Monthly Archives: September 2013

Harvest of evidence


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.

Any friend of coffee is a friend of mine

Beach spiral

As I begin to write this post rain is pattering against the windows with increasing frequency and a brisk wind stirs the browning horse chestnut leaves that overhang the garden from a neighbouring property.  Autumn is here.  It’s a chilly Sunday morning and beside me is a large cup of good coffee, hot, black, and bitter, warming and stimulating in equal measure.  It’s our first Sunday at home for a fortnight as last weekend was taken up by a speaking engagement in Hereford at a large bee keeping convention where coffee featured highly, as I’ll explain.

The Hereford convention wasn’t the kind of academic research conference that I’d normally attend, but I thought it would be fun to go with Karin, and I’d learn more about bee keeping (both proved to be true).  For this broad audience of amateur and professional bee keepers I presented a version of my professorial inaugural lecture from earlier this year entitled “How many bees does it take to wake up in the morning?  The importance of biotic pollination in a changing world”.  It’s a title with multiple layers of meaning, referring to bees as ecosystem service providers, my enjoyment of my work which gets me out of bed every day, and the energising effects of a strong cup of fresh coffee first thing.  

As part of that lecture I present some back-of-the-envelope calculations that are meant to put coffee production into a biodiversity perspective, rather than being a rigorous analysis, but which are nonetheless worth considering.  They go like this.

Global coffee consumption in 2010 (the most recent year for which I could find figures) amounted to 93 million export bags, each weighing on average 60kg (there are larger and smaller bags used in different parts of the world, so we’ll use this figure).  The export value of this crop was estimated at US$15 billion for the (largely tropical) countries that produced it.  That’s the value before it’s processed and sold, which is much more difficult to calculate, though coffee retailing is clearly big business.  For example, Starbucks’ total revenue for the same year was US$10.7 billion and it supports over 150,000 full time employees.  So it’s lucky for us that it pays its taxes.  

Although coffee is partly self pollinating, it relies on insect pollination to produce large crops, mainly involving bees of various types.  I tracked down a number of studies by researchers such as Alexandra-Maria Klein and Taylor Ricketts which showed that managed honey bees are responsible for anywhere between zero and over 90% of flower visits, depending on the diversity and abundance of local wild bees (over 40 species of which are known to pollinate coffee in Costa Rica alone).  At this point I throw out a question to the audience:  how well do we understand this globally important agricultural ecosystem service?  Do we have any idea of how many individual insects are required to support this industry?  Some more calculations:

Each coffee bean is the product of a single fertilisation event following the deposition of at least one pollen grain on a flower’s stigma.  The mean weight of a single coffee bean is 0.103g (I weighed a sample in preparation for the lecture) which means there are approximately 582,524 beans in a 60kg bag.   Total number of coffee beans produced in 2010 is therefore 93 million bags multiplied by 582,524 beans per bag, which equals  54,174,757,281,553.  In words, that’s  more than 54 trillion coffee beans.  As coffee is 50% self pollinating we can half that figure: coffee production requires at least 27,087,378,640,777 (over 27 trillion) pollinator visits.

But here I confess to the audience that it’s impossible to go further and answer the questions I posed above:  we really have no idea how many bees are supporting the coffee industry.  The problem is that there are big gaps in our knowledge of some basic aspects of the natural history of these bees and their interactions with coffee flowers.  For example, how many flowers does an individual bee visit in its lifetime?  How effective are different bees at pollinating  the flowers?  What is the minimum population size for these bees, below which they would go locally extinct?  All that we can say with certainty is that the global coffee industry (and the individual productivity of many workers) is supported by a LOT of bees.   Many billions is my best guestimate.  Perhaps we don’t need to know the number: perhaps it’s enough to know that if we provide sufficient good quality habitat for these bees, they will provide the service.  But at least it illustrates our reliance on these insects and is something to consider when you’re enjoying the first cup of the day.

Bees are not the only animals that we have to thank for coffee production as a recently published study has shown:  birds in Costa Rica help to reduce the impact of an important pest of coffee.  As Jana Vamosifrom whom I shamelessly stole the title of this posting, commented when I posted this link on Facebook:  any friend of coffee is a friend of mine!


Garlicky archipelago

Sunrise from train September 2013

“Garlicky” is a great word, redolent of hot, pungent flavour and nose-filling odour: a Pavlovian word that ignites the senses as it’s uttered.  Perhaps I love the word because garlic is one of my favourite vegetables, a pleasure to both eat and grow.  A Garlic Festival is therefore not to be missed, and my family and I had the opportunity to attend one on the Isle of Wight during a short holiday a couple of weeks ago.  We were joined by university friends I’ve referred to previously, as the first one of us to reach a half century celebrated his 50th birthday.  There was more to the festival than just garlic, but for me its highlight was seeing the sheer variety of different garlic types that can be grown, testament to how this vegetable has been modified from its ancient wild origins in central Asia.  Karin and I bought seed bulbs of four different varieties as additions to the horticultural biodiversity of our vegetable plot, to be planted later in September.   These included the notable Elephant Garlic with its massive individual cloves, which, I’ve just learned while researching that link, is not a true garlic at all but rather a variety of leek.  We live and learn!

Archipelago is another great word and the time we spent on the Isle of Wight, travelling over by ferry from Southampton, served to remind me that the British Isles, with over six thousand islands of various sizes, is by any standards a significant archipelago.  Since at least the explorations of Alexander von Humbloldt, island groups have  been known to host unique species, isolated taxonomically and physically from their closest continental relatives.  Darwin’s later researches showed that archipelagos such as the Galapagos Islands are important as natural evolutionary laboratories, and in previous posts I’ve briefly discussed his unrequited desire to visit to the Canary Islands.  The Isle of Wight is too close to the continent of Europe to have evolved any unique biodiversity but I did pick up the hint of a subtle Island Biogeographic Effect whilst compiling a list of all the bird species I saw over the course of the week.  The list topped out at about 30 species, which I thought was rather low.  Some of the omissions surprised me (not a single blackbird, for instance) and I saw very few individuals of some other common British species.  Now, it could be due to my lousy birding skills I suppose, but it could also be due to the fact that we were on an island, even though it’s less than 1500m across The Solent to the mainland at its closest point.  This is close enough for bumblebees to fly to the island: I’ve seen them shadowing the ferry.  But nonetheless it might be far enough to affect both the diversity and population sizes of the bird life.  Enough wild speculation; I’d be interested to know what serious ornithologists who actually know something about the subject make of this.   

As I finish writing this post I’m on the other great island of my home archipelago, sitting in a bar in Terminal 2 of Dublin Airport.  I’ve been working at University College Dublin as external examiner for their MSc Applied Environmental Science course.  It’s been a fun couple of days reading theses and interviewing chatty, engaged students, which began with a dawn alarm yesterday in order to get to the train station and then Birmingham International in time for a 0850 flight.  Whilst waiting for my taxi I popped into the garden and paused to enjoy the early morning stillness before opening up the chicken coop.  A large flock of black-headed gulls passed low above me, backlit by a thin sliver of moon and silent except for the shuffle of feathers.  From the direction they were travelling I think they were heading from a roost on Pitsford Water and on to destinations unknown.  The garden was also busy with early risen blackbirds and a couple of flitting bats, whilst a little later my taxi passed a rangy fox idly trotting through low mist on the Racecourse park.   It was urban biodiversity at its most sublime.  

All this talk of Northampton is making me feel homesick to be back with the family (Karin, kids, cats and chickens) and start planting garlic.  But there’s just time for another Guinness before my gate opens.  Sláinte!