2 More than just bees: the diversity of pollinators
3 To be a flower
4 Fidelity and promiscuity in Darwin’s entangled bank
5 The evolution of pollination strategies
6 A matter of time: from daily cycles to climate change
7 Agricultural perspectives
8 Urban environments
9 The significance of gardens
10 The shifting fates of pollinators
11 New bees on the block
12 Managing, restoring and connecting habitats
13 The politics of pollination
14 Studying pollinators and pollination
As you can see it’s a very wide-ranging overview of the subject, and written to be accessible to both specialists and non-specialists alike. To quote what I wrote in the Preface:
“While the book is aimed at a very broad audience, and is intended to be comprehensible to anyone with an interest in science and the environment, and their intersection with human societies, I hope it will also be of interest to those dealing professionally with plants and pollinators. The subject is vast, and those working on bee or hoverfly biology, for example, or plant reproductive ecology, may learn something new about topics adjacent to their specialisms. I certainly learned a lot from writing the book.”
The book is about 100,000 words in length, lots of illustrations, and there will be an index. My copy editor reckons there’s 450 references cited, though I haven’t counted. I do know that they run to 28 pages in the manuscript, and that’s with 11pt text. All going well it will be published before Christmas.
The Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire has invited me to run my Introduction to Pollinators and Pollination workshop again this year, but of course it will all be online. Details for signing up are on the images, or you can follow this link.
Here’s a description of the workshop:
Pollination of flowers ensures the reproduction of most British wild plants and many of our agricultural crops. This session will provide an introduction to the natural history of pollinators and how they interact with the flowers that they pollinate. The main groups of pollinators will be introduced, with guidance on how to identify them, and their ecology and behaviour will be explored. The session will also consider why conserving these species is so important, followed by a Q and A discussion showing what individuals can do to help ensure their future diversity and abundance.
As I near completion of the copy-editing phase of my forthcoming book it’s frustrating to see all of the great research that’s been produced in recent weeks that I probably won’t be able to cite! Here’s a few things that caught my eye:
In the journal New Phytologist, Rhiannon Dalrymple and colleagues, including Angela Moles who hosted me during my recent stay in Australia, have a great study entitled Macroecological patterns in ﬂower colour are shaped by both biotic and abiotic factors. The title pretty much sums it up: in order to fully understand how flowers evolve we need to consider more than just their interactions with pollinators. It’s another demonstration of how we must look beyond simplistic ideas about pollination syndromes to fully understand the complexities of the relationship between flowering plants and pollinators…..
…..talking of which, again in New Phytologist, Agnes Dellinger asks: Pollinationsyndromes in the 21st century: where do we stand and where may we go? It’s an insightful and far-reaching review of a topic that has intrigued me for more than 25 years. There are still a lot of questions that need to be asked about a conceptual framework that, up until the 1990s, most people in ecology and biology accepted rather uncritically. One of the main unanswered questions for me is how further study of largely unexplored floras will reveal the existence of new pollination systems/syndromes. Which leads nicely to….
…..an amazing paper in Nature this week by Rodrigo Cámara-Leret etal. showing that New Guinea has the world’s richest island flora. The described flora includes 13,634 plant species, 68% of which are endemic to New Guinea! And the description of new species each year is not leveling off, there’s still more to be discovered. A commentary on the paper by Vojtech Novotny and Kenneth Molem sets some wider context to the work, and quite a number of media outlets have covered the story. Why is this relevant to pollinators and pollination? Well, we actually know very little about this critical aspect of the ecology of the island: there’s only a handful of published studies of plant-pollinator interactions from New Guinea, mostly focused on figs, bird-flower interactions, and a couple of crops. For such a biodiverse part of the world that’s a big gap in our understanding.
Finally, James Reilly, Rachael Winfree and colleagues have a paper in Proceedings of the Royal Society series B showing that: Crop production in the USA is frequently limited by a lack of pollinators. Most significant findings to me were that of the seven crops studied, five of them have their yields limited by lack of pollinators, and that even in areas of highly intensive farming, wild bees provided as much pollination service as honeybees.
That’s a few of the things that I spotted this week; what have you seen that’s excited or intrigued you? Feel free to comment.
In the next few months my new book Pollinators & Pollination: Nature and Society will be published. As you can imagine, I’m very excited! The book is currently available to pre-order: you can find full details here at the Pelagic Publishing website. If you do pre-order it you can claim a 30% discount by using the pre-publication offer code POLLINATOR.
As with my blog, the book is aimed at a very broad audience including the interested public, gardeners, conservationists, and scientists working in the various sub-fields of pollinator and pollination research. The chapter titles are as follows:
Preface and Acknowledgements
1. The importance of pollinators and pollination
2. More than just bees: the diversity of pollinators
3. To be a flower
4. Fidelity and promiscuity in Darwin’s entangled bank
5. The evolution of pollination strategies
6. A matter of time: from daily cycles to climate change
7. Agricultural perspectives
8. Urban environments
9. The significance of gardens
10. Shifting fates of pollinators
11. New bees on the block
12. Managing, restoring and connecting habitats
13. The politics of pollination
14. Studying pollinators and pollination
UPDATE: turns out the figure I cited for number of bee species is out of date so I’ve corrected it below. Thanks to John Ascher for pointing this out.
Publication of my book Pollinators & Pollination: Nature and Society by Pelagic Publishing has been pushed back until the end of this year or early in 2021. The current pandemic has created problems for the printing and distribution sectors, as it has for so many industries. Therefore, to celebrate World Bee Day, here’s a preview of the bee section from Chapter 2 which is entitled (ironically enough) “More than just bees – the diversity of pollinators”.
2.3 Bees, wasps and sawflies (Hymenoptera)
The bees and their relatives rank only third in terms of overall pollinator diversity. Within this taxonomic Order, bees are not especially species rich (17,000 or so described species, perhaps 20,000 in total) – over 20,400 (see: https://www.catalogueoflife.org/col/details/database/id/67) compared with the other 50,000 social and solitary wasps, sawflies, and so forth. But what they lack in diversity the bees make up for in importance as pollinators of both wild and agricultural plants, and in their cultural significance. The general notion of what a bee is, and how it behaves, looks to the honeybee (Apis mellifera) as a model: social, with a hierarchy, a queen, and a large nest (termed a hive for colonies in captivity). In fact, this view of bee-ness, though long embedded within our psyche, is far removed from the biology of the average bee: most of them have no social structure at all, and a fair proportion of those are parasitic. In Britain we have about 270 species of bees, give or take (Falk 2015) though there have been extinctions and additions to this fauna (see Chapters 10 and 11). These species provide a reasonable sample of the different lifestyles adopted by bees globally. They can be divided into four broad groups.
Honeybees include several highly social species and subspecies of Apis, of which the ubiquitous western honeybee (A. mellifera) is the most familiar. Most colonies are found in managed hives, though persistent feral colonies can be found in hollow trees, wall cavities, and other suitable spaces. They are widely introduced into parts of the world where they are not native (e.g. the Americas, Australia, New Zealand) and there is some debate as to whether they are truly native to Britain and northern Europe, with supporting evidence and arguments on both sides. Colonies can be enormous and contain thousands of individuals, mostly female workers, with a single queen. Unmated queens and males (drones) are produced by the colony later in the season.
Bumblebees (Bombus spp.) are typically also social, though their nests are much smaller (tens to hundreds of individuals). Depending upon the species these nests can be in long grass, rodent holes, or cavities in buildings and trees. Twenty-seven of the more than 250 species have been recorded in the UK, but six of these are not strictly social; they are parasitic and belong to the subgenus Psithyrus which will be described below.
The so-called solitary bees are by far the largest group in Britain (about 170 species) and worldwide (more than 90% of all species). In the UK they belong to 15 genera, including Andrena, Anthophora, Osmia, Megachile, etc. The females of most of these bees, once they have mated, construct nests that they alone provision with pollen for their developing young. Nesting sites can be genus- or species-specific, and include soil, cavities in stone or wood, and snail shells. Some species are not strictly solitary at all and may produce colonies with varying levels of social structure, though without a queen or a strict caste system; we term them “primitively eusocial”. In fact sociality has evolved and been lost numerous times in the bees and in the rest of the Hymenoptera (Danforth 2002, Hughes et al. 2008, Danforth et al. 2019). It’s also been lost in some groups that have reverted back to a solitary lifestyle, and even within a single genus it can vary; for example in the carpenter bee genus Ceratina (Apidae: Xylocopinae) tropical species are more often social than temperate species (Groom & Rehan 2018).
The final group is termed the cuckoo bees and, like their avian namesake, they parasitise the nests of both social and solitary bees (though never, interestingly, honeybees). There are about 70 species in 7 genera, including the bumblebee subgenus, Psithyrus. Other genera include Melecta, Nomada and Sphecodes. In some cases the parasitic species are closely related evolutionarily to their hosts and may resemble them, for example some Psithyrus species. In other cases they may be only distantly related and in fact look more like wasps, e.g. Nomada species. Some genera of cuckoo bees are restricted to parasitising only a single genus of bees, others are parasites of a range of genera (Figure 2.4).
Although we often think of bees, overall, as being the most important pollinators, in fact species vary hugely in their importance. Pollinating ability depends upon factors such as abundance, hairiness, behaviour, body size, and visitation rate to flowers (Figure 2.1). Size is especially important for three reasons. First of all, larger animals can pick up more pollen on their bodies, all other things being equal. Secondly, in order to bridge the gap between picking up pollen and depositing it, flower visitors must be at least as large as the distance between anthers and stigma, unless they visit the stigma for other reasons. Finally, larger bee species tend to forage over longer distances on average (Greenleaf et al. 2007) thus increasing the movement of pollen between plants. However, most of the world’s bees are relatively small as we can see from the analysis of British bees in Figure 2.5. Many species have a maximum forewing length of only 4 or 5 mm, and the majority of species are smaller than honeybees. Remember also that these are maximum sizes measured from a sample; individual bees can vary a lot within populations and even (in the case of Bombus spp.) within nests (Goulson et al. 2002). So the assumption that all bees are good pollinators needs to be tempered by an acknowledgement that some are much better than others.
Figure 2.5: The sizes of British bees. Forewing length is a good measure of overall body size and the data are maximum lengths recorded for species, except for the social bumblebees and honeybee I have used maximum size of workers (queens are often much larger). The blue line indicates the honeybee (Apis mellifera). The biggest bee in this data set is the Violet Carpenter Bee (Xylocopa violacea) which, whilst not generally considered a native species (yet), has bred in Britain in the past. Data taken from Falk (2015).
The network of pollination ecologists and insect specialists who have confirmed that they are surveying plant-pollinator networks in their gardens now stands at 50. As the map above shows, most are in the UK, Ireland and mainland Europe, but the Americas are also becoming well represented, we have a couple of people surveying in North Africa, and three in Australia. An x-y plot of the coordinates of the gardens shows the spread a little better:
I’ve managed 13 formal 15 minute surveys so far, plus have a few ad hoc observations that I am keeping separate, and I will be continuing my data collection for the foreseeable future. I’ve started playing with the data as you can see below. This is a plot made using the bipartite package in R, with plants to the left and pollinators to the right. The size of the bars is proportional to the number of pollinators/plants a taxon connects to. In the plants you can immediately see the dominance of apple (Malus domestica) and greengage (Prunus domestica), which attract a wide variety of insects to their flowers. Of the pollinators, the hairy-footed flower bee (Anthophora plumipes) and dark-edged beefly (Bombylius major) are especially common and generalist in their flower visits. It will be really interesting to see how this changes over the season, and how our fruit and vegetables are connected into the wider network via pollinators that they share with the ornamental and native plants.
If you are experienced at surveying pollinators and want to get involved, follow that first link and check out the protocol and FAQs, and please do email me: jeff.ollerton [at] northampton.ac.uk
UPDATE: Following conversations with a couple of the participants of the garden surveys, we’ve changed the protocol slightly to make Survey type A more quantitative and to take into account when we get large numbers of individuals all visiting the same plant at the same time – it’s crazy to have a single line for each individual. Details are in the new spreadsheet which you can down load from here: Ollerton garden surveys 2020
The additions should be self explanatory. If you are not able to go back to retro-fit the additional data, that’s fine, just use the new spreadsheet format for future surveys: all data are going to be useful!
In the present format the data will be useful for modelling using GLMMs etc., in order to test predictions about which plants, and in which contexts, support the most pollinators. The data format will need tweaking slightly to make it analysable in bipartite, but that should be fairly straightforward.
If you are taking part in the surveys it would be really useful if you could email me your latitude and longitude as I’d like to start creating a map of where the surveys are happening.
Any questions, send me an email or ask in the comments.
Following up from my last post about ecologists using their gardens to collect standardised data, I’ve had a huge response from pollination ecologists all over the world wanting to get involved. So to streamline the process I thought that I would put the protocol and updates on my blog. Just to reiterate, this is really is designed for those who already have some experience of surveying pollinators and flowers. I didn’t intend this to be a citizen science project, there are plenty of those around at the moment for inexperienced people who want to contribute, for example:
If anyone wants me to publicise others, let me have the link in the comments below or send me an email.
OK, for those ecologists wanting to survey pollinators and the flowers they are visiting (or not visiting) in their gardens, here’s the protocol:
There are two types of survey – please do both if possible, it would be good to compare the results from the two approaches; otherwise choose the easiest one for you.
Type A surveys involve regular walks at a steady pace around the garden, recording what insects and other flower visitors are active on particular flowers (and noting the ones they are not visiting). Make your walks a standard time, proportional to the size of the garden. For example, in our 10m x 20m garden I am doing 15 minute walks, which involves walking the same route one way, then back, pausing to record data.
Type B surveys involve 10 minute focused observations of a patch of flowers of one species, no larger than 0.5m x 0.5m, recording the number of flowers each pollinator visits.
In both cases, identify the flower visitor to the taxonomic level to which you feel confident, e.g. it’s better to use Andrena sp. 1 or Calliphoridae sp. 2 or Diptera sp. 3 rather than guessing.
Record all data plus metadata about your garden on this spreadsheet which has examples of data that I have collected so far. When you return it, please change “Ollerton” to your own surname : Ollerton garden surveys 2020
Please don’t modify the format of the survey sheets, it will make life very difficult when we collate the data.
Collect data from now until the end of April. By then we will know whether to continue further data collection.
At the end of the month, send your spreadsheets to me: jeff.ollerton [at] northampton.ac.uk I will acknowledge receipt of each one, so if you don’t get an acknowledgement it may be that our spam filter has rejected your email, in which case message me on Twitter or comment below.
Finally – please respect local/national restrictions on movements and social isolation: safe safe and keep your community safe.
Here are some Frequently Asked Questions – I will update FAQs as they come in:
Q: What’s going to happen to all of the data?
I think that’s for the pollinator research community to decide. My feeling at the moment is that in the first instance there should be a data paper that summarises the results and makes the data freely available to everyone. That would include all data contributors as co-authors, probably under a project name rather than individually. After that it’s up to individuals and groups to work with the data to address their own research questions. I know that in the UK there are several PhD researchers who are worried about not being able to collect data this year and who want to contribute to this initiative and use it in their theses. I’m sure that there are others elsewhere. As a community it would be great to support these young researchers.
Q: I am not based in the UK, can I still take part?
A: Yes, of course, though check in your local networks to see if anyone is coordinating local efforts.
Q: How do I calculate “Total floral cover” for survey Type B?
A: The idea is to estimate the area covered by all of the patches of the plant in flower across the whole garden, and then add it up to get a total area covered. It is always going to be a rough estimate, but it at least gives us a sense of how abundant the flowers are in your garden.
Q: How do I classify “floral units” for survey Type B?
A: Use the UK POMS approach:
Q: Should I collect weather data?
A: You can certainly add data to another sheet on the spreadsheet if you want to, but the plan is to use data from local weather stations to capture standardised weather information.
Q: Should I collect nectar and/or pollen and/or pollinator behaviour data?
A: Again, collect any data that you have the time and equipment for and add it to a different sheet
Q: My garden has very few flowers and pollinators – can I still take part?
A: Yes, absolutely, we need a range of garden types, from the very large and florally diverse to small window boxes or lawns with just daisies and dandelions..
Q: How long should I survey for, and how many surveys should I do.
A: Try to aim for what you think is a representative assessment of the plant-flower visitor network in your garden. The idea is that people do as many surveys as they can, as often as they can, given their personal time constraints. I don’t want to dictate to people how to use their time, this needs to be enjoyable as well as useful. As long as we know the sampling effort and floral diversity within the gardens, we should be able to take account of sampling effort in any analyses.
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:
Sir John Robertson Kay-See-Emm-Gee Turned his head Into a home for bees The people came From far and near To watch the honey Dribble out of his ear pic.twitter.com/A3tz5Pz5kR
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.
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.