The second international Learning from the Bees conference featured a recurring theme: bees in trees. It left two lasting impressions on me:
- It will influence German beekeeping for years to come, catalysing the spread of natural beekeeping;
- A paradigm-changing insight making me re-evaluate everything I thought I knew about bees.
So, nothing much to report…
Here, I’ll discuss German beekeeping, how bees live in the wild and what we can learn from this, and related stuff I learned about trees, forests, hives and some cool stuff like a varroa-devouring mite. Let’s start with trees, as other subjects flow from this…
The Zeidler (tree beekeeping) workshop
If you think I am a hard line natural beekeeper, you haven’t met the Zeidlers. Re-introducing traditional husbandry techniques, they create bee-friendly cavities in living trees and harvest honey from these. The practice was primarily Polish, but died out in most of Europe when rulers had the large forest trees harvested for industry and war. It hung on in remote Russian areas and is now being re-introduced by Polish enthusiasts; here in the UK its highest profile proponent is Jonathan Powell. You can read more about the practice on his site beeswing.net and the Natural Beekeeping Trust website.
The main conference was preceded by a 2 day Zeidler workshop. I just popped my head in to say hallo above the sound of chainsaws. An interesting point to me there was how few people were attending, maybe 25 from across all Europe. It is a real niche interest – you need to be fit to climb trees, use chainsaws etc and you need access to really big trees you can cut cavities into.
Zeidler beekeeping caused a lot of re-thinking when it was rediscovered by Europeans a few years ago. Why do we have entrances at the bottom of hives? How come these bees thrive with no help in a simple hole? Maybe there’s more to a tree cavity and the natural nests within them than we thought?…! As you’ll see below, this has led to some valuable lessons about how to optimise bee homes.
Trees, forests, and bees in trees
I found a talk by Dr. Przemysław Nawrocki on what a primeval European forest was really like, particularly interesting. In brief it was not just a dark belt of continuous trees, but a network of open ground, ponds, a different tree mix (mainly Linden, aka lime or basswood trees) to the modern day, and 30% dead wood. Small fires and grazing kept undergrowth down so large, tree-destroying fires were rare, and allowed heather to thrive. Modern managed woods have about twice as much timber per hectare as ancient ones, largely fast growing conifers, and nearly continuous canopy cover.
Separately, I found that my belief that Germany has lots of wild forest is wrong: it’s almost all heavily managed, young pine trees grown for lumber. The Germans are jealous of British old growth forests and think we routinely plan things for 500 years in the future.
But young trees aren’t necessarily bad trees. Another conversation with a Berlin beekeeper of one year’s experience revealed they had harvested 70kg of honey from just 2 hives. That’s a lot. Berlin has a very high water table, it is built on a drained swamp, and the larger trees (planted 50 years ago after burning all previous ones to keep warm when West Berlin was cut off) never need watering. Perhaps they provide more nectar than the trees in my area?
Jonathan Powell gave a talk on wild bees in trees, explaining how with really old oaks, their maximum biodiversity occurs when they die and are colonised by fungi, insects in cavities etc. So huge old dying / dead trees are the key for healthy forests, and foresters plan for the long term. He showed us pictures of some really massive old trees. It seemed that the German audience was not familiar with the idea of naming individual trees, e.g. when showing a photo of an 800 year old oak, “this one’s name is Stumpy”. Surveying an ancient British wood, he has found wild bee colonies spaced about 200m apart: he finds the bees are not pure Amm (Black Bees), and their varroa resistance is probably linked to their low numbers and stop/start method of breeding. The mites cannot flourish when there are no brood to parasitise, and the bees don’t need large colonies to keep warm in such heavily insulated environments.
“Luckily,” said Jonathan, “in the UK we are terrible at following advice, and there are thousands of non treaters. When I visit areas like Spain where mite treatments are mandatory, I find weak bees. Torben is right, unmanaged colonies are healthier.”
This was all new to the German audience who gave him and Torben (see below) rapturous applause.
Other hives on display
The common theme was a huge amount of insulation and thermal mass, to create a stable internal environment. I’ve covered log hives elsewhere, but it was the first time I’d noticed how the wooden “doors” are shaped so the bark goes down one edge, not the outside, to form a friction lock. I thought this was an elegant design feature.
Professor Tom Seeley’s talk on wild bee survival traits
I have covered Tom Seeley’s research in a previous post, so all I’ll say here is that he pioneered the systematic investigation of wild colonies, trialling colony survival with groups of control hives, and others which varied by one factor. Some key findings can be seen in the photo.
A subtlety I had missed before was about genetic bottlenecking in survivor colonies. He found that populations which survived varroa were descended from just a few queens (by examining mitochondrial DNA, passed down female lines). But the nuclear DNA showed almost as much variation as in the pre-varroa populations, i.e. male drones propagated and conserved the genetic heritage of the lines that “died out”. So unlike bee strains selected by breeders, who select drones from”desirable” queens, naturally selected survivor colonies do not suffer from inbreeding(!!!)
Torben Schiffer’s latest research
Gareth had already told us some of this at the last OxNatBees meeting, such as the multiple benefits of insulation. Torben has compared colonies in tree cavities with those in hives. He finds the survival rate of untreated (for varroa) bee colonies in Germany in conventional hives is exceedingly low, but put those same bees into bee-appropriate hives and the survival rate jumps to 60%.
(He is an excellent communicator. He rephrased this on another occasion: “I have given prime swarms from colonies in my hives to conventional beekeepers, telling them not to treat the bees, and they died in those hives. The beekeepers complained and I told them, it’s the same colony, it’s even the same queen, it’s your hive that killed them.”)
Now, here’s the new stuff. It’s simplest to explain by watching this 2 minute video, taken by Stefan Grunert who was in the audience when Torben told us of newly observed bee behaviours: https://www.youtube.com/watch?v=gUya5YxcmS0 .
This shows revolutionary video footage taken by Torben with an endoscope inside a hive. Apart from showing washboarding inside the hive, which appears to be a behaviour to spread propolis and suppress mould, it shows a web of bees hanging under the combs guarding against intruders. They react instantly and ball wasps pushed into the hive, and it’s suspected that they would also ball intruding hornets.
Think about that. Perhaps the only reason European bees are vulnerable to hornets is the European framed hive designs do not allow space for this behind the entrance.
This under-cavity may not be that critical if the entrance has other defenses, for example, comb right behind it where bees can cluster to repel invaders.
Torben warned about cold spots in a hive, like corners. Even if these are actually fairly warm, they can still become mouldy because they will get damp. That’s because, warm air can hold so much more water vapour than cold. When bees maximise humidity round the honey processing area (concentrating nectar via evaporation), if that saturated airstream hits a relatively colder spot the water will condense there. One the plus side, his work shows that if you allow propolis to build up, and the hive is well insulated so this is above 10C, the propolis vapour inhibits mould.
I also finally grasped the importance of thermal mass as well as insulation for a hive. For a normal well insulated hive, graphs showing internal temperature and humidity showed small fluctuations over a few minutes, as external conditions varied. But the conditions inside a massive tree’s cavity were much stabler, which obviously requires less effort for the bees to regulate. So a light cedar or polystyrene walled hive may be well insulated, but lacks the mass to smooth out these blips. Of course many hives have huge lumps of honeycomb in them which helps smooth conditions.
He has noticed that when bees build comb behind an entrance, which is normal in wild colonies, it is heavily propolised. He suspects this is to sterilise incoming air: tests with Petri dishes show the air in such nests appears to be sterile (not so in framed hives!). This made me think about the propolis-and-wax entrance reducers I’ve seen several stressed colonies build across their entrances…
The take home insight to me was that maybe the real reason my bees thrive has little to do with my husbandry, and is mainly dependent on how well their hives happen to support natural behaviour. They evolved for deep, well insulated wooden hollows and have many subtle behaviours which match such cavities’ properties. We were already sure a low intervention style helped, but in the last few years discoveries like how helpful brace comb is as an air baffle have explained why.
Near the end of the conference, it became obvious that the German attendees were fascinated and inspired by Torben. They mobbed him asking questions after his last lecture, where he wasn’t backward in stating what was wrong with conventional beehives!
Torben has a website (in German) here.
Other cool stuff
Geert Steelant had a laptop hooked up to a microscope showing predatory Stratiolelaps scimitus mites creeping around in compost. He has used them on the floors of his Dutch hives for 5 years to control varroa. He gave a 5 minute talk on this technique. Note that this is a different predator to the book scorpions Torben Schiffer has used for the same purpose in Germany (previously discussed here).
A Californian beekeeper told me about the “killer bees” they keep. In California, bees of unknown origin are generally classified as killer (Africanised) bees. But their colonies vary widely in colour, and seem calm enough. They pointed out that Africanised bees left Brazil in 1957, and only reached the USA in 1975. Their experience indicates that the whole “killer bee” reputation is media hyperbole, and the legendary super-aggression has been diluted out after decades of migrating north. Their bees don’t seem to have any problems with varroa or small hive beetle.
To kill a varroa mite, all a bee needs to do is chew its leg. The mite will then bleed to death.
It wasn’t as large as the event last year, but they did a decent job of broadening peoples’ horizons. This is particularly significant in Germany, which is arguably the centre of conventional beekeeping research, and has a more rigid approach to beekeeping than the UK. This is being challenged by a large group of alternative beekeepers, Mellifera eV, who were the prime organisers of this conference.
However, miticide treatments are mandatory, so Germany has lagged behind places like Holland where treatment is optional and varroa resistance is now widespread.
Or so I thought. It seems that some German beekeepers monitor their mite drop levels and find they are below the threshold for treatment, so they do not treat. And there are some wild bees in Germany, though most people claim there are not. Combined with the lectures on how bees live in natural cavities, and how these bees are healthier, my impression was this conference was a pivotal moment in German beekeeping. It opened the eyes of many to the bee health implications of intensively managing colonies, and how hive designs could be improved.
I could go on about hive types and things but the important point is that the German beekeepers were in a bit of a bubble: I saw almost none at last year’s conference in Holland, but now they are aware that there is much to learn on their doorstep.
I was interested to hear Buckfast bees are common in Germany, as their creator Brother Adam was German (though he lived in England).
Everyone was intense and thoughtful, there to learn. Everyone seemed to leave with a smile on their face. I certainly had a good time!
The next LfB conference will be in Dartington, Devon, England in 2020.