On a trip to the Royal Botanic Gardens Sydney yesterday Karin and I came across an interesting colonial-era statue in which a colony of feral, non-native honey bees had taken up residence. These bees are yet another alien invasive species that can create conservation problems in parts of the world where they don’t belong naturally. But it was funny enough to inspire a bit of Ogden Nash-style poetry on Twitter; you need to watch the video to fully appreciate it:
Category Archives: Bees
Following on from my post last week on historical changes in honey bee numbers in Britain, I decided to add the two extra, earlier data points to the graph just to illustrate what they mean for our understanding in how honey bee numbers may (or may not) have changed over the last 100 years.
The first data point is the Bailey & Perry (1982) estimate of 800,000 hives in the 1920s (which I’ve placed at 1929) that, as I mentioned, I think is wrong in terms of how they did the calculation.
The second data point is of 32,500 hives in 1919. It’s from the article that Andrew Hubbard drew my attention to, which seems to be a fairly solid government statistic, or at least no less solid that much of the other government stats (unless anyone knows any better).
If we accept the 800,000 figure at face value then we see a massive increase in number of hives of over 76,000 new hives per year between 1919 and 1929. And remember that’s being conservative as to what “the 1920s” meant to Bailey & Perry; if we peg the date at 1925 then we’re talking more than 127,000 hives being added to the British stock every year. In my opinion that’s not a feasible proposition.
A much more likely scenario is that the number of hives grew during the second quarter of the 20th century and reached a peak in numbers at some point between the 1940s and 1950s. That’s an increase of around 13,000 hives per year. It’s still a lot, but is not unreasonable in light of post-World War 1, and subsequently World War 2, agricultural reforms that I highlighted in my post about British bee and flower-visiting wasp extinctions. I’ve termed that “Jeff’s speculation” in the figure above because, in the absence of hard data, that’s all it can be.
As always, I welcome your comments.
Last week the Israeli bee taxonomist Achik Dorchin published a new paper entitled “Taxonomic revision of the aequata-group of the subgenus Eucera s. str (Hymenoptera, Apidae, Eucerini)” . The paper focuses on a little-known group of “longhorn” bees from the Eastern Mediterranean region, a part of the world with an extraordinarily high bee diversity. In this taxonomic account, Achik has named two bees new to science in honour of two pollination biologists:
Eucera dafnii is named by Achik for Prof. Amots Dafni, whom he describes as his “teacher and friend…a pioneer pollination ecologist of the Mediterranean region, who has led the research project during which much of the type series was discovered”. Amots is almost legendary in the field, he’s been conducting research on the flora, fauna, and pollination ecology of the region since the late 1960s, and remains a productive and influential scientist.
Eucera wattsi is named in honour of Dr Stella Watts, “a talented pollination ecologist, who collected much of the type series and contributed important floral observation and palynological data for this study”. Stella completed her PhD at the University of Northampton in 2008, with a thesis on “Plant-flower visitor interactions in the Sacred Valley of Peru”, and then went on to do a post doc with Amots in Israel.
It’s fitting that these bees are named in their honour: congratulations Amots and Stella!
UPDATE: On Twitter, Andrew Hubbard kindly drew my attention to the short article from 1919 at the bottom of this post in which it was estimated that British bee stocks at the time were as low as 32,500 hives. As Andrew pointed out, this means that the estimate by Bailey and Perry of 800,000 hives in the 1920s cannot be correct.
In one of the chapters of the book that I’m currently completing I deal with the question of the evidence for changes in the abundance and diversity of pollinators over time, both in Britain and globally. Are we really in danger of losing most of our pollinator species? Have honey bee numbers plummeted? Has pollination of wild and crop plants been affected? The evidence is mixed and too complex to deal with in a short blog post: you’ll have to read the book 🙂 However I want to present some data that I’ve collated on changes in honey bee hives in Britain to gauge opinions on what has gone on. I’m not a specialist in bee keeping by any means, others are far more knowledgeable, so as always I’d be interested in peoples’ thoughts on this.
The graph above has been pieced together from data presented in various sources – see below. From a post-WW2 peak of about 450,000 hives, numbers dropped to about 150,000 hives in the 1970s. That seems very clear. Numbers remained fairly stable until the early 1990s and then….what? There are two possibilities: either numbers of hives crashed to fewer than 100,000 by 2008; or they increased hugely to more than 250,000. Both scenarios cannot be correct!
There are huge uncertainties about the data during this period, however the most recent data from Defra is fairly solid, though it does require beekeepers to register their hives on BeeBase. Given the wide range of the low and high estimates, the fact that bee keeping has become more popular over the past decade, and that the recent data sit more-or-less within this range (at least initially), I wonder whether honey bee numbers have actually remained quite stable over the past 25 years or so, and indeed have hovered around the 150,000 hives or so since the 1970s.
Of course an alternative scenario is that the varroa mite (which arrived in Britain in 1992) led to that huge collapse in bee numbers. But I wonder if there’s really any evidence for that? Were whole apiaries wiped out by varroa? It’s notable that the decline in this period started much earlier than the arrival of varroa, in 1985. Why was that?
The earliest data available are those in Bailey & Perry (1982 – Bulletin of Entomological Research 72: 655-662) that span 1946-1982. This should be fairly accurate for England and Wales, though their estimate of 800,000 hives in the 1920s needs to be treated with caution as they make a number of assumptions in their regression-based analysis that may be incorrect; I’ve therefore not included that data point on the graph. Unfortunately the UK stopped returning official numbers of hives to the United Nations’ Food and Agriculture Organisation (UN-FAO) in 1977, and their data up to 1987 is an unofficial estimate (http://www.fao.org/faostat/en/#home). From 2003 the UK had to report bee hive numbers to the European Union to claim money for the National Apiculture Programme (https://ec.europa.eu/agriculture/sites/agriculture/files/honey/programmes/programmes_en.pdf), but the figures were rather suspiciously constant between years. More recently beekeepers have been encouraged to register their hives with BeeBase (http://www.nationalbeeunit.com/) and hopefully these estimates are more realistic.
Data for part of this period were also presented in Potts, S.G. et al. (2010) Declines of managed honeybees and beekeepers in Europe? J. Apic. Res. 49, 15–22 Thanks to Prof. Simon Potts for sharing the data from that study.
UPDATE: I should really have linked to Charlotte de Keyzer’s “bee-washing” site – https://www.bee-washing.com/ – it’s making much the same argument in a more comprehensive and elegant way. That’s what happens when you post blogs first thing in the morning before the (bee pollinated!) coffee has properly kicked your brain into gear…..
I am fond of new words – neologisms – and if pollinators can be included, so much the better. For example see my recent post about autobeeography. That refers to memoirs which focus around work or encounters with bees, of course. So here’s a new one: “beexploitation”.
Beexploitaton is a play on “blaxpoitation“ of course, and refers to articles, campaigns, social media, etc., that seeks to make financial or reputational gain from making wild and unsubstantiated claims about pollinators, most often honeybees. Here’s an egregious example that caught my eye this morning and stimulated this post: https://www.boredpanda.com/influencer-bee-b-fondation-de-france/
Worryingly, this is set up by the French Government and is aimed at raising money from well meaning people to “save the bees”. But it’s full of nonsense claims such as that bees pollinate cocoa plants to give us chocolate. They don’t – the pollinators of cocoa are primarily, perhaps exclusively, small flies. There are other errors too and we know that honeybees, globally, are not as important as wild pollinators for crop plants. We need to highlight and critique this sort of rubbish because it diverts money and attention away from genuinely well thought out initiatives to conserve pollinators.
As always, I’m happy to receive comments and other examples of beexploitation.
In the post today I was pleased to find a copy of Brigit Strawbridge Howard’s first book Dancing With Bees that she had kindly signed and sent after I reviewed some of the text. It was great timing – I’ve just finished Mark Cocker’s Our Place, a really important historical and future road map of how Britain got to its present position of denuded and declining biodiversity, and what we can do to halt and reverse it. Highly recommended for anyone interested in environmental politics and action. So Brigit’s book will be added to the pile on my bedside table and may be next in line, though I still haven’t finished Dave Goulson’s The Garden Jungle – perhaps I will do that before I start Dancing With Bees?
And thereby lies a problem – there’s just too many interesting books to read at the moment if you are interested in the environment, or indeed even just in pollinators. Because a new genre of writing seems to be emerging that I call “auto-bee-ography”. A number of writers are using bees to frame their memoirs and anecdotes. Dave’s trilogy of Buzz in the Meadow, Sting in the Tale, and Bee Quest is probably the best known. Then there’s Buzz by Thor Hanson; Following the Wild Bees by Thomas Seeley; Bees-at-Law byNoël Sweeney; Keeping the Bees by Laurence Packer; Bee Time by Mark Winston; Bees Make the Best Pets by Jack Mingo; Buzz: Urban Beekeeping and the Power of the Bee
by Lisa Jean Moore and Mary Kosut; The Secrets of Bees by Michael Weiler; and The Bumblebee Flies Anyway by Kate Bradbury.
All of these books fall more-or-less into the category of auto-bee-ography, and I’m sure there are others that I’ve missed (feel free to add to the list in the comments below). They follow a strong tradition in natural history and environmental writing of using encounters with particular groups of organisms, for example birds and plants, as a way of exploring wider themes Which is great, the more high profile we can make all of these organisms, including pollinators, the better in my opinion*.
However there’s not enough written about the other pollinators, that does seem to be a gap in the literature. Mike Shanahan’s Ladders to Heaven has a lot about his encounters with figs and their pollinating wasps, but that’s about it, unless I’ve missed some? Perhaps in the future I’ll write something auto-fly-ographical called No Flies on Me. But before that, look out for Pollinators and Pollination: nature and society which I’m currently completing for Pelagic Publishing. It should be out in Spring 2020.
*Though not in everyone’s – I had a very interesting discussion on Twitter with some other ecologists recently about whether pollinators had too high a profile compared to organisms that perform other functional roles in ecosystems such as seed dispersers. You can follow the thread from here: https://twitter.com/JMBecologist/status/1165565465705496576
The book I’m currently completing is going to have a list of useful websites with information about bees and other pollinators, and pollination itself, that are not written in English. Following a shout-out on Twitter I’ve come up with the following list – can anyone add to it? There’s a lot of countries/languages missing. Please respond in the comments section or send me an email:
With thanks to everyone on Twitter who responded.
One of our Christmas presents from Karin’s son (my stepson) Oli and his girlfriend Kate was an “experience” – a chance to spend half a day with an urban beekeeping collective in London called Bee Urban. The group has a partnership with Hiver Beer which uses its honey in its brewing, and we were promised a tasting session. Bees, beer, London – what’s not to like? Karin and I finally made the trip down to Kennington yesterday and it was a really enjoyable experience, highly recommended. I know a little bit about beekeeping but it was great to see a small professional apiary at work and to take part in a hive examination. It certainly deepened my appreciation of these remarkable insects. It also made me think about having a hive or two when I retire and have the time to devote to the hobby – beekeeping is not to be entered into lightly! However there’s a time and a place for honeybees: in the wrong setting they can be a conservation problem by negatively affecting plant reproduction, out-competing native bees and passing on their diseases to bumblebees.
Bee Urban, however, is also doing its bit for wild bees in London by providing opportunities, such as drilled logs, for cavity nesting species. We saw lots of evidence that leaf-cutting bees (Megachile spp.) and those that seal their nests with mud (various genera) were taking advantage of these nesting sites.
Interestingly, one of the other attendees said at the outset that she was very scared of bees. I asked her afterwards if seeing beekeeping up close had helped and she said it had. Perhaps this is something that you could do with any insectophobes in your life?
The beer was great, by the way, also highly recommended!
Below are some pictures from the day. Thanks to Lena and Barnaby for hosting us and making it such an enjoyable experience.
When she saw this picture, Karin likened it to cult devotees attending a ritual – “All Hail the Bee Goddess!”:
Karin and I get up close and personal with the bees:
A real highlight of the day – seeing the queen of this hive (marked in red):
Yum! – :
Drilled logs being used by leaf-cutting bees (Megachile spp.):
This past week I’ve been hosting a postgraduate researcher from the University of New South Wales in Australia. Zoe Xirocostas has been recruited to work on a project on which I’m a collaborating with Prof. Angela Moles and Dr Stephen Bonser (University of New South Wales) and Dr Raghu Sathyamurthy (CSIRO). It’s funded by the Australian Research Council and will run from 2019-2022.
Zoe’s PhD is about understanding the role of herbivores and pollinators in determining how plant species native to Europe have become invasive in Australia. She arrived with a wish-list of species that she wants to study at sites in the UK (Northampton), Spain, Estonia, France and Austria, in order to compare them with populations in Australia. One of those species was small-flowered catchfly (Silene gallica), a plant that I hadn’t seen in Northamptonshire. The NBN Atlas account for the species shows almost no records for central England and when I checked the Northamptonshire Flora it stated that the species had last been recorded in the county in 1843. Clearly this was not a plant we could study for this phase of the project. Or so we thought.
By coincidence, the week of Zoe’s preliminary fieldwork coincided with two days of surveys of the University of Northampton’s new Waterside Campus by staff and students. This is part of an ongoing project to understand how the development has affected local biodiversity. Friday was to be the last spring bird survey of the season (see this recent post updating that project) and Thursday was to be devoted to plants and bees.
To help with this we had the assistance of two County Recorders: Ryan Clark for the bees and Brian Laney for the plants, both hugely knowledgeable and enthusiastic about Northamptonshire’s. We started the surveys on an area of short-cropped, species-rich turf that is being maintained by a combination of rabbit and Canada goose grazing:
In no time at all Brian had racked up dozens of plant species; it’s really a very rich site indeed. Bees were fewer and further between, but after an hour we had a list of about 10 species, including one of my favourites, the ashy mining bee:
Zoe and her field assistant Susmita were busy bagging flower heads for the pollination experiments when suddenly we heard an excited shout from Brian. He had moved on to look at some plants that were coming up in a disturbed area of ground some distance away. Unbelievably, Brian had found small-flowered catchfly! More than 170 years after it had last been record in the county. On our campus! We rushed over to take a look, and there it was, near a path that Zoe and I had walked just a couple of days before and completely failed to spot it. In our defence, although it is striking in close up (see the image at the top of this post) it hides itself very well among other plants:
An amazing discovery! But what is this plant doing here? The answer is that small-flowered catchfly is an annual species of disturbed areas, it requires soil to be turned over in order to allow its seeds to germinate from the soil seed bank. The construction work on the site has involved moving around hundreds of tons of soil and this has provided ideal conditions for the plant and for many others that are associated with this kind of habitat. The challenge now will be to work with the university’s estates department to decide on a management plan that involves regular rotovating of that area. That shouldn’t be too hard, they are as keen to maximise the biodiversity of the campus as we are.
The natural world is full of surprises, especially “lost” species turning up unexpectedly. Soil seed banks for some species can be very persistent, with seeds remaining dormant for decades or even hundreds of years until conditions are right for germination. It’s very satisfying to be present at just the right time to see it happen!
To finish here’s a shot of the survey team, minus one member (Vivienne) who had to leave early; from left to right – Ryan, me, Brian, Susmita Aown, Duncan McCollin, Zoe, Janet Jackson:
Pollinators such as bees and butterflies are highly dependent on flowers to provide nectar as food; at the same time, those plants are reliant on the pollinators for reproduction. Over the past few decades, declines in both flower and pollinator diversity and abundance have prompted ecologists to wonder about the consequences of flower loss for pollinator communities and for plant pollination.
In a ground breaking new study, a team from institutions in the Czech Republic and the University of Northampton in the UK have published the results of experiments that seek to answer these questions. Led by PhD researcher Dr Paolo Biella, the team performed experiments in both countries that involved temporarily removing thousands of flower heads from grassland plant communities. They assessed how the pollinator assemblage responded to their removal, and how effectively the remaining flowers were pollinated. The team focused on generalist plant species that support the majority of pollinators within a community because these have traditionally been less well studied than highly specialised relationships.
The results are published today in the open access journal Scientific Reports and provide the first demonstration of the ways in which pollinators flexibly adjust their behaviour when faced with a sequential loss of resources. This flexibility is constrained by the type of flowers they visit, however: pollinators will tend to switch to flowers of a similar shape to the ones that have been lost. From the plant’s perspective, things are less clear: the patterns of pollination for the remaining species were idiosyncratic and not as predictable. Some plants received more pollination during the experiment than before, others less.
For the first time we are seeing the consequences of sudden loss of flowers for both the pollinators and the plants in a habitat. That the pollinators can respond flexibly to this loss is a welcome indication that these insects might be more resilient to sudden changes than we had thought. However, the erratic pollination of the flowers shows that there is a great deal of random chance within these ecological systems that is not easily predictable. In the same week that the UN’s Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Global Assessment Report on Biodiversity and Ecosystem Services was published, our study reminds us that there is much that we do not currently understand about the consequences of sudden changes in the natural world.
One of the team’s recommendations is that pollination-generalist plant species should be given much more attention in conservation assessments than has previously been the case. These plants are at the core of plant-pollinator communities and without them the rarer and more specialised species could not exist.
Details of the study are as follows:
Biella P., Akter A., Ollerton J., Tarrant S., Janeček Š., Jersáková J. & Klecka J. (2019) Experimental loss of generalist plants reveals alterations in plant-pollinator interactions and a constrained flexibility of foraging. Scientific Reports 9: 1-13
Here’s the abstract:
Species extinctions undermine ecosystem functioning, with the loss of a small subset of functionally important species having a disproportionate impact. However, little is known about the effects of species loss on plant-pollinator interactions. We addressed this issue in a field experiment by removing the plant species with the highest visitation frequency, then measuring the impact of plant removal on flower visitation, pollinator effectiveness and insect foraging in several sites. Our results show that total visitation decreased exponentially after removing 1-4 most visited plants, suggesting that these plants could benefit co-occurring ones by maintaining high flower visitor abundances. Although we found large variation among plant species, the redistribution of the pollinator guild affected mostly the other plants with high visitor richness. Also, the plant traits mediated the effect of removal on flower visitation; while visitation of plants which had smaller inflorescences and more sugar per flower increased after removal, flower visitors did not switch between flower shapes and visitation decreased mostly in plants visited by many morpho-species of flower visitors. Together, these results suggest that the potential adaptive foraging was constrained by flower traits. Moreover, pollinator effectiveness fluctuated but was not directly linked to changes of flower visitation. In conclusion, it seems that the loss of generalist plants alters plant-pollinator interactions by decreasing pollinator abundance with implications for pollination and insect foraging. Therefore, generalist plants have high conservation value because they sustain the complex pattern of plant-pollinator interactions.