Category Archives: Mutualism

Recent reviews in pollination biology: an annotated list: UPDATED x 3

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As it’s my birthday today, I thought I’d reward myself by completing a blog post that I started just after Christmas and never got round to finishing.  Review articles that summarise recent developments in a field are an important contribution to the scientific literature that allow us to pause and reflect on where a topic has been and where it is headed.  Having recently (co)authored a couple of reviews I can attest that they are useful in this respect for both the writers and for the readers.

In the past couple of years quite a number of critical and timely reviews have been published which are proving very useful to me: I’m currently writing a book and these reviews have been invaluable in summarising aspects of a field that is currently publishing in excess of 1000 research papers per year. So I thought I’d bring them together into a single listing with a short commentary on each.  No doubt I have missed many other reviews so please feel free to point out any gaps and I will update the list as I go along.

Each review is hot linked to the source; a good proportion of the reviews are open access, notably those from the recent special issue of Annals of Botany devoted to the ecology and evolution of plant reproduction.  Some reviews are very focused, but most are quite broad.  Several of these complement one another.  I hope you find them interesting and useful.

Barrett, S. & Harder, L. (2017) The ecology of mating and its evolutionary consequences in seed plants. Annual Review of Ecology, Evolution and Systematics 48: 135-157

Mating systems, i.e. who breeds with whom, are just as complex in plants as they are in animals.  However some features of seed plants, such as the fact that they don’t move, that most species have both male and female functions, and that their growth is modular and often indeterminate, represent significant challenges that have been overcome in a bewildering variety of ways.

 

Braun, J. & Lortie, C.J. (2018)  Finding the bees knees: A conceptual framework and systematic review of the mechanisms of pollinator-mediated facilitation.  Perspectives in Plant Ecology, Evolution and Systematics 36: 33-40

In a community, if one plant species positively affects another, we term this “facilitation”.  It can occur at a variety of life stages, including reproduction whereby the presence of one species increase the likelihood of another species being pollinated.  This review shows that it occurs fairly frequently at a variety of spatial scales, but there are still significant gaps in our understanding of the phenomenon.

 

Fuster, F., Kaiser‐Bunbury, C., Olesen, J.M. & Traveset, A. (2018) Global patterns of the double mutualism phenomenon. Ecography https://doi.org/10.1111/ecog.04008

When species provide benefits to one another in two different ways, for example an animal is both a pollinator and a seed disperser of a plant species, we refer to it as a “double mutualism”.  As this fascinating review shows, double mutualisms are very uncommon, but they are widespread, and probably under-recorded.

 

Minnaar, C., Anderson, B., de Jager, M.L. & Karron, J.D. (2019) Plant–pollinator interactions along the pathway to paternity. Annals of Botany 123: 225-245 

The male aspect of plant reproduction, i.e. pollen donation, is often neglected when we consider how pollination systems evolve.  This review provides as up to date account of where we are in understanding how paternity influences floral characters such as shape and colour.

 

Ollerton, J. (2017) Pollinator diversity: distribution, ecological function, and conservation. Annual Review of Ecology, Evolution and Systematics 48: 353-376

A very broad over view of our current understanding of the biodiversity of pollinators, taking a deep time and a wide spatial perspective to put current concerns about loss of pollinators into a wider perspective.

 

Parachnowitsch, A.L., Manson, J.S. & Sletvold, N. (2019) Evolutionary ecology of nectar. Annals of Botany 123: 247–261 

We often take nectar for granted – it’s just sugar and water, isn’t it?  As this review shows, nectar is dynamic and complex, and affects a range of ecological functions beyond just providing pollinators with a reward.  However there’s still a huge amount we don’t understand about how nectar traits evolve.

 

Toledo-Hernández, M., Wangera, T.C. & Tscharntke, T. (2017) Neglected pollinators: Can enhanced pollination services improve cocoa yields? A review.  Agriculture, Ecosystems and Environment 247: 137-148

Chocolate is most people’s favourite confectionery and is famously pollinated only by small midges.  Or is it? As this review shows, lots of other insects visit cocoa flowers, but their role as pollinators has not been well studied.

 

Vizentin-Bugoni J, PKM Maruyama, CS Souza, J Ollerton, AR Rech, M Sazima. (2018) Plant-pollinator networks in the tropics: a review. pp 73-91 In Dáttilo W & V. Rico-Gray. Ecological networks in the Tropics. Springer.

This book chapter that I co-authored with some very energetic and creative young Brazilian researchers summarises what’s currently known about plant-pollinator interaction networks in tropical communities.  One of the conclusions is that they are really not so different to those in temperate and subtropical biomes.

 

Wright, G.A., Nicolson, S.W. & Shafir, S. (2018) Nutritional Physiology and Ecology of Honey Bees. Annual Review Entomology 63:327-344

A review of how bees use nectar and pollen at the level of both the individual and the colony, focused on the most widespread of pollinator species.

UPDATE 1:

As expected, several people have told me about reviews I’d missed, and in some cases ones that I had read but forgotten about!  I’ll list them below, though without annotations:

Bennett, J. et al. (2018) A review of European studies on pollination networks and pollen limitation, and a case study designed to fill in a gap, AoB Plants 10:  https://doi.org/10.1093/aobpla/ply068

Knight, T. et al. (2018) Reflections on, and visions for, the changing field of pollination ecology. Ecology Letters 21: 1282-1295

Vallejo-Marin, M. (2018) Buzz pollination: studying bee vibrations on flowers. New Phytologist https://doi.org/10.1111/nph.15666

 

UPDATE: 2

I had deliberately restricted the reviews to 2017 onwards, but via email David Inouye kindly sent a few older ones through which are equally useful:

Brosi, B. J. (2016) Pollinator specialization: from the individual to the community. New Phytologist: 210: 1190–1194

Hahn, M. and C. A. Brühl (2016) The secret pollinators: an overview of moth pollination with a focus on Europe and North America. Arthropod-Plant Interactions: 1-8

Inouye, D. W., et al. (2015) Flies and flowers III: Ecology of foraging and pollination. Journal of Pollination Ecology 16

 

UPDATE 3:

A more recent addition to this set of reviews was sent to me by Anne-Laure Jacquemart.  Although it’s focused just on one (rather variable) crop, I think it will be really useful for anyone interested in the pollination biology of crop plants:

Ouvrard, P. & Jacquemart, A.-L. (2019) Review of methods to investigate pollinator dependency in oilseed rape (Brassica napus).  Field Crops Research 231: 18-29

 

 

 

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Filed under Bees, Biodiversity, Brazil, Honey bees, Mutualism, Pollination

The biological mutualisms at the heart of sourdough bread

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During the road trip to Denmark that I mentioned in a post back in September – see “There ain’t no b(ee) in Starbucks” – my wife Karin received a special gift from her sister Pia.  It was a small jar containing a starter culture for sourdough bread, a culture that Pia has been using since she received it from a friend, who long ago received it from another friend.  I didn’t know much about sourdough bread and did some reading. That Wikipedia link is a good introduction but don’t be put off by the complexities of “refreshment” – we’ve kept the starter culture in the fridge since early September and it’s been fine.  Karin used the culture for the first time this morning and made the rye bread you see above.

But on to the biology.  In essence the sourdough culture is a mix of wild lactic acid bacteria and wild yeasts, plus flour and water.  When added to the bread mix (which in our case contained water, salt, seeds and molasses, as well as rye flour) the yeasts feed on some of the sugars within the mix and the lactic acid bacteria feed on other sugars that the yeast cannot metabolise.  During that bacterial fermentation, byproducts are also produced on which the yeasts feed.  The yeasts in turn produce carbon dioxide which serves to leaven the dough, and the bacteria produce lactic acid as another byproduct, which gives the bread its slightly sour flavour.  This lactic acid also lowers the pH of the environment and, together with the production of anti-fungal chemicals, the lactic acid bacteria prevent the growth of other bacteria and moulds.  The yeasts, however, can tolerate these conditions and they thrive.

At least six species of yeast and 25 species of lactic acid bacteria have been shown to be  involved in this process, often as multi-species mixtures.  The exact biodiversity of the culture is dependent upon its source: micro-organisms vary a lot across the world.  But the heart of the relationship between yeasts and bacteria is always the same: they each facilitate the growth and reproduction of the other, and so the relationship is mutualistic, much like (most) relationships between plants and pollinators, birds and berries, and sea anemones and clownfish.

Of course there is a third organism involved in this mutualism: Homo sapiens.  By producing the resources on which these organisms feed, and then distributing the starter culture, we are providing the right conditions for the yeast and lactic acid bacteria to increase their populations.  In turn the yeast and bacteria play an important role in producing food for us, and in fact this way of making bread is thousands of years old.  Microorganisms and people all benefit: what could be more mutualistic than that?  Indeed, these interactions could be classified as a rare example of a ménage à trois mutualism.

There’s also a social-cultural dimension to all of this as the passing of gifts such as the starter culture binds friendships.  If any of our local friends are reading we’d be happy to share the sourdough culture once we’ve bulked it up.  The bread that it makes is delicious and from now on we’re going to try to give up buying the shop-bought kind.

If you want to read more about all of this, and have a try at making your own starter culture from scratch, there’s some great information and links on the Microbial Menagerie blog.

Many thanks to Pia for sharing the starter culture, and to Karin for baking the bread!

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Trait evolution, resource specialization and vulnerability to plant extinctions among Antillean hummingbirds – a new study just published

Hummingbird bowl from BM

Hummingbirds are fascinating creatures and important pollinators for a wide range of plants in the New World (and, historically, possibly in the Old World – see this post from 2014: There were hummingbirds over the White Cliffs of Dover).  During the last decade I have been involved in some hummingbird-related research with several colleagues, particularly Dr Bo Dalsgaard and Dr Stella Watts, and it’s generated some really interesting findings about the biogeography, macroecology, and interactions with plants of these most elegant of birds.

The latest installment of this work is a test of some ideas relating to the vulnerability of hummingbirds on islands to the extinction of their plant partners.  It’s just been published and the reference is:

Dalsgaard B., Kennedy J.D., Simmons B.I., Baquero A.C., Martín González A.M., Timmermann A., Maruyama P.K., McGuire J.A., Ollerton J., Sutherland W.J. & Rahbek C. (2018) Trait evolution, resource specialization and vulnerability to plant extinctions among Antillean hummingbirds. Proceedings of the Royal Society series B (in press)

Here’s the abstract:

Species traits are thought to predict feeding specialization and the vulnerability of a species to extinctions of interaction partners, but the context in which a species evolved and currently inhabits may also matter. Notably, the predictive power of traits may require that traits evolved to fit interaction partners. Furthermore, local abiotic and biotic conditions may be important. On islands, for instance, specialized and vulnerable species are predicted to be found mainly in mountains, whereas species in lowlands should be generalized and less vulnerable. We evaluated these predictions for hummingbirds and their nectar-food plants on Antillean islands. Our results suggest that the rates of hummingbird trait divergence were higher among ancestral mainland forms before the colonization of the Antilles. In correspondence with the limited trait evolution that occurred within the Antilles, local abiotic and biotic conditions—not species traits—correlate with hummingbird resource specialization and the vulnerability of hummingbirds to extinctions of their floral resources. Specifically, hummingbirds were more specialized and vulnerable in conditions with high topographical complexity, high rainfall, low temperatures and high floral resource richness, which characterize the Antillean Mountains. These findings show that resource specialization and species vulnerability to extinctions of interaction partners are highly context-dependent.

As always I’m happy to send a PDF to anyone who drops me an email.

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Plant-pollinator networks in the tropics: a new review just published.

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As an ecologist who has carried out field work in the temperate zone (UK), the subtropics (Tenerife and South Africa) and the tropics (parts of South America, Africa and Australia)  I’ve always found the idea that the study of ecology can be divided into “tropical” and “non-tropical” a bit odd.  It’s as if the way that the natural world works somehow changes at about 23 degrees north or south of the equator, making things “different” around the equator.  The tropics are a very special, diverse place, it’s true, but so are many places outside the tropics.

With this in mind I was pleased when I was asked by some of my Brazilian colleagues to contribute to a chapter in a new book entitled Ecological Networks in the Tropics. It was an opportunity to review what is known about plant-pollinator networks in the tropics and the ways in which they are very similar to such networks at lower latitudes. Here’s the details of the chapter, followed by the abstract.  If anyone wants a copy please drop me an email:

Vizentin-Bugoni J, PKM Maruyama, CS Souza, J Ollerton, AR Rech, M Sazima. (2018) Plant-pollinator networks in the tropics: a review. pp 73-91 In Dáttilo W & V. Rico-Gray. Ecological networks in the Tropics. Springer.

Abstract:

Most tropical plants rely on animals for pollination, thus engaging in complex interaction networks. Here, we present a global overview of pollination networks and point out research gaps and emerging differences between tropical and non-tropical areas. Our review highlights an uneven global distribution of studies biased towards non-tropical areas. Moreover, within the tropics, there is a bias towards the Neotropical region where partial networks represent 70.1% of the published studies. Additionally, most networks sampled so far (95.6%) were assembled by inferring interactions by surveying plants (a phytocentric approach). These biases may limit accurate global comparisons of the structure and dynamics of tropical and non-tropical pollination networks. Noteworthy differences of tropical networks (in comparison to the non-tropical ones) include higher species richness which, in turn, promotes lower connectance but higher modularity due to both the higher diversity as well as the integration of more vertebrate pollinators. These interaction patterns are influenced by several ecological, evolutionary, and historical processes, and also sampling artifacts. We propose a neutral–niche continuum model for interactions in pollination systems. This is, arguably, supported by evidence that a high diversity of functional traits promotes greater importance of niche-based processes (i.e., forbidden links caused by morphological mismatching and phenological non-overlap) in determining which interactions occur, rather than random chance of encounter based on abundances (neutrality). We conclude by discussing the possible existence and direction of a latitudinal gradient of specialization in pollination networks.

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Local and regional specialization in plant–pollinator networks: a new study just published

Euphorbia canariensis pollinators 2016-04-29 17 58 00

A fundamental feature of the natural world is that no species exists in isolation: all organisms interact with other organisms during their lives. These interactions take many forms and the outcome varies with the type of interactions. For example predator-prey interactions are clearly negative for the prey species, but positive for the predator. Other interactions result in positive outcomes for both species, including relationships between pollinators such as bees, birds and flies, and the flowers that they pollinate. An important feature of such interactions is how specialized or generalized it is; that is, how many different pollinators are actually involved in pollinating a particular type of flower, or how many types of flower does a specific pollinator visits.

In a newly published study, I have collaborated with colleagues from Denmark and Brazil to assess how local specialization (within a community) relates to regional specialization (across communities) using two separate data sets from the Brazilian rupestrian grasslands and Canary Island/North African succulent scrub vegetation.

Here’s the citation with a link to the paper (drop me a line if you can’t access it and need a PDF):

Carstensen, D.W., Trøjelsgaard, K., Ollerton, J. and Morellato, L.P.C. (2017) Local and regional specialization in plant–pollinator networks. Oikos (in press) doi:10.1111/oik.04436

The abstract is as follows:

“Specialization of species is often studied in ecology but its quantification and meaning is disputed. More recently, ecological network analysis has been widely used as a tool to quantify specialization, but here its true meaning is also debated. However, irrespective of the tool used, the geographic scale at which specialization is measured remains central. Consequently, we use data sets of plant–pollinator networks from Brazil and the Canary Islands to explore specialization at local and regional scales. We ask how local specialization of a species is related to its regional specialization, and whether or not species tend to interact with a non-random set of partners in local communities. Local and regional specialization were strongly correlated around the 1:1 line, indicating that species conserve their specialization levels across spatial scales. Furthermore, most plants and pollinators also showed link conservatism repeatedly across local communities, and thus seem to be constrained in their fundamental niche. However, some species are more constrained than others, indicating true specialists. We argue that several geographically separated populations should be evaluated in order to provide a robust evaluation of species specialization.”

This is what those two different habitats look like:

If you would like more information on plant-pollinator networks, including details of an edible game for Christmas (!), follow this link to the standingoutinmyfield blog.

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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

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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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Generalist pollination can evolve from more specialised interactions: a new study just published

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There’s a long-standing idea in biology that ecological specialisation is an evolutionary “dead end” from which species can never emerge.  In other words, if a species becomes so adapted to a particular ecological strategy (could be feeding or habitat requirements or how it interacts with other species ) then no amount of natural selection will result in its descendants evolving different strategies, thereby diversifying into new species.  In particular it’s traditionally thought that evolving broader, “generalist” strategies from narrower, “specialised” ones is highly unlikely.

This has been much discussed in the literature on the ecology and evolution of pollination systems, where traditionally this “dead end” scenario has been accepted.  However a small number of case studies have shown that generalised pollination systems can evolve within much more specialised clades, beginning with Scott Armbruster and Bruce Baldwin’s study of Madagascan Dalechampia (Euphorbiaceae), published in Nature in 1998.

To this limited body of examples we can now add another case study: in the genus Miconia (Melastomataceae), generalist nectar/pollen rewarding strategies can evolve within a clade of plants that predominantly uses a more specialised, buzz-pollinated strategy involving just bees.

The work is part of the PhD research of Vinicius de Brito who is one of the researchers I was privileged to do some field work with in Brazil when I was there in 2013 – see my post: “It’s called rainforest for a reason, right?  Brazil Diary 6“.  Vini is the guy on the left of the photo accompanying this post.  Here’s the citation and a link:

de Brito, V.L.G., Rech, A.R., Ollerton, J., Sazima, M. (2017) Nectar production, reproductive success and the evolution of generalised pollination within a specialised pollen-rewarding plant family: a case study using Miconia theizans. Plant Systematics and Evolution doi:10.1007/s00606-017-1405-z 

Here’s the abstract:

Generalist plant–pollinator interactions are prevalent in nature. Here, we untangle the role of nectar production in the visitation and pollen release/deposition in Miconia theizans, a nectar-rewarding plant within the specialised pollen-rewarding plant family Melastomataceae. We described the visitation rate, nectar dynamics and pollen release from the poricidal anthers and deposition onto stigmas during flower anthesis. Afterwards, we used a linear mixed model selection approach to understand the relationship between pollen and nectar availability and insect visitation rate and the relationship between visitation rate and reproductive success. Miconia theizans was visited by 86 insect species, including buzzing and non-buzzing bees, wasps, flies, hoverflies, ants, beetles, hemipterans, cockroaches and butterflies. The nectar produced explained the visitation rate, and the pollen release from the anthers was best explained by the visitation rate of pollinivorous species. However, the visitation rates could not predict pollen deposition onto stigmas. Nectar production may explain the high insect diversity and led to an increase in reproductive success, even with unpredictable pollen deposition, indicating the adaptive value of a generalised pollination system.

As always, I’m happy to send a PDF to anyone who wants a copy, just drop me an email.

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Research seminar: Dr Hazel Chapman – “Conservation ecology of West Africa’s montane forest habitats – seed dispersers and their substitutes”

We start the new term with a guest speaker from New Zealand – Dr Hazel Chapman – who is coming to give a research seminar this Friday at 1pm in Newton NW205, University of Northampton, Avenue Campus. Here’s the details:
 
Conservation ecology of West Africa’s montane forest habitats – seed dispersers and their substitutes.
 
The Nigerian Montane Forest Project (NMFP) is a conservation and biodiversity research program founded on a field station located on the Nigeria-Cameroon border. Run out of the University of Canterbury, New Zealand, the Project is aimed at understanding the ecology of Nigeria’s montane forest fragments for informed management of this fragile ecosystem. The research focus is predominantly plant-animal mutualisms and forest restoration. This talk will introduce the NMFP and present research aimed at understanding how seed dispersal processes are changing in response to forest fragmentation and hunting.
 
Hazel Chapman is an Associate Professor at the University of Canterbury (UC) NZ, where she lectures in evolutionary ecology. Hazel’s research focus is tropical forest conservation and she is the Founder and Director of the NMFP. Since 2004, the Project has seen a stream of international and Nigerian postgraduate students enrolled at UC doing their field research in Nigeria. In addition the NMFP trains undergraduate Nigerian students in conservation biology, and works with local schools and the community. The Project is run almost entirely by the local community. It is home to a 20ha Smithsonian CTFS Forest Geo Plot.
 
All welcome.

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Insect pollinators boost the market price of holly and mistletoe: a new study just published

Holly and mistletoe 20161211_103252.png

Each year I’ve always added at least one Christmas-themed biodiversity post to the blog, for example: Thank the insects for Christmas, A Christmas vignette, and Six Kingdoms for Christmas.  That’s partly because I really like Christmas as a winter festival, with its folklore and customs.  But it’s also because these are a great vehicle to demonstrate how pervasive and important is natural capital and the ecosystem services it provides to society.

This year I’ve gone one stage further and actually published some Christmassy research to back up the blog post.  Now, in a new study published in the Journal of Pollination Ecology, we have shown how important insect pollinators are in determining the market value of two of the most emblematic of Christmas plants: holly (Ilex aquifolium) and mistletoe (Viscum album).  Here’s the full reference with a link to the paper itself, which is open access:

Ollerton, J., Rouquette, J.R. & Breeze, T.D. (2016) Insect pollinators boost the market price of culturally important crops: holly, mistletoe and the spirit of Christmas. Journal of Pollination Ecology 19: 93-97

Holly and mistletoe are two seasonal crops that play a culturally important role as symbols of Christmas across the world, though both also have pre-Christian pagan roots. Now for the first time the role of insect pollinators in determining the commercial value of these plants has been investigated, using sales records going back over the last eleven years from Britain’s largest annual auction of holly and mistletoe, held every year in Worcestershire.

Analysis of the sales records of Nick Champion Auctions in Tenbury Wells shows that insect pollination raises the sale price of these crops by on average two to three times. This is because holly and mistletoe with berries is more sought after than material without berries, with wholesale buyers paying higher prices at auction. These berries in turn are the result of pollination by insects such as flies and bees: both holly and mistletoe are 100% dependent on insect pollination due to their having separate male and female plants.

There is some annual variation to the prices, and in years where berries are scarce (possibly due to low insect numbers) the price difference can be four-fold.

Due to concerns about pollinator declines and food security there is huge interest in the role of bees and other insects in supporting agriculture, and how we can value that role. However we believe that this is the first study showing that insect pollinators play a large part in determining the value of culturally symbolic, non-food crops. Almost all of the economic valuations of insect pollination to agriculture have focused on food crops such as beans, apples, cocoa, coffee, and so forth. Very little is known about how the value of non-food crops (fibres, construction materials, pharmaceuticals, ornamentals, etc.) is enhanced by insect pollination. This is an area where much more research is required.

But in the mean time, where better to end than with a bit of seasonal John Clare?

The shepherd, now no more afraid,
Since custom doth the chance bestow,
Starts up to kiss the giggling maid
Beneath the branch of mistletoe
That ‘neath each cottage beam is seen,
With pearl-like berries shining gay;
The shadow still of what hath been,
Which fashion yearly fades away.

The Shepherd’s Calendar (1827)

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Filed under Bees, Biodiversity, Biodiversity and culture, Ecosystem services, Hedgerows, Mutualism, Pollination, University of Northampton