In my new book Birds & Flowers: An Intimate 50 Million Year Relationship I spend a bit of time discussing the idea of the bird pollination syndrome that we refer to as ‘ornithophily’, its limitations, and the fact that it has two distinct meanings that are often conflated. One of the problems with ornithophily, and indeed all of the syndromes, is that historically it’s sometimes blinkered scientists to the extent that they only look at the flower visitors that are “right” for the syndrome, ignoring the rest or dismissing them as “secondary pollinators”, a term I dislike.
Why do I dislike that term? Because it fails to capture the complexity of flower-pollinator interactions and relegates an important component of plant reproduction to a subsidiary role. I could go on about this at some length, but if you’re interested in discovering more, look at pages 62-65 of Birds & Flowers. There I contrast the classical Most Effective Pollinator Principle with the equally valid (but much less well studied) Least Effective Pollinator Principle, with a segue into one of my favourite tracks from Led Zeppelin’s second album: What is and What Should Never Be.
But back to the real subject of this post – a flower that corresponds to the classical bird pollination syndrome BUT is also pollinated by bees and (very surprisingly) wind! It’s such an interesting paper by Brazilian ecologists Amanda Pacheco, Pedro Bergamo & Leandro Freitas – here’s the reference and a link to the study:
For over 100 years the classical pollination syndromes have acted as a framework for understanding the ecology and evolution of plant-pollinator interactions. But we’ve long known that while they can be a useful shorthand, they do not fully reflect the complexity of how pollination systems evolve. That shouldn’t surprise us because, as I point out in my two recent books, we have data (of any quality) on no more than 10% of the 350,000 or so species of flowering plants!
In addition, those plants for which we do have good data are NOT a random subset of the flowering plants: they have been specifically chosen by researchers because they look to be good systems with which to address particular ecological or evolutionary questions.
Which is fine, but we MUST recognise that this imposes significant restrictions on our understanding of the biodiversity of plant-pollinator interactions. The authors of this paper expressed it very well when they wrote that assumptions about:
“predictability may cause researchers to take for granted that only birds pollinate ornithophilous flowers, hindering research on the contribution of other vectors.”
To which I’d add: it also hinders our understanding of how these interactions evolve over long time scales and across multiple populations.
An obvious question is: how frequent are these sorts of complex pollination systems, involving different pollen vectors of an apparently specialised flower? The answer is that we simply don’t know, because most researchers would have not gone into this level of detail. So a huge congratulations to the authors for a great study – I hope it stimulates others to look beyond the ‘expected’ pollinators of flowers.
Photos: Nathália Susin Streher from the original paper.
The final deliverable from the WorldFAIR Project with which I’m involved has recently been published and can be freely downloaded from Zenodo by following the link below. The report is called “Agricultural biodiversity FAIR data assessment rubrics” and in it we present the results from a series of six pilot studies that adopted the FAIR* standards and our recommendations from the previous report.
This document complements the previous one by giving examples and setting out guidelines that allow researchers and practitioners to ensure FAIRness in their plant-pollinator interaction data.
Here’s the full reference:
Drucker, D. P., Salim, J. A., Poelen, J., Soares, F. M., Gonzalez-Vaquero, R. A., Devoto, M., Ollerton, J., Kasina, M., Carvalheiro, L. G., Bergamo, P. J., Alves, D. A., Varassin, I., Tinoco, F. C., Rünzel, M., Robinson, D., Cardona-Duque, J., Idárraga, M., Agudelo-Zapata, M. C., Marentes Herrera, E., Taliga, C., Parr, C.S., Cox-Foster, D., Hill, E., Maués, M.M. Agostini, K. Rech, A.R., Saraiva, A. (2024). WorldFAIR (D10.3) Agricultural biodiversity FAIR data assessment rubrics (Version 1). Zenodo. https://doi.org/10.5281/zenodo.10719265
Although this is the last formal deliverable from our WorldFAIR work package, it’s not the final output that we have planned. I’ll report back on the journal paper(s) that we are writing as and when they are published.
*Findable, Accessible, Interoperable & Reusable (or sometimes Reproducible)
One of the most productive research collaborations in which I’ve had the pleasure to be involved has been with André Rodrigo Rech in Brazil. It started when he was a postgrad working on his PhD, and has now continued as André has developed into fully-fledged academic with his own research group. That productivity has been fueled by a lot of coffee, of course, as you’ll know if you’ve read my book Pollinators & Pollination: Nature and Society!
Here’s the reference – if you want a PDF of the paper, please send me a message via my Contact page:
Pereira Machado, A.C., Baronio, G., Soares Novaes, C., Ollerton, J., Wolowski, M., Natalina Silva Lopes, D. & Rech, A. (2024) Optimizing coffee production: Increased floral visitation and bean quality at plantation edges with wild pollinators and natural vegetation. Journal of Applied Ecology (in press)
Here’s the abstract:
Animal pollination is important for more than 75% of agricultural crops, including coffee, whose productivity can increase with adequate pollination. Bees, including many solitary species, are diverse pollinators, with around 85% of them considered more effective than honeybees in pollen transfer. We assessed the coffee plantation and its surrounding vegetation for solitary bee nesting throughout the coffee flowering season and measured their impact on coffee productivity.
We installed collection stations with trap nests inside a coffee plantation, on the border and inside the native vegetation in a farm in Diamantina, MG, Brazil. We used 10 weekly monitored replicates at least 1 km apart. We evaluated fruiting by autogamy in relation to natural pollination and used the increase in fruit set from pollinators to calculate the farmer’s monetary gain. We recorded bee visits to the exposed flowers during coffee flowering considering both on the edge and inside the coffee plantation. Ripe fruits were dried, counted and weighed.
We discovered 132 solitary bee nests outside the plantation, with 54% containing coffee pollen grains, indicating coffee as an essential resource for bees even outside the crop area. More bee visits occurred at the coffee plantation’s edge, resulting in increased fruit production, denser fruits, and rounder fruits in that area. Bagged flowers produced consistent seeds in all locations. The farmer could earn an extra US$1736.37 per hectare if the entire area received the same level of pollination contribution from bees as observed at the coffee border.
Synthesis and applications. Our study emphasises the key role of pollinators in coffee production and their impact on fruit and seed characteristics. Bee visits were more frequent on border areas, emphasising their reliance on natural nesting sites. Bee-mediated pollination positively affected fruit traits and self-pollinated fruits in plantation borders had reduced mass. Solitary bee nesting was primarily observed in native vegetation, underlining its importance for bee populations. Pollen composition in nests varied with proximity to coffee plantations, indicating landscape vegetation influences pollinator foraging. These findings support optimising coffee plantation design by preserving native vegetation to increase coffee yields and conserve biodiversity.
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Yesterday I received an email containing the following press release. I thought it might interest readers of the blog so I am copying it in full with no edits. I had a quick look over the report and it’s amazingly detailed and comprehensive. It’s a shame that the report only covers insects, but that probably reflects my current bias given that my next book, due out in February, is about pollinating birds! Press release follows:
Governor Polis and the Department of Natural Resources Release Pollinator Report
BROOMFIELD – Today, Governor Polis in partnership with The Colorado Department of Natural Resources (DNR), Colorado State University Extension, Xerces Society for Invertebrate Conservation, and University of Colorado Museum of Natural History released the Colorado Native Pollinating Insects Health Study which is the most robust and detailed account of pollinator health ever undertaken in Colorado history. As directed by SB22-199, Native Pollinating Insects Protection Study, sponsored by Senators Sonya Jaquez Lewis and Kevin Priola, and Representatives Cathy Kipp and Meg Froelich, signed by Governor Polis on May 27, 2022, the study assesses the health of Colorado’s native pollinators, evaluates state policies for safeguarding pollinators, and makes recommendations on how to preserve and protect pollinators in Colorado.
“Pollinators play a critical role in Colorado life. From Crested Butte’s beautiful spring meadows to Palisade Peaches and Rocky Ford melons, Colorado’s pollinators sustain our flora and enable many foundational industries in every corner of the state. As our climate changes, we must safeguard the pollinators that generate and regenerate the Colorful Colorado we love,” said Governor Polis
Colorado is home to various native insects and bats whose pollinating services are at the heart of healthy environments and economies. Pollinators are critical to Colorado’s economy and our agricultural production and food systems, and they are essential for flowering plants that support the state’s wildlife ecosystem and add color to Colorado’s beautiful landscapes.
“Colorado is fortunate to have a tremendous diversity of plants and animals, but pollinating insects are perhaps the least studied but most beneficial for our ecosystems, economy and quality of life,” said Dan Gibbs, Executive Director, Colorado Department of Natural Resources. “I greatly appreciate the time and effort of the study authors who truly did a deep dive into the current state of pollinating insects and state policies and structures. I look forward to working with Colorado legislators and stakeholders in pursuing the best policies to ensure pollinating insect protection and long-term health.”
Colorado is home to over 1,000 species of bees—nearly 30% of North America’s and approximately 5% of the world’s bee species—and nearly 300 species of butterflies, representing over 40% of the diversity of butterflies in North America north of Mexico, some of which are already listed under the federal Endangered Species Act. This report underscores the importance of the Polis administration’s goals to tackle Colorado’s greenhouse gas emissions, prepare industries for the impending effects of climate change, and create more sustainable living in Colorado for pollinator populations.
“Our ecosystems rely on pollinators, which is why I’ve championed measures that limit toxic chemicals from harming pollinators and put forth a statewide assessment to better understand the problems our pollinators face and identify practices to better sustain them,” said Senator Sonya Jaquez Lewis, D-Longmont. “Today’s report shows that there’s plenty to do moving forward, and I am looking forward to continuing our work to protect pollinators and the ecosystems that are dependent on them.”
“I’m excited that we have this report to help us understand the extent of pollinator decline in Colorado. While Colorado ranks fifth nationally for the rate of honey-bee die-offs, we haven’t known as much about native pollinating insects. This threatens our food production, biodiversity and health of our ecosystems,” said Rep. Cathy Kipp, D-Fort Collins. “We created the Native Pollinating Insects Protection Study in 2022 to identify ways to better protect and support the native Colorado pollinators, like different bee species, butterflies, and moths, that are also essential to maintaining a healthy environment. These findings will help direct future legislation to create a safer environment for our pollinators, protect our food supply and support biodiversity.”
Promoting policies that benefit native pollinating insects represents an opportunity to foster healthy and sustainable pollinator populations, especially in agricultural and urban habitats. This includes enhancing pollinator-friendly native plantings along I-76 following its designation as a Colorado Pollinator Highway by the Colorado Department of Transportation and other existing state plans such as the state’s Natural Areas Program, and Wildlife Action Plan among others.
“Working on the Pollinator Health Study has been an amazing opportunity to collaborate with so many locally, nationally, and internationally recognized experts in the field of pollinator conservation. In addition to the immense amount of information within the report, this study highlights the importance of collaboration between scientists and land management agencies to bring together the many facets needed for conserving native pollinating insects,” said Deryn Davidson, Sustainable Landscape State Specialist, Colorado State University Extension. “Having the existing research on Colorado pollinators paired with recommended land management practices in one, comprehensive document is an incredible tool for policy makers, land managers, and really anyone interested in actionable steps for pollinator conservation.”
Areas of immediate action and priorities highlighted by the Pollinator Report include:
Priority 2: Protect, restore, and connect pollinator habitats.
Priority 3: Mitigate environmental changes that negatively impact pollinators and their habitats.
Priority 4: Reduce the risks from pesticides to pollinating insects.
Priority 5: Monitor and support native and managed pollinator health.
Governor Polis announced his annual budget proposal on November 1, focusing on ensuring Colorado is more affordable, sustainable, and liveable. The Governor included $100,000 to support education and incentives to encourage the use of pesticide alternatives in agricultural production and residential or commercial landscaping. On May 17, 2023, Governor Polis signed Neonic Pesticides as Limited-Use Pesticides, sponsored by Senators Kevin Priola and Sonya Jaquez Lewis and Representatives Kyle Brown and Cathy Kipp, which protects pollinators from harmful toxins.
Obviously the title of this post is click-bait, as there’s LOTS of things that I wish more people knew about pollination! But here’s one that really gets my (Yule) goat.
I’ve lost track of the number of times that I’ve read statements in books and research papers such as “bees collect lots of pollen from flowers therefore they are good pollinators”. Even worse, I sometimes see studies where pollen has been removed from “pollen baskets” or other scopae, then used as a measure of the importance of those bees as pollinators.
In both cases it seems to have been forgotten that bees are collecting pollen to feed their larvae and pollen that ends up in scopae is generally not available for pollination.
That’s the purpose of the Venn diagram at the top of this short post, to remind us that there can be a disconnect between what bees are doing and what plants require: foraging for pollen only partly correlates with flower pollination. Indeed, the same argument applies to any animal that feeds itself or its young on pollen, including pollen wasps (Maserinae), Heliconia butterflies, and some flower-visiting hoverflies, birds and bats.
It’s not only loss of pollen from reproduction that’s important here: depending on the size and behaviour of the bees relative to the shape and size of the flower, they may go nowhere near the stigma, so even if they are carrying viable pollen, it can be lost as far as the plant is concerned.
Note also that many bee species will collect pollen from wind-pollinated plants such as grasses, oaks, etc. Indeed in some species the availability of such pollen is extremely important – see Manu Saunders’ review on this topic and more recent papers that cite it. Again, it emphasises the partial disconnect between pollen collecting by bees and pollination of flowers by bees.
Assessing which flower visitors are actually pollinators is not technically demanding but it can be time consuming. The minimum that you need is single visit deposition (SVD) experiments in which you expose unvisited flowers to one visit by the potential pollinator. Then you assess how much pollen has landed on the stigma or (better) whether the visit results in seed set.
If you want to know more about the evidence that’s required to determine if a flower visitor is or is not a pollinator, they are codified in the “Cox-Knox Postulates” that I discuss in my book Pollinators & Pollination: Nature and Society.
Biodiversity Net Gain (or BNG) promises to transform the way that we approach nature conservation in the UK. I’ve been giving a lot of thought to what this might mean for insect pollinators and have produced a new report that summarises the opportunities that BNG presents and how we can make the most of them. You can download a copy of that report by following this link.
This is meant to be a working document and as BNG progresses, and our understanding of its impacts on pollinators increases, I will update it. In the meantime, please do feel free to comment.
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:
If this is an important site for nature conservation, as claimed, then the #EnvironmentAgency should NOT put hives of honey #bees on it!
— Prof. Jeff Ollerton – @JeffOllerton@ecoevo.social (@JeffOllerton) July 12, 2023
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?
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.
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:
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.
I’m excited to announce that in March 2024 I will teach a week-long, Master’s-level residential course entitled “Pollination as an Ecosystem Service” at the University of Pavia in Italy. It will be taught in English. Here’s a summary of the course and a brief description of the the syllabus, which is broadly accurate but subject to change as it develops:
POLLINATION AS AN ECOSYSTEM SERVICE
A 3 credit Master’s course for the University of Pavia
Overview
The pollination of crops by bees, flies, birds, bats and other animals, is an ecosystem service that increases crop yields and quality. This is valued at hundreds of billions of Euros each year to European and global agriculture. In addition, these same animals pollinate around 90% of the world’s wild plants which in turn provide us with ecosystem services such as wild food, flood alleviation, microclimate modification, and carbon capture.
In this course, students will explore pollination as an ecosystem service from its first principles and historical roots through to the latest research findings around the consequences of pollinator decline and climate change. The emphasis of the course is on the students learning by actively participating during classes. Each day has a particular theme and will be a mix of interactive lectures, short video clips to illustrate particular points, discussion seminars (for which they will be expected to do some guided reading) and local excursions.
At the end of the course the students will have a developed a deep understanding of the diversity of pollinators, the ecological nature of their interactions with flowers, and the importance of these relationships to nature and to society.
Assessment
At the end of the course, the students will be asked to give a 10 minute presentation based on one of the topics covered in the course, and posed as a question such as “What is….?”, “Why does….?”, “What would happen if….?”, and so forth. The questions will be agreed with me in advance. Presentations will take place on the final day of the course and at the end of each presentation the students will have 5 minutes to answer questions posed by their peers and myself.
Syllabus
Day 1
Theme: Pollinators and pollination – first principles; including historical perspectives, the diversity of pollinators and flowers, and the biology of pollination. Introducing the course assessment.
Excursion: a walk around the local area to observe flowers and pollinators in action.
Day 2
Theme: Pollination as an ecosystem service; including the types of crops that are animal pollinated, how we calculate the value of pollination, and going beyond agriculture to look at the other ecosystem services provided by pollinators; approaches to studying pollinators and pollination.
Day 3
Theme: Pollinator conservation: including reasons for pollinator decline, impacts of climate change, the “politics of pollination”, the consequences of that decline for crop and wild plant pollination, how we can manage and restore habitats for pollinators.
Day 4
Theme: Urban pollinators: understanding the importance of pollinators in an urban setting and in gardens, and how towns and cities support pollinators. Excursion: How is the city of Pavia supporting pollinator populations and what could be improved?
Day 5
Theme: Summing up what we’ve learned, followed by assessed student presentations.
Prof. Jeff Ollerton - ecological scientist and author 