Category Archives: Butterflies

Get a 30% discount if you pre-order my new book Pollinators & Pollination: Nature and Society

PollinatorsandPollination-frontcover

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
References
Index

 

 

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Filed under Bees, Biodiversity, Biodiversity and culture, Birds, Butterflies, Climate change, Ecosystem services, Evolution, Flies, Gardens, History of science, Honey bees, Hoverflies, IPBES, Macroecology, Mammals, Moths, Mutualism, Neonicotinoids, Personal biodiversity, Pollination, Rewilding, Tenerife, Urban biodiversity

Garden plant-pollinator surveys: progress so far

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:

Some people have started to send me data already, which is great; if you’re surveying and haven’t let me know your latitude and longitude, please do so, preferably decimalised – you can convert degrees/minutes/seconds to decimal here: https://www.latlong.net/degrees-minutes-seconds-to-decimal-degrees

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

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Filed under Bees, Biodiversity, Butterflies, Ecosystem services, Flies, Gardens, Honey bees, Hoverflies, Pollination, Urban biodiversity

Pollination ecologists in gardens: protocol and links to other initiatives – UPDATE NUMBER 2

Andrena bicolor

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:

The Pollinator Monitoring Scheme’s  FIT (Flower-Insect Timed) counts: https://www.ceh.ac.uk/our-science/projects/pollinator-monitoring

Kit Prendergast’s “bee hotels” survey: https://www.facebook.com/groups/Beesintheburbs/announcements

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:

  1.  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.
  2. 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.
  3. 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.
  4. 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.
  5. 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
  6. Please don’t modify the format of the survey sheets, it will make life very difficult when we collate the data.
  7. Collect data from now until the end of April.  By then we will know whether to continue further data collection.
  8. 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.
  9. 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:

POMS flower heads

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.

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Filed under Bees, Biodiversity, Butterflies, Gardens, Honey bees, Hoverflies, Moths, Pollination, Urban biodiversity

Landscapes for pollinators: please take the survey!

BB on margin

One of the research projects and collaborations that I’m involved with is a BBSRC-funded project entitled “Modelling landscapes for resilient pollination services in the UK” with colleagues from the University of Reading, the University of Huddersfield, and the Natural Capital Solutions consultancy.  As part of that project we are surveying opinions on what people in the UK value as landscapes and how these landscapes contribute to supporting biodiversity.

If you are based in the UK and are interested in taking part in this short survey, please read the following text and click on the link to take the survey: 

Bees and other insect pollinators are major contributors to UK agriculture. Despite their importance for crop production, pollinator populations are threatened by many modern land management and agricultural practices. This raises questions about how secure this service may be to future changes: will we have enough pollinators where we need them? Will populations be able to withstand changes to the way we manage land? What might be the costs to us, both financially and socially, if we get it wrong?

Our research aims to address this knowledge gap. Our team of ecologist, economists and social scientists are working together to model the ecological, economic and ‘human’ costs of different land management methods.

As part of this we have designed a short online survey to capture the ways that people value and use the countryside, what features they prefer and why.

The survey takes less than 10 minutes and asks you to rate a series of images and say what you think about the landscapes that are illustrated.  It can be found here:

http://hud.ac/landscapes

For more information about the project visit:

http://www.reading.ac.uk/caer/RP/RP_index.html

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Filed under Bees, Biodiversity, Biodiversity and culture, Butterflies, Ecosystem services, Hoverflies, Pollination

Ecologists in a time of COVID-19

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Yesterday I was involved in what’s likely to be be my last face-to-face teaching and meetings from some weeks, possibly months.  In the morning my colleague Duncan McCollin and I watched our final year students take part in an assessed debate that pitted two sides against one another to argue whether or not Brexit will have a negative effect on biodiversity.  The students did very well, they had a great grasp of the issues and the facts and figures.  The end result was very much a draw:

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Teaching at the University of Northampton will go online from the end of the week and a field trip for our first year undergraduates that we had planned for this Thursday has been pulled.  Our annual Tenerife Field Course has also been cancelled: this will be the first year since 2003 that I have not visited the island and it’s going to leave a hole in my long-term data sets.  Perhaps the universe is telling me that it’s time to write them up for publication?

Last week I did a quick vox pop on Twitter to ask how COVID-19 has affected ecology field work at other universities:

The response was interesting and it’s clear that overseas field courses have been massively impacted.  Following the UK Government’s advice yesterday about limiting social contact it seems that local field work for student groups will also be affected.  Hopefully those undertaking individual field work, especially PhD and postdoctoral researchers, will still be able to carry out their data collection.  Do let me know in the comments if it’s affecting your work.

There were also some Twitter responses from professional ecological consultants pointing out that they may not be able to carry out surveys of sites for planning and development purposes.  This is yet another way in which COVID-19 is going to impact our economy.

Following the student debate, Duncan and I headed out to catch up with a meeting of the steering group of the Chequered Skipper Reintroduction Project   We missed the morning’s presentations but arrived in time for the lunch and a short field trip:

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The location of the reintroduction is still being kept secret, as is a second site where a further reintroduction of butterflies from the Belgium population is being considered.  However there was much discussion as to whether restrictions on travel means that this would have to be delayed until next year.

On the way to that site, during a 15 minute drive, we spotted seven red kites.  They are now so common that seeing these amazing birds hardly requires comment.  But we should never forget what an incredibly successful conservation story this has been.  To cap it all, when we arrived at the site I had the pleasure of meeting Karl Ivens, one of the main drivers behind the reintroduction of red kites to Northamptonshire. He now estimates the regional population to be a couple of thousand birds.  The guy deserves a statue, or at least a blue plaque on his house!

On the way home I was thinking about my next blog post and what to write, and whether or not to bring the pandemic into it.  There’s a lot of information, and misinformation, about COVID-19 online and I’m not qualified to add to that: I’m not an epidemiologist.  However I’d like to link to a few things I think are worth reading.

Over at the Dynamic Ecology blog, Brian McGill has posted an open thread on ecologists discussing the coronavirus pandemic.  There are some interesting contributions in the comments, particularly around the response of the UK Government to the crisis.  I was struck by Jeremy Fox’s comment that Britain has some brilliant epidemiological modelers and that “even if you don’t think much of Boris Johnson or his senior advisers, the modelers who are feeding them information and advice are intellectually honest, hardworking, care deeply about protecting the public, and are as good at their jobs as anybody in the world.”  As I pointed out in a reply, this is undoubtedly true, but a lot depends on whether the government is willing to implement that advice. And its track record so far is not inspiring: for years it ignored expert advice on the effects of badger culling on the spread of bovine TB and continued to kill badgers. It’s only just reversed that decision.  Let’s hope that they have learned from that experience.

I am also hoping that there will be at least one positive outcome from the current pandemic on top of recent extreme weather patterns linked to climate change (for example the drought and fires in Australia that I blogged about in January).  I hope that it serves to  remind the public, governments and large corporations just how dependent on the environment our society is.  Despite our advanced technologies, we are incredibly sensitive to disruptions in the natural world.  As this old piece from the New York Times points out: “most epidemics — AIDS, Ebola, West Nile, SARS, Lyme disease and hundreds more that have occurred over the last several decades — don’t just happen. They are a result of things people do to nature“.   That was in 2012, long before COVID-19 was discovered.  To update this, check out the Wildlife Conservation Society’s ongoing series of articles about the relationship between our destruction of natural habitats, the trade in illegally (and legally) hunted animals, and emerging diseases such as COVID-19.

I realise that I’m fortunate and that there’s a lot that I can do by working from home.  For the next few weeks I’ll be doing just that, supporting students online, completing grant and manuscript reviews, having Zoom/Skype meetings, and completing the book that I am writing.  Stay safe everyone.

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Filed under Australia, Biodiversity, Butterflies, Climate change, University of Northampton

Chequered skippers are back: extinct English butterfly breeds for the first time in over 40 years!

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Last year I wrote about our involvement with the chequered skipper reintroduction project that’s happening in north Northamptonshire, and specifically the work of University of Northampton postgraduate researcher Jamie Wildman.  For the past month we’ve been sitting on some news that we were not allowed reveal: the reintroduction has been a success!  That is to say, adult butterflies emerged in May this year, having overwintered as pupae, and have been seen breeding in Rockingham Forest.  The secrecy was to prevent hordes of butterfly twitchers (buttwitchers?) descending on the site and possibly doing unintentional harm as they searched for the adults.  The population just isn’t large enough to be able to withstand that sort of pressure.

The BBC has run with the story this morning – here’s the link – and we have issued a piece via the university’s press team: the link to that is here.

In a time when the media is dominated by profoundly depressing stories about wildlife and the environment it’s great to be able to end the week with some positive news.  Here’s to the long-term success of this lovely little critter!

 

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Monarchs and Milkweeds Workshop summary, Oak Spring, Virginia, June 2019

2019-06-12 09.24.58

As I recounted in my last post about a train ride through American climate change, my wife Karin and I have been in the USA for the past couple of weeks, visiting colleagues in the west and ultimately heading eastwards to Virginia for a workshop on monarch butterflies and their milkweed hosts.  The meeting was organised by Anurag Agrawal, professor at Cornell University and author of the recent book Monarchs and Milkweed, highly recommended to anyone interested in the natural history of plants and insects.  The monarch (Danaus plexippus) is an iconic migrating  species that travels from Mexico to Canada and back, over the course of a few generations.  This behaviour, and their vast over-wintering assemblages, have become the focus of intense efforts to understand their ecology and biology.  Their caterpillar host plants are mainly milkweeds (Asclepias spp.) and bringing together both plant and animal scientists is important for gaining a fuller over view of the issues facing the monarchs and the milkweeds, and how both can be conserved in a time of anthropogenic change.

The venue for the workshop was Oak Spring, Upperville, the former home of Paul and Rachel (“Bunny”) Mellon which has been turned into the base of operations for a philanthropic foundation specialising in plant science, horticulture, and botanical art.  The Oak Spring Garden Foundation (OSGF) is “dedicated to inspiring and facilitating scholarship and public dialogue on the history and future of plants, including the culture of gardens and landscapes and the importance of plants for human well-being”.  The OSGF generously funded the workshop, including accommodation and travel for participants.  This brought together a small group of scientists from the USA, the UK and Brazil, together with an artist, a milkweed horticulturalist, and two science writers.  Their brief was to discuss the latest developments in our understanding of monarch butterflies, their decline and conservation, and the taxonomy, evolution and ecology of milkweeds and the wider groups of Lepidoptera and the plant family Apocynaceae to which these organisms belong.  My invitation to take part was due to the research on the pollination ecology of this family I’ve conducted, spanning about twenty five years and culminating in a recently published assessment of the diversity of pollination systems in Apocynaceae.

First things first: Oak Spring is one of the most tranquil, beautiful, and inspiring places where it’s ever been my privilege to stay.  Here’s a few photographs, but they really do not do justice to the buildings and garden, their setting, nor to the unique atmosphere of Oak Spring.

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So to the science.  The workshop started with a set of short presentations on our recent research findings and the motivations for our interests in these organisms.  On the second day we then moved on to discussing ideas for future collaborations between the participants and how that work might be funded in the future.  Presentations and discussions were mainly held in the Basket House, named for obvious reasons:

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Each of us was also interviewed on camera to build an online archive of the work we do and why we do it.

The advantage of face-to-face meetings such as this, and why Skype and so forth can never fully replace them, is the free-flowing conversations that occur within the formal sessions and outside them.  Among the many things that I learned from presentations and discussions were:

  • The California monarch population has declined by almost 90% this year and there’s an urgent need to understand why this has happened.  Climate change has been implicated, especially in relation to the increased frequency of wildfires in this region.
  • Existing methods of nectar extraction from milkweed flowers may strongly underestimate the volume available to flower visitors, and overestimate the sugar concentration.  Using a small centrifuge to spin out the nectar seems to be the most effective method.
  • Asclepias arrived in the Americas (probably from Africa) some 10 million years ago (mya).  However Danaus only arrived about 3.7 mya, so there was a long period of time in which the plant was not co-evolving with one of its major herbivores.
  • There is strong evidence of migrations along the Andes by a close relative of the monarch, Danaus erippus.  Migrations in this group of butterflies therefore extends beyond the iconic D. plexippus.
  • Sonoran Desert Asclepias are sister group to the rest of the New World Asclepias spp.  The exact route by which the African ancestors made it to the Americas is unknown, it could be via Asia and the Bering Strait, or across the Atlantic by way of island stepping stones.  Either way, the phylogenetic position of the Sonoran milkweeds implies that a lot of Asclepias species have gone extinct over the past 10 million years.
  • Climate change seems to be resulting in more complex and unpredictable windows of opportunity for monarch egg laying and caterpillar development.  The monarchs are most successful in late spring and late summer, but not in all years.
  • Likewise, extreme precipitation of the kind I recently documented in the USA is also likely to have a negative impact on the monarchs and their host plants.
  • There is molecular evidence that monarch butterflies went through a huge genetic bottleneck in the 1960s-1970s, for reasons that are not altogether clear.

All of these findings, and more that there isn’t space to document, point to a need for further research to better understand these organisms if we wish to secure their futures.

By the end of the workshop we had made some concrete decisions on future steps:

  •  The African members of the genus Asclepias, plus about 20 other closely related genera, require more critical taxonomic and phylogenetic assessment in order to understand their systematic relationship to the North and South American Asclepias species.
  • A poster (or possibly series of posters) will be produced that explain the ecology of the monarch, its relationship with milkweeds, the patterns of migration, and the value of milkweeds as nectar sources for a diverse range of pollinators.
  • We will explore a multi-agency grant application to further develop the collaborations between participants.

The final day of the workshop involved a field trip around Virginia to see some of the local milkweed species, many of which live in woodland.  That surprised me: I always envision Asclepias spp. as grassland or desert plants.  The leader of the field trip, Mark Fishbein, had a hit list of 8 species that he wanted us to see and in the end we located all of them, including a rare hybrid population of A. syriaca x A. exaltata, plus the tropical milkweed Asclepias curassavica planted in the OSGF garden, plus the distant relative dogbane Apocynum cannabinum.  Here are some images from that day:

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Searching for milkweeds along Skyline Drive, Shenandoah National Park

 

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Poke milkweed – Asclepias exaltata

 

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Hunting that elusive hybrid milkweed!

 

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Caterpillar of the monarch butterfly feeding on a milkweed

 

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Alessandro Rapini intent on getting a good photo of the A. syriaca x A. exaltata hybrid

 

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A bumblebee and a butterfly visiting A. exaltata

 

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Purple milkweed – Asclepias purpurascens

 

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Common milkweed – Asclepias syriaca – with a visiting skipper butterfly

 

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Climbing milkvine – Matelea obliqua – a member of a largely fly-pollinated group of New World asclepiads

 

Thanks to my fellow workshoppers for such a stimulating and enjoyable meeting, and to all the staff at Oak Spring for making us feel so welcome.  Particular thanks go to Prof. Sir Peter Crane who, as President of the Oak Spring Garden Foundation, was hugely supportive of the workshop, and to Angie Ritterpusch, Head of Events and Guest Services, for logistical and organisational support.

 

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Filed under Biodiversity, Biogeography, Butterflies, Climate change, Evolution

What happens when pollinators lose their flowers? A new study suggests some answers

 

Biella et al image

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.

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Filed under Bees, Biodiversity, Butterflies, Hoverflies, Pollination, University of Northampton, Wasps

Are these first photographs of a living specimen of a rare African butterfly?

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Earlier this year my colleague at the Royal Botanic Gardens Kew, David Goyder, tweeted a link to a new book about the biodiversity of Angola which you can download for free by following this link.  David’s an authority on Apocynaceae, the family of plants on which I’ve also worked for many years (see this recent post), and has been sorking in Angola in recent years on a large biodiversity project.  So I was interested to see what was in the chapter  he had co-authored called “The flora of Angola: Collectors, Richness and Endemism“.  I was immediately struck by one of the images in Figure 5.3 showing an unnamed butterfly feeding on the flower of a species of Apocynaceae (Raphionacme michelii).

I made a note to myself to talk to David about adding the record to our Pollinators of Apocynaceae Database. But before I had a chance to do that, another apocynologist colleague, Ulrich Meve in Bayreuth, forwarded the chapter with a similar idea in mind.

We emailed David about the image and he sent us originals, but confessed he didn’t know what the insect was.  So I uploaded it to an African Lepidoptera forum on Facebook.  At which point a wave of excitement broke, because after some discussion as to whether it might be a new species, it turned out that the most likely candidate was an exceptionally rare butterfly called Acraea mansya in the family Nymphalidae.

According to Dominique Bernaud, an authority on the group, this species is hardly known beyond a few collections and he has never seen a photograph of a living specimen: if you follow this link you will see that the known distribution of the species does not include Angola,  and indeed it is not listed in the chapter on butterflies in the Angola biodiversity book.  So this is a new country record and (we think) the first images of living insects: so a double first for a beautiful species.

Here’s links to collection information for the plant and to David’s checklist of plants from the region, which gives details of the vegetation and the habitat.

An unanswered question, of course, is whether the butterfly is a pollinator of this species of plants.  Raphionacme belongs to a subfamily of Apocynaceae that have hardly been studied from the perspective of pollination ecology, so we simply don’t know.  Hopefully someone in the future will visit this remote region of Africa and find out!

Thanks to David for sending the images (a complete set of which is below), the National Geographic Okavango Wilderness Project, and the Wild Bird Trust, Parktown, South Africa.

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Filed under Apocynaceae, Biodiversity, Biogeography, Butterflies, Pollination

British phenological records indicate high diversity and extinction rates among late-summer-flying pollinators – a recently published study

Balfour et al Figure 1

Natural history records of plant flowering and pollinator foraging, much of them collected by well informed amateurs, have huge scientific importance. One of the values of such records to ecology is that it allows us to document where these species occur in space and when they are active in time. This can be done at a range of spatial and temporal scales, but large-scale patterns (for example at a country level) are, I think, especially useful because they provide scientific evidence that can inform national conservation strategies.

During 2017 I collaborated with a young early career researcher at the University of Sussex, Dr Nick Balfour, on an analysis of the phenologies of British pollinators and insect pollinated plants.  That study was recently published (see citation below) and I think that the results are fascinating.

Nick did most of the leg work on this, which involved assessing more than one million records that document the activity times of aculeate wasps, bees, butterflies and hoverflies held in the databases by three of the UK’s main insect recording organisations, the Bees, Wasps and Ants Recording Society (BWARS), the UK Butterfly Monitoring Scheme (UKBMS) and the Hoverfly Recording Scheme (HRS).  Information on flowering times was taken from a standard British flora (Clapham et al. 1990 – Flora of the British Isles. Cambridge University Press).

As well as looking at annual flight periods and flowering trends for these organisms we also focused on pollinator and plant species that were endangered or extinct. Here are some headline results and thoughts on what the work shows:

  • About two-thirds (62%) of pollinator species peak in their flight times in the late summer (July and August), though there was some variation between the different groups – see the figure from the paper above).  Particularly noticeable was the double peak of the bees, with the first peak denoting the activity of many early-emerging solitary bees, such as species of the genus Andrena, whilst the second peak is other solitary bees plus of course the bumblebees which by that time have built up their colonies.
  • A rather fixed phenological pattern with respect to different types of plants was also apparent, which I was not expecting at all: insect pollinated trees tend to flower first, followed by shrubs, then herbaceous species (again, refer to the figure above). This might be because larger plants such as trees and shrubs can store more resources from the previous year that will give them a head start in flowering the following year, but that idea needs testing.
  • Putting those first two points together, what it means is that trees tend to be pollinated by those earlier emerging bees and hoverflies, whereas the herbs are mainly pollinated by species that are active later.
  • When looking at the extinct and endangered pollinators, the large majority of them (83%) were species with a peak flight times in the late summer, a much larger proportion than would be expected given that 62% of all species are active at that time. However this was mainly influenced by extinct bee species and the same pattern was not observed in other groups.
  • The obvious explanation for that last point is that historical changes in land use have led to a dramatic reduction in late summer flowering herbaceous species and the subsequent loss of floral resources has been highly detrimental to those bees. But intriguingly no such pattern was apparent for the endangered pollinators and clearly there are complex reasons why pollinators should become rare or extinct, a point that I have discussed previously on the blog.
  • The lack of late summer flowering resources for pollinators is a contentious issue however as plant conservation groups have in the past recommend that meadows and road verges are cut in late summer to maximise plant species richness.  Mowing road verges once or twice a year certainly benefits plant diversity, as this recent review by Jakobsson et al. (2018) demonstrates.  But there’s very little data available that assesses how timing of cutting can affect pollinators.  The only study that I know of (and if I’ve missed any, please let me know) that has considered this is the PhD work of one of my former students, Dr Sam Tarrant who looked at pollinators and plants on restored landfill sites compared to nearby nature reserves.  In a paper that we published in the journal Restoration Ecology in 2012 we showed that on restored landfill sites the abundance of pollinators in autumn surveys (conducted September-October) was just as high as for summer surveys.  On nature reserves, which are routinely cut from mid-July onward, this was not the case.

Here’s the full citation of Nick’s study with a link to the publisher’s website, and a copy of the abstract is below.  If anyone wants a PDF, drop me a line:

Balfour, N., Ollerton, J., Castellanos, M.C., Ratnieks, F.L.W. (2018) British phenological records indicate high diversity and extinction rates among late-summer-flying pollinators. Biological Conservation 222: 278-283

Abstract:

The long-term decline of wild and managed insect pollinators is a threat to both agricultural output and biodiversity, and has been linked to decreasing floral resources. Further insight into the temporal relationships of pollinators and their flowering partners is required to inform conservation efforts. Here we examined the
phenology of British: (i) pollinator activity; (ii) insect-pollinated plant flowering; and (iii) extinct and endangered pollinator and plant species. Over 1 million records were collated from the historical databases of three British insect monitoring organisations, a global biodiversity database and an authoritative text covering the national flora. Almost two-thirds (62%) of pollinator species have peak flight observations during late-summer
(July and August). This was the case across three of the groups studied: aculeate wasps (71% of species), bees (60%), and butterflies (72%), the exception being hoverflies (49%). When species geographical range (a proxy for abundance) was accounted for, a clear late-summer peak was clear across all groups. By contrast, there is marked temporal partitioning in the flowering of the major plant groups: insect-pollinated tree species blossoming predominantly during May (74%), shrubs in June (69%), and herbs in July (83%). There was a positive correlation between the number of pollinator species on the wing and the richness of both flowering insect pollinated herbs and trees/shrubs species, per calendar month. In addition, significantly greater extinctions occurred in late-summer-flying pollinator species than expected (83% of extinct species vs. 62% of all species). This trend was driven primarily by bee extinctions (80% vs. 60%) and was not apparent in other groups. We contend that this is principally due to declines in late-summer resource supplies, which are almost entirely provisioned by herbs, a consequence of historical land-use change. We hypothesize that the seasonality of interspecific competition and the blooming of trees and mass-flowering crops may have partially buffered spring flying pollinators from the impacts of historical change.

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Filed under Bees, Biodiversity, Butterflies, Hoverflies, Macroecology, Pollination, Wasps