During the lockdown period of the COVID-19 pandemic in 2020, many pollination ecologists were stuck at home: universities and research institutes were closed and restrictions on travel meant that it was not possible to get out and do field work. In order to keep active and motivated, and to turn adversity into an opportunity, an ad hoc network of more than 70 researchers from 15 different countries (see the map above) decided to collect standardised data on the plant-pollinator networks in their own gardens and nearby public spaces.
When combined with information about location, size of garden, floral diversity, how the garden is managed, and so forth, this would provide some useful data about how gardens support pollinators. For those with kids at home it could also be a good way of getting them out into fresh air and giving them something to do!
The resulting data set of almost 47,000 visits by insects and birds to flowers, as well as information about flowers that were never visited, is freely available and will be an invaluable resource for pollination ecologists. For example, analysing the links between ornamental flowers that share pollinators with fruits and vegetables such as apples and beans, will allow us to make recommendations for the best plants to grow in home gardens that can increase yields of crops.
There’s an old saying about turning adversity into a positive outcome: “When life gives you lemons, make lemonade”, and the researchers were pleased to find that there’s one record of Citrus limon in the data set!
The paper describing the data set has just been published in the Journal of Pollination Ecology and you can download a PDF of the paper and the associated data for free by following this link.
Sincere thanks to all of my co-authors for their commitment to the project!
Over the weekend there was a discussion on Twitter about “beewashing” that was spun out of this tweet by London beekeeper Richard Glassborow. Richard and his colleagues are some of the most responsible beekeepers that I know and they are getting increasingly frustrated by claims from irresponsible companies that keeping a hive of bees in your garden will help to “save the bees”, backed up by spurious claims that “honeybee colonies are dying out”.
The Twitter exchange prompted me to produce the Condescending Wonka meme that you see above because, as I discussed in my recent book Pollinators & Pollination: Nature and Society, pollinator conservation is a really complex area. But there’s no doubt that beekeeping as it’s being widely promoted is not the answer to bee conservation. Let me explain why.
The word “honeybee” does not refer to just one species. It’s most often* applied to bees in the genus Apis, especially the Western Honeybee Apis mellifera, but there are another seven or so Apis species to which the word can be applied. Of those other Apis species, most have never been domesticated and they live as free-living colonies is the various parts of Asia where they evolved. Only Apis cerana is kept in hives, as far as I am aware. The conservation status of most of these other Apis species is unclear but given that they are predominantly forest species, and deforestation is a chronic problem in Asia, we can surmise that some species may be declining. If you want to know more about them the Wikipedia page is a good starting point.
In this short post I just want to consider the Western Honeybee (Apis mellifera). This is a really knotty species to get to grips with because there are multiple subspecies and within subspecies there are various genetic lineages. In addition, the Western Honeybee has been subject to artificial selection for desirable qualities, such as docility, amount of honey produced per hive, and disease resistance, as well as cross-breeding between different subspecies**. The best recent summary of our current understanding of Western Honeybee genetics and conservation is this 2019 review by Fabrice Requier and colleagues, from which I’ve drawn quite a bit of information.
For the purposes of this explaining what’s going on, it’s easiest to think about the species as comprising three “megapopulations”:
Western Honeybees that are managed in hives: For the most part these are not endangered. Britain has as many hives now as it did in the mid-1950s and indeed globally we have more hives than ever (about 90 million hives at the last count). They are found far beyond their natural range and have been introduced into places where they are not native such as the Americas, parts of Asia, and Australia. STATUS: doing just fine.
Western Honeybees that have founded “feral” colonies: These have escaped from hives in countries where they have been introduced and become naturalised. They are doing well, too well in fact: they are a significant conservation issue in places like Australia. STATUS: doing just fine.
Western Honeybees that are living wild in their native range: This is where things become a little muddier. The African populations of the various subspecies seem to be doing well, but more studies are needed to confirm this. In Europe, actually defining what constitutes “wild” honeybees across a region where a lot of selection and hybridization has gone on, probably for thousands of years, is tricky. However there’s no doubt that wild colonies of Apis mellifera are not uncommon in suitable woodland: see this paper about free-living colonies in Ireland by Keith Browne and colleagues, for instance. Note their statement that genetic evidence shows that “the free-living population sampled is largely comprised of pure A. m. mellifera“, i.e. the European Black Honeybee. STATUS: probably doing quite well though more data is needed.
Conclusion: as I said, it’s really complicated and I don’t pretend to have all of the answers, no one does. But what IS clear is that managed Western Honeybees are not declining and keeping yet more hives of them is not going to help us to “Save the Bees”. I’ll leave the last word to Requier et al., whose review I really do recommend: “We argue for the redirection of attention from managed honey bees to the neglected conservation of wild honey bees.” Amen to that.
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*The term “honeybee” is sometimes also used for other social bees that produce honey, for example stingless honeybees in the genus Trigona, but there’s no real consensus on what “honey” actually is, and as I’ve argued in another post, bumblebees (Bombus spp.) also produce honey.
If you’ve read my book Pollinators & Pollination: Nature and Society you’ll know that I have a section in the chapter “The shifting fates of pollinators” that deals with the honey bee situation. In that section I bring together the most comprehensive data set so far available on changes in number of hives in Britain. It’s based on a couple of earlier blog posts and if you’ve not read my book take a look at this one first and then this one to give you some context and more information about the sources of the data.
So far this year I have had several requests from people for the original data (which I’m happy to supply) and queries about what it means. So I thought that the time was right to update the graph with the latest official government figures from BeeBase.
The graph above brings the story up to 2021 where the official estimated number of hives is 272,631. That’s an increase of more than 40% since the first BeeBase estimate in 2015.
The take home from this figure is that the current number of honey bee hives in Britain is similar to what it was in the mid-1950s.
So the answer to the question “have honey bees declined in Britain?” is a resounding NO! They are at least as abundant as they were almost 70 years ago. This reflects the global situation where there’s been a substantial increase in hive numbers since the 1960s, as you can see in the figure below.
So if you want to “Save the Bees” or otherwise support pollinators, please focus on the wild, unmanaged species rather than the managed Western Honeybee (Apis mellifera). As always, comments and questions are welcome below or send me a message via my Contact page.
One of the projects with which I’ve been involved over the last year has been advising on a new book for children about bees and other pollinators, called Can We Really Help The Bees? Written by Katie Daynes and wonderfully illustrated by Róisín Hahessy, it tells the story of what happens when a swarm of bees comes to the window to let a group of children know that they, and their friends the other pollinators, are in trouble. Can they help? Yes they can!
It’s been a real pleasure working with Katie and Róisín on this project for Usborne Publishing and seeing the ideas, text, and illustrations evolve over time. I’ve written a short post over at the Usborne blog with some ideas about how to get children involved in helping the pollinators, and I think that it’s worth repeating one of the things that I wrote: everyone can make a difference to the wildlife around us and no one is too young to be involved!
Because of my involvement with Can We Really Help The Bees? I wasn’t able to include it on my curated list of the best books about bees and other pollinators at the Shepherd site. But it definitely should be on there and is highly recommended!
Recently Phil Stevenson and I advised on an art/science project called Minus Pollinators which considered what a small café menu might look like if there were no pollinators to help produce the many, many fruits and vegetables and nuts that are animal pollinated.
The project is a collaboration between writer and consultant Max Fraser and artist Freddie Yauner. To quote Freddie’s description on his website, the project represents:
A dystopian future in the form of a drinks kiosk where the staples such as coffee, teas, juices, chocolate etc. are no longer available due to pollinator decline…the mobile drinks kiosk acts as an exhibition display, with artworks painted in pollen…and a take-away pamphlet…detailing the importance of insect pollinators for our collective future on this planet.
Minus Pollinators was commissioned as part of a summer-long event called Food Forever at the Royal Botanic Gardens, Kew, after which it goes to the Groundswell festival.
It was a pleasure to work with Max, Freddie and Phil on this because art/science projects are a great way of getting the message across about the importance of biodiversity and the current environmental crisis that we are facing.
As kids, my friends and I did a lot of digging. We always seemed to be burrowing into slopes or excavating trenches, pretending to be archaeologists or treasure hunters. Indeed, there was a lot of ground treasure to be found in the part of Sunderland where I grew up. The area has a long history of pottery and glass making, and ship building, and the remnants of these industries could be uncovered every time we stuck a spade in the earth. Over time I developed my own small museum of interesting, unearthed fragments, including bits of hand-painted ceramics, glass bottles, and unidentifiable metal shards, alongside various animal bones I’d excavated. My parents quietly indulged this interest, and my muck-streaked face and clothes, even if they didn’t quite understand what I was doing.
Aged about 10, my first encounter with a bumblebee nest was during one such dig. On the waste ground behind a large advertising hoarding, we began digging into a low, grass-covered mound and accidentally excavated what was probably a small nest of Buff-tailed Bumblebees (Bombus terrestris). I can recall being fascinated by the waxy, odd shaped cells and by the sticky fluid that some of them were leaking. Being an adventurous sort of child I tasted the liquid: it was sweet and sticky, and that was my first encounter with bumblebee “honey”.
I’m going to leave those quotation marks in place because if you do an online search for “do bumblebees make honey?” you generally find that the answer is “no, only honey bees make honey”.
Now, defining honey as something made by honey bee strikes me as a circular argument at best. And it also neglects the “honey” made by meliponine bees that is central to the culture of stingless bee keeping by indigenous groups in Central and South America, and the long tradition pre-colonial tradition of honey hunting by Aboriginal Australians. So if we widen our definition of “honey” as being the nectar*-derived fluid stored in the nests of social bees, then Apis honey bees, stingless bees and bumblebees must all, by logic, make honey. And likewise there’s wasps in the genus Brachygastra from Central and South America that are referred to as “honey wasps” because, well, I’m sure you can work it out!
But this is where things become a little trickier, because turning nectar* into honey involves some complex evaporation and enzymatic activity, so that the resulting fluid is more concentrated and dominated by the sugars glucose and fructose. Although analysis of honey bee honey is commonplace, and there’s been some research conducted on the honey of stingless bees, I don’t know of any studies that have compared Bombus honey with that of other bees, or with what is stored in the nests of honey wasps**. If I’ve missed anything, please do comment and let me know, but this strikes me as an area of research demanding some attention.
So do bumblebees make honey? That very much depends on our definitions, but I’m happy to accept that they do because “honey” is not a single thing: it’s an insect-derived substance that can take a range of forms but serves the same broad purpose of feeding the colony. And although insects have probably been producing it for millions of years, I think I’ve known the answer to the question for almost 50 of them…
UPDATE: A couple of people have commented on social media that there are legal definitions of “honey” as a foodstuff. Here’s the definition according to UK law***:
“the natural sweet substance produced by Apis mellifera bees from the nectar of plants or from secretions of living parts of plants or excretions of plant-sucking insects on the living parts of plants which the bees collect, transform by combining with specific substances of their own, deposit, dehydrate, store and leave in honeycombs to ripen and mature”
So, legally, we can’t call anything that isn’t made by Apis mellifera “honey”, at least from a foodstuffs regulation perspective. But that’s clearly different to what we have been discussing above, which is about a biological definition of honey.
It’s also interesting to look at the compositional requirements of honey as a foodstuff (presented in Schedule one of that document, if you follow the link above). The lower limit for moisture content is 20%. Now if you consider that most nectar in flowers has a sugar content of between about 20% and 50%, clearly there’s been a lot of evaporative work done by the bees to reduce the amount of water in the honey. I would love to know how bumblebee (and other insect) “honey” compares to this: do they put the same kind of effort into evaporating the water from the stored nectar? Given that the purpose of reducing the water content is to prevent fermentation by yeasts when it’s stored for a long time, and that there are bumblebee species which have colonies that are active for more than one year, I imagine that at least some species in some parts of their range may employ similar tactics.
Thanks to everyone who has been commenting and discussing the topic. It never ceases to amaze me how much we still do not understand about some fundamental aspects of the natural history of familiar species!
*And honeydew to a greater or lesser extent.
**I’m going to ignore honey pot ants for now as this is complex enough as it is and they don’t store the “honey” in nest cells.
***From what I can gather definitions in other countries are similar.
First the misleading title. This ‘debunks’ claim actually compares two different things: 75% of CROPS being dependent on pollinators versus 10% of crop YIELD. However, even if we focus on the 10% claim, a small increase in yield can be the difference between profit and bankruptcy for small-scale farmers. And most of the world’s farmers are small-scale and living on the borderline between loss and break-even. In addition, there’s no acknowledgement of the food production from home gardens, allotments, and community gardens, which is significant but largely unquantified.
Next, by focusing on yield and comparing, say, wind-pollinated wheat with insect-pollinated apples, the article takes no account of the fact that many of these crops that depend to some extent on pollinators mainly provide essential vitamins and minerals – not calories – to diets. When I tweeted about this earlier in the week, one person commented that they describe the insect-pollinated foods as ‘an important source of flavour and colour in our diets, rice and wheat are all well and good, but you do kinda need something more than grey slop to live’. Another said: ‘I’m so glad you mentioned this. I’m sick of reading articles that praise innovations to increase calories, when what we need is better nutrition from vitamins, minerals & fibres’.
Both great points, and well made.
That essay was also factually incorrect when it described roots crops such as carrots or some of the leafy cabbages and lettuces as not requiring pollinators. Many varieties of these crops ARE pollinator dependent: how do they think we get the seed for the next year’s crop?! And there are many crops and varieties that have not been evaluated for their dependency on pollinators: the 75% figure actually refers to the 115 most productive crop plants (Klein et al. 2007).
When I tweeted about the essay I commented that I was very disappointed by ‘Our World in Data’ – they are usually better than this when it comes to the facts. What I hadn’t appreciated at the time was that in fact the Genetic Literacy Project had highjacked the original piece by Hannah Ritchie and reworked it to give it a very different slant*.
This is where it starts to get dishonest and in fact the Genetic Literacy Project (GLP) has form in this area. The Sourcewatch site describes the GLP as ‘a corporate front group that was formerly funded by Monsanto’ with a remit to ‘shame scientists and highlight information helpful to Monsanto and other chemical producers’. In other words it’s heavily tied to Big Agriculture which, of course, would like us to believe that there’s not an issue with declining pollinators, that pesticides and agricultural intensification are our friends, and that Everything Is OK. Read the full account here.
Frankly, the GLP is so tainted that I’d not believe anything that they publish.
Pollinator decline and the role of pollinators in agriculture are complex issues. If you’d like to know more about the importance of pollinators to agriculture, complete with some accurate and objective facts, then there’s a whole chapter devoted to the topic in my book Pollinators & Pollination: Nature and Society.
*Note that I’ve been communicating with Hannah about the root and leaf crop issue and she accepts that this needs to change in the original. She’s also asked the Genetic Literacy Project to take down their version as it contravenes copyright.
Reference
Klein, A.-M., Vaissière, B.E., Cane, J.H. et al. (2007) Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society of London B 274: 303–313.
As I mentioned in my previous post, it’s currently Invasive Species Week in the UK. Non-native species which have negative environmental impacts and disrupt infrastructure are a global phenomenon, of course, and almost all regions of the world have been impacted by species that originated elsewhere. One alien species that is of growing concern in Australia is the western honey bee Apis mellifera. We often think of bees as being relatively benign organisms, but a number of species have been introduced around the world and may compete with native species for nectar and pollen, and nesting sites.
In the second paper from my collaboration with Dr Kit Prendergast, we’ve assessed how introduced honey bees change the structure of bee-flower visitation networks in Australian urban habitats. The main finding is that when honey bees are common, they dominate these networks in ways that indicate significant competition with native bee species. You can get a sense of that from the figure above: the honey bees are in red, native bees in yellow, native plants in light green, and non-native plants in dark green. The length of the bars is proportional to the abundance of these plants and bees.
To say that honey bees ‘dominate’ these networks is an understatement: not only are they vastly more abundant than the other bees, but they visit almost all of the different types of flowers in the network, regardless of whether they are native or introduced.
Although the honey bee bullshit machine often claims that western honey bees are dying out, the exact opposite is true: across the world, managed Apis mellifera numbers are higher than ever, as you can see from the following chart based on figures from the United Nations Food and Agriculture Organization (UN-FAO):
Whilst the growth in honey bee numbers is a good thing for honey producers, bee farmers, and small-scale subsistence farmers, there are environmental consequences to the increase in hives, as we have shown.
If anyone wants a PDF of the paper, please use the Contactform. The full reference for the study and the abstract is:
The European honeybee Apis mellifera is a highly successful, abundant species and has been introduced into habitats across the globe. As a supergeneralist species, the European honeybee has the potential to disrupt pollination networks, especially in Australia, whose flora and fauna have co-evolved for millions of years. The role of honeybees in pollination networks in Australia has been little explored and has never been characterised in urban areas, which may favour this exotic species due to the proliferation of similarly exotic plant species which this hyper-generalist can utilise, unlike many native bee taxa. Here, we use a bipartite network approach to compare the roles, in terms of species-level properties, of honeybees with native bee taxa in bee-flower (‘pollination’) networks in an urbanised biodiversity hotspot. We also assessed whether the abundance of honeybees influences overall network structure. Pollination networks were created from surveys across seven residential gardens and seven urban native vegetation remnants conducted monthly during the spring-summer period over two years. There were consistent differences in species-level properties between bee taxa, with honeybees often differing from all other native bees. Honeybees had significant impacts on network properties, being associated with higher nestedness, extinction slopes of plants, functional complementarity and niche overlap (year two), as well as lower weighted connectance and generalisation. These associations all are indicative that competition is occurring between the introduced honeybee and the native bee taxa in bee-flower networks. In conclusion, the introduced honeybee occupies a dominant, distinct position in bee-flower networks in urban habitats in the southwest Western Australian biodiversity hotspot
Humans affect the land on which they live in many different ways, and this in turn influences local biodiversity. Sometimes this has positive effects on local wildlife: consider the diversity of birds to be found in well-managed suburban gardens, for example. But often the effect is negative, especially when the land is intensively managed or habitats are destroyed, for example via deforestation or urban development.
This is not a new phenomenon – according to a recent study, most of the habitable parts of the planet have been shaped by humans for at least 12,000 years (see Ellis et al. 2021). What is new, however, is the scale and the speed with which land-use is changing, which are far greater than they have been historically. An important question is the extent to which this change in land-use intensity is affecting pollinator diversity in different parts of the world. Over the past 18 months I’ve been collaborating on a project led by Joe Millard (as part of his PhD) and Tim Newbold which uses the Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (PREDICTS) database to address that very question.
A paper from that collaboration is published today in the journal Nature Communications; it’s open access and can be downloaded by following this link.
The study was global in scale and used data from 12,170 sites to assess the affect of land-use intensity on 4502 pollinating species. The findings are really fascinating; highlights include:
In comparison to natural vegetation, low levels of land-use intensity can have a positive effect on the diversity of pollinators.
For most land categories, greater intensity of land-use results in significant reductions in diversity and abundance of pollinators, however. For example, for urban sites there’s a 43% drop in number of species and a drop in 62% pollinator abundance from the least to the most intensive urban sites.
On cropland, strong negative responses of pollinators to increasing intensity are only found in tropical areas, although different taxonomic groups vary in their responses.
The latter finding is especially concerning given that: (i) most pollinator diversity is found in the tropics; (ii) the majority of tropical crops are insect pollinated; and (3) tropical agriculture is becoming increasingly intensive and land use is likely to rapidly change in the coming decades.
The full reference for the study, with all authors, is:
Millard, J., Outhwaite, C.L., Kinnersley, R., Freeman, R., Gregory, R.D., Adedoja, O., Gavini, S., Kioko, E., Kuhlmann, M., Ollerton, J., Ren, Z.-X. & Newbold, T. (2021) Global effects of land-use intensity on local pollinator biodiversity. Nature Communications 12, 2902. https://doi.org/10.1038/s41467-021-23228-3
As I write a slow haze of fine snow is falling, covering our garden with a thin white dusting. Spring feels a long way off, despite the emerging spears of daffodil leaves. But you can get a taste of what the new season will bring by signing up for a short series of free evening online talks on the topic of pollinators that has been organised by the Yorkshire Dales Millennium Trust – here’s the link for the Bee Together programme – and here’s more details of the talks:
Thursday January 28 at 7pm: Pollinators and Pollination: Nature and Society An overview of the diversity of pollinators in Britain, why they are important, and the threats to that diversity with Jeff Ollerton.
Thursday February 18 (7pm): The B-Lines Project Buglife’s B-Lines network is an imaginative solution to the problem of the loss of flowers and pollinators. B-Lines are a series of ‘insect pathways’ running through our countryside and towns, along which Buglife are restoring and creating a series of wildflower-rich habitat stepping stones. Catherine Jones talks about mapping the recently completed B-Lines map and some of the projects that have already created habitat for pollinators.
Thursday February 25 (7pm): The Hidden Lives of Garden Bees Brigit Strawbridge Howard will explain some of the basic differences between bumblebees, solitary bees, and honeybees – including lifecycles and nesting behaviour; the problems they all face; and, most important, what we can do to help. Brigit is a wildlife gardener, amateur naturalist and advocate of bees. She writes and campaigns to raise awareness of the importance of native wild bees, and is the author of Dancing with Bees: A Journey Back to Nature.
I hope to see some of you there: Happy New Year everyone!
Prof. Jeff Ollerton - ecological scientist and author 