Prof. Simon Potts & Duncan Costan, University of Reading
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Chris - On a farm in Berkshire, not far from Reading, you’ll find a rather unusual looking campsite. There are around 40 structures, about 4 metres square, but with white gauze instead of canvas. And inside these ‘pollinator flight cages’ are crop plants and buzzing bees.
Planet Earth podcast presenter Sue Nelson went to the experimental farm to meet Simon Potts - Professor of Biodiversity and Ecosystem Services at the University of Reading and also deputy director of the Centre for Food Security…
Simon - Well, what we've got here is a set of experimental cages where we can actually manipulate the types of pollinators we have inside them and then we can actually expose different plants, they can be wild flowers or they can be crops, and we can actually test what the impact of the different pollinators are on the pollination success.
Sue - What types of pollinators, is it strictly bees?
Simon - Well there's lot of different insects that pollinate but probably bees are THE most important, certainly in Europe. What we have here - we have honey bees which most people will know about but we have also managed bumble bees, and we also have some solitary bees. One particular sort is called the mason bees, because they nest in small tubes, and we also have some hoverflies as well.
Sue - Duncan Costan is with us, he's a research technician at the university. Could you explain the sort of crops that we've got? I think I can vaguely recognise the flower of one of those, possibly broad bean?
Duncan - Well, here it's a field bean.
Sue - That's why it's so much taller than a broad bean!
Duncan - Yeah, and they're grown quite often for things like cattle feed but here we're using them because we can use them as quite a nice indicator with our various different pollinator species. So, we've got them here in individual plant pots so we can move individual plants to expose them to our various pollinator species and then we can keep them in another cage, keep them excluded from all pollinators so we know the only thing that has pollinated that is the species that we've exposed it to.
Sue - So, let's just wander across here, because you've got the field beans there which is, as I say, new to me. And then in the one next to it there, that's very recognisable, the yellow flower...
Duncan - Yep, in this cage and in a lot of our other cages are full of oil seed rape, which is another one of the main crops we're using for the crops project.
Sue - Simon, last year you discovered that wild bumble bees play a much more important role in crop pollination than was previously thought.
Simon - I would say a very widely held belief was that honey bees basically did most of the pollination of crops in the UK and actually that was true back in the 70s and 80s, but since then we've had really catastrophic declines in the number of hives and it turns out that currently only about 10 or 15% of the work is actually done by honey bees, so the real heroes of our crop pollination turn out to be these wild bees. We have 267 species in the UK, including a number of bumbles bees, solitary bees and other small bees as well. So it's really important if we want to sustainably grow food and make sure we've got good pollination we need to know who does the work, and if it's the wild bees doing the work then we really need to think about how to manage the landscape to help them.
Sue - So do we know who does most of the work when it comes to crop pollination?
Simon - We're getting there!
Sue - So we still don't know.
Simon - Well it's amazing. People have known about pollination for decades but actually that really fundamental question, who actually does the work, we don't know for all crops. We're just starting to pick it apart. So quite often it's a combination, it's really good to have a diversity of pollinators because that provides insurance. So, for instance, bumble bees are really good in cold weather and they can fly in those sorts of temperatures. But when it's really hot they don't like it so much and maybe the more solitary bees come in and do the pollination. So as we've got climate change and environment change one of the big questions is how can we manage the landscape to make sure we have the right set of pollinators, not just a single one but a whole set of them so we can always have good pollination.
Sue - So this is partly why you've got these controlled conditions in our little bee flight cage camp site here so you know what crops you've got, as Duncan was saying, you know what pollinators you've got and then you're looking at the mix to see which one works best.
Simon - Yeah, so, the first question is on their own how well do they do? And the second question is; if we add them together do we actually get a greater benefit of having a different combination of pollinators? And what we do finally is then we cross check this by actually going out into the fields, into real farms, and looking at what's actually visiting the flowers. Not every flower is a pollinator, so there are some very crafty bumble bees out there, and they go to the flowers but if you watch very carefully they go to the base and they pinch a hole and in fact they are nectar robbers; they do nothing for the field beans at all, they just take the nectar away. So we've got to know a lot about their individual behaviour as well as which species are out there.
Sue - What about the research that has come out recently? There were two papers that cited neo-nicotinoid insecticides and the extremely negative impact that they have had on wild bees.
Simon - Well I think these studies are really important because we're just starting to see now not just the direct lethal effects of pesticides but also these sub-lethal effects where it may be changes in how reproductive they can be, or it may be changes in honey bees the way they forage and their homing behaviour. I think it's just a really clear warning that we don't know enough and actually as we look more and more we are finding these negative impacts and we should think more carefully about the types of pesticides we use and how we use them...