Keeping track of the infestation level

In the search for breeders for this season I tested a number of hives for the infestation level of Varroa mites in the beginning of May. Those choosen had not been treated for mites either not at all last season, or very little with thymol in the spring last year after showing an odd wingless bee. This was before the time of the Beeshaker with me. Better hade been to use the Beeshaker before using thymol to really know the infestation level.

I used the Beeshaker (more info about it and how to use it: http://www.elgon.es/diary/?cat=85). There were colonies with 0 mites from somewhat more than 300 bees. The best of those I use as breeders this year.

I also gave a number of colonies a thin tray with a coarse mesh that bees couldn’t pass hrough. High enough from the bottom of the tray so the bees couldn’t clean the tray. It covered almost the entire bottom. The purpose was to collect natural downfall of mites over a period of time.

I send some queens abroad and the Board of agriculture wants to be sure I have no tropilaelaps mites and no small hive beetles. (Both of those two pests have not been found in Sweden, tropilaelaps not even in Europe, the small hive beetle only in Italy.) Three weeks before the veterinary and the bee inspector came to visit for checking my bees I inserted these thin trays. Of course the inspector and vet also checked for American foul brood.

Varroagaller Varroa trays for checking natural downfall of mites. The one to the left without mesh cover.

Two of those hives I had checked with the Beeshaker got a tray. Three weeks later one of them had 7 mites on the tray. The other had 8. The bee shaker had given 1 mite each for these two hives.

1 mite per 300 bees is 0.3% infestation level on the bees (not counting the mites in the brood, those are usually at least the double amount).

Let’s say I missed 2-3 mites of the natural downfall. That would then be 10 mites in let’s say 20 days for easy math. That gives 0.5 mite per day. It’s been said that natural downfall per day during the brood season multiplied by 120 gives about the total number of mites in the colony. That would make 60 mites in total in those two colonies. The number of bees in those colonies were more than 30,000 each. But let’s say it was 30,000. If we divide 60 by 30,000 we get an infestation level of 0.2%. This level is though including the mites that had been in the brood during these 20 days, so the figure is not directly comparable with the 0.3% to confirm that the two methods give about the same result. The estimation of multiplying with 120 and other uncertainties makes comparison and/or the methods not exact anyway.

Does this comparison give an indication that these methods are good enough for checking the varroa infestation? Both methods have been used by others to decide when to treat or as a selection help for varroa resistance.

When the infestation level is so low as given above, it’s not possible to check the VSH trait either, as you will find too few pupae with mites. You can ask yourself if it’s at all necessary to test for mites anymore. I agree. But all my hives are not as good as these and reinfestation occurs. So I think I have to keep track in some way. Not in first place I think to find the best ones, but to find the ones with most varroa so I can protect the others from reinfestation.

The perfect resistant colony is of course such a one that is not very much affected by reinfestation, not letting in bees with mites on them for example. I will test colonies in August as well and I will check the hard boards in front of the hives for crippled wing bees or grey young bees crawling around as indications for viruses following to high varroa infestation.

The bee shaker and varroa resistance

Skak botten 2lc One mite from 300 bees.

I understand that sometimes it’s a good idea to get an idea of the infestation level of varroa mites in bee colonies. You can take samples from a couple of colonies in an apiary to get an idea when to treat. But my first concern is breeding varroa resistant bees.

I have never monitored the varroa infestation level in my colonies. I haven’t had time and I haven’t found any reason for it because I thought I had found a good compromise – treating with Thymol when I saw wingless bees on the hardboard in front of the hive entrance, checking every 10 days or so.

 

Good results up till now

I give a colony one or two pieces of dish wash cloth containing 5 grams of Thymol each when I see wingless bees crawling on the hard board in front of the hive. But this means I don’t treat every colony at the same time (hopefully some not at all in a season). This results in some colonies with higher mite loads not showing wingless bees yet. So these colony (-ies) will through reinvasion increase mite levels again quite quickly in those colonies recently treated.

But this way I’ve been able to develop more and more resistant bees and still produce a good crop. There have been a number of bees not producing any honey. Winter losses have been reduced from 30 % to 10-15 % (except the first year with varroa trouble when I lost 50 %).

The bees have been better chasing mites and remove infested brood. I’ve got good reports from for example Poland and Germany of low populations of varroa in colonies headed by Elgon queens, compared to other bees. And the VSH trait is becoming better and better. Daughters of my colony with the highest VSH % (80) gave colonies that in Poland dropped 2-5 mites after effective treatment while other colonies dropped more than 1000.

 

Thymol is useful but hinders total adaptation

I now have been aware that by having this regime I have a constant quite high varroa population in the apiaries as a whole, and thus probably a climbing virus pressure. In a way this is good as selection is done also on virus resistance.

How do I know that? Now when I’ve used the bee shaker somewhat this year I’ve seen that colonies may show wingless bees (DWV-virus) at low mite infestation. Such low infestation you didn’t expect them to do so, sometimes even as low as 2 % infestation (a daughter from a colony with high VSH trait [80%]! This experience and others similar, raise the question if very high VSH comes with higher susceptibility to viruses.). Wingless bees at 2 % infestation is totally different from a report I’ve got from a test further down in Europe. (There they normally treat effectively every year.) In that test where they didn’t treat at all, my bees didn’t show any wingless bees at 35% infestation while other bees had a lot.

 

How to explain the high infestation level in the test

Now I have to try to explain why my good bees could arrive at 35 % mite infestation. This is interesting and brings up another topic as well. The importance of memories of the worker bees (their knowledge how to chase mites), not only their genetics (and epigenetic history). My queens in this test down in Europe were introduced to bees that had not been selected the same way as mine, and those bees had been treated effectively every year. The bees could probably not chase mites as well as mine.

But of course the genetics from my queens would more and more influence the workers to build up a better behavior when it comes to chasing mites. When the bees have arrived at a good mite chasing mood they learn new bees born in the colony what they have achieved, more than what just come directly with the genetics. In Norway with Terje Reinertsen and Hans-Otto Johnsen experiences are achieved pointing strongly to this.

In an apiary where many colonies are non-resistant as in this European test, you get a mixture of all bees in the apiary through drifting and robbing. This is taking place more and more when the mite populations in the colonies rise. As it did in this test as the colonies were not treated at all.

In a situation when colonies are receiving a lot of mites from neighboring colonies, even the very best kind of mite chasing behavior is maybe not enough to keep mite levels low.

In the test apiary previous to this test, effective treating every year had kept the mite and virus levels low, so the mite population could grow much in the test without showing wingless bees – like in the beginning when the mite first arrives to an area. Then the virus levels are usually very low and there could be 10 000 mites and more in a colony without any signs of viruses (documented case in Sweden in 1987 when the mites were first detected on the island Gotland in the Baltic).

The bees in this test were on 5.5 mm cell size, while my bees are kept on 4.9 mm.

 

Also Thymol hinders total adaptation

I have talked to some beekeepers whose bees are totally treatment free since many years (Hans-Otto Johnsen in Norway, Richard Reid in Virginia and Myron Kropf in Arkansas). Their bees have now small populations of mites and are showing no wingless bees.

I have come to realize that also Thymol is a chemical that hinders the bees to fully adapt to handling the mites successfully on their own. It is in first place the epigenetic adaptation I have come to think of that is disturbed when alien chemicals (like miticides of all kinds) are present. Epigenetic changes take place when a chemical change occur due to environmental changes, like for example the presence of the mite. (But it should be said also that if you use Thymol regularly spring and late summer in a system not selecting better bees like I do, winter losses can be kept low. I know because beekeeper friends do like this.) Also Thymol like other miticides is lowering the immune system of the bees.

How do I then integrate these insights to go further in becoming totally treatment free?

 

A new strategy to try

I’m planning a new strategy, at least to start with in one quite isolated apiary. I have to stop using Thymol. First though I think I have to knock down the mites effectively to reduce the virus level. And then get a better control of the number of mites and take action without any chemicals if varroa populations are rising too much in colonies.

 

The role of the bee shaker

Here the bee shaker will play a role. And I have looked more into how Randy Oliver uses it. It’s much easier to shake a frame of bees into a bowl or pan and then with a measuring cup scope somewhat more than a deciliter (3.5 oz) of bees and pour them into one half of the bee shaker, half filled with alcohol (for example methylated spirit or rubbing[isopropyl] alcohol). Then screw it together and shake for a minute before reading the result. Compared to holding the bee shaker close to a frame side with bees and pour bees into it moving it slowly upwards, the alternative of Randy Oliver is quicker (at least for me). The next step is to test the VSH trait in the best colonies.

Skak yngelrum Start checking from one side in the uppermost box with brood. The queen hopefully will run to the brood if she is outside the brood area (probably not). The comb closest to brood you check so the queen is not there. 

Skak deciliter Shake the bees into a pan or bowl. Scope up somewhat more than a deciliter of bees (3.5 oz)

Skakburk sprit Pour the bees into one of the halfs of the bee shaker, which is half filled with alcohol. Screw the other half tight on top. Shake it for a minute.

Skak botten1lc Turn the shaker upside down and continue shaking until all the alcohol has poured down. Lift it up against the sky and count the mites. This colony had 14 mites on 300 mites and it got two pieces with 5 gram Thymol each. It showed no wingless bees.

What I hated to do

So what I’ve done so far is something I hated to do. In one quite isolated apiary I used an effective chemical miticide (only this time I promised myself) in August 2015. I wanted to use something else than Thymol to give the bees a break from that chemical. And I wanted to knock down the mite population effectively to lower the virus pressure in the apiary. I collected the knocked down mites. (In the rest of the apiaries I plan at the moment to continue as before.) The colonies that had needed most Thymol earlier in the season had the highest downfall of mites. They got probably continuously reinfested from other colonies that happened to not show wingless bees while they anyway had quite high mite loads. The defense system of these quickly reinfested colonies was probably lowered by Thymol, which made this relatively quick reinfestation possible.

One colony that hadn’t needed any Thymol at all (and very little the year before) and still had given me 80 kg (175 lb) of honey with 20 kg (45 lb) left for winter dropped less than 200 mites. And this happened in this very bad season of 2015. This colony is of course a breeder for the coming season.

 

The new strategy

Next year I will in this new strategy apiary make splits from the best colonies and place them in the same apiary (or if the number is enough there, place in other apiaries). In the least good colonies in this apiary (those with highest infestation level) I will kill the queen and give them a ripe queen cell bred from a good colony in this apiary. I check the number of varroa (infestation level) with the bee shaker twice a season in all colonies in this apiary. Each time it will take about 5 minutes per colony. And I look for eventual wingless bees on the hard board in front of the entrances. Before the number of mites rise too high (whatever that is), or when I see wingless bees, I plan to remove all capped brood (worker and drone brood) once or twice with a week in between. I haven’t decided what to do with those brood frames yet. Any suggestion?

 

 

Changing plans

I make notes. I’m sure you do to. How much is a good question. I made more notes as a beginner and quite some years after that. When I got well above hundred hives I began to question each kind of note and how much I could benefit from it. I wanted to save time, if I found it possible to skip doing some kind of notes.

For each year I use a fork binder. First I have a graph paper. On a horizontal line high up all the apiaries are numbered. On a vertical line to the left I make a note of the date, then an X for the apiary I have gone through that day. That’s the most important note, to be sure I don’t forget any apiary and to make sure it doesn’t take too long between my visits.

Fork Binder A spread in my fork binder.

I have made a map in the computer in the Excel application showing each apiary. On the spread is the map to the left. On the opposite side a blank graph paper for making notes. In the very early season (still winter/spring) I make note of the colony strength, how many “comb gaps” the bees occupy. Then of the progress of the colony (putting on boxes). At the end of the season, very late autumn/winter, again how many comb gaps the bees occupy.

I only make a thorough check of a colony if it doesn’t develop as expected. I check for eventual disease, if it has brood (thus a laying queen), and eventual other things to observe. I make notes only of things that depart from the average or the normal. No notes for a colony indicates an average or a normally functioning colony. Also notes are made concerning hot temper, no brood, wingless bees. I make notes of how much thymol in grams a colony get and what date, estimated amount of honey taken in kilograms (it doesn’t matter if I do a wrong estimation with 10-20%, the estimation is for comparison between the colonies).

When the season is over I compile the notes and do stats. Then I make a first probable selection concerning next year’s breeders and which queens I will shift next year. The final selections are made during May and June the coming season. Here the notes are invaluable as I tend to forget some colonies that I discover again when I’ve done the stats.

Before May comes there’s often a hard winter ahead, and a tough spring. And the spring this year was really tough, which changed the preliminary plans a lot. But the winter had been mild.

The spring was very rainy and very chilly. May was the coldest since 1962 in Sweden. The bees had small opportunities to get enough of fresh pollen for their usually quick buildup. And proteins they need desperately for everything for their rapidly expanding colony to function properly.

My bees have a higher varroa pressure than most others maybe, to let the least good colonies reveal themselves. Due to the season the immune system (rather defense system as their defense against diseases are different compared to mammals) among other things didn’t work fully due to lack of proteins. Viruses showed up even if the varroa population wasn’t big.

Maybe I should have stayed cool and not used varroa treatment, I don’t know. Varroa treatment affect the bees negatively as well, but of course not as much as mites. When should I stop treating altogether? And how should I do it? Just stop at any moment or do it in a certain way? I don’t know.

I have used more thymol this season than last. The colonies with high VSH value (VSH 80% the best one, included) and their daughters, most of them, showed wingless bees and many dwindled. I was surprised and disappointed. How was this possible? Can high VSH-value mean less good other traits than VSH? Sometimes such phenomena can appear with strong selection for strengthening a trait, as such selection often is made with the help of inbreeding.

Anyway, when I should decide which queens to breed from I went through the notes and found some interesting colonies I hadn’t payed enough attention to. Those colonies hadn’t needed any treatment for two years. So I made a VSH test. The S241 colony had three mites of 103 pupae checked. Two of the mites had no offspring. The third had one white daughter mite and no male. The H101 had one mite of 110 pupae checked, with no offspring. The neighbor colonies of these two colonies had wingless bees and many were dwindling. Of course I bred from these two good colonies.

Quite soon afterwards the H101 showed a wingless bee. I had split that colony and put the big split with the queen in the same apiary as the “mother” colony. The split with the queen lost most of its field bees that way. Was that a cause?

The S241-split was moved to the home apiary and kept its field bees. The split grew fine and is now a big colony. All the daughters are doing fine and building fine colonies. Both S241 and H101 are colonies that have shifted their queens themselves, whatever impact that may have.

To sum it up. I had to change my breeding plans quite a bit for this year, after this unusually cold and rainy spring. But I think it’s important to make good notes and from them plan for next season. Then when next season comes you know what to change and how.

The VSH 80%-colony was a disappointment and I don’t understand that, yet. There are though a couple of daughters from it that are very interesting. Those havn’t needed any treatment and didn’t show any wingless bees. One has shifted it’s queen. The second are showing a lot of bald brood and spotty brood (cleaned out brood with mites?). The queen is laying well. It seems it’s fighting reinvasion of mites and doing it well. So good that the colony hasn’t grown and hasn’t given any honey.

Bald brood One of the daughter colonies to the VSH 80-colony is fighting hard against the mites and havn’t shown any wingless bees, not yet anyway. Maybe a breeder next year.

This season is a disaster. The month of July has been the rainiest I have experienced ever. The honey crop is in average maybe 5-10 kg per hive (including winter losses and failing colonies) to compare with 25-35 kg for several years. And many colonies may need a good sugar feed to survive the coming winter.

But, the season isn’t completely over yet…

 

 

More viruses due to cold weather

The weather has given the coldest May since 1962, 12 years before I started with bees. The bees have had a hard time getting enough pollen to keep up egglaying to reach optimum nectar gathering strength when summer comes.

In agricultural areas winter rape has given some nectar during the few hours with good weather. It’s still in bloom… In the forest small blueberry bushes which in many areas cover the ground has done the same. Now lingonberry flowers give nectar and pollen.

Pollen is essential as amino acid and protein source. These are used for almost every thing the bees need to function as they should, for example the immune system.

This year I’ve seen wingless bees in colonies with no big population of mites, eve if it’s somewhat bigger than it had been if the colonies had been treated with an effective miticide last year. I use thymol only when wingless bees appear, on the hardboard in front of the entrance or on the brood combs.

Nosema have probably also contributed to health problems with the bees this cold May, in combination with viruses and plant protection chemicals, it can be disastrous.

Now sun and mating temperature for honey bee queens came upon us the other day. Nature dried up. The hard boards appeared “empty”. Bees are working like maniacs. Nectar is filling the supers, even in the forest. It must be the lingonberries.

More Virus lingonblom To the left there is a Swedish blueberry plant showing some berry babies. Now lingonberries are blooming.

But happiness is not perfect. In most colonies there hasn’t been egglaying as it should this time of the year. The field bees that will fly to death will not all be replaced by hatching new bees. But if the fine weather will continue the bees may collect quite some early honey, in spite of the earlier bad weather. And here in Sweden we hope for a good amount of wild raspberry flowers.

Meeting the sun

The second Sunday in March the temperature, wind and sun, together with filled intestines of the bees that had produced the heat for the winter cluster took these bees out to meet the sun. The main cleansing flight took place. What a relief!

MötaSolen2

Most often in Sweden you reach well into March before the main cleansing flight takes place. Now the colony has been brooding for some time, and this accelerates now. If the colonies started to make brood too early, for example due to a warm spell in January, or if you have Italians that have a hard times taking a break in brooding, this last winter was hard at them as winter never really came until February for two weeks. Those colonies have produced many Varroa and filled their intestines early because they have used a lot of food. The immune system is thus weak. Virus, Nosema and chemical residues contribute to the risk of defecating inside the hive, if there are bees left there. Many may already have left just flying out away from the hive (due to virus) leaving it sometimes empty of bees.

This winter should have been easy for the bees due to its mildness. But for many beekeepers that have trusted oxalic acid in late autumn and drone brood cutting in beginning of season (and just that) to fight the mite, this winter has been a bad experience. For a couple of years this concept may have worked okey. And the beekeepers, perhaps beginners, have thought they are safe.

But last year the longer brood season together with no or little checking of the mite population in July/August (mite population should not be too high then when the winter bees are produced), the mite population was too high when oxalic acid treatment came in October. The weakened bees then were still more weakened by the acid and overwintering became still harder. And it became even harder as the bees still had brood when the oxalic were used. Most mites were in that brood (that of course had well developed virus population by now) and escaped the oxalic. So it’s easy to explain the winter losses of such hives.

Now a beekeeper named Bengt Haglund just north of Stockholm have used thymol gel (Apiguard) with 25 grams of thymol in the gel in one small tray in spring. Upside down directly on the top bars, just above the brood. Next treatment was directly after late summer harvest. Another tray of Apiguard with the opening upward this time, between the two brood boxes. Winterlosses for five years in average 1 % for Bengt.

My goal is treatment free. I’m close. To get there I have chosen to use small cells, breed for resistance and use good quality natural food as much as possible. On my way to this goal I made the conclusion that I was about to loose almost all my colonies when the Varroa arrived. Therefore I treated, reluctantly, and lost “only” 50 %. The only season I have lost that much, in 2008-09.

So I used Thymol. But I don’t use anything until I see wingless bees. The virus causing it is the most common associated with Varroa mites. And I use as little as possible. I’ve found a piece of dishcloth with 4 grams of soaked in thymol is enough to start with, on top of the top bars close to the brood. Every ten days another piece as long as I see crippled wings. Strong hives might get two pieces at a time. Most hives get it in spring and later just after harvest. If there is some smelling left in the boxes when I harvest, it stays in the wax actually, and in the woodenware. The honey does not get any extra flavor (if it should it’s not unhealthy at all). Thymol residues are finally ventilated away.

Yes, Thymol kills microbes. But sometimes it’s better to have dead microbes and live bees, than dead bees and with them dead microbes. And Thymol is much less dangerous for me than oxalic acid – when making the oxalic solution, when handling it, when handling eventual fumigation and when handling equipment with crystals when cleaning up dead colonies.

But again, the goal is treatment free. And I’m almost there. Last year many colonies didn’t need any Thymol. Many got only 4 grams. Another lot 8 grams, and 12, and 16. A few more, and up to 40 grams at the most. Those that got 16 and more will have their queens shifted this year.

Winter losses for me up till now is about 5 %. Still some more % will not make it until May I’m sure.

Most colonies look very fine. And it seems I have several fine breeders to use. I’m happy the investment in breeding for resistance pays.

Reading the hardboard

Board colony

One of the most important parts in my management system has become a simple thin hardboard in front of the entrance. The first thing I do when I come to an apiary is going reading them. They give a lot of info, important for eventual actions.

If the hardboard is empty of  dead bees, litter etc – it’s the best. Very often you find a few dead worker bees there. It seems this is of no concern.

If you find a dead queen there, the old one or a virgin, you know the hive is shifting its queen, with or without swarming. Even if the colony has had no problems with mites or viruses for a short time with the last of capped brood, you can find a few wingless bees. It seems in such a circumstance it’s of no big concern. But be careful and watch the colony carefully for eventual thymol treatment.

Board Queen etc A dead queen! Drones, some workers and one old worker pupa (to the right).

If you find a lot of dead bees. Even without wingless bees among them, I consider it to be showing the bees are fighting something. Maybe another virus than DWV.

If the colony has a lot of drones maybe due to a lot drone comb, they might start throwing them out in the middle of the season, or at least some of them. I’m not sure  sometimes how to interpret this. Sometimes it seems the colony has shifted its queen and now it’s laying and the bees have no need for many drones.

When you see white parts or whole drone pupae, the bees most probably are fighting varroa, throwing out pupae with mites. And this is a very good sign actually. Varroa mites should be a drone parasite and not a workerbee parasite. And the bees should identify them in drone brood and clean those cells with mites (that have reproducedand and have offspring) – VSH in drone brood, or just cleaning out drone brood with mites.

Board 2 Drone pupae, quite some. This colony hasn’t needed any thymol, yet anyway. And given a good crop.

The next step that I usually see among my bees after seeing drone pupae on the hardboard is seeing wingless drones there. No big concern at this stage. If the reinvasion is big, if there are some colonies not fighting the mite very well they will spread many mites to other colonies. For some colonies that may mean they will need help in fighting the mites.

Next step among my bees may be seeing young grey bees walking on the hardboard, but with ok wings. Maybe another virus than DWV. And the next step wingless bees, one or two to begin with.

Now the colony gets one or two pieces of dishcloth with thymol (5 grams each), but not immediately before harvesting honey. I take away honey first. If there will be more than 14 days to harvesting they get thymol. It’s more important to have healthy bees that pollinate well, than some more thymol in the honey you can’t taste and is of no problem for health for anyone – and a dying colony. I know out of experience.

The breeder queens have not tasted any thymol for at least one year. My stock is making progress.

MT-colony conclusion

I have shared the performance of this colony which had almost a box of plastic small cell frames and natural positioning of these frames (as the uppermost broodbox). Which also had a tough experience with mice living in the bottom box during winter.

It gave top crop the first crop of winter rape, dandelions and some raspberry. It showed no wingless bees this year early on as it did last year. But it had an old queen. So the colony decided to shift it’s queen and did. Now they showed a few wingless bees. I concluded that was due to the declining amount of open brood to enter for the mites, son inte last brood of the old queen there was enough concentration of mites to develop some wingless bees. But to be consistent with my way of working I gave the colony 9 grams (two pieces) of thymol dish pieces. Next time no wingless bees.

My impression is that the colony is not performing less good with plastic small cell and natural positioning. Thus the conclusion is that plastic small cell frames are not negative for the bees, neither what I call natural positioning. If any of these configurations are positive is difficult to say. An overall smaller mite pressure in the apiary and the area could be the explanation. Due to epigenetic changes that have improved the bees, or/and conventional selection has done its job with the genepool in the apiary/area. Also plastic small cell frames and natural positioning may have contributed. At least plastic small cell may have good influence as there are more cells for each comb, thus faster buildup.

Plastic positioning and the mouse

You remember the previous post about the “multiple test”(MT)-colony, natural positioning, plastic frames, a mouse (or mice), mild winter and what a good condition this colony came out with now in spring. I’ve been thinking about it.

Mild winter

Yes the mild winter has contributed to the good condition. But what about varroa and viruses? Mild winter doesn’t help if you have too much of both in a colony. I would say maybe the contrary, or at least questionable. A lot of varroa triggers extensive brooding, to kind of replace the affected sick brood resulting in a bad rat race.

But less treatment

In fact one of the colonies in the apiary died during winter due to what looked like virus problems, in spite of some more treatment than the good colony got. And another colony which hadn’t received any treatment last year because it didn’t need it, it seemed, no DWV-bees, strong and healthy look – came out with fist size cluster and asking for survival until fresh pollen and steady temp around 60F (15C). We’ll see.

And this good colony got less Varroa treatment 2013 compared to 2012, actually half – at the most only a tenth compared to non-selected bees for Varroa resistance. With the same queen 2012 and 2013.

 Weaker varroa pressure

Now I think in spite of the dead colony and the one with the fistsize cluster, the average Varroa pressure, total amount of mites in the apiary, was less in 2013 compared to 2012. In fact I think this is the case in all my apiaries. Because I used in average about half the amount of thymol I used in 2012. This good colony I’m talking about specifically now got the average amount, 5 grams. Also, only 50% of the colonies going into winter had been treated during 2013, compared to 80% 2012. And, this spring winter die off will be less than 5% compared to more than 15% last spring.

The Varroa pressure I think is lower due to better Varroa resistance in average in my stock, also in this apiary. The least good ones are showing up every spring, either they die in spite of treatment, or they show up weak and get treatment and later their queens are shifted.

 Epigenetics and social learning

Also, from other beekeepers experiences, after about 5 years, mite pressure becomes weaker without any obvious reason. Probably some kind of epigenetic adaption (genes turned on and others turned off) is taking place that takes about 5 years from the first time the mites created problems. This spring is the fifth since the mites gave big problems the first time in all my apiaries.

This adaption to the presence of the mite and fighting it probably also involves social learning. Bees learning to handle the mite and pass this knowledge on to other bees in the hive (http://www.hindawi.com/journals/psyche/2013/768108/). Therefore it’s important not only to propagate good resistant bee colonies by making new queens from it, but also by making new bee colonies from it, including worker bees that can pass their knowledge to new generations of bees.

Plast49Yngel

 Uniform small cells

From the dead colonies through these diffcult years with Varroa I have harvested quite some badly drawn small cellsize combs. With too many patches of drone comb, and too many patches of bigger sometimes irregular “worker” cells. Good they have been culled.

These plastic frames with plastic foundation with cellsize about 4.95 from Mann Lake (http://www.elgon.es/diary/?p=119) that was used in the bigger part of the third (the uppermost) broodbox in the MT-colony at least didn’t have a big negative impact on the colony health. Plastic haters might draw such a conclusion right away. Now, I’m not a plastic lover. I don’t like using plastic. That’s because in general it isn’t degradable in nature. That’s what I want, degradable plastic. But here it is in our world and I tried it.

These plastic frames might even have contributed to the good health of the MT-colony. 10% more cells per comb, still quicker build up. No drone patches (BUT there should be drone patches here and there in the brood area to catch the mites that are there), no patches of bigger and irregular “worker” cells. No wavy combs (I use no wiring in my wax combs). No big bridges of hindrance of wood for the queen between brood boxes.

So I plan to try some more plastic frames from Mann Lake in brood boxes. But there should be a good balance between plastic and wooden frames as long as I will be using the plastic.

Only real treatment tell real mite population

Marco Moretti made a valid comment to the sugar shaker post. It doesn’t surprise me that Antonio Nanetti found checking mite populations besides a real treatment is unreliable. It is many factors making the results uncertain. Why beekeepers want to do this anyway is to get an idea when it’s time to treat against the mite.

If you do an oxalic dribble, or trickling, you make a real treatment. And that’s okey with me, if you choose to do that. Before making a real treatment the most reliable mite test is said to be alcohol washing like with the bee shaker described in this blog. The sugar shaker might do well for others. According to findings in USA described by Dennis van Engelsdorp those beekeepers that checked mite populations with alcohol wash, thus keeping track of the mite population had the lowest winter losses, of those beekeepers treating regularely.

John Harbo and his collegues at Baton Rouge lab found in the early 1990:s when they took help of a statistican to find out that checking mite population increase during a period of time was not a good way of testing mite resistance. That’s why they finally ended up checking  infertility of the mites, which finally became the VSH method. (Information from Harbo)

That’s also one of the resons I don’t count mites. I check for virus problems in the hive before treating. The easiest virus and the one most common when mites are becoming many is Deformed Wing Virus (DWV). Maybe that’s too late normally to save the colony. I don’t know. But fortunately I don’t have ”normal” bees. Also a reason for me not counting mites, but looking for DWV, is that I want my bee stock to develop strong varroa (and virus) resistance.

 

Bee shaker

I wrote about counting mites recently. Even if I don’t, others do, and sometimes it gives information that may help you make a decision.

John Harbo mentioned when he lectured in Sweden in May 2013 that before choosing the method for selecting for varroa resistance at the lab in Baton Rouge in the 1990th, their statistician helped them evaluate different methods. Their conclusion was that selecting for infertility of mites, then called SMR, later VSH, was the best method. Using one-drone insemination on 43 queens from a source of collected survivors they started the work in 1995 and in 1998 the goal was achieved. Impressing to say the least. Why havn’t this result have had more impact during the years. The queens produced at that early stage in the process were so inbred they were superceded quickly and the honeyproduction was low. They got bad reputation and beekeepers didn’t understand how to use the resistant queens fully. The situation today is very different.

One selection method among those not choosen, was checking the mite population. Though this method is still promoted buy others and used as well. Maybe because some have found it valuable in this matter. And most of us are living in free countries and can do our own choice.

Another reason for doing mite counts is for making a desicion if or when mite tretament is needed. In US it’s been said the threshold for treating is 3 mites per 100 bees in an alcohol wash. Some say this number seems to have to be lowered as viruses are worse nowadays. That probably is valid for all those moving their bees to almond pollination, where the bees share the latest in pathogens, pests and pesticides. Maybe all this treatment used during the years has forced the mites to answer with reproducing quicker in that they stay in the phoretic stage (on the bees and not in the brood) for a shorter period before they enter brood cells again.

Anyway, my small scale beekeeper friend cooperating with me, Leif Stromberg, quite on his own with his bees but not totally; he has 15 colonies, use the threshold 5 mites per 100 bees for treating, in october only when there’s no brood. It’s a help for deciding if he shall trickle oxalic acid. He trickled 4 colonies in autumn 2013. His winter losses are small. He lives 100 km north of me and cooperates there with Bjorn Lagerman, 90 colonies, with basically the same stock of bees as me too. His story could be told in another post.

HDRtist Pro Rendering - http://www.ohanaware.com/hdrtistpro/ Pouring bees in the bee shaker (pictures used with the kind permission of Randy Oliver).

Leif has compared natural dropping of dead mites through the season and this late alcohol wash. And there is actually very little correlation, if any. His conclusion is that natural downfall of mites is of no practical value to get a good idea of a mite population having an impact on the bee colony, at least when it comes to his bees (he gets a couple of virgin queens from me every second year or so) that apparently has some resistance to varroa. Randy Oliver has also lost faith in the natural mite drop method for determining the actual mite population. http://scientificbeekeeping.com/mite-management-update-2013/

Shaker2 After shaking for 1-2 minutes, turn the shaker around…

Randy Oliver uses a very practical way of alcohol wash, the bee shaker. For some time John Williamson produced it for sale, but doesn’t anymore. As far as I know, no one does at the moment. But it takes 5 minutes to make one yourself from two suitable cans with plastic lids and a piece of beetight netting that let through mites. Follow the instruction here: http://scientificbeekeeping.com/sick-bees-part-11-mite-monitoring-methods/

Shaker3 … and count the mites