worked when Varroa hit their operation in the Sonoran desert in Arizona. They lost 90 % of their hives due to the Varroa mite when it hit their bees. In some apiaries the number of colonies went down to just one single colony. Lusby's though didn't collect them together in apiaries, but let them keep their place and built up the number again, apiary by apiary. By making splits, but also by catching swarms, in the apiaries and at other places and bringing them there.

In nature feral colonies are stationary, or swarm. And there are never many colonies in an "apiary". Feral "apiaries" are also most often not very close to each other.
Anyway I reasoned it wouldn't hurt to stop moving splits between apiaries, instead keeping the splits in the same apiary and see if something could be concluded from that practise.

If moving a split to another apiary has a big negative influence I don't know. I just as a precaution decided to move hives and splits to other apiaries as llittle as possible. If I had been a migratory beekeeper I might not had been able to choose to do like this, at least not more than for a few apiaries to try to find out eventual differences.

5. Monitoring the varroa level

I didn't like the ongoing reinfestation of colonies in my apiaries. I had a feeling it contributed a lot to the difficulties my bees were having to stabilize their Varroa resistance at an effecient level. My thoughts went to the Bee shaker Michael Palmer gave me some years ago. (Thanks Mike!) I didn't understand then how it could benefit my operation.

The Bee shaker I got from Michael Palmer.

One day I read on Randy Oliver's website and found the Bee shaker there and how to use it. Also talked to Randy when he visited Sweden a couple of years ago. I finally realized it maybe could benefit a lot. Read about the Bee shaker on my blog:

Here's how to make one:

Watch a video clip how to use a bee shaker:

Eric Ericson had the limit 15% Varroa level when a colony was taken out from his Varroa resistance breeding program in 1995. When the program had went on for a couple of years he lowered the limit to 10%:

Today you can see recommendations of immediate treatment when Varroa level is above 2-5% in spring and somewhat higher in autumn. Today mites and bees have been more filled with viruses and they will quicker develop problems even with lower Varroa levels, which makes it more difficult for your bees to become treatment free.

After talking with Randy Oliver and considering my own experiences I say the Varroa level limit is 3% regardless of the time of the season (maybe a little lower in spring), if a shaker test is made at least twice during the season, in early May and in early August where I live. (In a climate with a shorter winter April and September may be approriate, with a third measurement in between.) If the May test gives a value just below 3% a new test is sheduled a month later with that colony.
This way I will get a good idea of the resistance value of my colonies without creating a lot of reinvasion problems. But still my bees can pick up mites from other beekeepers' bees of course. I have tried this strategy for a couple of years now and have had time to do it in some of my apiaries. It's very promising so far. I'll come back to this.

If I have my bees relatively isolated this procedure will give the best colonies a good chance to develop their resistance traits without getting a lot of mites from other colonies. The less good ones will get new queens as soon as possible. That's how I reasoned. It seems to work well.

HOW YOU CAN MAKE A BEESHAKER YOURSELF

HOW YOU CAN MONITOR THE VARROA LEVEL

2 varroa/300 bees = 0,6 varroa/100 bees = 0,6 % – < 3 %

19 varroa/300 bees = 6,3 varroa/100 bees = 6,3 % – > 3 %

6. Starting with almost zero mites

After thinking a lot on the experiences of Leif Hjalmarsson I concluded I had to try to make a relatively isolated bee yard as mite free as possible with an effective miticide and see what happened. I hated to do that, but I couldn't dismiss this option to learn more about achieving Varroa resistance.

NEW STRATEGIES

After considering the six points I have been discussing above, six different strategies formed. I started one in 2014. Another in 2015. The rest in 2016.

A.
The first new strategy involved one apiary on an isolated place far into the forest. Started in autumn 2014.
– An isolated place. Treat with thymol pads when varroa level is above 3%.

B.
The second new strategy was performed in one of my ordinary apiaries that is (was} quite "isolated" (2 km/1.5 miles). It started in autumn 2015.
– Begin with almost zero mites. Treat with thymol pads when varroa level is above 3%.

C.
The third new strategy in two small apiaries.
– Treat with thymol pads when varroa level is above 3%.

D.
The rest of my apiaries I planned to manage as I had done in previous years and treat when I see more than two wingless bees. When I only see one such bee I would do a bee shaker test and treat when the varroa level was above 3%.
– Manage as previous years, but when one wingless bee was seen monitor the varroa level and treat when it was above 3%.

E.
The colonies that I decided in the fall would have their queens replaced the following year, I would treat with thymol pads in May the following year before the queen replacement could take place. The reason was to give the new queen a good start. 15% of the colonies were managed this way in spring 2016. Winterlosses 2015-2016 was about 10%. It was about the same percentages in spring 2017.
– Treat with thymol pads in spring all less good colonies which would have their queens replaced a little later in the season, without monitoring the varroa level (Those queens have anyway previously shown that varroa populations grow too quickly in their colonies.)

F.
Splits are taken only from the best resistant colonies and placed in the same apiary as their mother colonies. Such splits will make their own new queens. If the new queen fails to be laying, such a split receives a mature grafted queen cell. As before, the least good colonies get their queens replaced by bred queen cells after the old bad queen has been removed.
– Splits from the best colonies are placed in the same apiary as the mother colonies.

A – Isolated apiary, treat above 3% varroa level

Will isolation and never allow the varroa level to reach high levels in any colony, make it easier to reach a treatment-free situation?

A project was started in the autumn 2014 involving LP:s biodling (a bee equipement dealer), me and a beekeeper named Arne Andersson. A report about this project will probably come on this site or/and other media. The project is continuing. One part of it involves an apiary I give a report from here.

I started this apiary with three colonies in the autumn of 2014, all on 4.9 mm cell size and somewhat different heritage. The colonies were splits with new queens. The colonies had not been treated during 2014 so I didn't know the Varroa level. They had not shown any wingless bees during 2014.

The apiary is placed in a forested area where it's normally difficult for the bees to survive. 2016 was as well a bad year as 2015, but in 2015 the heather flow gave a crop. 2016 was a bad year with almost no harvest at all. In 2017 spring was cold, summer was cold and dry, no summer harvest but a fall crop from heather, which though wasn't as good as in 2015.

During 2015 splits were made from all three colonies. One failed and got a new mature queen cell. But the split was weak when wintered and didn't make it till 2016.

Of the six colonies (including the splits) in 2015 four showed DWV-bees and 3% or higher Varroa level in June. One of those that showed wingless bees though had only 2% Varroa level.The mother colony of this one had a high VSH degree (80%). Other daughter colonies also showed wingless bees at low levels of varroa. This has led me to speculate that very high VSH can cause other genetic disadvantages, and that it is better with moderately high VSH and to combine this with other resistance traits. The four colonies with DWV were treated with two pieces of thymol pads with 5 grams of thymol each in June. The thymol pads were replaced with new ones 10 days later.

In 2016 it was possible to make splits from three colonies. They had enough strength. Varroa level in spring was 0-0.3% in the five colonies. Of the three splits two failed to raise queens in spite of that also new ripe queen cells were given to them. In the six resulting colonies the varroa level in autumn was 0-1.5% (the sixth colony with 1.7%).

As we had decided not to keep more than five colonies in the apiary I gave away the 1.7%-one to Arne Andersson. He tested it with short term treatment with formic acid to get another evaluation of the mite population. It dropped 10 mites from that treatment.

2017: Of the 5 colonies that was wintered in this apiary in autumn 2016 (the sixth had been moved to Arne), the strongest died of defecation. It had stood only a few meters from a forest "road" where a forest harvester had been driving during harvesting logs. The speculation is that the colony was severely disturbed in its winter rest. One of the four remaining had a failing queen (a split from the year before). In early May, this colony and the strongest one shifted place, so the bad one got all good field bees. The bad queen was taken away and the now queenless one got a good brood comb with both hatching brood and eggs to make a new queen from. This worked very well. The two remaining colonies had old queens that these colonies tried to supersede later in the season, but the new queens were lost probably during mating flights. Those two colonies got new egglaying queens introduced and an extra brood comb. They are number two and four (from left to right).
The varroa level was 0-1% in the summer, so no colony needed treatment. The strongest colony in the picture (wintered on three medium boxes [frame 448x159mm]) was the strongest in the spring. It was the one that changed place with the one with failing queen above. It later superseded her queen successfully. So now there are new queens in all 4 colonies. The season was so bad that it was not possible to make any more splits. No wingless bees were seen in any of the colonies.

Isolation has given good protection against reinvasion and a stabilazation on a varroa level well below 3%.

B – Somewhat isolated apiary, start with "zero" mites

Will somewhat isolation, a start with very low varroa level and quick treatment at a varroa level above 3% make it easier to become treatment free?

I choose an apiary that was quite isolated, 2 km from a couple of my other apiaries. In autumn 2015 I treated all colonies with an effective miticide giving mite drops ranging between 150 and 600 mites plus one 800 (in spite of thymol treatment earlier for this one). The 800-one was a swarm I caught, which probably came from another Elgon beekeeper in another area. I just happened to hive it in this apiary in 2015.

I had treated some of the colonies with thymol earlier in the season, but not the one giving 150 mites. That colony gave also a bumper crop in spite of the bad year, so I considered it a breeder actually.
I didn't measure the Varroa level in spring 2016 as the treatment had been of such an effective type the autumn before.

I made splits from those colonies I judged to be the three most Varroa resistant. I sold the three least varroa resistant colonies, but left one box of each with enough bees and brood to make a queen (it was in the middle of May) with the intent to replace the resulting new queens later in the summer.

I killed the queens in the rest of the colonies in June and gave those a grafted mature queen cell a week later. The swarm I didn't touch because I didn't know enough much about it. I was prepared to replace the queen.

In autumn I checked the Varroa level in this apiary with the Bee shaker. With the three splits the number of colonies now was 11 in the apiary. Four of them had 0% mite level, four had 0.3%. The three remnants from the colonies sold were so weak I didn't want to take any bees from them to check their varroa level. I decided to check them in spring if they survived and decide what to do then. They gained strength during the rest of the autumn and survived the winter well.

All colonies that were wintered in this apiary looked fine in spring 2017. But one tried to supersede the queen too early in spring and failed because of lack of drones and too low a temperature for mating. I sold two whole colonies. I made splits (Including the queen) from the best three colonies. I made one split including the queen from a below average colony, which I sold. The rest of the mother colony got a ripe grafted queen cell (a queen of better genetics). This split including the queen which I sold was later reported by the beginner that bought it that it gave a crop of more than 50 kg (110 pounds). Two queenless splits of the three from the best colonies failed to produce a laying queen and got laying queens introduced. These two splits were judged to be too weak to even take 300 bees from to monitor the varroa level in August, but they looked healthy (they had been without brood for a long period) and in harmony in October. I ended up wintering 10 colonies in this apiary. In August 4 of them had 0.3-1.4% varroa level. A colony had 3%. 3 colonies had more than 3% and received a thymol treatment of two pads times two, altogether during three weeks.

Later, I learned that another beekeeper had established (elgon) an apiary 1 km from this apiary in a different direction from my two apiaries 2 km away. It may well be part of the explanation for the dispersion of the varroa levels among the colonies. The colony with 1.4% was had not been taken any split from and it gave more than 100 kg of honey, top in the apiary. No wingless bees were seen in any colony.

To treat with an effective mite pesticide to bring down the varroa level to almost zero (to get a good start on your breeding work) seems to be of little value, at least if you don't have your apiary in an isolated place with more than 2 km to other bees (3-5 km).

1 km to another beekeeper is "too close", but the variation of varroa levels give room for good selection as there were enough many that had a very low varroa level to make a continued selection successful. There is no need to start the selection work with "zero" mites.

C – Small apiaries where the starting varroa level is what it is

Monitor the varroa level, thymol pads when it's above 3%. Make splits from the best colonies which make their own queens. Replace queens in the least good colonies. Will this strategy take the colonies in these apiaries closer being treatment free.

Another two small apiaries I decied I had time to keep track of concerning the Varroa level with the help of the Bee shaker.

APIARY 1
Three colonies in 2016. It is the apiary close to the source of the feral swarm from the wall. At a distance of 1 km in another direction there is another elgon beekeeper with a small apiary.

The first colony in this apiary had a daughter of this feral swarm. The second had a new queen mated in this apiary. The third colony was a weak colony that barely survived winter. The first colony was quite weak as well, but grew strong much better.

Spring 2016, mite levels: Col. 1 – 1%, Col.2 – 0.3%. Col.3 – . I didn't measure col. 3 because it was quite weak.
Autumn 2016, mite levels: Col.1 – 0.3%. Col.2 – 1.1%. Col.3 – 4.7%. Colony 3 got thymol treatment as the mite level was above 3%. No colony showed any DWV-bees.

2017: All thre colonies were split. Splits of col. 1 and col. 2 were meant to make their own queens. The split of col. 1 failed and dwindled down to nothing. Both parts of col. 3 got mature grafted queen cells.
Spring 2017, mite levels: Col. 1 – 1.1%, col. 2 – 0.75%, col. 3 – 0.5%
August 2017, mite levels: Col. 1 – 1.7%, col. 2(new) – 1%, col. 3A – 0.3%, col. 3B – 1,7%, col. 2(old) – >3% – thymol. No DWV-bees in any of the colonies. Colony 1 gave by far the highest crop.

APIARY 2
Two colonies in 2016. At a distance of 0.5 km there is an apiary of another elgon beekeeper.
Spring 2016, varroa levels: Col. 1 – 0.3%, col. 2 – 1.7%.
A split was made without the queen from col. 1. It succeded in producing a laying queen, but was somewhat weak.
August 2016, varroa levels: Col. 1A – 1,2%, col. 1B – , col. 2 – 11,7% – thymol
Colony 1 and 2 gave about the same amount of honey.
2017: All three colonies survived the winter well. I decided no monitoring of the varroa level was necessary. Col. 2 was also decided to have its queen replaced and therefore got thymol pads in May. The queen was removed and the colony got a mature grafted queen cell in beginning of June.
August 2017, varroa levels: Col. 1A – 5% – thymol, col. 1B – 2.3%, col. 2 – 1.7%: Colony 1 had a quite old queen and replaced her probably in 2016. It gave a good crop of honey. No DWV-bees in any of the colonies.

Both apiaries are most probably influenced by the neighboring apiaries. The variation of the varroa levels seem to be big enough to allow for progress in selecting for varroa reistance to increase. It seems it's working treating when the varroa level is above 3% and in May in those colonies that will have their queens replaced in June.

D – 2-3 DWV-bees –> tymol. 1 DWV-bee –> Bee shaker (above 3% use thymol)

E – Planned replacemednt of queen –> thymol in maj, mature queen cell in June

F – Splits place in the same apiary as the mother colony

The splits are made from the best colonies.. The queen goes with the split, which is placed on a new place in the same apiary as the mother colony.

During 2016 and 2017 I used the strategies D, E and F in the rest of my apiaries. This resulted in that I was more careful to find out when I should use thymol or not. When I saw a wingless bee I didn't wait to see what happened in two weeks or so. I monitored the varroa level with the Bee shaker.
– Fewer colonies developed higher varroa levels and thus fewer became a resource for reinvasion.
– Also when seeing more DWV-bees I was quicker in using thymol pads, with the same result – fewer reinvasion sources.
– And in May I used thymol pads on colonies I had decided should have their queens replaced – giving the new queens a better start and lower mite pressure in the apiaries.

The breeder S241 gave many good daughters concerning lower mite levels in 2016. The breeders used in 2016 increased the varroa resistance as well, H131, S183 (a daughter of S241) and C243. In 2017 I used mainly H131 again, S411 (another daughter of S241) and C290 (a daughter of C243). Feedback from buyers of queens have been encouraging.

A lot fewer colonies have needed treatment for varroa in 2016 and 2017, in spite of the fact that I have had kind of lower threshold values for using thymol pads. A lot fewer DWV-bees have been observed. The winter losses have been about the same for many years, 5-10%. But during thes later years fewer colonies have been very weak in spring (about 10%), which need thymol and barely are surviving. Earlier years this number was about 20%. Such colonies will not give a crop. About half of these colonies usually recover after they get a new queen.

There are some apiaries in which all, or almost all colonies have needed treatment. That is apiaries at the edge of the elgon area and closer to apiaries with other types of bees. Some of the beekeepers may have had problems controlling the varroa levels.

It's difficult to see any evidense that the strategy to place splits in the same apiariy as the mother colony has had any positive effect on the varroa levels and the resistance of the bees. Probably it's more adverse to regularely move whole apiaries, for example for pollination purposes, as this leads to at least temporarily more drifting among the colonies and evening out of mite levels.

CONCLUSION:
– Monitor varroa levels at least twice, Maj (April), (+ maybe june) and August (September).
– Treat with thymol pads when the varroa level is above 3% (maybe 2-2.5% in May [April]).
– Make splits from the best (most resistant and high producing) colonies. Let them raise queens.
– Breed extra queens from some of the best colonies.
– Replace queens in the bad (least good) colonies
– Try to establish a breeding apiary at least 3 km (2 miles) from other types of bees.

A BREEDING APIARY

1. Establish an apiary at least 3 km (2 miles) from other bees, on your own, or in cooperation.
2. Why not start with 5-10 colonies.
3. Begin if possible with bees that probably are more resistant than average bees.
4. Use smaller cells in the broodnest fo the bees, if possible 4.9 mm, or 5.1 mm.
5. Monitor the varroa level at least twice per season, maybe three
6. When the varroa level is above 3% (9 mites/1 deciliter bees) treat with thymol.
7. If you see more than two wingless bees – treat with thymol
8. If you see one wingless bee – monitor the varroa level.

9. Make splits from at least the best half of the bee colonies.
10. The worst colonies/splits get mature queencells from better colonies a week after the queen has been removed.
11. Queenless splits from the best colonies raise their own queens.
12. New queens are mated in the breeding apiary
13. If you produce too many colonies for the breeding apiary – establish another "breeding apiary" 0.5 - 2 km away.
14. Combine colonies in late summer that are too weak to winter
15. Let the colonies keep enough honey and pollen for winter storage to keep themselves healthy. It may differ in different climate and localities.
16. Exchange one or a few queens from similar projects to compare them with yours.