Tag Archives: Science

Corrections to the first edition of “Pollinators & Pollination: Nature and Society”

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Books are never perfect. In the run-up to publication of Birds & Flowers: An Intimate 50 Million Year Relationship, I am all too aware that this is a truth that’s a cause of anxiety, and sometimes sleeplessness, for all authors. One category of imperfection is tipographical* errors have been introduced at some point in the process of writing and editing. In the past these were corrected in the first edition of a book by the inclusion of errata slips, and such errors are sometimes important in determining the true first editions of older books. On page 20 of the first edition of Darwin’s Origin of Species, for example, there is a misspelling of the word “species”**. This was corrected in the second edition but is an important marker of an extremely valuable book, intellectually and (now) commercially.

A second category involves errors of fact or interpretation or expression that, with hindsight and reader feedback, require correction, or at least acknowledgement, by the author. These are the ones that really make an author squirm inside, even though we know that they are inevitable: we are, after all only human.

It turns out that there are a few examples of both categories in the first edition of my 2021 book Pollinators & Pollination: Nature and Society. Some of them have been corrected in the second edition, but if you purchased the first edition then these are what you should look out for:

P22 – ‘Unmated queens and males (drones) are produced by the colony later in the season’ changes to: ‘Unmated queens and males (drones) are produced by the colony from spring onwards.’

P30, Fig 2.9 – Correct ‘Tabaernemontana’ to Tabernaemontana

P51, Figure 3.8 – title – it should read C. rhynchantha [there’s an h missing]

P57 – ‘The bank that Darwin was referring to is on his property at Down House in Kent, and it was one he observed many times during his walks through the garden.’ changes to ‘The bank that Darwin was referring to is near his property at Down House in Kent, and it was one he observed many times during his walks in the area.’***

P146 – ‘I’ve even see them attack and kill honey bees’ should read: ‘I’ve even seen them….’

P169 – in the title for Figure 10.5, Anon (2019) should be Anon (1919) [in some presentation copies of my book I have corrected this and initialed the change]

P259 – this reference: Klein, A.-M., Steffan-Dewenter, I. and Tscharntke, T. (2003) Fruit set of highland coffee increases with the diversity of pollinating bees. Proceedings of the Royal Society B 270: 955–961. doi: 10.1098/rspb.2002.2306.

Should be replaced by:

Klein, A.-M., Steffan-Dewenter, I. and Tscharntke, T. (2003) Bee pollination and fruit set of Coffea arabica and C. canephora (Rubiaceae). American Journal of Botany 90, 153– 157. doi: 10.1046/j.1365-2664.2003.00847.x

The last two have yet to be corrected and will need to wait for the third edition:

P119 – the Rader et al. study did not include birds and bats, just insects.

P262 – “Nabhan, G.P. and Buchmann, S.” should read “Buchmann, S. and Nabhan, G.P.”

That final error is really embarrassing because, as I point out in the chapter ‘The Politics of Pollination’, their book The Forgotten Pollinators was an inspirational one for stimulating research and action around pollinator conservation! I can offer no explanation for why the order of the authors got reversed in my head.

My sincere thanks to those readers who pointed out some of these errors. My hope is that Birds & Flowers has fewer, but I may be fooling myself…

*You see what I did there?

**Proof-reading is boring and soul-destroying for any author, but really Mr Darwin?!

***If there is an after-life, I’d like to think that Darwin’s now enjoying this error after my snarky comment in the second footnote. To which I’ll respond: watch out for a doozy of a footnote about a Darwin footnote in Birds & Flowers!

Recent research and seminars on pollinators and pollination that have caught my eye

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There’s so much good science and so many great talks coming out of the (broad) field of pollinator and pollination research at the moment! Here’s a few things that have come up on my radar. Feel free to comment and add your own examples of things I may have missed.

We’ve just named a new species of fly from Yemen! And it came out of a flower from Kew

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Back in the late 1990s and early 2000s, whenever I had a (rare) day free from teaching, marking, supervision, meetings, writing, and other university commitments, I would hop on the train from Northampton to London. My destination was the Spirit Collection of the Herbarium at the Royal Botanic Gardens, Kew, where bottled flowers are preserved in their three-dimensional complexity, rather than squashed flat onto herbarium sheets. To this day, the smell of formaldehyde in the “Kew Mix” takes me back to the chilly basement space of that collection.

The Kew Herbarium is a massive, internationally important resource for taxonomy, evolutionary biology and ecology, and one which ought to stay where it is, in my opinion.

The purpose of my visits was to exploit the large number of Ceropegia specimens that had been collected by botanists working in Africa, the Middle East, and Asia. These amazing flowers are so complex that they are best preserved in spirit, and that complexity in turn is a function of their sophisticated pollination systems. The flowers temporarily trap their pollinators, releasing them unharmed after a period, during which they will have picked up pollen and/or the flower will have been pollinated. If you have ever grown String-of-Hearts as a house plant, that’s the group we are talking about.

The botanists who collected these flowers were, of course, only interested in the plants. But as well as pickling the blooms they sometimes pickled the insect contents of the flowers, giving us a record of what the flowers were luring into their temporary traps. Not only that, but Ceropegia belongs to the milkweed subfamily of Apocynaceae, which means that their pollen is in the form of pollinia. These are coherent packages of pollen that mechanically, and persistently, clip to the insect. This gives us an opportunity to sort out the real pollinators (with pollinia attached) from other insects that may be inside the flowers for other reasons, such as looking for prey or sheltering from the dry heat of the day.

It had occurred to me that if someone was to check these flowers for insects, and extract any that were found, then we could build up an unprecedentedly complete picture of the diversity of pollinators in a large, mainly tropical plant genus of around 200 species. So that’s what I did, whenever time allowed. Having gained permission to do this, I was pleased to discover that the process was considerably speeded up by the fact that preserving the flowers in this way clears the tissues, making them colourless and translucent. By shining a bench light through the bottles I could see which flowers contained insects and carefully dissect them out.

Most flowers were empty, but occasional visits over a period of a few years resulted in a data set of flower visitors and pollinators for about 60 species and subspecies of Ceropegia. The first paper from that work was published in 2008 in Annals of Botany as ‘Fly pollination in Ceropegia (Apocynaceae: Asclepiadoideae): biogeographic and phylogenetic perspectives‘. Later work by colleagues and myself meant that in 2017 we could publish an update in the journal Flora (Diversity of Diptera families that pollinate Ceropegia (Apocynaceae) trap flowers: An update in light of new data and phylogenetic analyses).

The work also fed into our large study of pollination systems in Apocynaceae and I even published a small note about an ant specimen that I had extracted which still had the evidence of its last meal (a fly’s wing) protruding from its mouth.

The work at Kew had given us a short cut to understanding how pollination systems have evolved in this big plant species radiation. The equivalent field work required to collect the same data would have taken many person years and no funding agency would have given it the time of day. Not only that, but a portion of the data is from parts of the word that are war-torn, dangerous, and largely inaccessible to field scientists at the moment. Which brings us to the present paper.

All of the pollinators, and most of the flower visitors, to Ceropegia that have been discovered to date are small flies (Diptera) often only a couple of millimetres in length. There are relatively few taxonomists who can identify such flies and most of the specimens I extracted were identified to genus or family by Andrew Whittington. One such specimen was determined to be a species of Lygistorrhina, known as ‘long-beaked fungus gnats‘. It was found in a flower of Ceropegia aristolochioides ssp. deflersiana, which is something of a generalist in this genus of specialists: it’s pollinated by at least four fly genera and 11 others have been collected from its flowers sans pollinia, including this one.

The flower was collected in 1975 by botanist John Wood, in Yemen – like I said, inaccessible – and the semi-arid climate in which it was found, whilst typical for Ceropegia, is unusual for Lygistorrhina. When National Museums Scotland entomologist Vladimir Blagoderov looked at the specimen he quickly realised that it was a new species and contacted Andrew and myself to discuss describing it. The paper documenting the new species, which we have named Lygistorrhina woodi in John’s honour, was published today. Here’s the reference with a link to the paper, which is open access:

Blagoderov, V., Ollerton, J. & Whittington A. (2023) A new species of Lygistorrhina (Lygistorrhina) Skuse, 1890 (Diptera: Keroplatidae, Lygistorrhininae) with a key to the subgenus. Zootaxa 5361: 151–158

Here’s the abstract:

A new species of Lygistorrhina (Lygistorrhina) Skuse, 1890, Lygistorrhina woodi sp. nov., is described. The specimen was dissected from an alcohol-preserved flower of Ceropegia aristolochioides ssp. deflersiana Bruyns (Apocynaceae, Asclepiadoideae, Ceropegieae) stored in the Kew herbarium. This is the first occurrence of the lygistorrhine gnats in a hot, semi-arid climate. A key to all known species of the subgenus Lygistorrhina (Lygistorrhina) is provided.

Key tropical crops at risk from pollinator loss due to climate change and land use – a new study just published

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PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) is one of the most important sources of data for large-scale modelling of how changes in land use is impacting biodiversity. Marry that with future climate models and you have a powerful tool for understanding how these two major factors in global change will shape both biodiversity and human society over the coming decades.

In recent years it’s been a privilege to be part of a project led by Joe Millard and Tim Newbold that’s using PREDICTS to model how pollinators and pollination services are likely to be impacted by human activities. The first paper from that work (which was Joe’s PhD) was entitled ‘Global effects of land-use intensity on local pollinator biodiversity’ and came out in 2021, as I documented on my blog at the time.

Yesterday a second paper was published, this time focused on how land use and anthropogenic climate change interact to potentially affect insect-pollinated crops across the world.

Our main finding is that it’s tropical crops, especially cocoa, mango, watermelon, and coffee, that in the future will suffer the greatest negative impacts from loss of pollinators. Although we can have perfectly healthy diets without consuming any of those, they currently support tens of millions of farmers across the tropics and are part of global supply chains worth billions of dollars per year.

Here’s the full reference with a link to the paper, which is open access:

Millard, J., Outhwaite, C.L., Ceaușu, S., Luísa G. Carvalheiro, da Silva e Silva, F.D., Dicks, L.V., Ollerton, J. & Newbold, T. (2023) Key tropical crops at risk from pollinator loss due to climate change and land use. Science Advances 9, eadh0756

Here’s the abstract:

Insect pollinator biodiversity is changing rapidly, with potential consequences for the provision of crop pollination. However, the role of land use–climate interactions in pollinator biodiversity changes, as well as consequent economic effects via changes in crop pollination, remains poorly understood. We present a global assessment of the interactive effects of climate change and land use on pollinator abundance and richness and predictions of the risk to crop pollination from the inferred changes. Using a dataset containing 2673 sites and 3080 insect pollinator species, we show that the interactive combination of agriculture and climate change is associated with large reductions in insect pollinators. As a result, it is expected that the tropics will experience the greatest risk to crop production from pollinator losses. Localized risk is highest and predicted to increase most rapidly, in regions of sub-Saharan Africa, northern South America, and Southeast Asia. Via pollinator loss alone, climate change and agricultural land use could be a risk to human well-being.

“Birds & Flowers” book update: here’s the list of chapters!

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Today I returned the final, edited files of the book manuscript to the publisher. It’s been a long summer of ‘fine distinctions and nice judgements’, to quote my editor, the inimitable Hugh Brazier. Now that’s all finalised, I thought that it was time to share the chapter titles with you – here goes:

Introduction: Encounters with birds and flowers

1         Origins of a partnership

              Understanding 50 million years of bird and flower evolution

2          Surprising variety

              The astounding diversity of pollinating birds

3           Keeping it in the family

                 Accounts of the different groups of bird pollinators

4          A flower’s point of view

              How many plants are bird-pollinated, and where are they found?

5         In the eye of the beholder

              What do bird flowers look like?

6          Goods and services

              The enticements given to birds for pollinating flowers

7         Misaligned interests

              The ongoing conflicts between flowers and birds

8          Senses and sensitivities

              How bird brains shape the flowers that they pollinate

9          Codependent connections

                Networks of interacting flowers and birds

10        Hitchhikers, drunks and killers

              The other actors in the network and how they affect the main players

11        The limits to specialisation

              How ‘specialised’ are the relationships between birds and flowers?

12         Islands in the sea, islands in the sky

                  Isolation, in oceans or in mountains, results in some remarkable interactions

13         The curious case of Europe

              Why did we believe that Europe had no bird-pollinated flowers?

14         ‘After the Manner of Bees’

              The origins of our understanding of birds as pollinators, and their cultural associations

15        Feathers and fruits

                Birds as pollinators of edible wild plants and domesticated crops

16        Urban flowers for urban birds

              Bird pollination in cities and gardens

17       Bad birds and feral flowers

              The impact of invasive species

18         What escapes the eye

                 The decline and extinction of bird–flower relationships

19         The restoration of hope

                  People as conservationists of birds and their flowers

There you have it! I’m incredibly excited that the book is now just about finished (I still have to proof read the typeset text and produce an index) and I look forward to finally having a copy in my hands. Birds & Flowers: An Intimate 50 Million Year Relationship is available for pre-order from Pelagic Publishing, or via online bookshops.

Weevily good pollinators – a recent review of a neglected interaction

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A pollination ecologist was recently working on the reproduction of a tropical plant species and discovered that the flowers were visited by two species of weevils, one large and one small.

The larger weevil was too big to access the nectar from the front, so it chewed its way into the flowers, destroying the petals, and in the process picking up no pollen.

The other weevil species was, however, able to enter the flowers, where it became smeared with pollen, which it then transferred to the stigmas in flowers of other plants.

The pollination ecologist therefore concluded that the true pollinator of this plant was, indeed, the lesser of the two weevils…

That’s not an original joke by any means – it comes from the movie Master and Commander. But it nicely sets up this short post about a review paper that came to my attention earlier in the summer and which fits neatly with my previous post about a special issue of the Journal of Applied Entomology dedicated to the “neglected pollinators”.

Writing in the open access Peer Community Journal, Julien Haran, Gael Kergoat, and Bruno de Medeiros have produced a really fascinating review of weevil pollination called:

Most diverse, most neglected: weevils (Coleoptera: Curculionoidea) are ubiquitous specialized brood-site pollinators of tropical flora

Weevils are beetles, members of the superfamily Curculionoidea, which contains an estimated 97,000 species. Many are herbivores, including seed predators – I first encountered them as a researcher during my PhD when I assessed the impact of one species as a seed predator of my study plant Bird’s-foot Trefoil. Surprisingly, however, pollinating relationships have evolved multiple times between weevils and plants. Drawing on published studies and their own unpublished observations, the authors conclude that such “associations have been described or indicated in no less than 600 instances.” Most of these are brood-site pollination systems that have probably evolved from seed predation relationships.

No doubt many more examples of weevil pollination remain to be discovered but as it stands, this review paper is a great summary of a fascinating and still rather neglected corner of pollination ecology.

“Enemy release” of invasive plants is unpredictable – a new study just published

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The summer of 2019, before the COVID-19 pandemic turned the world on its head, feels like a very long time ago. Early in that summer, as I recounted on this blog, Zoe Xirocostas joined my research group for a while in order to collect data for her PhD on the comparative ecologies of plants that are native to Europe but invasive in Australia. That work has proven to be very successful, and the latest paper from Zoe’s PhD has just been published.

The paper focuses on the “enemy release hypothesis” (ERH), a well-studied concept in invasion ecology that nonetheless generates significant debate and disagreement. In essence, the ERH posits that the reason why so many species become invasive is that they leave their consumers, pathogens and parasites behind when they move to a new locality. Those “enemies” would normally reduce the fecundity of the invader, putting a brake on their population growth. But in their absence, the invader can become far more successful. Of course, as well as leaving “enemies” behind the invader also loses its “friends”, such as pollinators, seed dispersers, and defensive or nutritional partners. This “Missed Mutualist Hypothesis” is something that I’ve recently explored with Angela Moles, who was Zoe’s main supervisor, and other collaborators in Australia. Expect to hear more about this from Zoe’s work in the near future.

But back to the enemies. Drawing on the most extensive set of standardised comparisons yet collected of the same plants in native and invasive habitats, Zoe found that plants in the invasive populations suffer on average seven times less damage from insect herbivores, as predicted by the (ERH). Rather remarkably, however, the amount of enemy release enjoyed by a plant species was not explained by how long the species had been present in the new range, the extent of that range, or factors such as the temperature, precipitation, humidity and elevation experienced by the native versus invasive populations.

In other words, it’s extremely hard to predict the extent of enemy release based on historical and ecological considerations that one might expect to impose a strong influence.

The study has just appeared in Proceedings of the Royal Society series B and is open access. Here’s the reference with a link to the paper:

Xirocostas, Z.A., Ollerton, J., Tamme, R., Peco, B., Lesieur, V., Slavich, E., Junker, R.R., Pärtel, M., Raghu, S., Uesugi, A., Bonser, S.P., Chiarenza, G.M., Hovenden M.J. & Moles, A.T. (2023) The great escape: patterns of enemy release are not explained by time, space or climate. Proceedings of the Royal Society series B 290: 20231022.

Here’s the abstract:

When a plant is introduced to a new ecosystem it may escape from some of its coevolved herbivores. Reduced herbivore damage, and the ability of introduced plants to allocate resources from defence to growth and reproduction can increase the success of introduced species. This mechanism is known as enemy release and is known to occur in some species and situations, but not in others. Understanding the conditions under which enemy release is most likely to occur is important, as this will help us to identify which species and habitats may be most at risk of invasion. We compared in situ measurements of herbivory on 16 plant species at 12 locations within their native European and introduced Australian ranges to quantify their level of enemy release and understand the relationship between enemy release and time, space and climate. Overall, plants experienced approximately seven times more herbivore damage in their native range than in their introduced range. We found no evidence that enemy release was related to time since introduction, introduced range size, temperature, precipitation, humidity or elevation. From here, we can explore whether traits, such as leaf defences or phylogenetic relatedness to neighbouring plants, are stronger indicators of enemy release across species.

Making plant-pollinator interaction data FAIR – a new draft report just published

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One of the projects in which I’m currently involved is the WorldFAIR project. Funded by the European Commission, WorldFAIR is exploring how to make data FAIR – Findable, Accessible, Interoperable and Reusable – across a range of different disciplines in the sciences and humanities.

My involvement is specifically with Work Package 10, which is focused on data standards for plant-pollinator interactions, particularly as they relate to pollination of agricultural crops. After a year of hard work, I’m delighted to announce that our interim draft report from this Work Package has just been published! You can read the summary and download the report from Zenodo – here’s the link: https://zenodo.org/record/8176978

In addition there’s an associated webinar taking place on August 22nd – more details here: https://worldfair-project.eu/event/rescheduled-worldfair-rdas-10-year-anniversary-the-worldfair-case-study-on-plant-pollinator-interactions-wp10/

There’s more to come over the next twelve months and I’ll post updates as and when they appear. In the meantime, do check out the WorldFAIR website for information about the other Work Packages, their webinar series, FAIR data standards, and so forth.

Should honey bee hives be placed on or near conservation sites?

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Earlier this week, the East Midlands Environment Agency proudly tweeted that they had placed honey bee hives on an ecologically important site that they own. As you might imagine, the response from pollinator experts such as myself, conservation NGOs, and some beekeepers, was not positive, as you can see if you look at the comments beneath my tweet:

By coincidence, overnight I received a message from someone in the USA asking for advice. Here’s a redacted version of their message:

My community has a 4 acre serpentine barren site that is part of a larger string of these unique barrens ….. Honey bee hives have recently been located adjacent to the barrens. Can you advise me as to the best way to determine whether there are, and to document any, adverse effects to the serpentine barrens native pollinators?

The question of how managed honey bees can impact wild pollinators and the pollination of wild plants is one that frequently comes up in the talks and training that I do. Many beekeepers share these concerns – see for example this very detailed blog post by Mark Patterson.

Going back to the question of how to assess any impacts, the simple answer is that it’s not easy and it relies on having good data. This was my response to my American correspondent:

Ideally you would need to take a before-and-after approach where you have data on things like number of native pollinator species, their abundance (including nest sites), rates of visitation of different pollinators to flowers, and fruit or seed set from particular plants. You’d then compare what was going on before the hives arrived with what’s occurring since their arrival.

If you don’t have the “before” data it’s much more difficult to assess if there has been an impact from the honey bees. However, the advice of most conservation groups is to adopt the “precautionary principle” and not site hives on or adjacent to areas of nature conservation value, especially if they are relatively small areas. See for example the Bumblebee Conservation Trust’s advice: https://www.bumblebeeconservation.org/managed-honeybees/

The precautionary principle is a well established concept across a range of areas, including health and engineering, as well as nature conservation. In the latter it needs to be more widely applied, especially when it comes to questions of where to site honey bee hives, and how many.

Plant-based diets are a problem for bees! A new study of the significance of the ratio of food K:Na in bee ecology and evolution

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At the moment Karin and I are in the UK for a couple of weeks. I had work to do as an external examiner at the University of Swansea, plus we wanted to catch up with some family and friends. Our main base has been the home of our mates Ian and Simone and we’ve enjoyed some warm, muggy evenings sitting in their garden chewing the fat. Every now and again my eyes have been drawn to the activities of bumblebees as they move in and out of the foliage of a small Silver Fir. The bees are attracted to the large colonies of an aphid that is feeding on the tree’s trunk, from which they are collecting honeydew, as you can see in the photograph above.

When we think of the diets of bees we automatically think “nectar and pollen”. Honeydew, as a sugar-rich fluid, fits broadly into this concept, though as far as I know there’s been little study of its relative importance as a food source for bees. Aside from a few “vulture bees”, all of the 20,000 or so species are vegetarian. And therein lies a problem. Bees evolved from carnivorous wasps and so the evolution of bees, and their complex ecologies, is tied into this profound dietary shift toward a plant-based diet.

A particular issue that has hardly been investigated until recently is that the ratio of elements within meat is very different to that of plants. In particular, animal tissue has a high ratio of sodium (Na) relative to potassium (K), whereas for plants the ratio is reversed – high ratio of K:Na.

In a new conceptual review paper with my colleagues Zuzanna Filipiak and Michał Filipiak, we have explored the implications of this difference in elemental ratios for bee ecology and evolution, and for the conservation of these important insects. The paper is open access and you can download a copy by following a link in this reference:

Filipiak, Z.M., Ollerton, J. & Filipiak, M. (2023) Uncovering the significance of the ratio of food K:Na in bee ecology and evolution. Ecology e4110. https://doi.org/10.1002/ecy.4110

Here’s the abstract:

Bees provide important ecological services, and many species are threatened globally, yet our knowledge of wild bee ecology and evolution is limited. While evolving from carnivorous ancestors, bees had to develop strategies for coping with limitations imposed on them by a plant-based diet, with nectar providing energy and essential amino acids and pollen as an extraordinary, protein- and lipid-rich food nutritionally similar to animal tissues. Both nectar and pollen display one characteristic common to plants, a high ratio of potassium to sodium (K:Na), potentially leading to bee underdevelopment, health problems, and death. We discuss why and how the ratio of K:Na contributes to bee ecology and evolution and how considering this factor in future studies will provide new knowledge, more accurately depicting the relationship of bees with their environments. Such knowledge is essential for understanding how plants and bees function and interact and is needed to effectively protect wild bees.