All in all, it’s just another brick in the wall

By Athayde Tonhasca

In 2022, the seaside resorts of Brighton and Hove in southern England came under international spotlight for making it mandatory to use ‘bee bricks’ in all new buildings higher than 5 m. These bricks are the size of standard house bricks but have holes of different diameters drilled into one side, which are intended to mimic natural cavities used as nesting sites by some solitary bees. The bricks’ purported objectives are to boost bee populations and their pollination services. The legal requirement may have stumped Brighton’s and Hove’s architects and builders, but serendipitously, a local company was on hand to sell them these bee-boosting devices. 

Bee bricks © Falmouth University.

Bee bricks caught people’s imagination, and other local authorities have been asked by their residents to adopt the initiative. Meanwhile, you can get in on the action right now by buying the product from a range of companies. One retailer offers a choice of yellow, grey or red bricks at £39.99 each (for comparison, a top of the range, handmade glazed brick costs £3). You want to join in but live in America? No problem: you can purchase a brick imported from the UK for US$ 34, shipping not included (UK and America are ripe for an entrepreneur with a set of masonry drill bits). 

One would expect that a mandatory planning condition – let alone a price tag of £39.99 for a chunk of concrete – would be backed by data. In other words, do bee bricks make a difference for bees and pollination? The answer is, at best, ‘we don’t know’. 

Around 12 of the 270 or so species of bees in the UK are cavity-nesting: they occupy or expand naturally occurring spaces such as crevices under or between stones, cracks in a wall, the underside of peeling tree bark, holes in dead wood or hollow stems to build their nests. These species – mostly mason (Osmia spp.), leafcutter (Megachile spp.), and yellow-faced (Hylaeus spp.) bees – also make themselves at home in man-made structures such as bee houses or bug hotels, a feature that has helped farmers boost crop pollination with commercially reared bees, and has inspired the idea of bee bricks.

A male hairy-footed flower bee (Anthophora plumipes) cosy at home in an artificial nest © gailhampshire, Wikimedia Commons.

But no ordinary hole in the wall would do for cavity-nesting bees. A female selects a spot where she can fit in snugly; a too-wide hollow is an invitation to parasites to sneak in, and also requires extra work when she plugs the nest entrance with mud or leaves after finishing stocking the nest with pollen. Nest diameters for most bees are in the 4-10 mm range, so the 5 to 8 mm holes in bee bricks are adequate. But they fall short in depth. Their dimensions are the same as those of a standard house brick (21.5 x 10.5 x 6.5 cm), and several experiments with bee houses indicate that cavities must be at least 15 cm long; some studies suggest 20 or even 30 cm. We don’t know whether bees make do with bricks’ cramped spaces, and what the consequences are if they do. We know that small nests may affect the sex ratios of some species. That’s because eggs that originate female bees are laid in the inner brood cells; males are in the outer part of a nest cavity, so they can emerge first in the spring. If there is not enough space for all brood cells, bees of one sex may be produced in smaller numbers, with unknown consequences to the population.

A cross section of two cavities occupied by red mason bees. Eggs that will turn into male bees are on the left, near the nests’ entrances.

Location of the nest is crucial: homes of cavity-nesting bees must be exposed to sunshine so that the brood cells are sufficiently warm for the proper development of eggs and larvae. These bees also are not keen on heights. They prefer to nest ~30 to 50 cm above ground (Henry et al., 2023); the higher up the cavities, the lower their occupancy (MacIvor, 2016). And the neighbourhood matters a lot. After mating, a female bee spends her short adult life frantically gathering pollen and building brood cells; she will collect food as close as possible to her nest and can’t afford wasting time on long foraging trips. Maximum foraging distances are correlated with body sizes, but 150 to 600 m seems to be the range for the main species. To be on the safe side, nests should be no further than 150 m from a food source. The upshot is that a bee brick in a north-facing position, shaded by a tree, too high, or too far from abundant flowers, is not likely to be occupied.   

A golden-browed resin bee (Megachile aurifrons) arriving home loaded with pollen © Colin Leel, and
sealing her nest with resin © Colin Leel, Wikimedia Commons.

The use of concrete does not seem to be a problem: Henry et al. (2023) recorded occupancy of holes drilled on concrete blocks increasing from 2.9% in the first year to 11.6 and 25.3% in the second and third year, respectively. These figures are promising, but the concrete blocks used in the experiment were placed in flower-rich spots in open areas under full insolation. And the possibility of concrete being insufficiently porous to prevent mould, a serious hazard to cavity-nesting bees, should not be neglected. 

Because of the limitations described above or some other factor, the occupancy rates of bee brick holes are not particularly encouraging, ranging from 1.3 to 2.8% (Shaw et al., 2021); another two unpublished reports put the figure of inhabited bricks at 3.5% (Alton & Ratnieks, 2020). These numbers are considerably lower than the average occupation rate of 38.3% for a variety of artificial homes in urban environments (Rahimi et al., 2021). One possible explanation for such poor uptake is that cavity-nesting bees don’t need our help in finding suitable nesting sites: urban and semi-natural environments offer a range of perfectly habitable nooks and crevices to compete with bee bricks (MacIvor, 2016).

Bee bricks don’t seem to be living up to their hype, but there’s a silver lining here. High density nesting encourages the proliferation of pests and diseases, which are massive headaches to farmers who rely on commercially bred solitary bees. The impressive bee housing estate built under the auspices of Brighton and Hove Council may be mostly empty, but in all likelihood is not insalubrious.

Bee bricks installation © Falmouth University.

More data may improve the perspective of bee bricks as tools for boosting bee populations. But based on the little we know, the initiative ended up in Alton & Ratnieks’ (2020) list of ineffective products sold to home owners keen to do their bit for conservation. Bumble bee nests (priced £34.95 for a humble wood unit or £161.20 for a fancy underground model) could be added to it, as they also do not perform as intended (Lye et al., 2011). 

Merchandise that purportedly help wildlife in your garden but don’t cut the mustard: a bee nest (a), a bee brick (b), balls of flower seeds (c), a butterfly house (d) and a shelter for ladybirds (e) © Alton & Ratnieks, 2020.

In Britain and probably elsewhere, conservation practices are based mostly on perceived ‘common sense’ and personal experience rather than evidence (Sutherland et al., 2004). The obvious shortcomings of such approaches are that decisions are often wrong, causing a waste of time and money, erosion of public trust, and possibly aggravating environmental problems. Recommendations not shored up by evidence may also be interpreted as greenwashing: actions claimed to solve environmental problems but that are in fact public relations smokescreens.

Greenwashing warning signs: sustainable, green, environmentally friendly, made from renewable resources, carbon neutral, climate-positive, natural, net zero, regenerative, ethically sourced © Grain.

To help bees and safeguard pollination services, local authorities and everybody else can take tried and tested measures such as creating, preserving and restoring flower-rich areas; reducing or banning the use of pesticides; reducing the frequency of mowing to give wild flowers a chance; planting pollinator-friendly trees and shrubs, that is, species that produce lots of pollen and nectar. 

The familiar and run-of-the-mill don’t make a splash in newspapers and social media, but they more often than not give better results than the novel and untested. There’s security in the boring option.    

Making a difference

Pollinators are popular. That however hasn’t protected them from multiple challenges, and it’s a source of comfort that bodies such as Aberdeenshire Council go out of their way to help these important insects. Amongst the first councils in Scotland to launch a Pollinator Action Plan, they are now onto their third such plan.  And the good news is they are making a difference.

It was back in 2015 that Aberdeenshire got its first Action Plan, almost a decade on the latest iteration adds more measurable, time limited actions to the impressive suite of tools. 

There is no doubt we operate in challenging times when it comes to helping nature. As if changes in land use, fragmentation of habitats, pesticides and disease were not enough of a catalogue of issues, we are increasingly looking with concern to climate change. Rather alarmingly figures released recently showed that some parts of the UK endured their wettest 18-month spell since records were first compiled back in 1836. Four of the top ten wettest winters have now occurred in the last decade.

Such conditions aren’t easy for pollinators. And that is a problem for us, as pollinators are key to supporting healthy landscapes and habitats. 

In Aberdeenshire the Council’s Ranger Service, Greenspace Officers, Natural Environment Team and Community Groups have all looked to see what they can do to help pollinators in the immediate future. That typically means addressing concerns around a good supply of nectar and pollen, looking to achieve habitat connectivity, and planting with an eye to pollinator needs throughout the changing seasons and insect life-cycles. 

So, what have they been up to in Aberdeenshire? How do things look on the ground?

One particularly pleasing measure is that at least 80 school grounds are earmarked to be pollinator-friendly by 2027. Encouraging the next generation to appreciate and help nature is time well-invested. The creation of a Biodiversity Education Pack for schools is a logical way to bolster this work. In both practice and theory, the school environment is increasingly geared towards helping pollinating insects. An extremely popular and successful B-Lines project creating pollinator habitat with schools in the north of Aberdeenshire further shows their desire to engage, practically and has worked with 12 schools to date.  

Simultaneously, perennial plant promotion (as opposed to reliance on annuals) is gaining traction with the Greenspace Project initiative ‘Perennials for Pollinators’, running for its third year in 2024. This initiative supports the gradual shift away from the endless cycle of replacing annual bedding plants in community planting schemes to something with practical value rather than short-term narrow aesthetic appeal. It’s likely that increasingly natural regeneration will come to supplement this approach. With the growing enthusiasm amongst communities, the Council nursery facility is also being considered in its potential for perennial plant production in years to come.

At least 10% of council manged public greenspace in Aberdeenshire will be managed specifically for pollinators and biodiversity by 2027. The council is exploring habitat creation at woodland sites they own, with a shift to native tree species (hastened by significant storm damage and woodland loss in 2021/22), and shrub planting in open rides and around woodland edges an emerging preference. And in a welcome, and highly-visible move, wildflower areas are steadily becoming more prevalent in parks and recreation grounds, active travel routes, road verges, and school grounds.

Many have been created with the support and help of people power, highlighting the enormous social value of these biodiversity projects. Allowing grass to flower longer was trialled in 2023 with No-Mow May and Let it Bloom June being introduced at several sites across the Shire. A massive bulb planting effort, facililated by the Greenspace Project, saw over 300,000 flowering bulbs planted by over 100 community groups across the region. This will not only provide a source of nectar in the bulb flowers, but also allows the grass to flower for longer. 

Whilst the council pursues its agenda to help pollinators, it also enthusiastically embraces partnership working. They seek allies in neighbouring local authorities and the busy North East Scotland Biodiversity Partnership. Support also comes from NESBReC training courses which often focus on volunteer recording of pollinating insects and habitat surveys. There is also a supportive collaboration with Buglife Scotland in exploring opportunities for a B-Line project next to the River Don. 

Pollinators generally enjoy a high profile within the public perception. There is broad awareness of the threats they face but messages need to be periodically reinforced. In Aberdeenshire that takes many shapes, one of the most visible being the 150 or so Ranger Service sessions run each year with local schools, nature groups and communities to raise awareness of pollinators. There is also an online training course, “Mowing for Biodiversity” created by the Ranger Service. The course highlights the importance of pollinators to Council staff and elected members and shares information on what actions can improve habitats for pollinators.  

The new plan is evolving to build on success. Habitat creation and management, the creation of green networks and corridors, and raising the profile of the plight facing our pollinators are all positive actions which are retained.  The willingness to review and modify actions to help pollinators is a sign of not being prepared to rest on their laurels. It’s that observe and learn method which is a key strength of the Aberdeenshire approach. 

Find out more:

Aberdeenshire Council Pollinator Action Plan 2022 to 2027

NESBReC Biological records for the North East of Scotland

North East Scotland Biodiversity Partnership

Greenspace biodiversity – Aberdeenshire Council

Sometimes snips, snails and puppy-dogs’ tails, other times sugar and spice

By Athayde Tonhasca

As the story goes, during a tour of a government farm, American First Lady Grace Coolidge was being shown around by a farmer when she saw a cockerel and a hen romantically engaged. She asked her guide how often the cockerel would mate, to which he responded: ‘dozens of times a day.’ Good-humouredly, Mrs Coolidge retorted: ‘tell that to the President’. The farmer dutifully did so, and President Calvin Coolidge asked: ‘same hen every time?’, to which the farmer replied: ‘No, Mr President, a different hen every time.’ And the president: ‘tell that to Mrs Coolidge.’

Psychology Professor Frank A. Beach (1911-1988) saw this improbable anecdote as an ideal model to name a widespread phenomenon among animals: the Coolidge Effect, which is the enhanced sexual interest of males whenever a new female is accessible, regardless of the availability of previous sexual partners – a behaviour rarely reported for females. This shocking manifestation of male chauvinism has been offered a biological explanation.

The term ‘gonochorism’ makes us scramble for the dictionary, even though one of the first things we learned from our Birds and Bees lessons is that our species is gonochoric (or dioecious), that is, it has two sexes: the male sex produces or is geared up to produce gametes (reproductive cells) called sperm, while the female sex is equipped to produce gametes known as ova or egg cells. The lesson’s climax was the revelation that some types of frolicking could result in the fusion of these two types of gametes to produce babies. 

Male and female Mandarin ducks (Aix galericulata), a gonochoric and sexually dimorphic (sexes have different morphological characteristics) species © Francis C. Franklin, Wikimedia Commons

Later in life, when we took biology courses, we were told that many plants and some animals are hermaphrodites (they produce male and female gametes), while other organisms don’t need sex to reproduce. But the overwhelmingly majority of animals, and all mammals and birds, are sexually binary: they either produce male gametes or female gametes – leaving aside the rare cases of individuals that don’t fit in either category. And, from humans to asparagus, that is, for virtually all multicellular organisms, the female gametes are larger – often much larger – than the male gametes; that’s to say they are anisogamous: the two types differ in size and shape. And anisogamy has much to do with the Coolidge Effect.

Because sperm are relatively small, energetically cheap gametes, males can afford to churn out and distribute lots of them. By mating with as many females as possible, males increase their chances of passing on their genes. If a male gamete ends up in an unsuitable female, it’s not a big deal: there are plenty more fish in the sea. It doesn’t work like that for females. They put a lot of energy into their eggs, which are gigantic when compared to sperm. So, a female can only make a few of them in her lifetime. Adding gestation and time spent nurturing their young, females have a much lower reproductive capacity. As they invest a great deal more in producing an embryo than males, they need to choose their mates well to maximize their chances of success; if their Romeos are weak and unfit, females may have wasted all their reproductive potential. For females, it’s a matter of quality, not quantity. 

Together at last. A human male sex cell (spermatozoon) penetrating a human ovum. The spermatozoon is ~100,000 times smaller than the ovum. Image in the public domain, Wikipedia.

These biological particularities are strong incentives to polygyny, the mating system where a male has multiple sexual partners while the female mates with one or a few males. Polygyny is the most common mating strategy for vertebrates; about 90% of mammal species are polygynous. These males are, like the Coolidges’ rooster, always ready for a new romantic adventure.

Angus John Bateman (1919–1996), a botanist who worked with fruit flies, found one important consequence of the Coolidge Effect. For most polygynous species, a small number of males monopolize the females and prevent other males from mating. That is, some males are highly successful in reproducing, while many more have no success at all. Things are more predicable for females: most of them will mate – the few successful males will make sure of that. The upshot is that males’ reproductive success is more variable than females’. 

The winner takes it all: while one red deer stag (Cervus elaphus) keeps harems of up to 20 hinds, other males go with no dates © Keven Law, Wikimedia Commons.

Enter evolutionary biologist Robert Rivers and computer scientist Dan Willard (1948-2023) to thicken the plot by proposing that differences in reproductive success can bias the production of male and female offspring. Trivers and Willard argued, reasonably, that sons and daughters of females in good condition (that is, well-fed, healthy, and not pressured by competitors) would also be in good condition, whereas sons and daughters of females in poor condition (malnourished or debilitated by parasites or competitors) would also be in bad condition. But, when the reproductive success of one sex – males, in the case of polygynous species – is more variable than the other, diverging strategies emerge. It pays for strong, healthy females to have many sons, who mate frequently and produce lots of grandchildren for their mother. Daughters on the other hand are a less promising investment because, despite being strong like mum, they are restricted by low reproductive rates. But if the mother is in poor condition, having daughters would be a better deal because despite being feeble like mum, those who survive to adulthood are likely to produce some offspring. Feeble sons on the other hand may never breed, as they would be no match for males in good condition (Trivers & Willard, 1973). In other words, when things get bad, it’s better to have more daughters than sons. This risk-spreading strategy is a form of biological bet-hedging to maximize fitness and applies beyond mammal polygyny. If females’ reproductive success is more variable, we should expect more sons than daughters when the going gets rough.

Representation of the Trivers-Willard hypothesis for polygynous species. Low-quality females are more successful than low-quality males, but high-quality males and more successful than high-quality females © Shyu & Caswell, 2015.

The Trivers–Willard hypothesis provides an explanation for a common occurrence among animals: sex ratios going astray. In theory, a species should produce about the same number of sons and daughters (1:1 ratio) to maintain long term stability. This is known as the Fisher’s principle – although it would be fairer to call it the ‘Cobb’s principle’ after the solicitor and amateur biologist John Cobb (1866-1920), who first proposed it (Gardner, 2023).

The Trivers–Willard hypothesis has had an enormous influence in evolutionary biology. Its predictions have been supported by studies with a range of species, although its universality has been debated and questioned. Nonetheless, the hypothesis has encouraged much theoretical and empirical research about sex allocation. This body of work has revealed that variation of reproductive success between sexes is not the only driver of sex ratio skewness. Food, mothers’ age, litter size, population density, the weather, or some other environmental or physiological factor may induce females to adjust the sex ratio of their offspring to maximise fitness. 

UK’s age-sex pyramid illustrating the population’s distribution by age groups and sex. The male to female ratio is 1.05 at birth, shifting to 0.73 for those aged 65 and over © Kaj Tallungs, Wikipedia.

It turns out that food availability is an important inducer of sex ratio fine-tuning for one group of animals of enormous ecological end economic importance: cavity-nesting solitary bees. Most of the 20,000 or so known species of bee build their nests in the ground, but about 30% of them took another path regarding housing. They occupy or expand naturally occurring cavities such as crevices under or between stones, cracks in a wall, holes in dead wood, hollow stems and tree bark, transforming them into cosy, safe environments in which to raise their young.

Like all solitary bees, cavity-nesting species are on the wing for a small portion of their lives, sometimes weeks. After mating, each female spends her short adult life tirelessly victualing her nest with pollen and nectar to provide for her brood. It’s a race against time and over hurdles such as bad weather, competitors, flower scarcity, pests and parasites. Reproductive success depends on the amount of food available for the young, and here their sex can be the decisive factor. Female bees – like most insects – are in general bigger than males, so they need more food. As these big eaters could be a survival risk, some tinkering may be in order.  

A red mason bee (Osmia bicornis) man-made nest with brood cells well-stocked with pollen.

A red mason bee couple. The female is 20-25% bigger than the male © Aka, Wikimedia Commons.

The orchard mason bee or blue orchard bee (Osmia lignaria), a cavity-nesting species from North America, is a valued pollinator of several fruit trees. During the early nesting season, when pollen and nectar are most abundant and mum is in top shape, her offspring comprise mostly females. As the season progresses, flowers become scarce, so she has to work harder to provision her nest. Now the sex ratio tilts towards the smaller males, who have better chances of survival because they need less food (Torchio & Tepedino, 1980). 

The scenario is similar for the related red mason bee, a Eurasian species, but here parasites play a part. As the nesting season advances, females become less efficient and take more time to gather food, creating opportunities for nest-invading parasites. Females deal with the problem by reducing the amount of food stored, with a corresponding shift in the sex ratio towards the less demanding sons (Seidelmann, 2006). In the case of the Australian endemic banksia bee (Hylaeus alcyoneus), the growing food scarcity causes the reduction of the brood’s body mass and a shift in their sex ratios. But contrary to the prevailing pattern found in bees, male banksia bees are significantly larger than females. So unsurprisingly, the energetically cheaper daughters became more abundant late in the season (Paini & Bailey, 2002). Other cavity-nesting bees have also shown declines in foraging efficiency as the season progresses, and these changes have been linked to reduced size of their offspring and shifts in their sex ratios. 

Seasonal variation in sex ratio of emerging banksia bee adults (sex ratio = number of males/total number of emerging adults) © Paini & Bailey, 2002.

A male banksia bee. They become progressively scarce in coastal areas of southern Australia as the season advances © The Packer Lab, Wikimedia Commons.

The facultative, condition-dependent shift of sex ratios is a remarkable survival tool. The power to quickly tilt the offspring’s sexual balance could make the difference for a species’ success. In the non-nonsense, unforgiving great outdoors, where long-term existence hangs on the ability to adapt to changes, boys and girls are not always equally valued: these are the times when a Sophie’s choice of sorts is necessary.

Biodiversity and Glasgow University

You have to go back to the fifteenth century to trace the roots of the University of Glasgow. Fast forward to the present, and you find a highly respected academic institution that remains relevant and dynamic. One area of increasing activity is the University’s approach to greenspace management. Paul Brannan is the Grounds Operations Manager, and in this guest blog he outlines many of the actions taking place across the University estate to help nature.

Founded in 1451, Glasgow University has more listed buildings than any other university in the United Kingdom. With such a remarkable architectural legacy you might think that greenspaces don’t get much of a look in. However, that’s not the case, the university has vigorously embraced action to help nature around its estates.  

There are three sizable Glasgow University estates dotted within Greater Glasgow. They are very different from each other, yet each has the common task of ensuring their natural spaces deliver a range of benefits, complement historic surrounds, and support the academic energy of the university. 

At the best-known of the trio — Gilmorehill campus, in Glasgow’s West End — David Jamieson as the University’s Grounds Lead, works with his team to achieve a nature-friendly environment within a bustling urban location. He and his team spend considerable time looking at ways the site can be made appealing to the students and academics who use it, whilst benefitting biodiversity. 

Arguably dominated by the famous Gilbert Scott building, the Gilmorehill campus sits amidst a wealth of mature trees. Beneath the impressive canopy David and his colleagues transform areas of shrubbery with native plant species, and enhance lawned areas with swathes of nectar-rich bulbs which increasingly support early-season pollinators.

The university recognises the opportunities presented by its location in the heart of the city, and acknowledges it can ‘dove-tail’ its own efforts with the wider Biodiversity Action Plan of the City of Glasgow. Their sites can contribute to green corridors and stepping stones, and thus boost pollinator-friendly work being carried out by the city council.

There is certainly more open space and greenery to tap into four miles along the road at the university’s Garscube estate just beyond Maryhill. 

Spanning 200 acres, Garscube is home to Veterinary Medicine students, the Wolfson Hall of Residence and impressive outdoor sports facilities. It was bought in 1947 and added to the university’s property portfolio as a solution to overcrowding at the popular Gilmorehill campus.

David’s enthusiastic team are taking decisive steps this year to encourage emerging pollinators, and to this end will be joining the increasingly high profile ‘No Mow May’ campaign. This fits neatly with the goals of the University’s Biodiversity Action Plan.  

Heading out beyond Garscube’s leafy surrounds, the next significant property in the University’s ownership is Cochno Farm. 

The estate was purchased in 1954 when it consisted of 220 acres, including 42 acres of woodland. Today the site, which lies just north of Clydebank, extends to approximately 850 acres. It is the Scottish Centre for Production Animal Health & Food Safety, as well as housing the University’s College of Medical, Veterinary & Life Sciences. 

During 2023 around 20,000 additional trees were planted here as part of the university’s long-term sustainability strategy and climate change response. Director of Sustainability Dr Roddy Yarr notes the impact this will have; “The new forest will increase our biodiversity effort, creating and enhancing habitats on the farm”.

Among those 20,000 or so trees planted at Cochno Farm are various native species, including Scots Pine, Silver Birch, Downy Birch, Rowan, English Oak, Sessile Oak, Hawthorn, Black Elder and Goat Willow.

This all chimes neatly with the University’s latest Biodiversity Action Plan. Built around Phase-One habitat surveys carried out at Cochno, Gilmorehill, and Garscube, the findings have emphasised the need to reduce non-native species across all of the university sites. 

David senses that within the University community his work to deliver positive biodiversity outcomes has strong support.  “We want to help biodiversity across the University campuses as much as we can,” he notes, “and our grounds management approach is one way we can do this. The mapping and surveying carried out by our students has been extremely valuable, and has helped direct us towards focussing time on reducing our non-native species during a period when traditionally we would normally be focussed on mowing areas. This, of course, will give pollinators a significant helping hand”. 

Telling contributions have been made across numerous spheres by University of Glasgow staff and graduates. From the fields of politics and medicine, through to famous authors and notable scientists, the list of high achievers is lengthy.

Today, the University of Glasgow remains one of the top universities in the world, and the drive to nurture a range of biodiversity-rich habitats on its estates is testament to a desire to merge local action with international vision. Scotland’s first university to declare a climate emergency, Glasgow University has always had an eye as much on the future as the past.

Further reading:

University of Glasgow, Biodiversity Strategy and Action plan (2022-2027)

The Glasgow University team: Stephen McAnenay (Biodiversity & Arbioculture Co-ordinator), Stewart Miller (Sustainability Team), Dr Stewart White (Senior Lecturer), Samantha Gibbons (Biodiversity Promoter with GUEST (Glasgow University Environmental Sustainability Team)) and Molly Davidson, GUEST Biodiversity and Gardening Coordinator.

Overhead image of Glasgow University courtesy and (c) Glasgow University website.

But first, coffee

By Athayde Tonhasca

Charles II (1630-1685), king of England, Scotland and Ireland, had a reputation for benevolence and learning – the Royal Society came to be thanks to his auspices. But the good king wasn’t happy at all about the gossiping trickling from coffeehouses. Londoners from all walks of life would get together in one of the city’s dozens of coffee establishments to socialise, enjoy their pipes, comment on the news and, alarmingly, discuss theology, social mores, politics and republicanism. The king, anxious about potentially seditious blabber, issued a proclamation in 1672 aiming to ‘Restrain the Spreading of False news, and Licentious Talking of Matters of State and, Government’ because some folk  ‘assumed to themselves a liberty, not only in Coffee-houses, but in other Places and Meetings, both publick and private, to censure and defame the proceedings of State, by speaking evil of things they understand not, and endeavouring to create and nourish an universal Jealousie and Dissatisfaction in the minds of all his Majesties good subjects.’ 

Nobody paid much attention to the king’s gripe, so two years later he came down hard on the miscreants with another proclamation: merchants were forbidden to sell ‘any Coffee, Chocolet, Sherbett or Tea, as they will answer the contrary at their utmost perils.’ But Charles had underestimated how much his subjects cherished their coffee: the proclamation triggered a huge outcry, and there were signs of public disobedience. Perhaps thinking of his father, who lost his head (literally) for being inflexible, the king quickly backpedalled. The proclamation was abolished within two weeks, and Londoners could go back to their chatting, reading, and sipping strong, bitter coffee.

Charles II, who was concerned about Fake News. Portrait by John Riley, The Weiss Gallery, Wikimedia.

Coffee made its way to Europe from Turkey in the mid-1600s, and the new drink quickly became popular and fashionable. The first British coffeehouse was opened in Oxford in 1652, and soon others popped up all over the realm. No alcohol was served, so sober and caffeine-boosted patrons could exchange and debate ideas or do business: Lloyd’s of London and The London Stock Exchange trace their origins to coffeehouses. In Oxford, they became known as penny universities: for one penny, the cost of a cup of coffee (the admission fee), any man – women’s presence was not encouraged – could rub shoulders with learned patrons and find out the latest on science, literature and philosophy. John Dryden, Isaac Newton, Samuel Pepys, Alexander Pope and Christopher Wren were some of the famous coffeehouse fans.

A 17th century London coffeehouse. Image in the public domain, Wikipedia.

Eventually, as the British empire expanded through the East India Company‘s endeavours from 1720 onwards, tea became the country’s most popular hot beverage. Coffee began to make its way back to the top position in the late 1990s and early 2000s, helped in part by the arrival of mass-market coffee chains. Britain is not alone: coffee has become one the most popular drinks around the world, and consumption is increasing. 

The expanding coffee market is good news to millions of small farmers and land holders in about 80 countries, who supply the bulk of the internationally traded coffee. Brazil accounts for ~40% of the global trade, followed by Vietnam, Colombia, Indonesia and Ethiopia. Coffee is the most valuable crop in the tropics and a significant contributor to the economies of developing countries in the Americas, Africa and Asia. Arabica coffee (Coffea arabica) makes up 75-80% of the world’s production, and the remainder comes mostly from Robusta coffee (C. canephora), which is easier to cultivate than Arabica but produces an inferior beverage.

The Brazilian Empire (1822-1889) showed its gratitude to the two addictive drugs that sustained the county’s economy by displaying them on its flag: coffee (on the left) and tobacco © Almanaque Lusofonista, Wikimedia Commons.

Arabica coffee has long been understood to be an autogamous plant, that is, it fertilises itself. This reproductive mechanism has the obvious advantage of doing away with pollinating agents such as insects. On the other hand, self-fertilising plants lose out on genetic diversity, so that they are more susceptible to unpleasant surprises such as novel pathogens. And autogamy does not guarantee fertilisation for species as finicky as C. arabica. Plants bloom a few times during the season, but flowers come out all at once and don’t stick around: they wither and drop off in 2-3 days. And if it’s too hot, too cold, too dry or too wet, flowers don’t even open. A coffee plant produces 10,000 to 50,000 flowers every time it blooms, but almost 90% of them fall without being fertilised. So, Arabica coffee bushes could use a little help with their pollination.

Coffee plants in bloom ©FCRebelo, Wikimedia Commons.

It turns out that the autogamous label is not quite correct for Arabica coffee. A growing body of observations and research have shown that fruit size and overall yield increase when flowers are visited by insects, especially bees. The proportion of well-formed, uniform berries also increases, resulting in a better-quality beverage. These results demonstrate that Arabica coffee relies on a mixed mating system: some flowers are self-fertilised, others are cross-fertilised by insects. And the figures support this view. On average, insect pollination increases fruit set by about 18%. The naturalised European honey bee (Apis mellifera) is one of the most important contributors to this service, but several other native bees visit coffee flowers, attracted to their abundant nectar and pollen.

The stingless bee Partamona testacea is one of the many coffee pollinators in Central and South America © John Ascher, Discover Life.

There could be more to the pollination of Arabia coffee than the abundance of bees. Some studies suggest that having lots of bee species around also helps, possibly because a range of pollinators provide greater temporal and spatial flower coverage, thus reducing the chances of a receptive flower going without pollen transfer. If it’s proven to be the case that bee diversity makes a difference (the jury’s still out), the conservation of forest remnants that typically border coffee fields would be a judicious crop management practice, as they are home for many native bees.

Shaded coffee plantation, a habitat favourable to native bees © John Blake, Wikimedia Commons.

When you are in the queue for your over-priced double espresso, long macchiato or cortado, you may have a negative thought about greedy coffee barons. In fact, for a £2.30 cup of coffee, the retailer keeps £1.70; five pence (~2%) goes to the grower. Fairtrade estimates that 125 million people depend on coffee for their livelihoods, but many of these small growers can barely scrape a living (World Economic Forum). Boosting productivity is one sure way of increasing farmers’ income, and here bees have much to contribute. Higher productivity also reduces the pressure on natural habitats, as  coffee is often planted in areas previously occupied by native forests.

A typical coffee plantation in low or mid-elevation areas adjacent to native forest remnants © CoffeeHero, Wikimedia Commons.

The Arabica coffee story exemplifies the reach of pollination services. The income of small farmers, revenues of developing countries, the conservation of tropical forests and related matters such as carbon storage and global temperatures, let alone your morning caffeine kick, are all linked in different degrees of relevance to the diligence of bees, some of them poorly known. Keep that in mind while you enjoy your next cup of coffee.

Ad for A Brasileira, Lisbon’s oldest coffee house. Selling Brazilian coffee since 1905. Image in the public domain, Wikipedia.