Hello Taynish – I’ve missed you!

By Caroline Anderson

It’s been hard hasn’t it?  I think this lockdown has been more difficult than the last one, apart from not seeing my family for a very long time which has been hardest of all, I’ve also missed insects and haircuts in that order – and believe me I’ve really missed haircuts!   However with the improvement in the weather, the longer days and hairdressers being opened again things are looking up! 

I ventured to Taynish towards the end of March and though ever hopeful, I wasn’t really expecting to see anything, but as always Taynish delivered with a first sighting of a Small Tortoiseshell butterfly this year followed closely by a bee, what joy that brought.

As usual the first stop was the boardwalk – again ever hopeful but probably about 6 weeks too early for damselflies.   However the lochan was absolutely alive with the sound of toads, it was very calming just to sit and listen for a while.

Then down at the picnic area more butterflies and bees, and a hoverfly of unknown origin, but which made its presence known by hovering right in front of my face – it seemed as curious about me as I was about it. 

The next visit to test out the new road down to the car park (it’s marvellous) was made last Friday.   There was a noticeable difference in the number of leaves on the trees and flowers on the plants – lovely to see patches of wood anemone and wood sorrel and of course the ever faithful primroses. 

Again the butterflies were out – but more Peacocks this time all fresh and new their markings were so bright and eye-catching.

I also spotted this fly, which I am assured is a male Tachina ursina. 

Lots more activity on the bee front too – you could hear the buzzing from the tree tops which was glorious, they were also very active on the whin.

So after a couple of visits to Taynish NNR (and a haircut) I still have seeing my family to look forward to.  All in all though I am feeling hopeful with good Taynish fresh air in my lungs and lots still to emerge, here’s to the next visit. 

On a more serious note, the positive impact nature can have on your mental health cannot be underestimated. Get out there – even if you have to force yourself – get outside, breathe it in, listen to nature going about its business, and I guarantee you will feel better.

Down to Earth

By Athayde Tonhasca

Of the more than 20,000 known species of bee in the world, most (~80%) are solitary, that is, each female constructs and provisions a nest by herself. And most (~70%) nest underground; these are fossorial (from the Latin fossor for ‘digger’), a term applied to animals adapted to digging and living underground. In the UK, about half of the 250 or so bee species are fossorial. They are better known as ‘mining bees’ or ‘miners’.

Common furrow bee (Lasioglossum calceatum) and Gwynne’s mining bee (Andrena bicolor), two widespread fossorial species © gailhampshire, Wikipedia Creative Commons

There are many types of mining bee nests, but a typical design comprises an entrance surrounded by a small ‘volcano’ of excavated soil, known as a tumulus. This entrance leads to a tunnel, which may branch into cells. The female bee lines these chambers with a waterproof waxy or paper material, or sometimes with mud, pebbles or pieces of leaves and petals. She will then stock each cell with a ball of pollen and lay an egg on it. The larva will feed on the pollen until it is ready to emerge as an adult. 

A tawny mining bee (Andrena fulva), a regular occupier of garden lawns, and its nest entrance © entomart (L), Sarah (R) Wikipedia Creative Commons
Multiple life stages of the alkali bee (Nomia melanderi) © Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org

Bees and their pollination services have been the subject of numerous initiatives around the world, largely focused on safeguarding pollen and nectar. These plans are laudable and helpful, but fall short. All the food in the world is no good to bees if they cannot build nests and raise their young.

Underground nesting does not sound like a tricky housing specification – after all, we are surrounded by solid ground. But the properties of a patch of earth can determine whether a mining bee can move in. Many fossorial bees need bare ground at a certain angle, so that nests are adequately warmed by the sun and protected from flooding. The physical properties of the soil must be just right: too hard, and the bee can’t dig; too soft, and the nest may collapse. Even soil acidity and organic matter content are important for some species.

This fussiness about nesting spots may help explain why females of some species nest near each other despite the risk of attracting parasites. These nest aggregations may be thousands strong, all sharing an area of suitable habitat – which could be a section of a well-trodden footpath or dirt road: these bees don’t mind sharing their space with us.

An aggregation of tawny mining bee nests © Africa Gomez, BugBlog

Mining bees and other solitary bees pollinate wild plants and crops, especially fruit trees such as apples. Despite the importance of these bees, conservation programmes have paid scant attention to their dietary needs, and even less to their nesting requirements. This omission is partially understandable because we know little about bees’ biology and behaviour. But broadly speaking – and this is certainly not applicable for all species – bare ground creation is a promising management option. This can be done by digging and compacting the soil on field margins, or by scraping the ground surface with farmyard machinery, ideally on south-facing slopes. The vegetation should be kept low by mowing or trimming.

Bee nests in a surface scraped with a digger © Nichols et al. (2020) Conservation Evidence 17: 15-18

In some situations, all it takes is to leave bees alone. Land managers may be tempted to ‘tidy up’ exposed ground by planting or landscaping it. By doing that, a well-intentioned practitioner may destroy whole colonies of mining bees.

Eroded ground, prime real estate for mining bees

In other cases, mining bees need protection. The Northern colletes (Colletes floralis) is one of the rarest British bees. It is present in low densities in continental Europe, but the bulk of its population is confined to coastal areas of Ireland and Scotland, with a couple of locations in England. In Britain, the greatest threat to this bee is the destruction of its nests, which are built in bare or sparsely vegetated coastal sand dunes. Housing, golf courses, motor racing tracks, marinas, wind farms, sand quarries and sewage treatment plants are all wearing away Northern colletes habitat.

Bees and people can often coexist, but sometimes we need to give them a break. 

The Northern colletes © Arnstein Staverløkk, Wikipedia Creative Commons

Norway’s pollinator progress

The Nordic and Baltic nations share Scotland’s desire to help pollinators. Last November, a virtual gathering of entomologists and environmentalists celebrated the work taking place to help pollinators in Northern Europe. In our blog today we take a look at the Norwegian experience.

The Norwegian approach to a pollinator strategy echoes our experience in Scotland.  Once the challenges facing pollinators were acknowledged, they produced a strategy identifying actions with a strong emphasis on partnership with municipal authorities, volunteer groups, individuals, beekeepers, science and research groups, energy sector, transport bodies, environmental bodies and farmers. 

Their strategy identified influencing land management as crucial for success. Parks, gardens, green infrastructure, meadows, coastal heaths, woodland margins, road verges and agricultural settings were all identified as areas where pollinator-friendly practices would have a huge impact. 

La Humla Suse is one of the key organisations working to help pollinators in Norway. Its primary goal is to create and improve habitat for bumble bees and they have a range of activities to encourage Norwegians to get involved. They organise guided bumble bee walks, give advice to farmers, local authorities and communities, help to create bee-friendly streets, and offer courses for nursery and school teachers. Their latest project is set to improve transport verges throughout Norway.

Campaigns such as the ‘Buzzing gardens’ aim to explain why pollinators are important, and  outlines what individuals can do on their own doorstep to help. Several urban towns, including Oslo, Trondheim and Moss, have implemented pollinator-friendly approaches, to the delight of their residents. 

Oslo’s  ‘bee highways’ are rather like the B-Lines here in Britain. The project sees the creation of feeding and travel routes through Norway’s capital via small meadows, floral verges, rooftop gardens and planted containers. There are moves to transform the Mindemyren district of Bergen into a greenspace haven.

Others have picked up the challenge. There is a drive to encourage the introduction of floral strips along farms, the creation of meadows adjacent to transport networks and a growing raft of advice on what to plant for pollinators. 

Of the 35 species of bumble bee in Norway, five are listed as near threatened. Indeed across Norway some 200 pollinators are on the national red list, of which around 30% are bees. To reverse these figures a bold strategy and a mixture of tactics is necessary and the indications are that change is afoot.

Astrid Loken, a Norwegian entomologist and member of the resistance movement, would have been in the vanguard promoting help. Her 1971 Studies on Scandinavian bumble bees is the highlight of a life-time devotion to the subject. The first female member of the Norwegian Entomological Society and a noted academic, she would have been thrilled to know that almost 200 delegates gathered for a Promoting Pollinators conference.  Thanks to her drive and influence we can celebrate progress built on solid foundations years later.

Find out more:

Read : Norwegian Pollinator Strategy is available in English.

Visit : La Humla Suse website

Enjoy : Scandinavian / Baltic States webinar on pollinators.  


Things move on

So it’s farewell to snowdrops, winter aconites, and crocus. Now we welcome coltsfoot, lesser celandine and butterbur to the floral stage. All have an appeal for pollinators, and deserve a very warm welcome.

Coltsfoot can be mistaken for a dandelion at first glance.  But look closely and you will see differences. The  coltsfoot’s stem is a give-away;  it is like a close up view of fish-scales. In Sweden the plant was known as Hästhov (horse hoof), reflecting the shape of the scales. Leaves come later, and initially the bright daisy-like yellow flowers lure early pollinators including queen bumble bees and a variety of flies.

Named Tusilago or fárfara, in Spanish coltsfoot also had the equivalent popular name of ‘pie de caballo’ or ‘uña de caballo’, which means ‘horse hoof’ or ‘horse nail’ – there seems to be similar folklore names in other parts of Europe (the Portuguese equivalents are arguably more fun and go along the lines of ‘mule hoof’ or ‘donkey hoof’).

Like many plants, coltsfoot was used as an early medicine. You might have thought those scaly stems would have put folk off.  However, it was reckoned to be a cure for colds, coughs and sore throats.   But eating any part of this plant causes an array of illnesses, including liver damage. 

The coltsfoot was also viewed at one time as a substitute for tobacco, and smoked! This strikes me as likely to have simply made it even more useful as a cough remedy, a vicious circle perhaps! In some quarters the sight of coltsfoot apparently indicated that somewhere, somebody was about to experience justice being done.

If dandelion and coltsfoot are often confused, the same can perhaps be said of winter aconite and lesser celandine. The yellow flowers of the latter are associated with the confirmation that spring is truly here. The glossy petals are vivid yellow in the centre but often fade to near white at the tips.  The distinctive heart shaped leaves are perhaps the most reliable sign of this plant.   Lesser celandine is widespread, being found in woods, on roadsides, beneath hedges and along river banks. The petals, and there are usually nine, remind many of buttercups and are noticeably pointy.

Flies as well as bees pollinate these flowers. There are ancient tales of the plants being crushed and applied to bleeding wounds. Others refer to it by the name of pilewort and as you might suspect it was used to tackle haemorrhoids.  Remains of the plant have shown up in the Mesolithic middens on Oronsay. In pre-war Germany it was grown to feed livestock, such were the prices for conventional foodstuffs.

Finally, to the delightfully named butterbur . This rather striking plant grows in clusters, and there are several near our Battleby office just north of Perth. The star-shaped flowers sit at the end of comparatively thin stalks. The leaves eventually become so big that they were once used in some parts to wrap butter.

The plant has an interesting male-female divide and which might even be related to how our ancestors actively looked after honey bees.  Further information on the butterbur species can be found in ….was the feature of a NatureScot (then Scottish Natural Heritage) blog. This is the explanation behind the peculiar distribution … “One of the most fascinating things about the butterbur is the odd distribution of the male and female plants.  For some reason male plants have a wider distribution, with almost all butterbur in the south of England being male.  How could that be?  The answer could be that male plants produce both nectar and pollen at a time of year when few native species are flowering.  There is a suggestion that in the past the male plants were deliberately moved about as a source of food for honey bees during the early spring.  We might buy our sugar from shops, but in the past honey was highly valued and used for sweetening so planting butterbur to help the bees is a plausible explanation.”

The star-shaped flowers sit at the end of comparatively thin stalks. The leaves start as delicate under-stated heart-shaped elements, but eventually become so big that they were used in some parts to wrap butter.

The non-native, and often invasive, white butterbur is more abundant at this time of year, particularly beside rivers. It has a couple of interesting names in Gaelic – gallan mòr is the more common of the two and means ‘big stalk’, the other is puball beannach meaning ‘peaked tent’. The Spanish name most commonly used for butterbur is Petasita from Petasites hybridus. Petasites is the generic name derived from the Greek ‘petasos’ meaning “wide brim hat”, in recognition of the large leaves of the plant.

These plants aren’t what you would classify as garden plants. But at this time of year they do add a lovely blast of colour on rivers, verges and margins.

Sonicate to pollinate

By Athayde Tonhasca

For most species of flowering plants, fertilization depends on the transfer of pollen from the male anthers of one flower to the female stigma of another. 

© Dianaperezval, Wikipedia Creative Commons

For the majority of those flowers, pollen is released through the splitting open (dehiscence is the technical term for it) of mature anthers. But for approximately 6% of the world’s flowering plants, pollen is kept locked inside non-dehiscent anthers and accessed only through small openings – pores or slits – in their extremities. We refer to them as poricidal anthers. 

Left: stamens, consisting of filaments and anthers. Most flowers release pollen by the splitting of the anthers along a line of weakness (top right); some only do it through a small hole or pore (bottom right) © Wikipedia Creative Commons

Sometimes the whole flower has a poricidal arrangement, as it is the case for the tomato and related plants (Solanum spp.). Pollen is concealed inside a cone-shaped cluster of fused stamens and can only be released though a pore at the tip. Botanist say these flowers have a solanoid shape, after the name of the plant genus. 

Solanoid-shaped tomato flowers © Muffet, Wikipedia Creative Commons

Extracting pollen from poricidal structures is not easy, but some bees know a way to do it. 

A bee lands on one of these flowers, bites an anther and curls her body around it. She then let out bursts of fast contractions and relaxation of her thoracic muscles – those used for flying, but here the wings don’t move. This produces cyclical deformations of her thorax that last from fractions of a second to a few seconds, and can be repeated many times (think of a body builder flexing his pectoral muscles really, really fast). These movements generate vibrations that are transmitted to the anther, causing pollen grains to fall though the apical pores and land on the bee’s body, perhaps aided by electrostatic forces. Watch the whole sequence of events here and here

This fancy pollen-harvesting manoeuvre creates a high-pitched buzz, hence it is known as ‘buzz pollination’; or as ‘sonication’ in technical reports. A physicist or an engineer could point out that this mechanism is not strictly sonication because it’s not sound that agitates and extracts pollen (such as in this example), rather direct vibrations on the flower. But ‘sonication’ is the term commonly adopted, so we will keep it. Bumble bees (Bombus spp.), carpenter bees (Xylocopa spp.), and some other bees can buzz pollinate: honey bees (Apis spp.) and most leafcutter bees (Megachile spp.) cannot. And apparently only females know the trick; males have never been recorded buzz pollinating.

A bee engaged in buzz pollination © Bob Peterson, Wikipedia Creative Commons

Plant species with poricidal floral morphology are distributed across at least 80 angiosperm families, which suggests that buzz pollination has evolved independently many times. This has probably been helped by bees’ readiness to buzz for other reasons such as warning potential enemies, compacting nest materials, or cooling/warming their nest with wing beats.

Buzz-pollination syndrome, the name given for this plant-bee association, is not just a biological curiosity. It makes a huge difference for crops such as tomatoes, raspberries, cranberries, blueberries, aubergines, kiwis and chili peppers. These plants don’t necessarily need buzz pollination to reproduce, but they produce more and better fruit if they are buzzed because more pollen is transferred and more ovules are fertilised.

In the late 1980’s, Belgian and Dutch companies developed techniques to rear on a large scale the buff-tailed bumblebee (Bombus terrestris), the ultimate buzz pollinator. Local producers of greenhouse tomatoes began replacing costly mechanical pollinators with boxes containing bumble bee hives, and a global, multi-million pound industry was born. Today, every tomato bought in a European supermarket has matured with the help of a commercially reared bumble bee.

A commercial bumble bee hive used in greenhouses © Elaine Evans, The Sustainable Agriculture Research and Education

We may see pollination as a harmonious relationship where plant and insect go out of their way to help each other, but this is mistakenly romantic. A bee aims to take all the flower’s pollen: pollination happens because a few grains are dropped or rubbed off by accident. And a plant produces as little nectar and pollen as necessary to entice a flower visit. So the association between pollinators and flowers is best described as a mutual exploitation. Buzz pollination fits nicely into this scenario. Poricidal anthers prevent excessive pollen expenditure by rewarding only buzz-pollination specialists, which increases the chances of pollination. Plants with poricidal structures typically secrete little or no nectar but their pollen is rich in protein, which convinces a bee to go to the trouble of buzzing to gain a small dose of the yellow stuff. It’s a clever, efficient trade agreement in the pollinator’s world.

The star of the show

Should you ever find yourself in Edinburgh’s Trinity or Newhaven areas, and seeking some relaxing greenspace, then head for Starbank Park. You won’t be disappointed. Here you will find a green oasis, sure to soothe and re-energise in equal measure.

Starbank is well-connected, not just physically but socially. Starbank House – which still sits in the park – was once owned by Alexander Goalen, You may not have heard of him, but you will recognise the name of a distant relative of his, the four-time British Prime Minister William Gladstone. 

Looking out over the Firth of Forth the park boasts a rich mix of trees, flower beds, areas devoted to herbs, and much more besides.  There is interest all year round.  In a few weeks time the cherry trees here will deliver their wonderful annual display, and pollinators will make the most of the feast this offer.

The Keep Scotland Beautiful ‘It’s Your Neighbourhood’ scheme is nothing short of a modern national treasure.  When they opened up a Pollinator Friendly award it chimed with many community and volunteer groups. The Friends group at Starbank Park were one such group and keen to submit an entry. In went an entry that was glittering with pollinator-friendly practices. From top to toe their’s was a submission up with the very best.  As Janet McArthur explained their approach mirrors the intentions of putting nature at the very centre of this category.  

“We encourage pollinator-friendly planting through our planting plans. We have planted many bee friendly bulbs and have a wide selection of fruit trees, shrubs and annual flowers to feed a variety of pollinators. It’s an important element of our planting action plan that we choose plants, herbs and flowers which are attractive to pollinators throughout the year. In short we want to attract as many pollinators to our community garden as possible by creating a welcoming habitat in our neighbourhood. That’s why we did little things too like put up a few bee hotels in our nature trails.”

They have followed up those inspiring words with a range of impressive actions.

Even the pandemic couldn’t stop them in the tracks. 

Janet takes up the story.  “When lockdown began we knew we needed to try to bring the spirit of the park to people’s homes. We kicked off a sunflower competition encouraging our community to participate in growing this nectar rich plant. This resulted in some spectacular sunflowers grown by all ages (and we now have a young volunteer working with me) which I’m sure really cheered people up in the late summer months. Appreciating the challenge our community had in obtaining seeds during the early weeks of lockdown we opened up our seed library to those interested in growing a little bit of Starbank Park in their own gardens, patios or window boxes.”

And the good news didn’t end there.  

There has been a significant pollinator bonus in a wonderfully ambitious switch from bedding plants to annuals. Keeping a park vibrant and appealing is not an easy task. It requires impressive detail as well as breadth. One of the most admirable actions is the seemingly straightforward one of leaving dandelions to flower in the park for hungry early bumblebees. That might seem an easy step on the surface, but in parks this is switch from the old engrained ethos of neatly manicured lawns that requires a bit of explanation and engagement to convince folk that things are actually being managed better for nature rather than simply being left to go to ruin.  

That job of persuasion and convincing was well done and now it is another popular and beneficial move for pollinators that is part of the ethos here.  

The Friends of Starbank Park formed in October 2013 and have not only restored this park to its former glories but carried forward a range of activities and actions that have engaged the local community. Today local schools, edible growing projects and space for toddlers are all part and parcel of a very broad appeal. There are even a couple of ‘little free libraries’ where locals share and swop books.

My own experience of parks is mixed, but of late the swing has been towards nature and community friendly spaces. Starbank combines pleasure, practicalities and pollinators in what is, by any standards, a really pleasing mix.

Find out more and visit:

Starbank Park are active on social media and have an excellent website which gives a lovely flavour of the delights that wait in store. The park also has a regularly updated twitter feed.

The park has a lot to offer at any time of the year.  If you would like to see the cherry trees in bloom, weather depending, the first week in May is a good date for your diary!

A welcome migrant?

By Athayde Tonhasca

If you spot a bumble bee in a garden, park or street from now until July, there’s a good chance it will be a tree bumble bee (Bombus hypnorum). Which is remarkable, considering this species was not even recorded in Britain until 2001. From the first sightings near Southampton, the tree bumble bee took Britain by storm: it has spread throughout England, Wales and much of Scotland. This represents an expansion of about 56 km/year. Today this species is often the most abundant bumble bee in urban and semi-urban environments. 

The tree bumble bee has a unique colour pattern among British species: ginger-brown thorax, black abdomen and white tail © Graham Ekins, The Essex Field Club

One of the characteristics that helped the tree bumble bee make itself at home in Britain is being a synanthrope. From the Greek syn (together) and anthropos (man), this term refers to species that benefit from humans and their habitats. Cockroaches, house sparrows, pigeons and the brown rat are quintessential synanthropes: their distribution and even survival depend on people. The tree bumble bee doesn’t go that far, but its life is greatly improved by our presence. Most bumble bees – most bees, in fact – nest on the ground, and appropriate sites are sometimes scarce. The tree bumble bee, as its name suggests, prefers to nest high up in a tree cavity. But many manmade structures above ground level such as bird boxes, compost bins, gaps under roof tiles, house eaves, and holes in walls and fences are perfectly suitable substitutes. And these sites are usually not disputed by other bees.

Compared to other bumble bees, the tree bumble bee starts the season early and forages at short distances from the nest. It also feeds on a wide variety of flowers, has a high nest density and may have two generations per year. Some or all these factors may have contributed to its success. Whatever the reasons, the speed and reach of tree bumble bee invasion have few parallels among alien species. 

An endearing creature such as the tree bumble bee is frequently referred to as ‘a recent arrival’, ‘a welcome addition to the UK’s fauna’ or ‘a newcomer’, because ‘alien’ has bad connotations. Alien species (those introduced outside their normal distributions) are often assumed to be harmful, therefore demanding eradication or control. But this is misguided. Most introduced species are neutral, as they neither damage nor help the environment. Some are beneficial, improving ecological services or providing food for native species.  Others become invasive, that is, they are harmful to habitats or other species. And bees can be invasive, such as the buff-tailed bumble bee in Asia and South America or the giant resin bee (Megachile sculpturalis), which is spreading in continental Europe and is known to displace native bees. 

So is the alien tree bumble bee a non-invasive species? Apparently, yes. So far it seems to cause no harm to other bees, and it may contribute to the pollination of our crops and wild flowers. But if its numbers keep increasing, other species may feel the nudge of competition. We have to wait and see.

Other bees seem to be fine with the newcomer, but its synanthropic nature has raised some human eyebrows. Tree bumble bees may take over bird boxes by expelling existing occupants, and their nesting sites may feel too close for comfort. Some people are also apprehensive at tree bumble bees’ apparent ‘swarming’. These are drones (male bees) hovering near a nest entrance, waiting for the opportunity to mate with a virgin queen flying from or into the nest – watch it. These events are called nest surveillances, and can last several weeks. But since drones are stingless, like all male Hymenoptera (bees, wasps and ants), nest surveillances are harmless.

A local arrival of tree bumble bees provokes spikes in calls to local authorities, beekeepers and pest controllers from people who want reassurance or, in a handful of cases, to get rid of bees buzzing nearby. Although most people are thrilled to have bumble bees as their close neighbours, this may change if bee numbers increase much further. Once again, time will tell.

The tree bumble bee, just like the ivy bee, seems to be a benign alien. But the consequences of its expansion are being watched closely.

Bumblebee conference broadens horizons

You can’t go out and see bumblebees anywhere other than on your doorstep these days, but that doesn’t mean you can’t hear all about them.  A couple of Saturday’s ago I joined a pan-European video conference and got what you might term ‘a continental pollinator fix’.

The European Bumblebee Conference subjects were many and varied, and truth be told I felt that I had been on a fantastic journey when the conference closed.  It is impossible to do them all justice here, so I can point you to them all online @ https://www.bestuivers.nl/hommelsymposium.

Vincent Kalkman of the Naturalis Biodiversity Centre of Leiden, chaired the conference, and opened proceedings by saying “Why he disliked bumblebees”. This proved a rather tongue-in-cheek title. He explained there were aggravating similarities between some species, and variations of colour within species, that make for difficult field identification between the likes of terrestris and pascorum.  He summed this up by saying “They seem easy to understand, but in fact their identification can drive you insane and understanding their requirements is mind-boggling!”  It was a good scene-setter for some great presentations.   

Challenges were the focus of the very first talk – ‘Mind the gap’ – by Bristol University’s Thomas Timberlake.

He highlighted the problem of seasonal floral resource gaps for bumblebees, particularly on farmland. Despite progress via Agri-Environmental schemes, the timing of floral resources remains an obstacle that future schemes could tackle.  Plant species have distinct flowering windows, which results in a seasonal pattern of nectar and pollen availability. Sometimes there is more than enough to go around, but at other times – like the early-spring and late-summer – there is a dearth of forage for bumblebees.

For bumblebees like this one (Bombus terrestris), it’s not just about how much food is available, it’s also when that food is available through the year. A dandelion flowering in early spring for example, would be more valuable to a bumblebee than an equivalent flower in mid-summer. Image: T. Timberlake 

Tom looked at foraging patterns of emerging queen bumblebees and young queens preparing for hibernation in farms in the South-West of England. The lack of September nectar on farms highlighted the potentially positive role of adjacent gardens as a consistent supply of nectar. 

How to boost resources in late summer?  Planting late-flowering cover crops, sowing margins with beneficial seed mixes, improving hedgerow quality, and introducing late flowering species (especially red clover, ivy and scabious) were all offered as actions which would have a positive effect.

Species which flower in September such as dandelions, red clover, ivy and scabious (clockwise from top left) are likely to be disproportionately important to bumblebees and other pollinators. Including these and other late-flowering species in conservation schemes will help fill the late summer hunger gap. Images: T. Timberlake & Wikimedia Commons

Paolo Biella gave us an inspirational update on bumblebees in the Alps. As a key part of bumblebee life-cycle is dedicated to collect resources, he intercepted Bombus terrestris returning to their nests which were, by scrutinising their pollen, found to be visiting 34 or so plant species, thus confirming their generalist feeding and how plant diversity is important for pollinator diet, even at high altitude.

More than 50% of Europe’s bumblebee species are found in the Alps – that’s around 39 species. – despite the area accounting for around just 10% of Europe’s surface. Paolo looked at the habitat requirements of three alpine species to see if any distribution changes could be identified in since the 1980s. Temperatures in the areas studied have risen, narrowing environmental resources to cold-adapted bumblebees and making them more sensitive to changes. All three were shown to be feeding at higher altitude now.

Given that the Alps is a core area for many European bumblebees, it was a sobering and thought-provoking presentation.

Working in partnership was a constant theme across the presentations. This came across vividly in the presentation by Nikki Gammans (Bumblebee Conservation Trust) which was a practical exploration of working with farmers. 

Based around the reintroduction of the Short-haired bumblebee, Nikki explained that Kent is the UK’s hot spot for rarer bumblebee species and that they tend to be late emerging and longer tongued, factors that influence targeted habitat creation. 

The aim was to work on a landscape scale, and this could only be effectively done by connecting working farms. Connections provided by Natural England opened up avenues to explore agri-environment schemes and the options for individual farms by giving bespoke advice. 

Management and maintenance methods were explored to enhance the prospects for flower-rich meadows. Grazing regimes, field margins, cutting cycles, seed mixes and rotation of stock also fell under the spotlight. The honest appraisal that patience is essential for work that can take between 5 and 9 years to show significant changes, and acknowledging the value of advice from the farming community, wrapped up a most impressive talk.

Indeed each and every one of the talks was inspirational and educational. From the Netherlands, to the Himalayas, via the Alps and the south of England.  Too much ground was covered for me to capture it all in a short blog, but hopefully the above gives a flavour of what was presented and encourages you to log in and explore:

To see the presentations visit https://www.bestuivers.nl/hommelsymposium.

About the organisers: Based in the Netherlands, the European Invertebrate Survey (EIS Foundation) shares knowledge on insects and other invertebrates and conducts and promotes research to aid policy and management to help insects in The Netherlands. More at  https://www.eis-nederland.nl

Sweet, sweet poison

By Athayde Tonhasca

In 401 BC, an army of Greek mercenaries led by Xenophon crossed Anatolia (modern day Turkey) to seize the throne of Persia. Xenophon kept a diary of the expedition, entitled Anabasis, or ‘The March of the Ten Thousand’, which today is a classic of ancient Greek literature. Among many battles and other adventures, the commander described one curious episode. His troops come across an abundance of honey, and some of the men went for it with gusto. In no time they regretted their excess: they could not stand up, vomiting and suffering from diarrhoea. Xenophon’s army had been overpowered by honey. ‘So they lay, hundreds of them, as if there had been a great defeat, a prey to the cruellest despondency. But the next day, none had died; and almost at the same hour of the day at which they had eaten they recovered their senses, and on the third or fourth day got on their legs again like convalescents after a severe course of medical treatment.’ (Anabasis, Book IV).

The march of the Ten Thousand. Image in the public domain

The Romans had their own taste of Anatolian honey, this time with grimmer consequences. In 97 BC, General Pompey the Great led an army across Turkey in pursuit of king Mithridates of Pontus, an old enemy of Rome. The local people, known as the Heptacomitae, withdrew. But they left an unpleasant gift for Pompey’s men, possibly on Mithridates’ orders. The geographer and historian Strabo tells us what happened: ‘The Heptacomitae cut down three maniples [around 1,500 soldiers] of Pompey’s army when they were passing through the mountainous country; for they mixed bowls of the crazing honey which is yielded by the tree-twigs, and placed them in the roads, and then, when the soldiers drank the mixture and lost their senses, they attacked them and easily disposed of them.’ 

Strabo’s ‘crazing honey’ that incapacitated those Greek and Roman troops is known today as ‘mad honey’. It comes from nectar produced by the common rhododendron (Rhododendron ponticum), which is endemic and abundant in northern Turkey. This plant is full of grayanotoxins, a group of toxic substances that protect it against herbivores, but also accumulate in the nectar. 

Common rhododendron, a source of mad honey © Rasbak, Wikipedia Creative Commons

Rhododendron honey is eaten in tiny amounts by local people for its perceived medicinal, hallucinogenic or aphrodisiac properties. But an adventurous gourmet taking even a spoonful of the stuff risks being struck by a long list of unpleasant and dangerous clinical symptoms. Indeed, it is not uncommon for people in Turkey – some of them tourists – to end up in the hospital after experimenting with mad honey. For reasons not yet known, invasive plants have lower levels of grayanotoxins than native plants, so mad honey is not a problem here in the UK.

A plant that secretes toxic nectar may seem to be engaged in self-harm, as this sugar-rich substance is the main incentive for pollinating insects to pay a visit to its flowers. But hundreds of plant species produce nectar laced with secondary compounds such as alkaloids, terpenes and phenolics, which are noxious or unpalatable to pollinators. And rhododendron’s mad honey is not unique: pure honey from mountain laurel (Kalmia latifolia) and bog-rosemary (Andromeda polifolia), for example, have a range of possible ill effects on people, including death. So there must a reason for this apparent paradox. Toxicity may be a way of excluding inefficient pollinators, reserving the metabolically expensive nectar for a few specialists that are immune to secondary compounds. It may also discourage nectar robbers, that is, flower visitors who avoid contact with the floral reproductive structures and therefore do not pollinate. Some of these chemicals may have antimicrobial properties that preserve the nectar. Perhaps toxicity is just incidental: secondary compounds act as chemical defences against herbivores, so seepage into nectar may be unavoidable. Poisoning a few pollinators would be a small price to pay for immunity from plant grazers. 

Sources of honey to be avoided: mountain laurel and bog-rosemary © Vlmastra (L), Pmau (R), Wikipedia Creative Commons

The bees that produce mad honey, the Caucasian (Apis mellifera caucasia) and Anatolian (Apis mellifera anatoliaca) honey bee subspecies, seem to be immune to grayanotoxins. So, too, are bumble bees, who take full advantage of rhododendron’s profusion of nectar-rich flowers. But other honey bee subspecies and some solitary bees are not: they die, or become paralysed, sluggish or erratic after consuming R. ponticum nectar (although honey bees learn to avoid rhododendron flowers). 

The common rhododendron is an incredibly efficient pioneer species. Each plant produces more than a million small seeds that are dispersed by the wind over large distances. It forms a dense canopy that shades out other plants, and it may release chemicals that inhibit the germination and growth of other seedlings. And thanks to grayanotoxins and other phenolic compounds, rhododendron has few grazers and sap feeders. Not surprisingly, this plant is a serious invasive wherever it grows unchecked. It is threatening natural and semi-natural habitats in Britain, much of Western Europe, New Zealand, and even in its native range in the southern Black Sea Basin. 

A Perthshire native woodland invaded by rhododendron © Lorne Gill/NatureScot

Because of its nectar, common rhododendron may contribute to the reduction of pollinators’ populations either by intoxicating some bee species or by decreasing food availability for others (invaded areas have fewer alternative flowers). It may also shift local species composition, leaving fewer solitary bees and more bumble bees. Indeed, colonies of the white-tailed bumble bee (Bombus lucorum) and the common carder bee (Bombus pascuorum) occur at higher density in areas invaded by common rhododendron when compared to uninvaded areas. We have no idea of the long term consequences of these disturbances to pollinator communities, but they are not likely to be trivial. Toxic nectar is one more reason for keeping common rhododendron on the list of bad gardening ideas.

Torino’s green vision

It’s undeniably one of Europe’s great cities. Home to the iconic Fiat Lingotto building, the famous Turin Shroud, birthplace of Cavour – Italy’s first prime minister. Steeped in compelling history, industry and culture, an economic powerhouse. Framed by distant views of the dramatic Alps and stunning baroque architecture Torino seemingly has it all.

However, this is a city that looks forward as well as over its shoulder, and good green infrastructure and pollinator-friendly projects are very much in vogue in Piedmont.

Torino is at the cutting edge of Italy’s evolving green infrastructure ambitions. Along with cities including Zagreb, Dortmund and Ningbo (China) it is part of the proGIreg project which is adopting nature-based solutions to transform post-industrial cities. It’s a project that will run until at least 2023 and has drawn a deal of praise.

There are eight agreed nature-based solutions being applied, and some of them, such as accessible green corridors, green roofs and walls, pollinator-friendly approaches and community based gardens, are familiar elements of Scotland’s evolving green infrastructure approach too.

There is an admirable, dynamic green vision to make the famous Piedmont capital a healthier and more environmentally friendly city for residents and wildlife.

Having a positive mind-set certainly helps. Take the Orto Wow project for example, based in the Mirafiori Sud district — a classic post-industrial neighbourhood near the old Fiat Factory — once synonymous with manufacturing. As we have learned in a post-industrial Scotland, when big industry relocates it can leave behind a legacy of brownfield sites, decaying and derelict buildings and sizeable transportation scars.

Orto Wow overcomes the undoubted challenges of transforming a former industrial neighbourhood by harnessing the collective power of partnership working. Their bold plans skilfully draw on the considerable expertise of the city council, university departments, and enthusiastic local associations.

The upshot is the creation of a green oasis, with centre stage perhaps the impressive pollinator garden (with no fewer than 16 raised beds). The idea is to create a city ‘pasture’ for bees and other pollinators.  It should succeed, as it has been worked up with the input of the highly respected University of Turin, and in planting classic pollinator-friendly plants such as borage, calendula, thyme, chives, dandelions and wild mustard a guaranteed feast for pollinators is on the menu. 

The increase in pollinator-friendly surroundings goes beyond the conventional. The proGIreg group in Torino created two large green walls to cover the Night Hospitality House in Corso Tazzoli. It gives new life to a once vacant building and the soothing green infrastructure fits well with the belief that urban greenery can contribute positively to health and well-being.  Regenerating former industrial buildings and making them available for new community ventures whilst greening their fabric is a bold, positive development that the locals are understandably proud of. 

It is worth dwelling on the fact that green walls have more than pleasing aesthetic qualities. They reduce noise, filter the air, and help cool buildings – a particularly welcome benefit as Torino can be a hot city in summer.

The ability of good green infrastructure to contribute to citizens’ health and well-being is also evident in the bold ‘Farfalle in ToUr’ project. The project focusses on butterflies, and began in the central district of Cenisia. By creating an urban butterfly oasis the project seeks to help the city on many levels. At the most basic level habitat is restored and connectivity improved for species. However, by engaging with a raft of citizen scientists, which includes both staff and patients from local mental health centres, vital monitoring work can be run in parallel with enhancing social inclusion and tackling mental health issues – all by tapping into the positive influence of involvement with nature.

A city commitment to steadily remove pesticide usage dovetails with moves to ensure green spaces are geared to offer forage and shelter for bees, hoverflies, butterflies and other pollinators, whilst the green networks themselves will act as corridors to better link potentially isolated populations of pollinating insects. This is fitting in a city which hosts one of the three major Italian lepidoptera research group in the University of Torino’s Department of Life Sciences and Systems Biology.

ProGIreg are evidence-based in much of their work. They have two pollinator transects inside Piemonte Park, one between the allotments and one in a wide meadow close to the River Sangone. Since 2018 bees and butterflies here have been surveyed to assess the specific impact of nature based solutions. The butterfly monitoring is the first Italian butterfly monitoring scheme using urban transects.

Physical health will also benefit from the pollinator friendly networks in Torino. The evolving parks, green corridors and river banks around the city support active travel ambitions are good for people and nature alike. A series of pleasant cycle paths allow for safer, healthy active travel routes from the periphery into the city centre. Routes along the banks of the River Sangone (as it flows towards the mighty River Po) typifies the delivery of a cycling plan formalised by the development of Torino’s ‘Biciplan’ to increase cycling to 15% of all 5km trips in the city.

The reassessment of public spaces is also gathering momentum. Piemonte Park is being dramatically redesigned and used for community urban gardens, the drive has included new social farming activities to help with teaching, training and creation of job placements. The social farming project (Orti Generali) is creating interest beyond the city as even small details deliver notable benefits, for example something as simple as animal grazing results in savings for park maintenance budgets.

A particular challenge faced in Torino is being situated in a valley associated with low levels of natural ventilation. The greening steps are going to prove key if the city is to overcome occasional poor air and meet its environmental ambitions. Like all cities there are financial challenges to overcome, but the green approach is clearly gaining momentum.

We may associate Torino with Fiat, Bicerin and Juventus for a bit longer, but the signs are that positive change is afoot in this famous Piedmont city.

With sincere thanks to Francesca Martelli for all of her help with this article.