Category Archives: Bees

All pollinators are equal, but some pollinators are more equal than others

The infamous line from George Orwell’s Animal Farm asserting that “All animals are equal, but some animals are more equal than others” nicely captures an ecological view of pollinators and their relationships with plants. “Pollinators” by definition move pollen between flowers, but not all pollinators are equally good at transferring pollen of any particular plant: some are more effective than others. I’ll illustrate this with examples from the urban garden that Karin and I are developing, which I’ve discussed before.

As you can see from that link, the garden is modest in size, but nonetheless this year it contains a significant biodiversity of edible plants that require pollinators for some or all of the fruit and seed set, including: strawberries, apples, greengages, cherries, blackcurrants, squashes, courgettes, blackberries, fennel, runner beans, french beans, passion fruit, tomatoes, raspberries, and radishes.

“Radishes?!” I hear you ask. “But they are grown for their edible swollen roots which don’t require pollination!” True, usually. But we let our radishes flower because we mainly grow them for their seed pods which, picked young, are delicious in salads and stir fries, like mustardy mange tout. They look like this:

The radish flowers are pollinated by a diversity of insects including butterflies, bees, and small flies:

These insects will vary in their effectiveness as pollinators of radish, depending on the frequency of visits, how often they move between flowers, and the amount of pollen on their bodies. This last factor is largely a function of size and hairiness (bigger, hairier insects carry more pollen as a rule), though cleanliness also plays a part: insects often groom the pollen from their bodies and, in the case of bees, may pack it into their pollen baskets where it’s not available for pollination.

The size and behaviour aspect is best illustrated by some recent photos that I took of visitors to the flowers of passion fruit (Passiflora caerulea var.). We have a large, sprawling plant growing up a fence which is currently being visited by honey bees, hoverflies, solitary bees and bumblebees. In comparison to the size of the flower and the position of the anthers (male, pollen producing parts) and stigmas (female, pollen receiving parts), the hoverflies, honey bees and solitary bees are relatively small. These two images are of honey bees (Apis mellifera):

Here’s an unidentified solitary bee:

These bees were occasionally touching the anthers, mainly with their wings, so some pollen will be moved around. But from what I observed it’s likely to be a relatively small amount in comparison to bumblebees, which are usually much larger and hairier, and don’t groom themselves as often as honey bees. Here’s a Buff-tailed bumblebee (Bombus terrestris):

They were actively collecting pollen as well as nectar. Much of this pollen is packed into the pollen baskets on the rear legs and will go back to the nest to feed the developing larvae, but some will be involved in pollination:

So it seems to be the bumblebees we have to mainly thank for the deliciously sweet-sour fruit we will enjoy later in the season. Of course to test this properly we would need to set up an experiment in which we excluded larger bumblebees from the flowers and only allowed smaller bees to forage, with appropriate experimental controls. Would make a great project if any of my students are interested! But it should give you a sense of just how complex the interactions between flowers and their pollinators are: the ecology of pollination is far from simple, despite what some would have us believe.

From Chester to Copenhagen

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It is 6.30am on Sunday morning but I’m wide awake and can hear the hotel in which we are staying stirring into life. Time to reflect on what has been a long and busy week, rather than the start of a long and relaxing summer holiday as some assume academics enjoy. That’s a myth: summers for many of us are at least as busy as the main teaching part of the year, though that’s not to say we don’t teach in the summer – I have final year project students to advise, and for students who did not pass first time round there’s still re-sit exams and assignments to be undertaken.

Of course I’m not complaining and the busyness is part of the fun of my job, which includes opportunities to travel, as I’ve previously described on this blog. Before any travelling this week, however, Monday was taken up listening to my PhD student Kat Harrold give a seminar about the progress of her research on pollinator mapping and habitat modelling in the Nene Valley Nature Improvement Area. This was followed by an hour’s grilling from the supervisory team and an independent colleague, as we drilled down into the research and suggested ways in which Kat could improve on the already excellent work that she’s doing. All of this is a formal part of our PhD programme and Kat aquitted herself very well indeed.

Tuesday was the start of the travelling, and was spent in Chester helping with filming for an episode of a new four-part BBC2 series provisionally called Plant Odyssey, fronted by Carol Klein, Gardener’s World presenter and Honorary Fellow of the University. The series is being produced by Oxford Scientific Films and will be broadcast in the spring. In the following scene we were making a rose perfume based on an ancient Roman recipe from the writings of Pliny the Elder.

Now, I know very little about how to make perfume, but I do know a bit about flower scents and how they attract pollinators, so my role was to act as both a foil for Carol’s scent experiment and to add some science to the mix. This is not the first filming I’ve done with Carol, having also helped out with her Science in the Garden special edition of Gardener’s World a few years ago. While looking for that last link I discovered that all three episodes of Bees, Butterflies and Blooms is also available on YouTube, which is great to see as the BBC didn’t repeat the series or produce a DVD. I was involved in the making of episode 2, which helped to kick-start the RHS’s Perfect for Pollinators plant labelling campaign. Television work is fun and brings science, and the scientists who do it, to a much wider audience.

Wednesday I prepared my talk for Friday’s lecture in Copenhagen (more of which later) and Thursday involved attending the University of Northampton’s annual postgraduate research conference. This is a highlight of the year for me as it’s an opportunity to see the breadth of postgraduate research going on across the university, something that would be impossible in a larger and more research intensive institution. I was only able to attend the first session, but that alone covered research on the research process itself; feminist cyborg literature; the legality of the World Bank’s scrutiny panel; pollinator conservation (Kat Harrold again); and the experiences of families with children who have difficulties communicating. Questions from the audience tended to be broad and non-specialist, and all the better for that: often it’s the straightforward, naive questions which test specialist knowledge.

The rest of Thursday Karin and I packed and then travelled up to Birmingham International for an early evening flight to Denmark. I’d been invited by my colleague Bo Dalsgaard to present a research seminar at the University of Copenhagen’s Center for Macroecology, Evolution and Climate. Coming from a small and very diverse department, it was great to visit such a large and specialised group of researchers, though over lunch the Center’s Director Carsten Rahbek told me that a common complaint from his staff was: “Why can’t we employ more people doing what I’m going?” Everything’s relative I suppose.

The title of my talk was “Pattern and process in pollination at large geographic scales”, which gave an overview of some of the research I’ve published over the last decade or so, framed around the following questions:

Globally, how many plant species are animal pollinated?
Are plant-pollinator interactions more ecologically specialized in the tropics?
How predictable are pollination syndromes in different parts of the world?
What are the historical and contemporary drivers of the relative importance of animal versus wind pollination? [No link here as that manuscript is currently in review!]

Quite a number of people in the Center were out doing field work or were otherwise engaged so I spoke to a modest-sized audience of some 30 people: certainly not the smallest audience I’ve ever presented to – that was three people, including the two who had invited me to give the talk!

The lecture seemed to be well received and there were some stimulating questions afterwards, though also a couple of challenging ones about statistical analysis. One of these I couldn’t answer until afterwards because I’d forgotten the details of the methods we’d used (note to self: re-read old papers before you present their findings). In answering the other I agreed with the questioner that the data could now be analysed in a more sophisticated way (future task, if I ever get the time). If Kat’s reading this, I hope she takes satisfaction in not being the only person to be asked difficult questions about their research this week!

Afterwards I chatted with Bo and Carsten about the limitations of the current and paleo-climate data sets we’ve been using in some studies, which are indeed very limited. But there are only two options. Do we work with data sets that are flawed, whilst acknowledging that any conclusions are tentative? Or wait until better data become available, which could be a decade in the future? My choice is definitely to go with the former, otherwise we’d never publish anything because there are always limitations to data used in studies of ecology and biodiversity. Personal and public honesty about such limitations, and ideas as to how they can be overcome in the future, are surely preferable to stalling research.

Later that afternoon I discussed science with two of Bo’s collaborators, Pietro Maruyama a Brazilian PhD student whom I’d met last November, and Peter, a Danish undergraduate. Both are doing excellent work on that most charismatic group of pollinators, the hummingbirds.

Friday evening I was exhausted, and Karin and I opted for dinner in the hotel restaurant and an early night, as Saturday was to be spent exploring Copenhagen. It’s a great city for wandering around, with fascinating architecture and unexpected additions to buildings, such as bronze dragons:

And parks with statues of artists and writers, such as Hans Christian Andersen:

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After a roundabout wander, via a gallery selling African tribal art (which we couldn’t afford) and a small lunch (which we could only just afford – Copenhagen’s an expensive city!) we eventually ended up at the University’s Botanical Garden, which has a superb living collection of cacti and succulents, orchids and other epiphytes, and alpine plants.

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It beautifully illustrates the huge morphological diversity encompassed within the 352,000 or so species of flowering plants, one of the many reasons why I love visiting botanical gardens: I always see something new. This included two species of bumblebees (Bombus) which I’m sure don’t occur in Britain. I’ll have to look them up when I get back: from Chester to Copenhagen and, tomorrow, back to Northampton.

Nature as gardener (Darwin’s Unrequited Isle part 5)

“These things aren’t to study. They’re to turn up very loud and say, hey, once upon a time, everything was just as easy as this”

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The title of this brief post is a quote by Led Zeppelin frontman Robert Plant, from an interview that the BBC reported just this morning, regarding the forthcoming release of previously unheard Zeppelin material. You can read the story and hear the interview here.

Regular readers of this blog will know that I’m not averse to sprinkling musical references into my posts, and this was a great quote that seemed to chime with something else I read this morning. Over at the Small Pond Science blog, evolutionary ecologist Amy Parachnowitsch has a thought provoking post entitled “Save the bees, but maybe not this way“. I’ll let you read it for yourself, but in a nutshell Amy is concerned about the scientific legitimacy of a “Save the Bees” campaign being crowd funded by online activist network Avaaz.org.

I share this concern and it worries me that whoever is organising the campaign is exploiting the genuine desire by people to “do something for the bees” without any regard for what exactly it is that’s “being done”. It seems to me to be purely a campaign fund-raiser by people who don’t understand the issues or how science works, the message being: “These things aren’t to study. They’re to turn up very loud and say, hey, once upon a time, everything was just as easy as this”.

The organisers promise “the world’s first large scale, grass-roots supported, totally independent study of what’s killing our bees that decisively challenges the junk science of big pharma”. As Amy notes, this is hugely offensive to independent scientists who are working on bee conservation issues (such as myself). But without ever actually saying what they are going to do with the money, they’ve already had pledges of money from over 78,000 people! If only raising funds for real research was that easy!

To reiterate what I said in the comments to Amy’s post, something that really worries me is that over-emphasis on pesticides and honey bees as single issues affecting “pollinator conservation” deflects attention from other factors which are at least as important, such as habitat loss. Colleagues and I have a manuscript in preparation at the moment showing that native bee and flower-visiting wasp extinctions in Britain began in the mid-19th century and reached their highest rate during the period 1929-1959, during a time of rapid agricultural intensification (but prior to the introduction of neonicotinoid pesticides that is currently exercising many people). Loss of pollinator diversity is an issue that has deep roots.

In actual fact, although wild bee diversity is declining in the UK, overall abundance seems to be stable as some species are doing extremely well, including a new natural colonist, the Tree Bumblebee (Bombus hypnorum) which is spreading fast and is locally common. But clearly greater diversity provides us with future insurance against losses of other species.

There are positive things that can be done for pollinator populations by every citizen, beyond giving money to crappy, pseudo-scientific campaigns, as I talked about in a recent post of mine. So please don’t contribute to this Avaaz.org request, and use the money you save to buy some wild flower seeds and/or the Led Zeppelin reissues. It will make the world a better place.

Book review: “Pollination and Floral Ecology” by Pat Willmer

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Review of “Pollination and Floral Ecology” by Pat Willmer (2011) Princeton University Press. £65. pp. 832.

Some backstory: In early 2012 I was asked by the review editor of the journal Annals of Botany to review this book, and I jumped at the chance as it’s the first major single-author overview of the field of pollination ecology for a number of years, by a well respected academic in the field. Unfortunately the review took a lot longer than I expected, in part because I was also coordinating my department’s Research Excellence Framework submission, on top of other teaching, research and admin duties, and it was taking up quite a bit of my time.

In addition I had mixed feelings about the book and wanted my review to do it justice, not be over-critical but at the same time highlight what I saw as flaws. In the words of the Fairport Convention song, Who Knows Where the Time Goes? – my review was only completed last Christmas and duly submitted. Turns out that the journal has a backlog of book reviews to publish and the editor asked that, given it’s been a couple of years since the book was published, would I mind if the review was posted on the Annals of Botany blog rather than in the printed journal. I happily agreed as it’s likely to get more readers on the blog, and said I’d also post it on my own blog. So here it is:

Any text book that tries to assess and summarise the whole of a multidisciplinary research field such as pollination ecology and floral biology is required to be four things: (1) comprehensive in its scope; (2) up to date in its coverage of the literature; (3) accurate in its assessment of the current state of the field; and (4) authoritative in the conclusions it presents.

This volume by Professor Pat Willmer of the University of St Andrews certainly ticks the first box. It’s a huge book, and covers everything relating to the evolution of flower attraction and reward systems, ecological interactions with pollinators, biochemistry, physiology, agriculture and conservation; all in 29 chapters split into three sections, with 87 pages of references. The literature extends to 2010, which is impressive for a book published in 2011 (though see my comments below about completeness of the literature). Specialist terms are highlighted in bold to direct the reader to the glossary at the back, a useful device even if there are a few inaccuracies, which I’ll mention later.

So far so good, and the author is to be congratulated on putting together such a comprehensive, not to mention timely, single-author book. It’s clearly the summation of a career devoted to studying pollinators and flowers, and the author’s passion for her subject is apparent throughout.

However when we come to points 3 and 4, things are less straightforward. There are some issues with accuracy that are troubling in a book aimed at newcomers to the field as well as established researchers. To give just a few examples:

– on p.18 we are told that asclepiads have “one stamen” (they have five); on p.169 and in the glossary that asclepiad pollinia are the pollen grains from one anther (they are the contents of half an anther); and on p.170 that the pollinaria are “glued” to pollinators (they actually clip on).

– in the glossary, tree ferns are referred to as “cycads”, an error that is repeated on p.89.

– on p.88 there is a statement suggesting that tree fern spores were dispersed by “animal fur” 300 million years ago, long before the evolution of mammals, and that this (and dispersal of spores of fungi and mosses) is the equivalent of pollination: it is not, it equates to seed dispersal.

These are troubling errors of basic botany that are forgivable in an early draft of the book (everyone makes mistakes) but not in the final published version, after it’s been read, reviewed, checked and edited. If the book goes to a second edition I hope that these (and other) mistakes will be fixed. But they do hint at a fundamental problem with a book (and a field) as large and complex as this: a single author is arguably unlikely to be able to do justice to all of the subject matter.

There are parts of the book where it is unclear (to me at least) what the author is actually saying. For example, on p.96 there is a graph which, it is suggested, demonstrates that pollination by animals is “technically uncommon when assessed in terms of the numbers of broad taxonomic groups that use it”, though the legend to the figure claims that “most orders of plants have no families” that possess wind pollination. This is confusing: what is to be concluded by someone new to the field? Is animal pollination common or rare? Likewise, on p.91 we are told that the “first angiosperms…would probably have had their pollen moved mainly by wind…”, but then on p.92 that “an element of insect pollination could be regarded as almost ancestral”. Which is correct?

There are other aspects to the book that are simply out of date; for example the linear, rather deterministic schemes set out in Figures 4.6 and 4.8 showing that Cretaceous flowers were open and radially symmetrical, and only later evolved into complex, bilateral flowers in the Tertiary, ignores fossil discoveries showing that orchids evolved in the Cretaceous (Ramírez et al., 2007). Likewise, discussion of “counterproductive” crypsis in flowers (p.124) neglects recent findings of cryptic, wasp-pollinated plants in South Africa (e.g. Shuttleworth & Johnson, 2009).

There is a theme emerging here: some of the botany that the book presents is inaccurate, confused or out-dated. Fortunately the zoological aspects of the book are much better, as one might hope from a Professor of Zoology.

The final criterion, that the book should be “authoritative in the conclusions it presents”, is however, in my view, the main weakness of this volume. The author is unhappy with recent developments in the field, particularly as they relate to community-scale assessments of plant–pollinator interactions, in terms of network analyses and predictive utility of pollination syndromes. Clearly Professor Willmer is on a mission to rebalance what she perceives as failings within some of the current trends in studying pollination. A book review is not the place for a technical dissection of the author’s arguments, which is best left to the peer-reviewed literature (though I would argue that that’s also the place to present some of the criticisms the author introduces, rather than into a text book such as this). I could focus the whole of this review on these topics because: (a) they take up a large proportion of the book, about one-third of the text pages; and (b) they are highlighted on the cover as being one of the main contributions of the book; specifically, that the author provides a critique of previous work that does not distinguish between “casual visitors and true pollinators” that can in turn result in “misleading conclusions about flower evolution and animal-flower mutualism”. Unfortunately her targets are straw men, and one – I believe quite telling – example will suffice.

On p.447 there is a criticism of the use by Waser et al. (1996) of Charles Robertson’s historical data set, and specifically that the analyses they present “…did not distinguish visitors from pollinators even though Robertson’s database did include information on this”. However Waser et al. clearly state (p.1045 of their paper) that only pollinators were included in the analyses, not all flower visitors, and that “visitation is not a synonym for pollination…non-pollinating visitors are excluded (as in Robertson 1928)” (p.1048).

Why should Professor Willmer make a statement to the contrary? Evidently she wishes to impress upon her readers that (in her opinion) there are fundamental problems in current approaches to studying pollination at a community level. But even if that were the case (and I don’t believe it is) misrepresenting previous studies to suit an argument is poor scholarship at best.

Regardless of whether some of her criticism is well founded, the author does not seem to appreciate that plant–flower visitor interaction networks are ecologically important regardless of whether or not a flower visitor acts as a pollinator. More fundamentally, true pollination networks possess similar attributes to flower visitor networks, for example a nested pattern of interactions, and arguments about level of generalisation of species are a matter of scale, not category (Ollerton et al., 2003).

At the end of her Preface, Professor Willmer reveals to us quite a lot about her personal attitude to research when she states that some readers might find her approach “too traditional” in an “era where ecological modelers [might be claimed to] have more to tell us than old-style field workers”. What the author fails to appreciate is that this is a grossly false dichotomy and that most of the pollination ecologists who have embraced new analytical methodologies for understanding plant–pollinator interactions are also “old-style field workers” with considerable experience of studying the ecology of flowers and their pollinators beyond the computer screen.

In summary this is a book that, for all its good qualities of comprehensiveness and (mostly) up to date coverage, should be read with caution: parts of it are neither as accurate nor as authorative as the field of pollination and floral ecology deserves.

LITERATURE CITED

Ollerton J, Johnson SD, Cranmer L, Kellie, S. 2003. The pollination ecology of an assemblage of grassland asclepiads in South Africa. Annals of Botany 92: 807-834.

Ramírez SR, Gravendeel B, Singer RB, Marshall CR, Pierce NE. 2007. Dating the origin of the Orchidaceae from a fossil orchid with its pollinator. Nature 448: 1042-1045.

Shuttleworth A, Johnson SD. 2009. The importance of scent and nectar filters in a specialized wasp-pollination system. Functional Ecology 23: 931-940.

Waser NM, Chittka L, Price MV, Williams N, Ollerton J. 1996. Generalization in pollination systems, and why it matters. Ecology 77: 1043-1060.

What are YOU doing for our pollinators this year? (reduce, reuse, recycle part 6)

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Earlier this year I was asked to write a short article by my former PhD student, and still a current collaborator, Dr Sam Tarrant. Sam works for the RSPB as the CEMEX UK-funded Biodiversity Advisor, and wanted something on pollinator conservation that could be circulated in the CEMEX company’s e-newsletter. In the spirit of reworking and reusing odd bits of writing, I thought I’d post it here too.

Insects are vital for our country’s economy. Don’t believe me? Then read on….

Beneath a large black mulberry tree near the University of Northampton’s Newton Building there is a plaque that commemorates its planting “On Shakespeare Commemoration Day, 3^rd May 1916”. Despite its age this tree annually produces large crops of succulent berries, aided by the fact that wind eddies are sufficient to disperse its pollen, ensuring pollination and fruit set. Each year it’s a scramble between students, lecturers and birds, to see who can eat the most.

In contrast, the old apple trees in the grounds possess a different strategy – pollination by insects that move from flower to flower each spring. This form of pollination is both more sophisticated and less reliable than wind pollination, and is currently under considerable threat: whilst there will never be a shortage of wind currents in Britain, insect pollinators are in decline.

The apples trees are not alone in requiring insects to pollinate them, so to do other farm and garden crops, including oil seed rape, field beans, courgettes, runner beans, and strawberries and other soft fruit. It’s worth at least £440 million annually to the British economy, and most of it is done by wild bees and hoverflies, rather than managed hives of honey bees.

But all is not well with these insects in Britain – they are in decline. Although the extent of the “pollination crisis” is debated by scientists, long term records show us that these insects are under pressure: 23 species of bee and flower-visiting wasp have gone extinct since the mid 1800s, as have 18 species of butterflies. Less obviously, other species have considerably reduced in abundance so that they are now found in only a small part of their previous distribution.

There are lots of gardeners who want to “do something” for the pollinators, and keeping honey bees is often mentioned. By all means, if you wish to help the honey bees (which are suffering their own problems) then keep a hive or two. That will not, however, help our wild, native pollinators; the analogy I use is that it’s the equivalent of trying to help our declining songbirds by opening a chicken farm!

If you want to make a real difference for pollinators in your own garden, here are a few ideas:

start by planting nectar and pollen rich flowers; there’s a useful list on the Royal Horticultural Society’s website (see below).
allow plants such as clover and dandelion to flower in your lawn, bees love them.
as well as food, pollinators also need nest and egg laying sites, so you could help by allowing some of the far corners of your plot to run a little wild.
wait until late Spring to cut back hollow stemmed perennials as they are used as hibernating places by some of our bees.
allow mason bees to nest in old walls and don’t worry about them, the wall won’t fall down.
And finally, stop using pesticides!

Changing some of our gardening habits can help a group of insects on which we rely and which supports our economy in a very real way.

Further reading and information:

Bees Wasps and Ants Recording Society: http://www.bwars.com/

Bumblebee Conservation Trust: http://www.bumblebeeconservation.org.uk/

Butterfly Conservation: http://www.butterfly-conservation.org/

Hoverfly Recording Scheme: http://www.hoverfly.org.uk/

Royal Horticultural Society’s list of plants for pollinators: http://www.rhs.org.uk/Gardening/Sustainable-gardening/Plants-for-pollinators

Thank the insects for Christmas (REBLOG)

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It’s become a tradition (ok, only for the past two years, but a tradition has to start somewhere!) for me to post a version of this festive blog entry. I’ve updated the stats for 2013. Hope you enjoy it.

Christmas! A time to relax and enjoy ourselves, to share time with family and friends, and to unwind during the cold and gloom of winter. Whatever your faith, or lack of it, Christmas should be about taking a break and reflecting on the year that has passed. We’re helped in that respect by the ceremonial seasonal trimmings: the Christmas tree, strings of flashing lights, baubles and tinsel. So while you’re kissing a loved one under the mistletoe, admiring that glossy holly wreath, or tucking into your Christmas dinner, spare a thought for the insects.

“What in Saint Nicholas’s name” you are asking ”have insects got to do with Christmas?!” Well, like the turkey, we’d be stuffed without them: they play an essential part in providing us with the things we associate with Christmas. If we had no flies, wasps, bees and other bugs acting as pollinators there’d be no berries on your mistletoe or your holly. Kissing and admiring would be a less festive affair and that’s just for starters. These insects also pollinate many of the vegetables, herbs and spices on your plate, as well as some of the forage that went to fatten your roast bird or tender joint of meat. Not to forget much of what went into the nut roast that’s feeding the vegetarian relatives.

The economic value of insect pollination in the UK was estimated by the recent National Ecosystem Assessment to be about £430 million per year. In fact this is a huge under valuation because the labour costs alone of paying people to hand pollinate those crops would run into billions of pounds. This sounds far fetched but it’s already happening to fruit crops in parts of China. The answer is to encourage wild insects, not artificially managed honey bees, because collectively the former are far more abundant, and often more effective, as pollinators. Their diversity is an insurance against losing any one species in the future. The NEA’s valuation is also too low because it only deals with commercial edible crops, and does not include those we grow in our gardens and allotments. It also does not take account of ornamental crops such as mistletoe and holly, both of which are dioecious species, which is to say that individuals are either male or female, rather than hermaphrodite as are most plants. This means that the plants cannot self pollinate and insects are absolutely vital to their reproduction and to the production of the decorative berries we so value (a holly wreath without berries is just a big spiky doughnut, in my opinion).

Whilst researching the economic value of the annual mistletoe and holly crops for this blog posting last year I had a conversation with Jonathan Briggs over at Mistletoe Matters and he told me that “the mistletoe trade in Britain is entirely unregulated and not documented in any tangible way”, and the same is true of holly. We therefore have no idea what the economic value of these non-food crops actually is. But some back-of-the-red-and-gold-Christmas-lunch-napkin calculations can at least give us an insight. Auction reports for 2013 show that on average the best quality berried holly was selling for £2.50 per kg whilst equivalent quality holly without berries sold for only 80p per kg. In other words, pollination by insects increases the value of that crop by more than 300%! Similarly the high quality mistletoe averaged £1.20 per kg, whilst the second grade stuff was only 40p per kg. And the best holly wreaths (presumably with berries!) were averaging £7.00 each.

These are wholesale prices, of course; retail cost to the customer is much greater. A decent holly wreath will set you back between £15 and £30 whilst online shopping for mistletoe is in the £5 to £20 range, depending on how much you want. The national census of 2011 shows us that there are 23.4 million households in England and Wales, plus there are 2.36 million in Scotland and 0.70 million in Northern Ireland. Let’s round it down and say there’s 26 million households in the whole of the UK. Let’s also be very conservative and estimate that only 5% of those households bought one holly wreath and some mistletoe at a total cost of £20. Multiply that by the small proportion of households buying these festive crops and you arrive at a figure of about £26.5 million! And that doesn’t include non-household use in shops, offices and businesses. So there you have it: an industry worth a few tens of millions (at least) all being ultimately supported by insects.

With pollination, timing is everything, and Jonathan also made the point that spring flowering mistletoe and holly can be important early nectar sources for insects. Therefore despite the poor summer weather in 2012, that year was a good one for mistletoe berries because the pollination happened before the heavy rains began. Despite being quite common plants, rather little research has been done on either holly or mistletoe pollination in the UK and it would make for an interesting student project. The Landscape and Biodiversity Research Group here at the University has for many years been working to understand the ecology of plants and pollinators, and how to best conserve them. In this blog I’ve referred a few times to some ongoing projects researching how the wider landscape is supporting pollinators in habitats such as country house gardens (Hilary Erenler’s PhD work which she completed this year) and urban centres (ongoing PhD work by Muzafar Hussain). There’s also the work completed a few years ago by Sam Tarrant and Lutfor Rahman on pollinator (and other) biodiversity on restored landfill sites. Plus research that’s recently started by Kat Harrold on how whole landscapes support pollinators in the Nene Valley Nature Improvement Area. This is all part of a broader programme of research into the conservation of biodiversity in our region and beyond, including our Biodiversity Index, a contribution to the Shared Enterprise Empowering Delivery (SEED) sustainability project.

Biodiversity matters and its importance to our society is being increasingly recognised by government, business and the public. So if you make one New Year’s resolution on the 31st December, let it be that you will put away your garden bug sprays for 2014 and learn to love the insects (even wasps!) who give us so much and help to support our economy in a very real way. It costs us nothing; all we need to give them is well managed, diverse, unpolluted habitats in which to live. Have a great Christmas everyone!

The strange and the familiar….. (back from) Brazil Diary 8

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The first bird I identified when I arrived in Brazil on 1st November was a feral pigeon (Columba livia) foraging around the airport; the first bee I spotted, visiting flowers around FUNCAMP, was a honey bee (Apis mellifera). This tells you a lot about the widespread, near ubiquitous distribution of such species, which have been moved across much of the planet, accidentally and on purpose, by human activities. For someone who is deeply interested in biodiversity, seeing these species is both humdrum and interesting. Humdrum because they are so familiar, we see them everywhere we go, they are not exciting and exotic. Interesting because they tell us a lot about the effects that humans have on their environment, how we are altering it by the introduction of non-native species.

Away from the large cities I saw introduced species such as these less and less frequently, such is their association with humans. But of course there were also plenty of native Brazilian species that have become associated with human activities. Some of these had a familiarity about them which transcended the fact that they were species I’d never see in Britain. Black Vultures (Coragyps atratus) are the best example. I would frequently observe them perched on lamp posts in towns, scanning for food or squabbling amongst themselves, and also spotted a huge number feeding on the refuse being piled into a landfill site. Back home I associate this sort of behaviour with various species of gulls. Strange and familiar.

Back in Northampton I’ve been reflecting on my month-long visit to Brazil, catching up with colleagues, telling stories that get more impressive with each iteration. It’s been a packed couple of weeks and Brazil seems a long way away, not just geographically.

The Biodiversity Index did not win the Green Gown Award that it was short listed for, as I previously reported, but it did receive a Highly Commended citation. Green Gown have asked us to produce a video, so a few days after I returned home, and still with a bit of my brain in Brazil, I took part in a short recording session about the Biodiversity Index, which will be released shortly. The video is produced by Jo Burns and her company Amplitude Media. Jo is a graduate of the University of Northampton and this is a nice example of how the University is supporting former students as they develop their careers.

At the end of last week we also got the news that the Biodiversity Index has been shortlisted for a Guardian newspaper University Award in the sustainability category. More recognition for the work we’ve done on that project, and we are very pleased! The result will be known early next year.

As of this week our paper on “How many plants are pollinated by animal?“, published in the journal Oikos in 2011, has notched up its 100th citation according to Web of Knowledge. The less conservative Google Scholar puts it at 164, so the true answer will be somewhere in between. Clearly peers think it’s a useful bit of work. And to think it was almost rejected by Oikos, saved only by an appeal. The idea for the paper arose when I was trying to find a solid figure in the literature for the proportion of plants that are biotically pollinated. Lots of figures were being bandied about, but once you follow the reference chain back through the papers that cite them you find that numbers which are cited as solid facts disappear into speculation and guestimates. Like many of the simple and obvious questions, the assumption is that we “know” the answer. That’s no basis for science-informed policy, but I suspect that it happens all too frequently.

Je ne egret rien

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Conservation does not mean the same as preservation, despite the popular synonymy of these two words. Preservation implies that something remains the same, is static and held in the same unchanging state. One can preserve an old book, or fruit, or traditions for instance. But one cannot preserve biodiversity because species change in abundance and distribution, regardless of the activities of humans. That’s just how nature is. One could take a deep time view of such change and consider the ancient habitats and organisms that built much of Britain’s underlying geology, as I mentioned when I described some walking on the Dorset coast a while back. But even over shorter time scales that are comprehendible to humans, biodiversity changes, by the day, the month and the year.

That’s where egrets, and the pitiful punning title of this post, come in. At the end of last week Karin and I spent a long weekend on the Suffolk coast, in the village of Walberswick. It’s an old stomping ground for Karin but I don’t really know this area very well at all. We spent our time talking and reconnecting, eating local food, drinking the good local Adnams beer, walking along the beaches, through saltmarsh and reed beds, and collecting stones and sea glass (I really like sea glass and have amassed bottles of the stuff over the years that we keep on sunny windowsills – think of it as aesthetic waste management). And we looked at birds as we encountered them in these rich, diverse habitats. Final total for the weekend was a respectable 37 species, including a few I couldn’t identify, helped along by a trip to the RSPB’s Minsmere Reserve (with, it seemed, every other birder in Suffolk; we had to queue to get into some hides).

Two of the species we saw were egrets, a common name that covers several genera in the heron family Ardeiedae. As the Wikipedia entry for egrets notes: “The distinction between a heron and an egret is rather vague, and depends more on appearance than biology”, as good an argument for the importance of scientific species names as any I’ve encountered.

The first of the two species I spotted was the Little Egret (Egretta garzetta), an elegantly roaming bird that actively hunts along river margins and through marshland and flooded fields. I was able to get within 10 metres or so of a bird at Walberswick and could admire its poised movements on vivid yellow feet, contrasting with black legs to make it look like a woman wearing footless stockings, as Karin put it (she took the photograph that accompanies this entry). The second species of egret was the Great White Egret (Ardea alba), a much taller bird than the first, and an ambush hunter; like the related Grey Heron its strategy is to stand still and wait until prey comes to it.

The earliest record of a Little Egret in Britain was almost 200 years ago, in East Yorkshire in 1826. However it is not known to have bred in this country until a pair did so in Dorset in 1996. In other words, just 20 years ago this was an uncommon bird in Britain whose rare arrival would have generated a flurry of local twitching. Now it hardly gets a mention on birding sites, we are so familiar with it. Not so the Great White Egret which still raises some excitement when it appears. Although this species was also recorded as early as 1821 in Britain, Great White Egrets only began to breed in Britain in 2012 and there is considerable anticipation that it will follow the Little Egret in expanding its population in this country.

We could add other birds to this list of species which have naturally colonised Britain within living memory, such as the almost ubiquitous Collared Dove (Streptopelia decaocto) as well as insects such as the Tree Bumblebee Bombus hypnorum and the Ivy Bee Colletes hederae. Others will undoubtedly follow in the future, and perhaps the Cattle Egret will be the next member of the heron family to take up permanent residence on our shores.

Of course the flip side of new arrivals such as these is extinction, a topic that I will return to at some point as we’re currently putting the finishing touches to what I hope will be an exciting new paper on British bee and wasp extinctions. Understanding the ebbs and flows of biodiversity over time requires data to be collected and we are fortunate in Britain to have a number of active monitoring schemes that regularly survey different groups of organisms. This activity is vital if we are to be able to monitor our wildlife and to take action if we see declines, though the most recent results for the Status of Priority Species index makes grim reading: the overall abundance of threatened species in the UK declined by 68% between 1970 and 2010. It’s a complex message, though, and there are some success stories within those statistics. But the animals that have fared worst have been the insects, particularly moths and some of the bees, wasps and ants.

Against this background of monitoring and decline I was happy to accept an invitation last week to attend a Defra-sponsored meeting at the Natural History Museum in London to discuss the setting up of an insect pollinator monitoring scheme. A group of about 50 scientists and conservationists discussed what such a scheme might look like and how it could be implemented. I’ll report back in more detail about this in the future once some decisions have been made as to how to proceed.

Meetings such as this, as well as being important in their own right, provide an opportunity to catch up with old friends and colleagues and discuss their latest work, or latest child/house move/job move, as appropriate. So it was good to have a couple of beers after the meeting and chat with a few people including Dave Goulson, arguably one of the most significant scientists working in British pollinator conservation, and an outspoken critic of the current use of neonicotinoid pesticides. Dave founded the Bumblebee Conservation Trust and has produced a lot of the scientific literature on bumblebees as he describes with wit and passion in his recent book A Sting in the Tale. I’ve known Dave for over twenty years (we were PhD students together) so I was a little embarrassed to ask him to sign my copy of his book, but as a collector of signed editions I wasn’t going to let the opportunity slip. Dave mentioned that the book has been shortlisted for the Samuel Johnson Prize and I hope it wins: ok, I’m biased, and can read it in Dave’s own voice which adds enormously to the book. But it’s a great read for anyone interested in pollinators, or conservation, or just in the processes which turn a natural history obsessed kid into a professional scientist.

This will be my last blog entry from Britain for a month; on 31st October I fly out to Brazil to spend time with André Rodrigo Rech, running a short pollination biology course, speaking at the Brazilian Botanical Congress, and conducting field work. I’ll try to blog as I go along. In a happy coincidence the Great White Egret is depicted on the Brazilian five real banknote. I’ll look out for it.

Harvest of evidence

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The last entry I posted was premature in its prediction that autumn is here and for the past week we’ve enjoyed some bright, warm weather: an Indian Summer before autumn proper envelops us. Sunday afternoon was spent in the garden, digging up potatoes and planting the garlic we bought on the Isle if Wight. Neither of these crops requires pollinators, but others we’ve been harvesting this month do, including squashes, runner beans and greengages. The latter are from a mature tree that, when we took over the house in 2012, I assumed was a bog standard Victoria plum. The tree did not crop last year but has more than compensated this season with abundant deliciously sweet fruit.

All of this provides useful anecdotes for public lectures. Since appearing on Bees, Butterflies and Blooms I’ve regularly been asked to give talks to gardening societies and I try not to refuse because they are usually fun with attentive, knowledgeable audiences. At one such event earlier this year I was asked: “Is there any evidence that declining pollinators are resulting in lower crop yields in Britain?” It’s a great question that goes to the heart of evidence-based conservation and the notion that science should be informing such policies as strategies to conserve biodiversity.

As far as I’m aware there is no indication that British insect pollinated crop yields have declined. And if the evidence of our greengages, runner beans and squashes is anything to go by, there’s currently plenty of wild bees, hoverflies and other insects (we get few honeybees in this garden) to service those food plants that require their pollinating activities. But that doesn’t mean we should be complacent and monitoring is required, because the evidence from other countries is that yields are down for insect pollinated crops and hand pollination is required in some places.

Evidence should inform everything that we do and believe as scientists, gardeners, informed members of the public, whatever label we choose for ourselves. This is especially true of currently controversial issue such as the causes of global climate change or the effects of neonicotinoid pesticides on pollinator health (see Dave Goulson’s slides from a recent conference talk, for example). But we should also understand that a basic tenet of science is that it can never “prove” anything: new evidence may appear at any time that refutes our cherished notions, or disproves that pet hypothesis. We make decisions on weight of evidence not on proof. So it was depressing to read a widely publicised article about a Nigerian postgraduate student’s claims that he has “proved” that homosexual relationships are “unnatural” because only the opposite poles of magnets are attractive to one another, the same chemical compounds do not react together, and roosters only love hens. At first I thought it was a spoof but it appears that the research student is perfectly serious and, more, has been tipped to win a Nobel Prize by his equally deluded supervisors.

It’s easy to scorn the guy’s findings and point out that people aren’t magnets or simple chemical compounds and that homosexual activity is widespread in the animal world (so how do we define “unnatural”?) But Karin, as always, had a deeper and more nuanced view of this story than did I. Perhaps it’s her training in psychotherapy but whatever the reason, she gave an alternative perspective and pointed out a sad possibility. Karin suspects that the student has been manipulated by academic and political powers that have a vested interest in such “proof” because of threatened sanctions on aid. Under this scenario the student has been encouraged by the academics at the university to pursue this misguided work, which can only support the Nigerian government’s anti-gay stance. Of course the research will never be published by any reputable scientific journal and the story has harmed the University of Lagos’s international reputation. But for the narrow minded and biblically fundamentalist, the story itself will be evidence enough to shore up their own prejudices. One person’s crackpot claims is another’s decisive evidence.