Category Archives: Wasps

A poem for Valentine’s Day

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I have to confess that I forgot completely about Valentine’s Day, it’s not a celebration that I generally pay much attention to, as expressions of love are something that everyone should be doing all the time, surely?

Anyway, this bastardised version of “Roses are red” is for my wife Karin:

Some bees are red
Others are blue
There’s twenty thousand species
Of every hue

Some flies are yellow
Some wasps are cerise
Many of them pollinate
Better than bees

 

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Filed under Bees, Biodiversity, Poetry, Pollination, Wasps

Tantalising evidence for a new type of pollination system in Madagascan Apocynaceae

cynanchum obovatum with wasp_madag -angavokely_meve 1

As I recounted in my post last summer, the plant family Apocynaceae contains species with a very wide diversity  of pollination systems – see:  The evolution of pollination systems in one of the largest plant families: a new study just published – download it for free.  Confirmed pollinators include bees, birds, moths, butterflies, flies, beetles, and wasps of a dizzying diversity.  So I was intrigued to receive an email earlier this week from my colleague Prof. Dr Ulrich “Ulli” Meve of the University of Bayreuth with the subject line “Wasp expert needed”.  Ulli is an authority on Apocynaceae taxonomy, also has an interest in their pollination biology, and is a co-author of the study last year.

Attached to the email were a couple of images showing a wasp visiting flowers of Cynanchum obovatum, an endemic species of Apocynaceae from northern and eastern Madagascar.  Ulli had taken the photographs during field work there in preparation for the Flora of Madagascar project.  Here’s the global distribution of the species according to GBIF records:

cynanchum obovatum from gbif

I was excited because Madagascar has a very rich diversity of Apocynaceae (between 500 and 1000 species).  However we have flower visitor observations for only a small fraction of them, fewer than 20 species, and good evidence that the visitors are pollinators for only a couple of those.

I didn’t immediately recognise the family to which the wasp belonged: it didn’t look like either Vespidae or Pompilidae, two groups that are known pollinators of Apocynaceae.  So I uploaded the shots to the Hymenopterists Forum on Facebook and within minutes had received an answer:  it was a species of Scoliidae, commonly referred to as scoliid wasps.  The distinctive wing corrugation found in this family is clearly visible on this image:

cynanchum obovatum with wasp_madag -angavokely_meve 2

Scoliids are parasitoids of beetles and are some of the world’s largest wasps, but it’s not a very diverse family, with only about 560 described species, and only a single species in the UK (on the Channel Islands).  Compare that with the Pompilidae and Vespidae, both of which contain c. 5,000 species worldwide.

Ulli tells me that when he saw the scoliid on C. obovatum “the wasp knew what to do with the flowers”, something I’ve experienced with vespid and pompilid wasp pollinated species in Africa: these wasps are really familiar with the flowers, they know how to work them to get a reward as they are regular and committed visitors.  We believe that this is likely to be the legitimate pollinator of the plant, in which case it’s one of the few records for Scoliidae pollinating Apocynaceae, and the first for Madagascar.  Other examples are mainly in South America, India and South Africa, and usually as one of a broad set of other wasps and/or bees visiting generalist flowers.

It’s interesting that this species of Cynanchum is one of the few in which the corona which covers the gynostegium (the fused sexual parts) is closed over:

cynanchum obovatum_madag - angavokely_meve

That means it requires quite a strong, large insect to get inside and access the nectar.  So the prediction is that the pollen masses (pollinaria) will be found on the mouthparts of these wasps.  Intriguingly, a very closely related species C. repandum has no such closed corona, begging the question of whether it might be pollinated by a different type of insect:

cynanchum repandum sl 2867_low

For now this record will go into the Pollinators of Apocynaceae database as pollinator unproven, but i would be great if someone working in Madagascar could confirm the status of this pollination system.

My grateful thanks to Ulli for sharing his pictures and allowing me to tell the story of what may be a whole new Madagascan pollination system for our favourite family.  Apocynaceae is full of surprises!

cynanchum obovatum with wasp_madag -angavokely_meve 3

 

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Hornets are pollinators too!

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This morning I spent a very pleasant couple of hours walking around the farm that’s at the heart of the Warner Edwards Gin Distillery, in Harrington just north of Northampton.  We are setting up some collaborations around conservation and sustainability between the university and Warner Edwards.  The first of these involves surveys of their farm by one of our final year undergraduates, Ellie West, to assess pollinator diversity and abundance, and opportunities for habitat enhancement on the farm.

One of the highlights of this morning’s visit was seeing this gorgeous hornet (Vespa crabro) taking nectar from common ivy (Hedera helix).  I think that she’s a queen stocking up on energy prior to hibernating.  But just look at how much pollen she’s carrying!  There’s every chance that she’s a very effective pollinator of ivy, which is a key nectar resource at this time of year.  It’s such an important plant in other ways too: ivy binds the landscape physically and ecologically, in ways few other native plants do.  Pollination by insects such as hornets (and hundreds of other species) results in berries that are eaten by birds and mammals, whilst the branches and dense, evergreen canopy provides nesting sites for birds and shelter for over wintering insects.

Hornets and ivy: two of my favourite native British species.

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The evolution of pollination systems in one of the largest plant families: a new study just published – download it for free

Figure 1 JUNE revision

Interactions between flowering plants and the animals that pollinate them are known to be responsible for part of the tremendous diversity of the angiosperms, currently thought to number at least 350,000 species.  But the diversity of different types of pollination system (bird, bee, moth, fly, etc.) is unknown for most large, related groups of plants (what systematists term “clades”) such as families and subfamilies.  In addition we know little about how these interactions with pollinators have evolved over time and in different parts of the world.  Only a handful of groups of flowering plants have been studied with respect to questions such as:

How much do we currently know about the diversity of pollination systems in large clades?

How is that diversity partitioned between the smaller clades (e.g. subfamilies, tribes, genera) of a family, and what are the evolutionary transitions between the major groups of pollinators?

Do these pollination systems vary biogeographically across the clade’s range?

These sorts of questions have been addressed for the massive, globally distributed Apocynaceae (one of the top 10 or 11 largest angiosperm families with more than 5,300 species) in a study just published using a new database of pollinators of the family.  What’s more, the work is open access and anyone can download a copy for free.  Here’s the citation with a link to the paper:

Ollerton, J., Liede-Schumann, S., Endress, M E., Meve, U. et al. [75 authors in all] (2018) The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study. Annals of Botany (in press)

In this study we have shown that (among other things):

  • The family is characterised by an enormous diversity of pollination systems involving almost all of the major pollen vectors and some that are nearly unique to the Apocynaceae.
  • Earlier diverging clades have a narrower range of pollination systems than those that evolved later.
  • Transitions from one type of pollination system to another are evolutionarily constrained, and rarely or never occur, whereas others have taken place much more often, e.g. between wasp and beetle pollination.
  • There is significant convergent evolution of pollination systems, especially fly and moth pollination, by geographically and phylogenetically distinct clades.

You’ll notice that there are 75 (!) authors on this paper.  That’s because we’ve pulled together a huge amount of previously unpublished data and used some state of the art analyses to produce this work.  It was a monumental effort, especially considering that my colleague Sigrid Liede-Schumann and I only decided to push ahead with this project about a year ago when we chatted at the International Botanical Congress that I posted about at the timeIn truth however the origins of this paper go back over 20 years to 1997 when when Sigrid and I published a study of what was then known about pollination systems in the Asclepiadaceae (the asclepiads).

In that paper we said that the research “is intended to be ongoing…[we]…hope to re-review asclepiad pollination within the next decade”.  At the time I didn’t think it would actually take more than 20 years!  However over that period a lot has changed.  For one thing the Asclepiadaceae no longer exists, broken up and subsumed within a much larger Apocynaceae.  Also, I’ve done a lot of work in the field and in the herbarium on some of the smaller groups within the family, such as CeropegiaOthers, including many of my co-authors, have also been working on different groups in various parts of the world.  Finally the level of sophistication of the analyses we are now able to do has increased beyond recognition compared to what we could achieve in the mid-1990s.  All of this means that now is the right time to produce this study.

Having said all of that, this is still a work in progress.  Our Pollinators of Apocynaceae Database contains a sample of just over 10% of the species in the family.  So lots more data on plant-pollinator interactions needs to be collected before we say we fully understand how pollination systems have evolved in this most remarkable family.  I’d be happy to talk with anyone who is interested in the family and being involved in future data collection.

The database will be freely available to anyone who wants to use it – lots more can be done with this information and, once again, I’m happy to chat with potential collaborators.

I was recently interviewed about the study, and about plant-pollinator interactions and the Apocynaceae more generally, for the In Defense of Plants podcast – here’s a link to that interview.

Finally, I’d like to express my sincerest thanks to my co-authors on this study – I really couldn’t have done it without you guys!

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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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Pollinators, flowers, natural selection and speciation: a virtual conference

Ashy Mining Bee 2017-06-17 10.55.45

It’s been a couple of years since I posted my previous “virtual conferences” on Pollinators, Pollination and Flowers and Ecology and Climate Change, a lapse that has largely been due to lack of time (my default excuse for most things these days….).  However Judith Trunschke at Uppsala University in Sweden has risen to the challenge of guest-curating her own virtual conference*.  The theme here is how pollinators impose (or sometimes don’t impose) natural selection on flowers that results in the formation of new plant species:

Timo van der Niet (IIASA 2010): Plant-diversification through pollinator shifts

Timo van der Niet (Congresos UCA 2014): Disentangling the contribution of pollinators in shaping angiosperm orchid genus Satyrium

Anne Royer (Evolution 2016): Plant-pollinator association doesn’t explain disruptive selection & reproductive isolation

Brandon Campitelli (Evolution 2016): Pollinator-mediated selection and quantitative genetics

Yuval Sapir (Evolution 2016): Rethinking flower evolution in irises: are pollinators the agents of selection?

Ruth Rivken (Evolution 2014): The mechanisms of frequency-dependent selection in gynodiocious Lobelia siphilitica

Gonzalo Bilbao (Botany 2017): Pollinator-mediated convergent shape evolution in tropical legumes

My grateful thanks to Judith for curating this great set of talks; if anyone else would like to do the same, please get in touch.

Feel free to discuss the talks in the comments section and to post links to other talks on the same topic.

 

*I’m assuming that, as all of these videos are in the public domain, none of the presenters or copyright owners objects to them being presented here.  If you do, please get in touch and I’ll remove it.

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Pollinator biodiversity and why it’s important: a new review just published – download it for free

P1110763

In a new review paper that’s just been published in the Annual Review of Ecology, Evolution and Systematics I have looked at the question of just how diverse the pollinators are, and why pollinator biodiversity is ecologically important and therefore worthy of conservation.  I’ve taken a deep time and wide space approach to this, starting with what the fossil record tells us about when animal pollination evolved and the types of organisms that acted as pollinators in the past (the answer may surprise you if you’re unfamiliar with the recent paleontological literature on this topic).  Some of the most prominent biogeographical patterns have been highlighted, and I have tried to estimate the global diversity of currently known pollinators.  A conclusion is that as many as 1 in 10 described animal species may act as pollen vectors.

As well as this descriptive part of the review I’ve summarised some recent literature on why pollinator diversity matters, and how losing that diversity can affect fruit and seed set in natural and agricultural contexts.  Extinction of pollinator species locally, regionally, and globally should concern us all.

Although I was initially a little worried that the review was too broad and unfocused, having re-read it I’m pleased that I decided to approach the topic in this way.  The research literature, public policy, and conservation efforts are currently moving at such a fast pace that I think it’s a good time to pause and look at the bigger picture of what “Saving the Pollinators” actually means and why it’s so important.  I hope you agree and I’d be happy to receive feedback.

You can download a PDF of the review entitled Pollinator Diversity: Distribution, Ecological Function, and Conservation by following that link.

Pollination ecologists should also note that in this same volume of Annual Review of Ecology, Evolution and Systematics there’s a review by Spencer Barrett and Lawrence Harder called The Ecology of Mating and Its Evolutionary Consequences in Seed Plants.  If you contact those authors I’m sure they’d let you have a copy.

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The Buzz Club: citizen scientists protecting pollinators

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This is a guest post by Charlie Dance who is Development Officer at The Buzz Club.


It’s hard to over-stress the importance of pollinators. Not only do they play an indispensable role in global food security, they’re also essential in maintaining the diversity of plant species in natural habitats, thus supporting nature as a whole. The UK is home to thousands of different pollinators including bees, wasps and hoverflies. However, while many of these species seem to be declining or disappearing, we know surprisingly little about the majority of them. Why are some disappearing, and how quickly is it happening? What can we do to help? How can we turn our gardens into pollinator havens? It was to help answer questions like these that the Buzz Club was founded in 2015.

Run by volunteers at the University of Sussex, The Buzz Club is a citizen-science charity using the power of the public to provide important data on pollinators. We run a variety of nationwide surveys and experiments suitable for all ages and ideal for wildlife and gardening enthusiasts. Furthermore, we provide information about how to make our urban landscapes more pollinator friendly.

For more information and for a list of current projects, please visit our website: http://thebuzzclub.uk/

As a membership-based organisation, we rely on the small donation of £2 per month from members, all of which goes directly towards running the charity. Not only do new members receive a complementary welcome pack containing a specially designed seed mix, bee identification chart, pollinator-friendly gardening guide, magnifying lens and stickers (see photo below), they also get to learn more about pollinators whilst helping to generate useful data that can be used in our projects.

We believe that with your help we can find out how best to conserve bees and other pollinators. Our ultimate goal is to ensure that we look after insects, giving them and us a future.

Join the Buzz Club here: https://alumni.sussex.ac.uk/buzzclub

Facebook: http://www.facebook.com/TheBuzzClubUK

Twitter: http://www.twitter.com/The_Buzz_Club


From Jeff:  if citizen science is your thing, don’t forget that the Ivy Pollinators project will run again this year: https://jeffollerton.wordpress.com/2016/10/11/ivy-pollinators-citizen-science-project/

 

Buzz Club 2.png

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6000 scientists can’t be wrong: the International Botanical Congress 2017

IBC 1

A late afternoon flight from Heathrow got me to Beijing International Airport just in time for me to enjoy a nine hour delay in my connecting flight to Shenzhen in southern China.  I finally arrived at my hotel at 2:15am, exhausted and sweaty in the 30 degree night time heat.  The one consolation is the the hotel was short of rooms so upgraded me to a suite the size of a small city, with a shower like a tropical rainstorm.  Perfect to wash off the dirt of travelling before collapsing into bed.

Why am I here and why is the hotel short of rooms?  Because 6000 scientists have descended on Shenzhen for the 19th International Botanical Congress (IBC).  The IBC is a six-yearly event that rotates around the world; I attended in 1999 in St Louis and 2005 in Vienna, but missed Melbourne in 2011.  At this IBC I’m giving two talks, one at the beginning and one at the end of the conference.  More on that later in the week.

Six thousand botanists need a big conference venue and this morning, after a late breakfast, I strolled up to the convention centre where it’s being held.  It’s enormous, the scale of the thing is overwhelming.  I wandered around whilst they were getting ready for registration opening this afternoon and took some images on my phone.

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There are some fabulous displays of living plants, including this one at the main entrance:

IBC 5

These are attracting pollinators: in 10 minutes I counted lots of honey bees, one butterfly, at least two species of wasps, and a large carpenter bee (Xylocopa sp.) visiting flowers.  I only managed to photograph the first two though:

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On the way back to my hotel I gatecrashed an international turtle expo.  Who knew turtles were such a big thing in China….?

OK, that’s all for now: I have to head back to the convention centre to register, so I’ll leave you with the view I’m seeing from where I’m writing this.  Shenzhen is quite a place and I’ll write more about it later in the week:

IBC 8

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Plant-pollinator networks, the time dimension, and conservation: a new study just published

Biella network

After rather a long gestation period, involving much re-analysis and rewriting, we’ve finally published Paolo Biella’s research from his Master’s thesis.  It’s a really neat plant-pollinator network study from mid-elevation grasslands in Italy’s Northern Apennine.  In it we have considered the way in which such networks could be analysed in relation to plant phenology (i.e. the timing of when they flower) rather than arbitrary time slices (e.g. months, weeks).  We have also discussed how this approach may inform conservation strategies in grasslands such as these.  The full citation with a link is:

Biella, P., Ollerton, J., Barcella, M. & Assini, S. (2017) Network analysis of phenological units to detect important species in plant-pollinator assemblages: can it inform conservation strategies?  Community Ecology 18: 1-10 

I’m happy to send a PDF to anyone who is interested in seeing the full study.

Here’s the abstract:

Conservation of species is often focused either only on those that are endangered, or on maximising the number recorded on species lists. However, species share space and time with others, thus interacting and building frameworks of relationships that can be unravelled by community-level network analysis. It is these relationships that ultimately drive ecosystem function via the transfer of energy and nutrients. However interactions are rarely considered in conservation planning. Network analysis can be used to detect key species (“hubs”) that play an important role in cohesiveness of networks. We applied this approach to plant-pollinator communities on two montane Northern Apennine grasslands, paying special attention to the modules and the identity of hubs. We performed season-wide sampling and then focused the network analyses on time units consistent with plant phenology. After testing for significance of modules, only some modules were found to be significantly segregated from others. Thus, networks were organized around a structured core of modules with a set of companion species that were not organized into compartments. Using a network approach we obtained a list of important plant and pollinator species, including three Network Hubs of utmost importance, and other hubs of particular biogeographical interest. By having a lot of links and high partner diversity, hubs should convey stability to networks. Due to their role in the networks, taking into account such key species when considering the management of sites could help to preserve the greatest number of interactions and thus support many other species.

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