Category Archives: science policy

A songbird makes a welcome return

The Cirl Bunting is an attractive songbird once found throughout the southern half of the UK.  Its numbers declined precipitously in the second half of the 20th century following changes in farming practice and, by the late 1980s, it was confined to coastal farmland in south Devon and might have become nationally extinct.  The Royal Society for the Protection of Birds (RSPB) recognised the problem and worked with farmers to support the bird resulting in a dramatic increase in its numbers. In a recent expansion of its range the bird has established itself in East Devon at Stantyway Farm near Otterton having been absent for more than 30 years.  I wanted to find out more so I went to Stantyway to see for myself.

Male cirl bunting (photo generously given by David R White)
Female cirl bunting (photo generously given by David R White)

The Cirl Bunting was first reported in the UK by Montagu in the winter of 1800 near Kingsbridge in south Devon in the west of the country.  It is roughly sparrow-sized and the male, in particular, is very distinctive with its black and yellow striped head and olive-green breast band.  The bird gradually spread across the southern half of the UK, its numbers peaking in the early years of the 20th century.  Since then it has declined and by the late 1980s only 118 pairs remained, confined to coastal farmland between Plymouth and Exeter.

With the Cirl Bunting facing national extinction, the RSPB identified changes in farming practice linked to agricultural intensification as responsible for the precipitous decline.  In the winter, the bird forages for insects and spilt grain in weedy stubble fields.  In the summer, it nests in hedges or scrub and forages on unimproved grassland rich in invertebrates with grasshoppers being important food for chicks.  With agricultural intensification, there was a shift from spring-sown cereals to autumn sowing so that far fewer arable fields were left as winter stubble; grubbing out of hedges took away nest sites and loss of the hay meadows and increased use of pesticides reduced invertebrate numbers and summer food for the bird.

Once the cause of the decline had been identified, the RSPB worked with farmers in south Devon to support the birds by reinstating some traditional agricultural practices, supported by government agrienvironment schemes.  The effect was spectacular and by 2016, numbers of Cirl Buntings had increased to over 1000 pairs. Most of the increase occurred in the bird’s core range but there was some spread along the coast and inland where habitat was suitable.   This was a major conservation success, also benefitting other species.

The coast of south Devon showing the core range of the cirl bunting and the location of Stantyway Farm across the Exe estuary in East Devon (from British Birds).

The bird has a reputation for being sedentary and it had been assumed that the estuary of the river Exe would be a barrier to further eastwards expansion of its range.   So, it was a surprise when, around the end of 2010, a single Cirl Bunting was seen at Stantyway Farm near Otterton in East Devon followed by several more sightings early in 2011.  Since then, the numbers at Stantyway have increased suggesting that the local conditions suit the birds and from 2015 it was clear that a breeding population existed.

Stantyway Farm is owned by Clinton Devon Estates and when the tenant, Mr Williams, retired in 2014, the farm was taken back into Clinton’s own Farm Partnership.   Clinton Devon Estates were keen to support Cirl Buntings and other species on their arable farm at Stantyway so they took advice from the RSPB and applied for agrienvironment support.  This was awarded in 2016 and supports planting hedges to provide more nest sites, leaving wildlife margins around fields to provide invertebrates as summer food, and planting spring cereal crops that are harvested in the autumn leaving weedy winter stubbles with seed as food.  These are all activities shown to be critical in supporting these birds in south Devon.  The farm was also put into organic conversion in 2016; organic farming by its nature supports wildlife and increases invertebrates.  Cirl Bunting numbers at Stantyway gradually increased across this time.

In 2017, Clinton Estates advertised for a new tenant farmer at Stantyway and Sam Walker was appointed.  Although the farm is still mainly arable, Sam keeps 52 cows whose calves are raised and sold on to beef finishers.  About a third of the land is now devoted to grass for silage production for winter animal feed.  Sam has, however, embraced the existing philosophy of the farm in supporting wildlife: he has maintained the organic status and intends to apply for further agrienvironment support when the current scheme runs out in 2021.

I wanted to see the farm for myself so, on a mild early April day, I went to Stantyway.  I left the car on the rough ground across from Stantyway Farmhouse and stood for a few moments enjoying the sunshine.  The air was filled with the endlessly inventive song of the skylark and occasionally a buzzard mewed as it circled lazily overhead.  Sometimes a low buzz cut through all of this and when I looked, I realised this was from all the insects about.

I walked away from the farm along the gentle downhill slope of Stantyway Road with views developing over rolling East Devon countryside on one side and to the hazy mid-blue sea on the other. The lane descended between wide grassy verges backed by luxuriant hedges. Spring flowers grew through the thick grass including stitchwort, celandine, dandelions, violets and white dead nettle.  The dominant flowering plant was, however, alexanders, with its fleshy green stems, copious shiny dark green foliage and pale mop head flowers.  This was proving very popular with many kinds of fly and a selection of solitary mining bees, some collecting large lumps of white pollen on their back legs.

My walk included a long section of the coast path skirting the edge of Stantyway fields.  Thick scrubby hedges, mainly flowering blackthorn, lined the cliff edge along with more alexanders. The occasional hedge break afforded spectacular views along the red cliffs of the Jurassic Coast towards Ladram bay with its crumbling stacks, past the white elegance of Sidmouth and finishing in the chalk of Beer Head (see picture at the top).   Again, there were many solitary mining bees taking advantage of the flowers.    I did not see any Cirl Buntings on my walk but, on two occasions I heard their distinctive, rattling, metallic trill telling me the birds were about.

It’s a beautiful place made all the better by glorious early April weather and I was surprised to see so many insects along the paths.  Perhaps this reflects the methods used at Stantyway, showing that productive farming and wildlife can coexist and prosper. Around the farm, each field gate has an information board giving the crop and some other useful information.  An Honesty Café has been installed near the farmhouse providing continuous hot water for tea or coffee and homemade cakes that I can strongly recommend.  All of this suggests an outward looking, open approach to farming.  When I met Sam Walker, the farmer, he explained that, in addition to the provisions of the agrienvironment scheme, he has put skylark plots in cereal fields, created wild bird seed corridors and put up swift boxes to support wildlife.  I came away feeling that at Stantyway, Cirl Buntings were getting the best support they could.  His methods have already benefitted other farmland birds with numbers of skylarks and reed buntings doubling over the past year and in a further twist to the Cirl Bunting story, some of the birds have now been seen to the east of Sidmouth.

I should like to thank Sam Walker, Doug and Joan Cullen, Kate Ponting and David White for generous help in preparing this article which appeared in the May edition of the Marshwood Vale Magazine.

 

sign
One of the farm gate signs

 

Alexanders and blackthorn
Alexanders (greenish-yellow) and blackthorn (white) along the coast path. The cliff edge is behind the hedge!

 

Solitary mining bee on Blackthorn
A solitary mining bee (probably Andrena flavipes) feeding from blackthorn.

 

Solitary mining bee on Alexanders
A solitary mining bee (probably Andrena nitida) feeding from Alexanders

 

Honesty Cafe
The Honesty Cafe at Stantyway Farm

 

Change is coming whether they like it or not

[This post is dedicated to the 100s of  MPs who  chose not to attend a debate in parliament on climate change in a week when the UK experienced its hottest ever winter’s day.]

 

Blizzards, strong winds, drifting snow, bitter cold – that was the story in early March last year when the “Beast from the East” collided with storm Emma bringing extreme weather and disruption to life across large parts of the UK.  Towards the end of June, by contrast, the sun began to shine and daytime temperatures climbed into the thirties and stayed that way across much of the country until August (the picture at the top of this post shows the effect of the long hot summer on the UK countryside).  Elsewhere across the globe, reports came in of flooding, wildfires, severe tropical storms and unusually high and low temperatures.  Many of these weather extremes can be attributed to climate change and there is considerable concern that the planet is heading for climate catastrophe.  David Attenborough expressed this fear at a climate change conference in Poland:  “If we don’t take action, the collapse of our civilisations and the extinction of much of the natural world is on the horizon.”

 

Heavy snow falling in early March while a great tit continues to feed

 

In the UK, it was the long, hot summer, the joint hottest on record, that made people think most about a changing climate.  The weather here is, of course, notoriously fickle and some will remember that in 1976, we experienced a similar long, hot, dry summer, so how can we disentangle normal weather variation from climate change?  One way of looking at this was shown by Simon Lee, a PhD student at the University of Reading, who shared graphs on Twitter of the global temperature anomalies in June 1976 and in June 2018 (see pictures below).  These show that in 1976 the UK was one of a few unusually hot spots in an otherwise cooler than average world whereas in 2018 much of the world, including the UK, was hotter than the average.   The 2018 picture shows climate change in action: the planet is warmer making heatwaves more likely.

 

The pictures show temperatures across the world in June 1976 (upper panel) and in June 2018 (lower panel) compared to the average across the period 1951-1980. Red and yellow mean higher, blue means lower. Kindly supplied by Simon Lee who generated the images from NASA/GISS data.

Careful measurements of the average surface temperature of the planet show that it is currently about 1oC hotter than in pre-industrial times.  This may not seem very much but it is enough to disturb the complex systems that create our weather.  As a result, heatwaves may be more frequent in summer and, in winter, polar air may be directed southwards bringing abnormal, freezing temperatures.  Also, a warmer atmosphere holds more moisture so that rain and snow may be more severe.  Climate breakdown might be an apt description of these changes.

This global heating is a result of human activity.  The emission of greenhouse gases, particularly carbon dioxide produced by burning fossil fuels such as coal, gas, oil and petrol, traps heat in the atmosphere so the temperature of the world increases.  We have known this for some time and we have also known that the solution is to reduce carbon emissions. Atmospheric levels of carbon dioxide have, however, continued to climb because no government has had the will to introduce the extreme lifestyle changes required to curb emissions.  Some governments, including our own, have even encouraged the continuing extraction of fossil fuels.

It is, therefore, significant that in October 2018, the Intergovernmental Panel on Climate Change (IPCC) issued a report containing a dire warning: we must make urgent and unprecedented changes to the way we live if we are to limit heating to 1.5oC above pre-industrial levels.  To achieve this target, we must reduce net global carbon emissions by 45% by 2030 and to zero by 2050 – fossil fuel use must be drastically reduced by the middle of the 21st century but we must start the reduction now.  Should we fail to achieve this 1.5oC target, the risks of drought, flooding, extreme heat, poverty and displacement of people leading to wars will increase significantly.  The world will no longer be the place we know and love and parts of it will become uninhabitable for humans and the rest of nature.

How do we achieve this reduction in carbon emissions? Voluntary measures such as suggesting people fly or drive less will not work.  The only way this reduction can be achieved is through coordinated government action based on recommendations made in the IPCC report.  These include the planting of more forests and the chemical capture of carbon dioxide to reduce atmospheric levels of carbon dioxide.  There must also be a drastic shift in energy production and in transport away from fossil fuels and this can be driven in part by investment and subsidies directed towards clean technologies.  A carbon tax can also help drive this shift but the tax will need to be high enough to force change, for example by taxing energy companies who burn fossil fuels so that they invest in cleaner technologies.  In the short term, costs to consumers may rise, so politicians would need to keep the public on side, for example, through tax incentives.  If we grasp the opportunity, the scale of change may have the unexpected bonus of allowing us to design more sustainable and equitable societies.

The IPCC report set out very clearly the changes required to avoid damaging global climate change so there was great anticipation when the UN Climate Change Conference convened in Katowice in Poland just before Christmas.  Astonishingly, given the gravity of the situation, the 200 countries represented there failed to agree new ambitious targets for greater reductions in carbon emissions. Four countries (USA, Saudi Arabia, Russia and Kuwait) would not even sign a document welcoming the IPCC report; these countries are of course all oil producers.

It was at this conference that David Attenborough issued his warning about the collapse of civilisations but there was another hugely impressive intervention.  This came from 15-year old activist Greta Thunberg from Sweden.  She had already achieved some notoriety through her weekly climate strikes where she missed one day of school to protest about climate change.  Her actions have stimulated many thousands of young people around the world to do likewise.  Thunberg also spoke in London at the launch of the new grass-roots movement, Extinction Rebellion, which intends to use peaceful protest to force governments to protect the climate.  These new trends offer some hope for the future since it is the young of today that will bear the climate of tomorrow.

Greta Thunberg, 2018 (cropped)
Greta Thunberg

Here is part of Greta Thunberg’s speech given at the Katowice conference:

“For 25 years countless people have come to the UN climate conferences begging our world leaders to stop emissions and clearly that has not worked as emissions are continuing to rise. So, I will not beg the world leaders to care for our future, I will instead let them know change is coming whether they like it or not.”

“Since our leaders are behaving like children, we will have to take the responsibility they should have taken long ago. We have to understand what the older generation has dealt to us, what mess they have created that we have to clean up and live with. We have to make our voices heard.”

I am grateful to Simon Lee for generously supplying the temperature anomaly graphs.

This article was published in the March 2019 edition of the Marshwood Vale Magazine.

A country walk, a clean beach and the fallacy of perpetual growth

The Christmas weather in south Devon was stormy and very wet so when we woke on December 27th to bright sunshine and clear, pale blue skies we had to get out for a walk.   We chose one combining countryside and sea, one we often walk after heavy rain as it mostly follows minor roads or paved paths.

We started at Townstal, a suburb on the edge of Dartmouth.  Townstal is noted for its leisure centre and two supermarkets but it does provide easy parking and quick access to open countryside.  Our route headed gradually southwards towards the sea along narrow roads edged by high grassy banks.   Volleys of gulls and crows rose from adjacent fields and the low sunshine created strongly contrasting areas of light and dark on the deep valleys and rolling countryside, emphasising even the slightest undulation.

Some steep ups and downs took us to Venn Cross where we turned to descend along the Blackpool Valley with its spirited stream, growing ever fuller as it gathered water from springs or from the sodden fields.  This part of the walk is tree lined and the minor road is cut into the hillside well above the stream.  Several former water mills are dotted along the valley; they are now rather grand private houses but one has installed a turbine to harness the power of the water once again.

Old Mill in the Blackpool Valley
Blackpool Mill, one of the old mills found along the Blackpool Valley. This hidden valley has changed very little over the years. Have a look at the painting below of a nearby farm to see how the area looked nearly a century ago.

 

Apple Blossom, Riversbridge Farm, Blackpool by Lucien Pissarro, 1921, from Royal Albert Memorial Museum Exeter

 

At this time of year, the trees are dark latticeworks of bare branches but pale brown immature catkins were showing well on some of the trees, readying themselves for the spring.  Patches of winter heliotrope spread along verges enclosing the ground with their fleshy, green, heart-shaped leaves.  Purple and white lollipop flowers struck through the leaves, broadcasting their characteristic almond odour.

Catkins and running water in the Blackpool Valley
Catkins above running water in the Blackpool Valley

 

Winter Heliotrope in the Blackpool Valley
Winter heliotrope in the Blackpool Valley

 

Eventually, we reached Blackpool Sands, a popular shingle beach and café, surrounded by pine trees and sheltered by steeply rising hills.    The low winter sun created strongly contrasting colours: the yellowish- brown shingle, the fringe of frothy white waves, the sea a rich dark blue tinged with turquoise highlights, and there were clear views across the bay to Start Point with its lighthouse.   Near the café, a hardy group of swimmers were struggling on their wet suits in readiness for a dip.  They passed me as they ventured in to the sea accompanied by audible yelps and shrieks.

View across Start Bay from Blackpool Sands to Start Point
View across Start Bay from Blackpool Sands to Start Point

 

Swimmers at Blackpool Sands
Swimmers at Blackpool Sands …… with friend.

 

I was keen to have a look at the shingle beach for two reasons.  There had been a very successful beach clean four days previously organised by Amanda Keetley of Less Plastic.  We hadn’t been able to be there owing to family commitments but there had also been storms since then and I wondered how much more plastic had washed up.  I didn’t find any, the beach was still clean which should have been good news.

To be honest, however, I was feeling disheartened about efforts to reduce the load of plastic in our seas after reading two articles in the Guardian over the Christmas period.  It seems that the US, along with financial support from Saudi Arabia, is planning a huge increase in plastic production, the driver being cheap shale gas.  If we are to reduce the amount of plastic in our seas we need to reduce the amount in circulation and this new plan runs directly counter to this.

Here are links to the two articles:

$180 billion investment in plastic factories feeds global packaging binge

World’s largest plastics plant rings alarm bells on Texas coast

I am not sure how this can be stopped but I am convinced that the drive for perpetual economic growth, espoused thoughtlessly by so many of our politicians, is ultimately very damaging for our planet.

Bees and neonicotinoids – another twist in the tale.

To the agrochemical companies and to many farmers they are essential tools ensuring efficient crop production. To environmentalists and to many bee scientists they are dangerous chemicals contributing to declining bee populations. I am talking, of course, about the neonicotinoid insecticides widely used in this country to control insect pests.

Last week two papers were published on-line in the journal Nature emphasising the dangers posed by these chemicals.

One paper, from a team at Newcastle University, investigated whether honeybees and bumblebees showed any preference (positive or negative) for food containing neonicotinoids; there had been suggestions that bees might avoid neonicotinoid-treated crops in the field. The new lab-based work showed that, when offered a choice, bees preferred to eat sucrose solution (nectar) containing neonicotinoids (imidacloprid or thiamethoxam) rather than control sucrose solution. If this occurs in the field then bees may forage preferentially on crops containing chemicals toxic to their health and inadvertently bring back these toxins to their nests.

The second paper, from scientists at Lund University in Sweden, showed that the neonicotinoid clothianidin, when used in the field, damaged wild bee (bumblebee and solitary bee) populations but was without effect on honeybees. I want to focus on this paper as it is the first controlled study of the effects of a neonicotinoid on honeybees, bumblebees and solitary bees under field conditions. Let’s start by looking at the background.

Three years is a long time in science

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Back in 2012, two studies were published showing that neonicotinoids, even when they didn’t kill bees, could affect bee behaviour in a way that impaired survival of honeybee and bumblebee colonies. The findings showed that these chemicals could contribute to a decline in the numbers of bees and other pollinators. These observations had a big effect on policy and indirectly contributed to the current partial ban on the use of three neonicotinoids in Europe.

One of the papers was from Dave Goulson’s lab, then at Stirling, and found that even at the low doses typically encountered on treated crops in the field, neonicotinoids substantially reduced the number of queens produced by bumblebee colonies, so impairing survival. In Goulson’s study, bumblebees were treated with neonicotinoids in the lab before being allowed to fly freely. This is called a semi-field design and some have suggested that the findings cannot be extrapolated to the real world. The levels of neonicotinoids have also been criticised although these were very carefully thought through.

There was considerable media interest in this work, nicely described in Goulson’s latest book (A Buzz in the Meadow) and the UK Food and Environment Agency (FERA) labs in York hastily set up a preliminary field trial to examine the problem. During the spring and summer of 2012 they studied three fields of oil seed rape, one treated with the neonicotinoid, imidacloprid, another treated with the neonicotinoid, clothianidin and a third untreated field to act as a control. Bumblebee (Bombus terrestris) nests were placed by each field and the occupants were left to fly freely and build their colonies. Extensive analyses were performed including colony growth, the pollen collected by the bees and pesticide residues detected in pollen and nectar.

Superficially this sounds like a rigorous study (free flying bees, compare neonicotinoid-treated with control, plenty of analyses and so on) and it should have given an indication of the effect of neonicotinoids under real-world field conditions. The success of the trial depended on the bees foraging on the crop near their nests so there should have been clothianidin-exposed colonies, imidacloprid-exposed colonies and neonicotinoid-free controls. Unfortunately the bees had other ideas; they largely ignored the flowering oil seed rape by their nests, foraging further away and returning with pollen from crops treated with another neonicotinoid, thiamethoxam. This completely negated the original design so that, in my view, no valid conclusions can be drawn from the study, despite official pronouncements.

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The new Swedish study

The FERA work was a valiant but flawed attempt to study the effects of neonicotinoids on bumblebees under field conditions and it was clear that a properly conceived field trial was required. The ambitious new study from Lund University mostly fills that void.

The Lund team selected 16 landscapes surrounding spring-sown oil seed rape fields in different parts of southern Sweden in 2013. The landscapes were divided in to 8 pairs on the basis of the nature of the surrounding countryside and for each pair one was sown with seed treated with the neonicotinoid, clothianidin and the other was sown without neonicotinoid, to act as a control. All seed also contained a fungicide. The neonicotinoid-treated seed also contained a pyrethroid to protect plant roots but there was no evidence that the bees came in to contact with this chemical.

Honeybee hives, bumblebee (Bombus terrestris) colonies and solitary bee (Osmia bicornis) cocoons were placed by each field during the flowering season and their progress was followed. Additionally, the numbers of free flying wild bees (bumblebee and solitary bee) were assessed at each field during the flowering season. Pollen brought back by bees was analysed for flower type and for pesticide residues. The study was large enough to allow statistical analyses to be performed so that valid conclusions could be drawn although the design was unable to detect effects smaller than 20%.

Unlike the FERA study, bees did forage on the oil seed rape adjacent to their colony based on pollen analysis, although this was not an exclusive choice. Bees near treated fields brought back pollen and nectar containing clothianidin whereas those near untreated fields did not. The study design seemed to have been successful and the results were clear:

1. Honeybee hives behaved similarly by treated and untreated fields; there was no effect of the pesticide on colony strength. This is good news for honeybees and for beekeepers and agrees with a 2014 field study from Canada also using clothianidin.

2. Bumblebee colony growth and reproduction were reduced near treated fields. This agrees with earlier semi-field studies so that it is now difficult to avoid the conclusion that agricultural use of neonicotinoids has damaging effects on bumblebees.

3. Whereas solitary bees placed by untreated fields emerged from cocoons and built new nests, this did not occur for cocoons situated near treated fields, possibly because of navigational problems caused by insecticide exposure.

4. The number of free-flying wild bees was reduced by about 50% at the treated fields.

The implications of the new Swedish study

Honeybees were not affected by foraging from a neonicotinoid-treated crop whereas wild bees (bumblebees and solitary bees) suffered reductions in numbers and reproductive ability. Wild bees are, therefore, more sensitive to neonicotinoids than honeybees. This may be because, as James Cresswell at Exeter has shown, honeybees break down neonicotinoids more quickly than bumblebees so that honeybees experience lower doses.

The effect of the neonicotinoid on wild bees is an important result for several reasons. Wild bees are important pollinators, contributing more than half of the “pollination service” required for crops. Crop yield and quality will suffer if these insects are lost so we need to look after them and that may need to include rethinking use of pesticides.

The differential sensitivity of bee types to neonicotinoids shows that environmental risk assessment of new and existing insecticides, typically performed in short term lethal studies on honeybees, is inadequate to determine long term effects on different bee types in the field.

These new data will add to the pressure to extend the European moratorium on the use of three neonicotinoids as seed dressings after the initial two year period ends in December. There is, however, concern that if neonicotinoids are not available then farmers will use older insecticides that may be more dangerous for bees. Perhaps farmers should rethink their use of pesticides and return to a “treat when required” policy rather than using neonicotinoids prophylactically.

When the three neonicotinoids were temporarily banned in 2013, farmers claimed that the yields of crops would be drastically reduced. It is interesting that in the first season when crops were grown from untreated seed in the EU, the yields actually increased. Perhaps we should rethink the use of chemicals more generally in modern farming.

500 dead bumblebees – the chemical blitz of modern farming

In September I wrote about the mysterious death of 500 bumblebees. New information has emerged about this incident so I have rewritten the post:

Earlier this year, Sheila Horne was walking at Hacton Parkway, a public park and conservation area in Havering, East London. April is normally a good time to see insects in their prime so she was very surprised to find many dead and dying bees near the path. She alerted local naturalist, Tony Gunton who identified the insects as bumblebee queens from three species, red-tailed, buff-tailed and common carder. This was not a minor incident, there were as many as 500 bees affected.

Chemical analysis of the dead bees

Natural England was appointed to investigate the insect deaths and samples of dead bees were sent to FERA in York for analysis. The results were released in August and showed that the bees were contaminated with the neonicotinoid insecticide imidacloprid and two fungicides, flusilazole and epoxiconazole. Imidacloprid can be very poisonous to bees and bumblebees are more susceptible to this chemical than honeybees. Imidacloprid is currently subject to a two year partial ban for some agricultural uses in the EU. Neither fungicide on its own is especially toxic to bees although flusilazole was phased out this October because of its high toxicity to fish and because of other potential toxic effects.

A nearby field of oil seed rape as the source of the chemicals?

The chemical analysis raises two questions. Where did the bumblebees pick up these chemicals? Were these chemicals responsible for the bee deaths?

Neither question can be answered definitively but as so many dying bees were found together in one place, it seems likely that the source of the poisoning was close by. Hacton Parkway lies alongside arable farmland and at the time of the poisoning some of the land was planted with flowering oil seed rape, so it is a reasonable conclusion that the bees had been feeding there. Because of the chemical analysis, it was initially assumed that the crop had been planted using seed treated with imidacloprid ahead of the ban and that the imidacloprid had killed the bees. Natural England have recently concluded their investigation and found that in fact the seed used to plant the crop had been treated with another neonicotinoid, thiamethoxam. Neither imidacloprid nor epoxiconazole had been used on the crop and the last spraying with flusilazole was in November 2013. Analysis of the dead bees for thiamethoxam failed to detect any of the chemical but this could have been due to losses before the analysis.

What killed the bees?

So, why did these bees die? Because there are so many unanswered questions we cannot be sure. The dead bees were contaminated with imidacloprid but the oil seed rape crop was not the source. We can only assume that the bees fed elsewhere on imidacloprid-treated crops and were flying with this chemical in their systems. It is known that at typical field concentrations, imidacloprid does not kill bumblebees.

There is also the question of how the bees were exposed to the two fungicides if the oil seed rape had not been sprayed with these chemicals during the flowering season. As with the imidacloprid, we have to assume that the bees were exposed elsewhere. It is possible that the fungicides weakened the bees or made them more susceptible to the neonicotinoids. There is some evidence for such interactions for other insecticide/fungicide pairings.

Because the bees died close to the treated crop, the focus of lethality has to be on the thiamethoxam, now known to have been used on the oil seed rape. Although thiamethoxam is indeed an insecticide, there is evidence from one lab-based study and another field study (albeit lacking controls) that, at field-realistic concentrations, thiamethoxam is not lethal to bumblebees. I find it unlikely, therefore, that thiamethoxam alone killed the bees, providing the farmer followed safety guidelines.

We shall never know what actually happened at Hacton Parkway but my best guess is that these bees were flying with the three chemicals in their system and encountered the thiamethoxam-treated oil seed rape. When they fed from it, they picked up the additional neonicotinoid. Two neonicotinoids, with perhaps synergistic effects of the fungicides, were too much and they died.

The investigation is now closed!

The investigation is now closed and it will be impossible to resolve the many questions raised by this incident, which is a pity. Despite this uncertainty, the results of the chemical analysis stand. These bees died with three chemicals in their bodies: one neonicotinoid and two fungicides. They were also exposed to a second neonicotinoid. This was no laboratory experiment; this reflects what is happening around us when these chemicals are used. Have a look at this report to see more evidence of the widespread use of chemicals in UK farming. Our agricultural practices have led to this chemical blitz and the result is the deaths of important pollinators. How often is this occurring on a lower level but not being noticed or reported?

I should like to thank Tony Gunton (local naturalist) and Helen Duggan (Press Officer, Health and Safety Executive) for sharing information about this incident.

Disturbing the natural order – the case of neonicotinoid insecticides and farmland birds

Apus apus 01.jpg
A swift

 

One of my favourite nature writers is Mark Cocker who has the ability to capture a scene or an idea in a few hundred words. Despite his immense knowledge he never loses his sense of awe and with clever use of metaphor, his descriptions of nature leap in to life.

Here is Cocker writing about the interdependence of birds and insects:
“…… that vast efflorescence of insect life is integral to spring. After all, those swifts newly screaming over our village and the chorus that greets us at first light are little more than arthropods processed by avian digestive systems”.

Another favourite nature writer, Kenneth Allsop wrote, nearly fifty years ago, also about bird/insect interdependence. He took the example of a pair of dunnocks in the breeding season who consume more than 1000 insects each day just to maintain their chicks. Many of those insects, he pointed out, will be garden pests, “worth bearing in mind when irritated by bird damage to the green peas and apple buds”.

Despite this obvious dependence of bird life on insects, we still dump insecticides on to our gardens, parks and farmland with little real thought about the long term consequences.

One class of insecticide that has recently attracted scrutiny is the neonicotinoids. The neonicotinoids were introduced in the 1990s and are now very widely used to kill insect pests on a broad range of crops. In the UK, for example, a large proportion of the oil seed rape is grown using seed treated with neonicotinoids. One of the advantages of the neonicotinoids is their selectivity for invertebrates; in principle they have low toxicity towards vertebrates. There has, however, been increasing concern about effects of the neonicotinoids on non-target insects such as bees and the accumulation of the chemicals in soil and water courses with more general effects on invertebrates.

New worries about the neonicotinoids surfaced last week in a paper published in Nature by Hallmann and colleagues from Radboud University in the Netherlands. The Dutch group investigated whether these chemicals might be affecting the numbers of farmland birds indirectly by reducing the numbers of insects that these birds depend upon especially in the breeding season.

They took advantage of long-term monitoring schemes in the Netherlands to compare the average concentrations of one neonicotinoid (imidacloprid) in surface water between 2003 and 2009 with bird population trends over the same period. The comparison was made in different regions across the entire country and focussed on 15 species of common farmland bird that depend on invertebrates during the breeding season.

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Yellow wagtail (one of the farmland birds suffering a decline)

 

The comparison showed that in regions where concentrations of imidacloprid in surface water were higher, population growth rates of these insectivorous birds were lower or negative. Although superficially this suggests that imidacloprid has caused the decline in bird numbers, we first need to rule out alternative explanations for the apparent association.

Hallmann and colleagues consider two possible alternatives: first, the apparent effect of imidacloprid might actually reflect an ongoing decline in bird numbers that predated the introduction of this insecticide; second, the apparent imidacloprid effect might actually reflect changes in land use linked to agricultural intensification. They eliminate both of these alternatives.

Another possible confounding factor that the authors seem to have ignored is the effect of other pesticides. The Netherlands is a very intensively farmed country with more than 60% of land under cultivation. Many different chemicals are used to control pests including imidacloprid. It seems likely that areas with high imidacloprid use will be associated with high usage of other chemicals. Another Dutch group has analysed the large numbers of chemicals present in Dutch agriculture and shown that, in some regions, concentrations of imidacloprid are high enough to kill invertebrates but levels of other chemicals also exceed toxic doses. So, it could be imidacloprid that is leading to the decline in farmland birds or it could be a generally toxic environment. Either way, the conclusion is bleak and ought to make us reflect on the way we are producing our food.

Although the effects of imidacloprid described in this paper are open to interpretation, the evidence against the neonicotinoids continues to accumulate and some authors believe they are having widespread deleterious effects on the natural environment. George Monbiot, writing in the Guardian last week, called for a complete ban on the use of these insecticides.

The Center for Food Safety, a US-based non profit organisation, recently took a different approach to the neonicotinoid problem by asking how much the insecticides actually increase crop yield. Analysing 19 published studies, they found either inconsistent or no evidence that neonicotinoids increase yield. So, astonishingly, dumping neonicotinoids on farm crops has little discernable effect on productivity. Have we all been conned by the agrochemical companies?

 

[picture credits:  “Apus apus 01” by Paweł Kuźniar (Jojo_1, Jojo) – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

Yellow wagtail” by Andreas TrepteOwn work. Licensed under CC BY-SA 2.5 via Wikimedia Commons.]

National Pollinator Strategy – if you love your pollinators, now is the time to speak out

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Last year the UK Government agreed to prepare a National Pollinator Strategy to address the decline in pollinators and the potential impact of this decline on growth of crops, flowers and fruit. The draft Strategy was published earlier this month and barely caused a ripple in the mainstream media. Andy Atkins of Friends of the Earth wrote about this on the Huffington Post blog and it’s worth having a look at what he says.

I think it’s very positive that the government has compiled this Strategy, it means they recognise that there is a problem. The devil is in the detail, however, and although there are some very good aspects to the Strategy there are several rather surprising proposals. Damian Carrington, writing in the Guardian, skewered some of the ideas around pesticides, especially the proposal to leave field testing to the pesticide companies. The National Allotment Society also made some good points.

The most important issue, however, is that a consultation about the draft Strategy is now open and anyone can contribute on line with a deadline of May 2nd 2014. If you love your pollinators then this is the time to have your say.

Even better, they are also holding a series of workshops related to the consultation. These are being held in London, Bristol and York during March and April. I would like to go to one of these but I can’t make the dates; perhaps others can. The workshops will be very interesting and very important sessions to attend and report on.