Reading The Barefoot Keeper, inspired me to do some further reading of scientific papers on honeybees with the aim of trying to understand how I need to adapt the classical methods I had been taught on courses and in beekeeping manuals.
One of the key issues raised in The Barefoot Beekeeper was the use of pre-printed wax foundation. In his book, Philip states that, given the opportunity honeybees will “build slightly smaller worker cells than those dictated by the preformed sheets of foundation, used in framed hives”. Philip goes on to say “according to the observations of a several long-time top bar beekeepers, these smaller cells appear to be less attractive to Varroa mites.”
Crikey. If this is true, that’s important to know. But was there any rigorous, scientific research into these issues? I am shifting my reading from beekeeping manuals to science papers.
Scientific Papers
So where does one find the evidence? I made contact with a leading academic in honeybee health and he pointed me in the direction of Google Scholar and SpringerLink. The ApiNews Beekeeping Research page publishes new research every week. The International Bee Research Association publishes research.
I have only had a limited amount of time, but my searches on keywords like “varroa destructor” and “brood cell size” have already yielded interesting papers (like the ones described at the end of this post). What I have read so far led me to understand:
- Dusting honeybees with icing sugar does not reduce varroa destructor (Whoa!! I was not expecting this. Numerous experts had told me this was effective – and this evidence has been known since at least 2009. See papers below.)
- Natural selection in some wild colonies has helped improve mite resistance (not forgetting that many wild colonies have died due to varroa infestation)
- Small-cell combs do not inhibit varroa mite reproduction
Evidence-Based Beekeeping
So, what does this initial research mean for how I keep bees? Is there enough evidence here on which to base my beekeeping practices? I’m not sure. But if you want to join me on this journey, follow this blog (top right of screen) and you’ll find out what happens. In the meantime, read on …
Dusting Bees With Icing Sugar
I might as well stop. The evidence is pretty clear and on reading the FERA guides on varroa again, I notice there is no mention of icing sugar.
Natural Selection
It seems that if I don’t get involved in artificially selecting the Queen then my colonies might become better at resisting or living with varroa. But that said, how much can I (novice beekeeper) influence gene selection of my honeybees? Not a lot.
Action:
- Perhaps at some point in the future look into Queen breeding for positive characteristics such as: productivity, not swarming, naturally resistant/hygienic to varroa mites – but not for the time being
Natural Comb
I like the idea of natural comb in the brood box. I like the idea that the bees make their own sized cells, but evidence suggests this does not impact on the level of varroa infestation. In The Barefoot Beekeeper, Philip, suggests that it is possible that there are less pesticide residues in new comb, as opposed to the recycled wax in foundation that we buy.
Actions:
- None
Summary Of Research
My reading of scientific papers has only just started. I have only “read” Seven so far, two in full and five abstracts. So in the scale of things, this is very little. If there are other useful scientific papers you think I should read, please let me know.
Here is a summary of the seven papers including links:
2012 Paper (link / pdf of full article): Host adaptations reduce the reproductive success of Varroa destructor in two distinct European honey bee populations; authors: Barbara Locke, Yves Le Conte, Didier Crauser, Ingemar Fries (Ecology and Evolution, Volume 2, Issue 6, pages 1144–1150, June 2012)
A key sentence in this article is “Besides suppressing mite reproduction, both Varroa resistant European honey bee populations in this study also share the fact that they have been unmanaged, enabling natural selection (as opposed to artificial) to shape the evolution of their mite resistance. This is an important consideration since it highlights the impact that apicultural practices otherwise have on these host–parasite interactions (Fries and Camazine 2001), suggesting a human interference in coevolution between species.”
There is a good reading list at the end of this paper.
2011 Paper (link): Small-cell comb does not control Varroa mites in colonies of honeybees of European origin
I have not paid for the full article but the abstract concludes, “We suggest that providing small-cell combs did not inhibit mite reproduction because the fill factor (thorax width/cell width) was only slightly higher in the small cells than in the standard cells (79% and 73%, respectively).”
2010 Paper (link): Brood-cell size has no influence on the population dynamics of Varroa destructor mites in the native western honey bee, Apis mellifera mellifera
I have not paid for the full article but the abstract concludes, “there is no evidence that small-cell foundation would help to contain the growth of the mite population in honeybee colonies and hence its use as a control method would not be proposed. “
2010 Paper (link): Brood cell size of Apis mellifera modifies the reproductive behavior of Varroa destructor
I have not paid for the full article but the abstract concludes, “No significant correlation was observed between brood cell width and number of offspring of V. destructor. Infertile mother mites were more frequent in narrower brood cells.”
2009 Paper (link): The efficacy of small cell foundation as a varroa mite ( Varroa destructor ) control
I have not paid for the full article but the abstract concludes, “We found no evidence that small cell foundation was beneficial with regard to varroa control under the tested conditions in Florida.”
2009 Paper (link): The efficacy of dusting honey bee colonies with powdered sugar to reduce varroa mite populations
I have not paid for the full article but the abstract concludes, “Within the limits of our study and at the application rates used, we did not find that dusting colonies with powdered sugar afforded significant varroa control”. I.e. It had no effect in the conditions they used. Crikey. Now there’s a surprise. The researchers dusted every two weeks for 11 months with 120 g powdered sugar per application. They treated by sifting icing sugar over the top bars of the brood nest and then brushing it between the frames. That’s how I’ve been doing it!
2001 Paper (link / pdf): Effectiveness of confectioner sugar dusting to knock down Varroa destructor from adult honey bees in laboratory trials
I have attached the full paper. I thought it worth including this paper, as it is probably the origin of all the icing sugar dusting that has been going on. It seems that in lab conditions varroa are knocked off but please see the 2009 paper above for evidence of what happens in real life conditions (or at least conditions similar to how I have been treating varroa).
There are also some interesting papers on using biological plants extracts and essentials oils to reduce varroa but this area needs more research:
- Repellent and acaricidal effects of botanical extracts on Varroa destructor (2011): link
- Biological activity of some plant essential oils against Varroa destructor (2011): link
Future
I am going to start developing an Evidence-Based Beekeeping page. I will rely on blog readers to improve my amateur notes.
If there are any other useful scientific papers, please let me know. I will read them and see what conclusions I can draw or we can all draw. Alternatively, please let me know what the conclusions are!
If you would like to be one of the first to receive this new page, please follow this blog.
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An evidence-based beekeeping page is a great idea, Roger! Emily and me heard an interesting theory about drones and varroa at the weekend. A beekeeper at our apiary, Thomas, lets his bees make their own comb and noticed that they like to make 20% drone. He doesn’t like to cull his drone either and thinks that the drone mop up the varroa, otherwise without them the mites would feed on the workers. Look forward to hearing what you think about those papers.
I like the way you’re going, it’s always a good idea to question what we’re told and rely on the scientific evidence to guide us in the right direction.
When I’ve been to talks by FERA bee inspectors they have cautioned that using icing sugar dusting alone as a varroa control method is not enough. It can only affect the thoretic mites feeding on the bees, which in the summer is only a small percentage of the mite population. There’s no harm in doing it during warm weather, but don’t expect it to knock back mite numbers much.
I haven’t trried in brood box but 1 thing i have done is to have a mix of starter strips and foundation in my supers as an initial experiment to see the difference in comb produced. Of course it also gives me the advatage of having some cut comb to harvest, yum!
I will follow yiur experiment with brood starter strips with interest.
Roger,
I have started going the foundationless frame route. It was hard to get one of my hives to draw out straight wax. My teacher, Serge Labesque, suggests that putting a foundationless frame between two frames of either capped honey or capped brood will help them to draw out straighter. I want to do this also because I want less pesticides and residues from bought wax foundation too.
I only did the sugar dusting method the first year we had bees. I know what I’m about to say isn’t scientific, but the bees didn’t lie it. They were mad.
Glad to have found your website.
Thanks Mil. Sounds like we are trying similar approaches. Stay in touch.
I too was thinking about not using foundation on my hives when I started at the end of last summer, my motive was slightly different to yours. I’d worried about contamination in the foundation on sale. In the end I didn’t go for it because I’m using 14×12 and I was more concerned about the combs holding up to inspection especially in the hot weather!
But I’d be interested to read more about your experiments. Incidentally I knocked up a few empty super frames and put these in between the drawn pre-foundationed ones and due to the hot weather and nectar flow the bees have started drawing down comb on 2 of them – and i didn’t even start them off with any wax strips!
I will have to read some papers around this. I don’t know if there is more contamination in foundation (because it is recycled, but they might reduce contamination in the process) or new comb (they might bring in more pesticides)? In the scale of things, on a typical frame, I guess there is less foundation wax than there is drawn comb wax, which might mean it is not a critical issue? In summary, I need to read more to understand the science.
I believe the issue with using bought foundation is that the wax has been found to contain pesticides that have been banned for many years. If I remember correctly, even ones that were banned a couple of decades ago.
Allowing your bees to draw their own comb will minimize their exposure to chemicals that have been banned for years.
However, you need to consider the length of time these chemicals may persist in the environment and unscrupulous people who may have remnants of these pesticides/fungicides, etc. and will still apply them.
Wax is the hive’s filter, it retains most of the bad stuff. This is why it is recommended to cull old wax combs every few years.
This is the main reason they recommend