I once knew a man with cardoons ………..

Each week we have a vegetable box delivered to our house and back in August I got a surprise when I collected the week’s box from our front path. A large flower lay across the colourful array of carrots, lettuce, beetroot and other vegetables. I felt a little like Sophie in der Rosenkavalier but this wasn’t a rose; with its spiny stem and its rich burst of purple florets it looked like an artichoke flower. But I was wrong – a neatly printed card told me helpfully that the flower was from a cardoon.

The cardoon flower


A cardoon? I had a vague recollection that this was some kind of exotic vegetable. I looked at the flower more carefully and I could see that the head was smaller and spinier than an artichoke although the colour and shape were quite similar.

Some artichoke flowers


The card told me that the flower was a special gift and, if we wanted to nurture it, we should place it in water in a rustic glass bottle. Rustic glass bottles are in short supply here but we have a rustic-ish vase so that had to do. The purple flower did look beautiful sitting on our kitchen table and I was inspired to find out more.

The cardoon flower in its rustic-ish vase.


The cardoon originated in the Mediterranean region and is grown for its fleshy, leafy stems which feature on menus in France, Italy, Spain and North Africa. It was a popular vegetable in 19th century Britain but has long since fallen out of favour. The cardoon plant can grow to impressive heights and with its spiny, silvery-green foliage it’s worthy of a John Wyndham novel. It’s such an imposing plant that it can also be used to provide ornamental interest to a garden and with its many, showy, purple flowers it is a bee-favourite. When the cardoon is grown as a vegetable, the fleshy stems should be blanched by piling earth around them or by covering them with brown wrapping paper. This removes much of the bitterness that most varieties suffer from. Some people also recommend blanching the prepared stems by boiling in water. I believe there are new less bitter varieties available now.

Guy Watson with cardoons


Cardoons do not come high on most people’s agenda, so how did a cardoon flower find its way to our veg box? The missing link is Guy Watson, the boss of Riverford Organic who deliver our veg box. Watson is a great enthusiast and very keen to try growing forgotten or exotic vegetables. Cardoons are his latest thing and he has grown a small plot of them on his Devon farm. Our gift flower came from this plot and the vegetable has been available to buy this autumn from Riverford. Some nice publicity for his efforts came from Xanthe Clay of the Telegraph who made the pilgrimage to Devon to meet “farmer, veg-box supremo and Martin Shaw-lookalike, Guy Watson” and spent a happy time learning to prepare and cook the sinister vegetable. Xanthe was won over by Guy’s cardoons and asserted that, after removing the stringy bits and cooking until tender, the cardoon is “delicately, addictively delicious, distinctly artichoke-y” and “baked in a creamy, cheesy gratin they tasted sublime”.

Xanthe, you have convinced me. I will try some cardoons when I get a chance but I am still wondering what the relation is between the cardoon and the artichoke. Superficially, the two plants look rather similar but when you get down to the important business of eating them, they are quite different. Globe artichokes are grown for their edible immature flower heads and I can still remember my horror at being presented with an artichoke for the first time in a little restaurant in south west France. Luckily I was with a friend who knew what to do. Artichokes are an important commercial crop in Southern Europe, North Africa, California, South America and China. Cultivated cardoons, as we now know, are grown for their fleshy stems and stalks and are cultivated on a smaller scale in Northern Italy, Spain and Southern France. To complicate matters further, there is another member of the family, the wild cardoon, a smaller, spinier plant that grows in countries around the Mediterranean.

End of season artichoke flower heads


So, how did these seemingly related but actually rather different plants arise? More than twenty years ago, a scientist from the University of Madrid spent some time on this question. She examined a very large number of artichokes, cultivated cardoons and wild cardoons, growing in different locations, looking at their shape and structure. She concluded that all three were variants of the same species Cynara cardunculus. Presumably the artichoke and the cultivated cardoon were derived from the wild cardoon by selection for the desired characteristics. A recent study by a team of scientists from Italy used modern genetic techniques to examine the relationship between the three variants. They concluded that the globe artichoke and the cultivated cardoon were indeed both derived from wild cardoons, probably growing in Sicily or North Africa. Domestication of the artichoke started earlier and was probably under way in Roman times. Domestication of the cultivated cardoon began later but the wild cardoon was also the progenitor.

Let’s finish by returning to the man with the cardoons, Guy Watson. His latest venture is to bring Riverford to London at the Duke of Cambridge pub in Islington. Cardoon fritters have recently been on the menu!

Birches, shaggy ink caps and a wagtail: the October garden

O hushed October morning mild,
Thy leaves have ripened to the fall;
Tomorrow’s wind, if it be wild,
Should waste them all.

(From Robert Frost’s poem October)


Norway Maple in Autumn
The Norway Maple with its orange crown


The beginning of October brought tangible change with alternating periods of heavy rain and cheerful sunshine. I suppose the weather had to shift but I’d got used to the warm and dry. More rain followed and when the remnants of hurricane Gonzalo passed through I saw airborne leaves, gutter-filling leaves and now rotting leaves. It still felt unseasonably mild but despite this, nature moves forward, the flowers have mostly gone and, from my kitchen window, I watched the gradual change in colour as each tree moved ahead but at its own pace. One belligerent punk of a tree (a Norway Maple) tried hard to shock by putting on a bright crown of orange foliage.

Mullein in October
The continuing new growth on the mullein


Honeybee on Mullein
A honeybee enjoying the mullein flowers


Down in the Leechwell Garden I continued to wonder at the tenacity of a mullein which, despite the season, was now a tangled mass of new flowering stems. The fresh, lemon-yellow flowers proved popular with the honeybees now that other forage is becoming scarce.

Mrytle 1
Myrtle: flowers, fruits and leaves

I also discovered a largish evergreen shrub, a myrtle, by one of the old stone walls. It was the brilliant white flowers that first caught my attention, their long yellow-tipped stamens bursting from the petals like a bonfire-night rocket lighting up the sky. The myrtle’s cloak of small, glossy, dark green leaves was complemented by many immature fruits in a variety of colours from pink to green to black. Crushed myrtle leaves emit a eucalyptus-like smell and the berries and leaves are widely used in Mediterranean and Middle Eastern cooking.

A fig tree clothes a large part of the ancient stone wall


Perhaps because of the dearth of flowers, I have spent some time this month looking at the grove of young trees planted near the three mature silver birches. These are a mixture of willows and birches and their height allowed me to look closely at their leaves and fruits. The young birches divide in to two groups, one still covered with large ovate green leaves, the other rapidly losing their smaller, yellowing, diamond-shaped leaves.

Himalayan Birches 1
Four himalayan birches (willows behind)


Himalayan Birch bark
Himalyan birch bark with apricot coloured lenticels


Himalayan Birch bark peeling
Peeling bark on a himalayan birch

The green-leafed birches impress for another reason – their slender, smooth trunks with luminous white bark, characteristic of the Himalayan Birch. On a dull day, the pale, narrow trunks seem to shimmer like ghosts in the gloom. On the upper parts of these trees the bark is peeling away like old wallpaper on a damp wall and, in the past, this white paper-like bark was used for writing Sanskrit scriptures and texts.

Himalayan Birches
Brownish-red markings on one himalayan birch

One of this group of birches also has crazed patterns of dark, brownish red superimposed on the white bark. I didn’t know that Himalayan Birches showed this kind of patterning and it makes me slightly uneasy about my identification.

Male catkins on Himalayan Birch
Male catkins on himalayan birch


Himalyan Birch female fruit and leaf
Seed head on himalayan birch

Around the branches, signs of reproduction and renewal abound. A few chunky male catkins are already present showing their prominent helical structure overpainted in washes of brown and green. In the spring, these catkins will become the familiar pendulous structures brimming with yellow pollen waiting to fertilise the female flowers as they emerge with the new leaves. But the tree hasn’t finished with this year’s cycle and some mature female seed heads are still waiting to discharge their seeds.

Young silver birch
Young silver birch showing reddish pink bark and many mature seed heads

The second group of young birches share many of the features of the three mature silver birches, particularly the foliage. Confusingly, the bark shows varying shades of pink, red and brown but my tree identification book tells me this is typical for young silver birches. New leaf buds are still very small as are the male catkins but this year’s mature female seed heads are very prominent. They fall apart easily if touched, releasing hundreds of seeds.

Male and female fruits on Silver Birch
Seed heads and new male catkins on silver birch

You may already know this, but the birch tree is a Celtic symbol of growth, renewal, stability etc and in Finnish sauna culture, participants gently beat themselves with leafy fragrant boughs of silver birch!

Shaggy Ink Caps
Shaggy Ink Caps

This month’s mild, damp weather has been good for fungi. On the 22nd I came across three fine upstanding shaggy ink caps (Caprinus comatus), also known as Lawyer’s Wig fungi because the bell-shaped cap develops flaking scales that protrude. These ink caps are edible although, I am told, they lack a very distinctive flavour. If you intend to eat them, pick and consume them young as they deteriorate rapidly. They should not be confused with the egg-shaped common ink cap which is poisonous in combination with alcohol.

Grey Wagtail
Grey Wagtail (from a distance)


Writing this diary takes me fairly regularly to the Leechwell Garden. On my visits, there has always been something to look at in the Garden, something to remark on, with one exception: birds. Why do I see so few birds, I don’t have an answer. So, it was a pleasant surprise to encounter an interesting bird this month as I walked away from the Garden towards the Leechwell. I saw the bird ahead of me as its flight traced an arc from the water to the wall above. When it reached the relative safety of the wall, it bounced about before settling; its habitual tail flicks and sleek shape told me immediately that this was a wagtail. I could see flashes of lemon yellow so this was most likely the resident, water-loving grey wagtail. It was there again a few days later. So, there are some birds about!

Autumn sculptures
Some “autumn sculptures” I found in the Garden one day.

Chemistry and politics at the time of the First World War

The terrible conflict of the First World War changed life for everyone in the UK. Few could have predicted, however, that a quiet backwater in rural Dorset in the South West of the country would become a secret First World War explosives centre which would provide vital support for troops and have an indirect influence on the formation of the state of Israel. This is the story of the Royal Naval Cordite Factory at Holton Heath.

A century ago, when the First World War began, Holton Heath, near Wareham in Dorset was a quiet tract of heathland bordering Poole Harbour. Within a year everything had changed and the heath had been transformed into a busy construction site for the highly secret Royal Naval Cordite Factory. This factory provided critical support for ammunition production for the Navy during WW1 and again during WW2. The site was finally closed in 1997 and is now partly a nature reserve and partly a business park.

What was cordite?

In 1914, all bullets and shells used by British forces depended on cordite as a propellant. Cordite was packed in to ammunition and once ignited, produced hot gases whose pressure propelled the shell or bullet towards its target. Cordite was made by mixing the viscous liquid nitroglycerine with fibrous guncotton (nitrocellulose), a little petroleum jelly and the solvent acetone to form a paste. This paste was extruded through a hydraulic press to produced spaghetti-like strands of cordite which were dried and cut to convenient lengths for use in ammunition.

Brisanzgranate 1 db.jpg
A World War I shell showing the cordite strands used as propellent (from Wikimedia Commons)


Superficially, this sounds like a simple process but don’t forget that the WW1 conflict was on a scale previously unimagined. This placed huge demands on cordite production requiring industrial-scale chemistry to make the raw materials. Many of these were potentially explosive so that there were great risks for workers.

Preparing strands of cordite during WW2 (from the Imperial War Museum © IWM (A 24936))


The Royal Naval Cordite Factory at Holton Heath

The main administrative buildings at the Royal Naval Cordite Factory Holton Heath


In 1914, Winston Churchill, then First Lord of the Admiralty, decided that the Navy needed its own protected supply of cordite; perhaps he foresaw problems with supply. He commissioned building a factory to produce cordite exclusively for the Navy and a search began for a suitable site. Holton Heath was finally chosen because it was away from centres of population but with good transport links by rail and by sea. Work began in 1915 and the factory opened the following year. The site employed more than a thousand people during WW1 and Holton Heath station was built to help people get to work. Many of the workers were women, the so-called munitionettes, and the steam trains carrying staff to work were nicknamed “glamour puffers”. We should not, however, underestimate the courage of these women. They were performing dangerous work, they were handling explosive materials and they were exposed to toxic chemicals. They risked their lives every day and their work could be seen as an echo of the lives of the men fighting abroad.

The Holton Heath station sign as it is nowadays (photo kindly donated by Pat English (http://squirrelbasket.wordpress.com/))
Holton Heath Station
Holton Heath Station as it is nowadays (from Wikimedia Commons)

The acetone crisis and Chaim Weizmann

Acetone was a critical ingredient in the manufacture of cordite and the scale of the conflict meant that huge amounts of the chemical were required. At the start of the war, acetone was imported from the major timber growing countries of the United States, Canada and Austria where it was made by distillation from wood. By 1915 there were supply problems and it became clear that another source would be needed to satisfy the huge demand of the munitions industry. The Synthetic Products Company in the UK tried to produce acetone on a large scale using bacteria to break down potato starch but ultimately failed to deliver the amounts required.

Weizmann's passport photo.jpg
Chaim Weizmann’s passport photo 1915 (from Wikimedia Commons)

The solution to the acetone problem was supplied by a Russian Jewish immigrant, Chaim Weizmann, working in the chemistry department of the University of Manchester. Weizmann was an expert in what we now call biotechnology, the use of biological processes to perform chemical transformations. He had collaborated with the Synthetic Products Company in their work on bacteria but eventually they parted company and he worked alone. After several frustrating years of research between 1912 and 1914 he finally isolated a bacterium that would produce acetone from maize starch in good yield. This microbe came to be called “Clostridium aceto-butylicum Weizmann” and provided the answer to the acetone problem.

Weizmann’s work had been performed on a small scale in the lab but, in 1915, when the Admiralty heard about his findings, they asked him to try to scale up the process. This was done in stages, first in a former gin factory in London and then in a 15,000 gallon tank built specially at Holton Heath. Weizmann must have paid regular visits to Dorset at this time to oversee progress. The work went well and the Admiralty decided to build a full scale acetone plant at Holton Heath employing Weizmann’s process. The new facility generated 2000 tons of acetone a year from maize starch. The success of the work in Dorset encouraged the Ministry of Munitions to adopt Weizmann’s process for production of cordite required for ammunition for all British forces.

Weizmann’s work on acetone, much of which was implemented in Dorset, was, therefore, fundamental to the outcome of the First World War. It was also the first application of industrial biotechnology, the use of biological systems to make valuable products on a large scale, now widely used for the production of drugs and vaccines.

Weizmann and Zionism

Flag of Israel


Flickr - Government Press Office (GPO) - President Chaim Weizmann.jpg
Weizmann in 1949 (from Wikimedia Commons)


Weizmann was a passionate Zionist and in 1917, became President of the British Zionist Federation. His principal wish was that the Jewish people should return to their homeland. The contribution he made to the war effort put him in a unique position of respect and influence. Although he was not a member of government, he knew and was respected by many of the politicians of the time. His views would have been listened to and he had long discussions with the Foreign Secretary Arthur Balfour. Indeed it was Balfour who in 1917 issued a Declaration supporting Palestine as a national home for the Jewish people. Israel was established in 1948, Weizmann was its first President and chemistry had influenced politics. The Royal Naval Cordite Factory in Dorset was inextricably interwoven with these events which still reverberate.

Some of the old buildings of the Cordite Factory as they are nowadays (photo kindly donated by Pat English (http://squirrelbasket.wordpress.com/))


The image featured at the top of this post is of a tract of nearby heath called Arne Heath.  It is how I imagine Holton Heath looked before the factory was built.  The image is © copyright Graham Horn and licensed for reuse under this Creative Commons Licence.

This article appeared in the October edition of the Marshwood Vale Magazine.

For another article on this factory see Squirrel Basket.

More ivy, more Ivy Bees !

Last Sunday, we enjoyed a walk around the small Devon seaside town of Salcombe. It’s a pleasant place now that the season is over and we relished the views over the estuary on this cooler but dry day. I don’t know whether I am looking more carefully or perhaps I haven’t previously visited Salcombe at this time of year? I didn’t remember the profusion of flowering ivy.

The Salcombe estuary on a sunnier day, viewed from the cliffs (Photo by Hazel Strange)


A narrow coast road links the town to its two beaches, North Sands and South Sands. On one side of this road there are low cliffs dropping to the sea and all along the cliff tops were huge banks of ivy. Given my recent experience, I now search any stand of flowering ivy for Ivy Bees and the Salcombe cliffs did not disappoint.

Ivy bee on ivy Salcombe 3

Wasps were the predominant insect on the ivy flowers but there were also quite a few of the sleek, slender, yellow and black-banded Ivy Bees (Colletes hederae) with their characteristic russet hairs. The wasps mostly tolerated their company although I did see one attack an Ivy Bee. The bee fell away but I could not be sure if it died or just sloped off.

Ivy bee on ivy Salcombe 2

The Ivy Bees at this site seemed to be moving about less than when I had seen them before. Once they had found a suitable flower head they spent some time exhaustively probing its flowers. Perhaps there was more pollen and nectar available? Perhaps it was cooler? I looked for colonies but did not locate any; I presume the nests are in nearby cliffs but as these are mostly private land they are out of bounds to Ivy Bee-nerds like me.

Ivy bees on ivy Salcombe

What I am beginning to realise is that, in this part of Devon, Colletes hederae is doing rather well with large colonies and large numbers. They also don’t seem to mind the cooler damper weather we have been experiencing.

It’s good to have a positive bee story to tell.

We visited Salcombe on October 12th 2014.

For those interested in Ivy Bees, they featured in the Guardian Country Diary this week

We see our first Ivy Bees!

We picked our way carefully down the steep, stony path to the beach at Mansands, one of the many small coves dotted along the South Devon Coast. At this time of year, the banks lining the path celebrate the season with silky draperies of “Old man’s beard” punctuated by bonfire-sparks of red rose hips and great outbursts of flowering ivy. Pale sunshine coaxed a sickly sweet perfume from the ivy flowers and encouraged a busy profusion of wasps, hoverflies and honeybees but we were hoping to spot another kind of insect. Suddenly my attention was grabbed by a different shape and there it was: marginally longer than a honeybee, its abdomen slender and pointed with clearly defined regular stripes of black and yellow. This sleek insect was an Ivy Bee (Colletes hederae), with a fringe of russet hairs around the thorax and its manner of browsing the ivy flowers in a crescent shape. We saw a few more but they were elusive and moved about quickly. It didn’t matter, we had seen our first Ivy Bees!

Ivy bee on ivy

Ivy bee on ivy flower

I was pretty sure that if there were Ivy Bees about, there must also be nests nearby but the conundrum was how to find them. At other sites in Devon, the nests are said to be near the beach so that seemed a good place to start the search. Ivy Bees generally choose soft friable soils to build the tunnels that form their nests. The beach at Mansands is book-ended by south-facing cliffs containing buff-coloured sandy soil, some shale and some rock. Scrubby grass provides cover in places. This is probably an ideal environment for these bees and, when I looked, I saw many small holes pock-marking the cliffs. Numerous bees were buzzing around and based on their patterning and shape these were probably Ivy Bees. Rather like commuters at a busy rush-hour railway station, some bees were going in and out of the holes and some were moving about, occasionally colliding with others. The nests were distributed along a stretch of cliff about 50 metres wide; there must be thousands of bees here. It seemed too easy but, almost by accident, I had stumbled across a massive Ivy Bee settlement, a truly impressive natural phenomenon.

Detail of Mansands cliffs with ivy bee nests
Close-up of the nest area


Mansands cliffs with Ivy Bee nests
Cliffs to the north-east of Mansands. Much of this area is populated by Ivy Bees

When I looked more closely, I noticed that the female bees returning to their nests carried chrome-yellow pollen along their legs, looking as if they were wearing bright yellow lycra cycling shorts. They mostly disappeared in to the holes presumably to unload the pollen to provide food for their larvae. A few returning females rested on blades of grass before entering their nests. As they cleaned themselves, they were bombarded by other bees. These may have been hopeful males but the females showed no interest at all, having probably already mated.

Ivy bee with pollen
Ivy Bee with pollen


Ivy bee approaching nest


Ivy bee resting on grass blade
Female resting before finding her nest


Ivy bee at nest
Having a look


The Ivy Bee is a relative newcomer to the UK having been first identified on mainland Britain in Dorset in 2001. Since then it has colonised many sites along the south coast and is also spreading north. It is the last solitary bee to emerge, flying between early September and early November. It shows a strong preference for pollen and nectar from ivy although it will feed from other sources. Some call it a mining bee as it digs tunnels for its nests but others refer to it as a plasterer bee from its habit of lining the nest with a protective cellophane-like coating. Although it is a solitary bee in that it does not form cooperative colonies, many Ivy Bees tend to nest in the same area.

There are two other solitary bees that are on the wing around this time and which could be confused with Ivy Bees. The sea aster mining bee (Colletes halophilus) looks very similar but it is confined to salt marshland on the East and South East coasts of the UK. Another look-alike is Colletes succinctus but this is a bee of heather moorland. The Mansands bees are unlikely to be either of these species, especially as there are large banks of ivy in the area.

These Colletes hederae are the last solitary bees I shall see until next spring and I can’t help marvelling at their behaviour. Ivy Bees spend a frantic period of roughly eight weeks on the wing when they have to mate and build nests. They must also lay eggs and provide them with supplies of pollen and nectar, helping to pollinate the ivy along the way. During the next ten months the miraculous transformation of egg to larva to pupa to bee occurs but we don’t see any evidence of this until the new bees emerge next year and the cycle starts again.

We visited Mansands on October 3rd 2014;  the photos were taken by Hazel Strange.

I should like to thank Amelia, who writes two fascinating blogs: A French Garden and Bees in a French Garden, for kindling my interest in solitary bees.

Crab apples, arsenic and suburbia – the September garden

Silver birch in autumn

Early in the month, autumn was more of an idea than a fact but as September progressed, the predominantly green view from my kitchen window gained increasing yellow and brown tinges. But this was no New England “Fall”, rather a gentle and gradual transformation as the new season took hold. In particular, I watched the three silver birches become increasingly flecked with yellow, transforming their foliage in to a patchwork of bright yellows and dull greens which glowed in the light of the morning sun. By the end of the month, yellow had overtaken green and a thin carpet of autumn leaves began to form under the trees.

Sedum and bumblebee
Sedum and bumblebee
Himalayan honeysuckle and bumblebee
Himalayan honeysuckle and bumblebee

Down in the Leechwell Garden the signs of autumn were clear although a few residual flowers struggled on. These were received gladly by the bees and I saw them enjoying the thick pink mop heads of sedum and the pendulous white trumpet-flowers and deep red chandelier-bracts of Himalayan honeysuckle (Leycesteria formosa).

Overbalancing mullein

A mullein that had overbalanced under its own weight to form a surprising arch sprouted vertical shoots and flowers as if desperately trying to grab the light; an occasional bee deigned to try these late offerings.
By the end of the month, ivy growing on walls outside the Garden had flowered and the huge clumps announced themselves with their sickly-sweet smell and insect-hum. The bees were lured by this sudden profusion of pollen for a final binge of the year but many other insects also contributed to the ivy-buzz.

Away from the flowers, interest this month has been provided by fruits and seeds as the plants and trees shut down for the season.

Snowberry fruit

A few squidgy white fruits appeared on a snowberry (Symphoricarpos) and, looking at them, I was transported back nearly half a century to a primary school playground where we used these as ammunition. No-one told me at the time that the fruits were highly poisonous but had I eaten one, their strongly emetic effects would have expelled the berry before I succumbed!

Spindle tree
Spindle tree foliage and fruit


Spindle tree fruit
Fruits of the spindle tree

In a somewhat gloomy corner of the Garden, a low shrub glowed with surprising pink leaves and even pinker fruit; this is a Spindle tree (Euonymus Europaeus). There is something slightly unsettling about the fruit with their bulbous four-lobed structure and brash colour. From Cathy, on her Words and Herbs blog, I learnt that the fruit are termed Bishop’s Hats in Germany; this seems most appropriate and the bishops refer to the colour as amaranth. A euonymus gets a mention in one of my favourite poems, “A subaltern’s love song” by John Betjeman. I believe Betjeman chooses the shrub as a symbol of mid 20th century suburbia. Read it to find out!

Crab apples
Crab apples

On the Crab Apple I noticed a few fruit: almost perfect green spheres tinged subtly with red. I am not sure why there are so few fruit given the number of pollinators in the Garden and I shall be intrigued to see how these mature as by last December the residual fruit were yellow.

Cedar flowers
Cedar flowers with pollen

The blueish needles of a cedar (Atlas Cedar I think) made a statement, and the tree was also adorned with squashy pollen-laden pale brown flowers. The plentiful pollen will be wind-carried from these male flowers to the female flowers higher up the tree to form cones.


September this year has been notable for its lack of rain and mild temperatures. Although this has not been good for gardeners, it has prolonged use of the Leechwell Garden by visitors and local residents especially those with children. An unexpected use of the Garden this month was as an outdoor classroom for one of the town’s primary schools. Groups of small children in the Garden gathered around one of the benches with their teacher or ran through the water – mums and dads will have been pleased! The teachers used the Garden in this way when rebuilding work at the school was delayed by the unexpected discovery of contamination. The school occupies land formerly used as the site of the town’s Victorian gasworks and, during the rebuilding, underlying soil was found to be contaminated with arsenic, lead and benzopyrene.

500 dead bumblebees – pesticides leave their deadly trace

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.

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 a few weeks ago and showed that the bees were contaminated with the neonicotinoid insecticide imidacloprid and two fungicides, flusilazole and epoxiconazole. Imidacloprid is very poisonous to bees with bumblebees being more susceptible to this chemical than honeybees. Imidacloprid is now subject to a two year partial ban for some agricultural uses. Neither fungicide on its own is especially toxic to bees although flusilazole is due to be phased out this October because of its high toxicity to fish and because of other potential toxic effects.

But where did the bumblebees pick up these chemicals? We cannot be sure 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. It is thought that the crop had been sown in autumn 2013 using seed treated with imidacloprid, just ahead of the ban. According to John Rennie of Natural England there had been no spray applications of insecticides or fungicides since the beginning of 2014.

So, why did these bees die? Because there are so many unanswered questions we cannot be sure. The imidacloprid used on the oil seed rape has been blamed by some but I can’t see how this could be a problem if the farmer followed safety guidelines. There is good evidence that exposure to typical agricultural levels of imidacloprid does not kill bumblebees although there is also good evidence for sub-lethal effects on behaviour and reproduction. It is, however, becoming apparent that neonicotinoids such as imidacloprid accumulate in soil so perhaps exposure levels of the dead bees were higher than expected. Soil testing would be informative here.

There is also the question of how the bees were exposed to the two fungicides if no spraying was performed during the flowering season? Does this mean that these chemicals persist for long periods or has there been spraying elsewhere? Perhaps the fungicides weakened the bees or made them more susceptible to the imidacloprid. There is some evidence for such interactions for other insecticide/fungicide pairings.

Although the investigation continues, it may be quite difficult to resolve some of these questions. Despite this uncertainty, the results of the chemical analysis stand. These bees died with three chemicals in their bodies: one insecticide and two fungicides. This was no laboratory experiment; this reflects what is happening around us when these chemicals are used. Our agricultural practices have led to this and the result is the deaths of important pollinators. How often is this occurring on a lower level but not being noticed or reported?

With thanks to Tony Gunton for talking to me about this incident


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