Category Archives: Pollination

Bees and pesticides – a major new study just published – UPDATED

Male B lap on Salvia cropped P1120309

An important new study about the effects of neonicotinoid pesticides on wild bees has just been published in the journal Nature Communications – here’s the details and a link to the paper, which is open access:

Woodcock, B. A. et al. (2016) Impacts of neonicotinoid use on long-term population changes in wild bees in England. Nat. Commun. 7:12459 doi: 10.1038/ncomms12459

As I’ve previously discussed on this blog (e.g. here and here) there are widespread concerns amongst environmentalists, and some scientists, about the impact that these relatively new pesticides are having on pollinators and other biodiversity. The Woodcock et al. paper is a major contribution to this discussion as it uses a huge dataset to model the changes in populations of 62 wild bee species that are known to forage on oilseed rape (canola) over 18 years. These changes can be related to the spatial extent of oilseed rape cultivation and the authors found that whilst bees “….foraging on oilseed rape benefit from the…[nectar and pollen provided by]….this crop….[they]….were on average three times more negatively affected by exposure to neonicotinoids than…” bees which didn’t forage on the crop.

The authors further conclude that “This study provides the first evidence for community level national scale impacts on the persistence of wild bee populations resulting from exposure to neonicotinoid treated oilseed rape crops.”

Neonicotinoid pesticides are, of course, not the whole story when it comes to understanding declines in pollinator diversity and abundance. But these pesticides are the latest in a long history of changes to British agriculture that have had significant consequences for the biodiversity of our country (as we showed in our study of bee and wasp extinctions).

Reactions to the study have been, well, predictable. A long feature on the BBC News website* quoted a representative from Bayer as saying:

“we believe….[the study’s]….findings would be more correctly headlined that intensive agriculture is causing some issues with pollinators….. Whether this is due to the use of insecticides is not clear; a lack of nesting sites and pollen and nectar sources in these areas may also be critical factors.”

Which rather ignores the fact that this was a comparative study of bees that forage on oilseed rape versus those that don’t.

Likewise the National Farmer’s Union’s position was that:

“While this study claims to provide an important contribution to the evidence base underpinning the current EU moratorium on some uses of neonicotinoids, experts reviewing all the evidence have concluded that there are still major gaps in our knowledge and a limited evidence base to guide policymakers”

Which sounds to me like a statement designed to fudge the issue: the “experts reviewing all the evidence” would not have reviewed this particular study! And which begs the question – how much evidence and how many studies would be enough for the NFU?

The study’s authors do not make any suggestions as to what the next step should be in this continuing saga but are quoted as saying that “simplistic solutions” such as banning these pesticides are not the answer because this will encourage use of pesticides that are even more damaging. That may be the case but it’s clear that an independent root-and-branch reassessment of the use of pesticides (and herbicides) in UK agriculture is long overdue.

*As an aside, this BBC News piece wrongly states that bumblebees were not included in the study, which is not the case.

UPDATE: After I published this post I noticed that Manu Saunders has also written about the bee study, plus a second study that I’d not seen linking neonicotinoid use to declining butterfly populations in California. Here’s a link to Manu’s blog.

Just published: A horizon scan of future threats and opportunities for pollinators and pollination

The influence of floral traits on specialization and modularity of plant–pollinator networks in a biodiversity hotspot in the Peruvian Andes – Watts et al. (2016)

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Watts et al Figure 1

The second paper from the PhD thesis of my former student Dr Stella Watts has just been published in Annals of Botany – here’s a link to the journal’s website. It summarises the major findings from her field work on plant-pollinator interactions in the high Andes of Peru:

Watts, S., Dormann, C.F., Martín González, A.M. & Ollerton, J. (2016) The influence of floral traits on specialization and modularity of plant–pollinator networks in a biodiversity hotspot in the Peruvian Andes. Annals of Botany doi: 10.1093/aob/mcw114

This paper represents a major piece of research, including extensive field data collection over multiple sites in a challenging environment at altitude; state-of-the-art data analysis; and then summarising all of this into a single, digestible paper, with some great figures. I’m very proud to have been part of it!

Here’s the abstract; please email me or Stella if you’d like a copy of the full PDF:

Background and Aims: Modularity is a ubiquitous and important structural property of ecological networks which describes the relative strengths of sets of interacting species and gives insights into the dynamics of ecological communities. However, this has rarely been studied in species-rich, tropical plant–pollinator networks. Working in a biodiversity hotspot in the Peruvian Andes we assessed the structure of quantitative plant–pollinator networks in nine valleys, quantifying modularity among networks, defining the topological roles of species and the influence of floral traits on specialization.

Methods: A total of 90 transects were surveyed for plants and pollinators at different altitudes and across different life zones. Quantitative modularity (QuanBiMo) was used to detect modularity and six indices were used to quantify specialization.

Key Results: All networks were highly structured, moderately specialized and significantly modular regardless of size. The strongest hubs were Baccharis plants, Apis mellifera, Bombus funebris and Diptera spp., which were the most ubiquitous and abundant species with the longest phenologies. Species strength showed a strong association with the modular structure of plant–pollinator networks. Hubs and connectors were the most centralized participants in the networks and were ranked highest (high generalization) when quantifying specialization with most indices. However, complementary specialization d’ quantified hubs and connectors as moderately specialized. Specialization and topological roles of species were remarkably constant across some sites, but highly variable in others. Networks were dominated by ecologically and functionally generalist plant species with open access flowers which are closely related taxonomically with similar morphology and rewards. Plants associated with hummingbirds had the highest level of complementary specialization and exclusivity in modules (functional specialists) and the longest corollas.

Conclusions: We have demonstrated that the topology of networks in this tropical montane environment was non-random and highly organized. Our findings underline that specialization indices convey different concepts of specialization and hence quantify different aspects, and that measuring specialization requires careful consideration of what defines a specialist.

Third International Conference on Pollinator Biology, Health and Policy – Pennsylvania – 18-20 July, 2016

Bees’ Needs week (9th to 17th July) #BeesNeeds

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Inula at Ravensthorpe 20160710_145426.png

In the current political turmoil around the Chilcot Enquiry, Brexit, leadership challenges and a change of Prime Minister you’d be forgiven for having missed the fact that 9th to 17th July 2016 has been designated “Bees’ Knees” week, as a follow on to the Pollinator Awareness Week of 2015.

Here’s the link to the Defra press release.

Unlike last year I’ve no specific plans to do any regular posts on the topic, but I will provide links to relevant items as and when I see them, starting with these two:

Why insects are declining globally, and why it matters.

Dave Goulson is trying to crowdfund a project to look at pesticides in plants from garden centres.

How to deal with bumblebees in your roof [UPDATED]

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Bombus hypnorum

This week I’ve had two enquiries from colleagues at the University of Northampton asking advice on what to do about colonies of bumblebees that have set up home in their roofs. In both cases these were nests of the Tree Bumblebee (Bombus hypnorum), a species that only colonised the British Isles in 2001 and has since spread rapidly (see this post from last year for a more detailed account). Because of their association with human settlements they are significant pollinators of garden produce: over the past few weeks I’ve been watching them pollinating the raspberries in our garden and we now have a large crop.

But having a bee nest in your home is, for many people, a real concern. I thought it might be useful to discuss the issue by quoting from the email correspondence I had with my first colleague, Paul.

Paul wrote: I wonder if you can give me some advice. I returned home from holiday on Saturday to find that a colony of bees had taken up residence in a roof space above my front porch. The bees are not domestic honey bees but large bumblebees with white rears. I am not sure how many there are, they buzz furiously when I close the door….. They are not in the house and I cannot see them from my loft…..so they are not causing a problem at the moment other than a moderate dead rabbit smell in the porch.

I am considering contacting the local council pest controllers, but fear they may just gas and kill them as they are not honey bees. What would your advice be, would it be safe to leave them alone, if so how long are they likely to stay, how large is the colony likely to become, are they likely to cause any damage or mess?

Here’s my response: From your description they are almost certainly Tree Bumblebees which often use loft spaces, bird boxes, etc. As the name suggests they naturally nest in holes in trees. The colony is not likely to get much bigger though over the next few weeks you may find males patrolling the front of the nest, waiting for the virgin females to emerge so that they can mate. That sometimes makes the colony seem larger than it actually is – there are not likely to be more than about 150 bees in there.

I’ve had Tree Bumblebees in my roof a few times and they’ve never caused any damage. All bumblebee colonies die over the winter and the newly-mated females fly off and hibernate. So by late August or September (perhaps earlier if the weather ever gets warmer….) the bees should have gone. At that time you could seal the entrance to the roof space, though they are unlikely to return next year (although it’s not unknown).

Yes, a pest controller would kill the colony. But they are unlikely to be aggressive unless you stick your fingers in the nest hole! My advice is to let them be and take pride in your own bee colony – they are very discerning and don’t nest just anywhere 🙂

So there you have it: my advice is, leave them alone. Of course if you or your family have a particular sensitivity to bee stings you may need to think carefully about this advice, but in my experience bumblebees are only aggressive if they feel directly threatened. In over 25 years of field work focused on bees and other pollinators, I’ve only ever been stung a few times, and mainly by honey bees.

UPDATE: A commenter on Facebook had a great suggestion, that I provide a link to Dave Goulson’s nice little video showing what the inside of a bumblebee nest looks like – so here it is.

Silver Medal for the BES’s pollinator’s display at RHS Chelsea Flower Show!

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RHS Silver Medal

An early train to London yesterday got me to the RHS Chelsea Flower Show in time for the gates opening at 8am. I’d agreed to spend the day staffing the British Ecological Society’s Animal Attraction: The garden and beyond display, which deals with the relationships between plants and their pollinators – see my recent posts here and here.

The first thing I noticed as I approached the display was how impressive and well designed it looked, with some wonderful planting to complement the simple, bold scientific information. The second thing I noticed was that we had won a Silver Medal! The whole team was very pleased – it’s the third year that the BES has been represented at Chelsea, but the first time that it’s won a medal. I’m proud to have made a small contribution to that by advising on the plants and the scientific content, but the main kudos goes to the BES’s staff and to the garden designer Emily Darby.

Over the course of a long day we talked to hundreds of visitors about the display, what it represented, and the different ways that flowers are adapted to their pollinators. There was a huge amount of public interest and support, very gratifying to see. Here’s some pictures from the day:

RHS display

RHS crowd

RHS crowd with fig

RHS Jeff

RHS display

Pollinators, yeast, and the BES at RHS Chelsea – official press release

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The official press release for this week’s British Ecological Society display at the RHS Chelsea Flower Show, which I talked about last week, was embargoed until this morning; here’s the full text that’s been tailored by the University of Northampton press office:

Scent, colour and form all shape the choices we make about what to plant in our gardens. Gardeners know that flowers produce nectar and scent to attract the birds, bats, insects and other animals they rely on as pollinators, but few realise that organisms too small to see with the naked eye also play a vital role in this process.

Ecologists have discovered that a yeast called Metschnikowia plays a key part in the pollination story and next week, for the first time, visitors to the RHS Chelsea Flower Show will be able to get a sniff of it and see how it looks under the scanning electron microscope.

The yeast forms part of the British Ecological Society‘s Animal Attraction: The garden and beyond display, which focuses on the relationships between plants and their pollinators – relationships that are amazing in their diversity as well as crucial to global food security. The University of Northampton’s Professor of Biodiversity, Jeff Ollerton, has been advising the British Ecological Society on the project.

Metschnikowia is ubiquitous, present in most flowers in most gardens, yet ecologists are only just beginning to uncover its mysterious role in pollination. The yeast is studied in only four laboratories in the world and Dr Manpreet Dhami from Stanford University has donated the yeast for the British Ecological Society’s garden.

Like other yeasts, Metschnikowia may produce volatile chemicals that mimic the scent flowers use to attract pollinators, thus helping the flower to attract more pollinators and therefore set more seed. In return, the yeast becomes attached to birds, insects and other pollinators, which it relies on for dispersal.

Professor Ollerton explained: “It was a pleasure to work with the British Ecological Society on this project as it highlights two important points about the natural world: that pollinators other than bees are just as important to both wild plants and crops, and that the diversity and abundance of many of these groups is declining worldwide.” Professor Ollerton’s recent study, published in Science, found that 23 species of British bees and flower-visiting wasps have gone extinct since the 19th century.

According to Jessica Bays of the British Ecological Society: “To tackle this decline, we need to understand its causes, including climate change, habitat loss and pesticide use, and we also need to understand the role played by yeasts such as Metschnikowia, which is why we decided to bring it to Chelsea this year.”

Tickets are still available for the RHS Chelsea Flower Show 2016 – for more information click here.

Pollinators at RHS Chelsea Flower Show

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Pollinators, as regular readers of this blog will know, are diverse and important, both ecologically and agriculturally. But that diversity is declining and it’s an issue that deserves greater publicity and action.

To that end, for the past eight months I’ve been advising a team from the British Ecological Society (BES) on the content for a display at the RHS Chelsea Flower Show which is running all next week. The display is called “Animal Attraction: The Garden and Beyond” – if you follow that link you’ll get a sense of what the display is all about, but in essence there are three key messages that the BES is trying to get across:

Celebrating the diversity of pollinators (not just bees!) both in the UK and globally.
Flowers have evolved many different ways of attracting and rewarding pollinators, leading to the fantastic diversity of floral form that gardeners appreciate.
Planting a diversity of flowers in your garden can only be a good thing for helping conserve pollinator populations.

As you can see from my wristband, I’ll be helping to staff the stand all day Tuesday 24th May, so if you’re at the show come and say hello and take a look at what the BES team has produced.

Design and Testing of a National Pollinator and Pollination Monitoring Framework – report published today

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B pasc on sunflower

This morning there were swifts flying above the garden – summer’s [almost] here! As if on cue, the eagerly anticipated report on “Design and Testing of a National Pollinator and Pollination Monitoring Framework“, one of the key recommendations of the National Pollinator Strategy, has been published today by Defra. Here’s a link to the report and its annexes.

I’ve not had time to read the full report, and even the Executive Summary (ES) is quite long and detailed, but the Conclusion to the ES captures the key points (emphases in bold are mine):

“…there is considerable scope to enhance monitoring of pollinators and pollination services to ensure a robust and rigorous evidence-base to support the needs of policy, however this project has demonstrated clear trade-offs between likely cost and data quality, especially in terms of the taxonomic resolution and accuracy of species identifications. Currently the volunteer sector, namely the NSS*, provides the expertise to deliver monitoring of changes in species occurrence or distributions at a national scale for many, but not all, species. Indeed the total value of voluntary work provided by BWARS and HRS….is estimated, based on current levels, to reach in excess of £5M over ten years. Repeated systematic sampling from a stratified network of sites not typically covered by the NSS has the potential to add considerable value, providing data on pollinator abundance that may link with provision of pollination services and filling gaps in the spatial extent and species coverage. Enhancements to improve the range and accuracy of monitoring pollinators and pollination services over large spatial and temporal scales will depend on adequate resources to support capacity building, coordination and implementation.”

In summary, the volunteer schemes are a hugely valuable asset that need to be enhanced by funding from the public purse in order to set up a pollinator and pollinator monitoring scheme that will be fit for purpose. Will the current Government show the necessary vision and leadership to provide that funding? Watch this space….

* NSS = National Recording Schemes and Societies, e.g. Bees Wasps and Ants Recording Society (BWARS), Hoverfly Recording Scheme (HRS), etc.