̽��ֱ�� of Cambridge - bees

Flowers use adjustable ‘paint by numbers’ petal designs to attract pollinators

Anonymous — Fri, 13 Sep 2024 18:00:51 +0000

̽��ֱ��study, by researchers at the ̽��ֱ�� of Cambridge’s Sainsbury Laboratory also found that bees prefer larger bullseyes over smaller ones and fly 25% faster between artificial flower discs with larger bullseyes – potentially boosting efficiency for both bees and blossoms.

Patterns on the flowers of plants guide insects, like bees, to the centre of the flower, where nectar and pollen await, enhancing the plant's chances of successful pollination. Despite their importance, surprisingly little is known about how these petal patterns form and how they have evolved into the vast diversity we see today, including spots, stripes, veins, and bullseyes.

Using a small hibiscus plant as a model, researchers compared closely related plants with the same flower size but three differently sized bullseye patterns featuring a dark purple centre surrounded by white – H. richardsonii (small bullseye covering 4% of the flower disc), H. trionum (medium bullseye covering 16%) and a transgenic line (mutation) of H. trionum (large bullseye covering 36%).

They found that a pre-pattern is set up on the petal surface very early in the flower’s formation long before the petal shows any visible colour. ̽��ֱ��petal acts like a 'paint-by-numbers' canvas, where different regions are predetermined to develop specific colours and textures long before they start looking different from one another.

̽��ֱ��research also shows plants can precisely control and modify the shape and size of these patterns using multiple mechanisms, with possible implications for plant evolution. By fine-tuning these designs, plants may gain a competitive advantage in the contest to attract pollinators or maybe start attracting different species of insects.

These findings are published in Science Advances.

Dr Edwige Moyroud, who leads a research team studying the mechanisms underlying pattern formation in petals, explained: “If a trait can be produced by different methods, it gives evolution more options to modify it and create diversity, similar to an artist with a large palette or a builder with an extensive set of tools. By studying how bullseye patterns change, what we are really trying to understand is how nature generates biodiversity.”

Lead author Dr Lucie Riglet investigated the mechanism behind hibiscus petal patterning by analysing petal development in the three hibiscus flowers that had the same total size but different bullseye patterns.

3_hibiscus_bullseyes-2-01-01_sml.jpg

She found that the pre-pattern begins as a small, crescent-shaped region long before the bullseye is visible on tiny petals less than 0.2mm in size.

Dr Riglet said: “At the earliest stage we could dissect, the petals have around 700 cells and are still greenish in colour, with no visible purple pigment and no difference in cell shape or size. When the petal further develops to 4000 cells, it still does not have any visible pigment, but we identified a specific region where the cells were larger than their surrounding neighbours. This is the pre-pattern.”

These cells are important because they mark the position of the bullseye boundary, the line on the petal where the colour changes from purple to white – without a boundary there is no bullseye!

A computational model developed by Dr Argyris Zardilis provided further insights, and combining both computational models and experimental results, the researchers showed that hibiscus can vary bullseye dimensions very early during the pre-patterning phase or modulate growth in either region of the bullseye, by adjusting cell expansion or division, later in development.

Dr Riglet then compared the relative success of the bullseye patterns in attracting pollinators using artificial flower discs that mimicked the three different bullseye dimensions. Dr Riglet explained: “ ̽��ֱ��bees not only preferred the medium and larger bullseyes over the small bullseye, they were also 25% quicker visiting these larger flower discs. Foraging requires a lot of energy and so if a bee can visit 4 flowers rather than 3 flowers in the same time, then this is probably beneficial for the bee, and also the plants.”

̽��ֱ��researchers think that these pre-patterning strategies could have deep evolutionary roots, potentially influencing the diversity of flower patterns across different species. ̽��ֱ��next step for the research team is to identify the signals responsible for generating these early patterns and to explore whether similar pre-patterning mechanisms are used in other plant organs, such as leaves.

This research not only advances our understanding of plant biology but also highlights the intricate connections between plants and their environments, showing how precise natural designs can play a pivotal role in the survival and evolution of species.

For example, H. richardsonii, which has the smallest bullseye of the three hibiscus plants studied in this research, is a critically endangered plant native to New Zealand. H. trionum is also found in New Zealand, but not considered to be native, and is widely distributed across Australia and Europe and has become a weedy naturalised plant in North America. Additional research is needed to determine whether the larger bullseye size helps H. trionum attract more pollinators and enhance its reproductive success.

Reference
Lucie Riglet, Argyris Zardilis, Alice L M Fairnie, May T Yeo, Henrik Jönsson and Edwige Moyroud (2024) Hibiscus bullseyes reveal mechanisms controlling petal pattern proportions that influence plant-pollinator interactions. Science Advances. DOI: 10.1126/sciadv.adp5574

Flowers like hibiscus use an invisible blueprint established very early in petal formation that dictates the size of their bullseyes – a crucial pre-pattern that can significantly impact their ability to attract pollinating bees.

If a trait can be produced by different methods, it gives evolution more options to modify it and create diversity, similar to an artist with a large palette or a builder with an extensive set of tools

Edwige Moyroud

Bumblebees prefer bigger targets

Lucie Riglet

Artificial flower discs designed to mimic the bullseye sizes of the three hibiscus flowers

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Birds and honey badgers could be cooperating to steal from bees in parts of Africa

jg533 — Thu, 29 Jun 2023 11:27:19 +0000

̽��ֱ��tale of two charismatic species cooperating for mutual benefit has captivated naturalists for centuries – but evidence has been patchy. Researchers have now carried out the first large-scale search for evidence.

Discovery of RNA transfer through royal jelly could aid development of honey bee vaccines

ta385 — Thu, 02 May 2019 14:40:21 +0000

̽��ֱ��findings suggest new ways to protect bees against viruses and the deadly Varroa mite that have been responsible for the recent dramatic decline in honey bee populations. Since around one third of the human diet globally is dependent on honey bee pollination, we need solutions urgently to help maintain flourishing bee colonies, for our food security and sustainability.

Dr Eyal Maori from the Wellcome Trust/Cancer Research UK Gurdon Institute, ̽��ֱ�� of Cambridge, and his collaborators in Israel and the USA had been trialling a new type of antiviral therapy for bees when they got a hint that the bees were able to transmit biologically-active RNA molecules between colony members. ̽��ֱ��scientists today publish the evidence for such a bee-to-bee RNA transfer phenomenon in the journal Cell Reports.

These transmissible RNA molecules are produced by the honey bee’s genes and by disease agents such as viruses. Unlike other RNA in the body, these RNA molecules do not code for protein. Instead, they play a direct role in immunity, gene regulation and other biological mechanisms.

In previous studies, Maori and colleagues fed bees with RNA fragments that included a segment of an RNA virus. They found that similar to how vaccines work, the dietary RNA activated an immune response that prevented disease and death when hives were later exposed to the live virus. Intriguingly, the colony maintained a healthy performance for several months after treatment had finished, suggesting that it was still immune to infection – even though the original treated bees would have died off and been replaced by new generations. This suggested that the immunising RNA fragments were being passed among colony members as well as across generations.

In the study released today, the researchers demonstrated that dietary RNA is taken up from the ingestion system into the bee’s circulatory fluid and spread to the jelly-secreting glands. ̽��ֱ��dietary RNA is then secreted with the jelly and taken-up by larvae fed on the jelly.

While scientists have previously shown in plants and animals that movement of RNA between cells within an organism is possible, these findings identify a molecular mechanism for transmission of RNA molecules between organisms.

“We found that RNA spreads beyond individual honey bees, being transferred not just between parents and their progeny, but also among individuals in the hive,” says Maori.

Further experiments showed that transmissible RNA was able to activate a mechanism called 'RNA interference' to block the activity of some genes and reduce the production of certain honey bee proteins. Importantly, RNA interference is known to provide defence against viral infection in honey bees and other organisms. In other words, these RNA molecules are likely acting to immunise the bees against infections.

̽��ֱ��researchers next analysed the worker and royal jellies and revealed diverse types of naturally occurring RNA, some derived from bee genes and some from pathogens such as fungi and infectious viruses, suggesting that over time the bees had developed – and shared – immunity to these pathogens.

"Our findings demonstrate that bees share ‘transmissible RNA’ among members of the colony, likely as a way of sharing immunity among members and generations in the hive and to enable other bees to adapt to different environmental conditions," says Maori.

In a second study, published last month in the journal Molecular Cell, Maori, working with Professor Eric Miska's lab at the Gurdon Institute, investigated how RNA, which is an unstable molecule, is transferred through the jelly diet. They found that an abundant jelly ingredient, Major Royal Jelly Protein-3 (MRJP-3), binds the RNA to form granules that concentrate and protect it from environmental damage. This is the first identification of RNA granules with functions outside cells and organisms.

Maori added: "Honey bees have evolved a type of ‘glue’ that binds RNA into granules, making it more stable and so able to be shared with other bees. If we can harness this technology, we might be able to use it to develop new ‘vaccines’ that could be used in agricultural settings, in particular to help immunise bees against the devastating losses being suffered by their colonies.

“It is possible that this honey bee protein may even have applications, too, for new vaccines and medicines for humans.”

References:
E. Maori et al. 'A transmissible RNA pathway in honey bees.' Cell Reports; 2 May 2019; DOI: 10.1016/j.celrep.2019.04.073.
E. Maori et al. 'A secreted RNA binding protein forms RNA-stabilizing granules in the honeybee royal jelly.' Molecular Cell; 18 April 2019; DOI: 10.1016/j.molcel.2019.03.010.

Researchers have discovered that honey bees are able to share immunity with other bees and to their offspring in a hive by transmitting RNA ‘vaccines’ through royal jelly and worker jelly. ̽��ֱ��jelly is the bee equivalent of mother’s milk: a secretion used to provide nutrition to worker and queen bee larvae.

Bees share ‘transmissible RNA’ among members of the colony, likely as a way of sharing immunity

Eyal Maori

Courtesy of Cam Miller under a CC license.

Honey bee approaching a flower.

Acknowledgements

This work was supported by the Orion Foundation and the Israel Science Foundation, a Marie Curie Intra-European Fellowship for Career Development, a Leo Baeck Scholarship and a Herchel Smith Postdoctoral Fellowship a Cancer Research UK Programme Grant and a Wellcome Investigator Award; and by a core grant to The Gurdon Institute from Cancer Research UK and the Wellcome Trust.

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Think of honeybees as ‘livestock’ not wildlife, argue experts

fpjl2 — Thu, 25 Jan 2018 19:01:52 +0000

̽��ֱ��‘die-off’ events occurring in honeybee colonies that are bred and farmed like livestock must not be confused with the conservation crisis of dramatic declines in thousands of wild pollinator species, say Cambridge researchers.

Writing in the journal Science, the conservationists argue there is a “lack of distinction” in public understanding – fuelled by misguided charity campaigns and media reports – between an agricultural problem and an urgent biodiversity issue.

In fact, they say domesticated honeybees actually contribute to wild bee declines through resource competition and spread of disease, with so-called environmental initiatives promoting honeybee-keeping in cities or, worse, protected areas far from agriculture, only likely to exacerbate the loss of wild pollinators.

“ ̽��ֱ��crisis in global pollinator decline has been associated with one species above all, the western honeybee. Yet this is one of the few pollinator species that is continually replenished through breeding and agriculture,” said co-author Dr Jonas Geldmann from Cambridge ̽��ֱ��’s Department of Zoology.

“Saving the honeybee does not help wildlife. Western honeybees are a commercially managed species that can actually have negative effects on their immediate environment through the massive numbers in which they are introduced.

“Levels of wild pollinators, such as species of solitary bumblebee, moth and hoverfly, continue to decline at an alarming rate. Currently, up to 50% of all European bee species are threatened with extinction,” Geldmann said.

Honeybees are vital for many crops – as are wild pollinators, with some assessments suggesting wild species provide up to half the needed “pollinator services” for the three-quarters of globally important crops that require pollination.

However, generating honeybee colonies for crop pollination is problematic. Major flowering crops such as fruits and oilseed rape bloom for a period of days or weeks, whereas honeybees are active for nine to twelve months and travel up to 10km from their hives.

This results in massive “spillover” from farmed honeybees into the landscape, potentially out-competing wild pollinators. A recent study by the co-author of today’s Science article, Dr Juan P. González-Varo, showed honeybee levels in woodlands of southern Spain to be eight times higher after orange tree crops finish blooming.

“Keeping honeybees is an extractive activity. It removes pollen and nectar from the environment, which are natural resources needed by many wild species of bee and other pollinators,” said González-Varo, also from Cambridge’s Zoology Department.

“Honeybees are artificially-bred agricultural animals similar to livestock such as pigs and cows. Except this livestock can roam beyond any enclosures to disrupt local ecosystems through competition and disease.”

As with other intensively farmed animals, overcrowding and homogenous diets have depressed bee immune systems and sent pathogen rates soaring in commercial hives. Diseases are transferred to wild species when bees feed from the same flowers, similar to germs passing between humans through a shared coffee cup.

This puts added pressure on endangered wild European bee species such as the great yellow bumblebee, which was once found across the UK but has lost 80% of its range in the last half century, and is now limited to coastal areas of Scotland.

Both wild and cultivated pollinators are afflicted by pesticides such as neonicotinoids, as well as other anthropogenic effects – from loss of hedgerows to climate change – which drive the much-publicised die-offs among farmed bees and the decline in wild pollinator species over the last few decades.

“Honeybee colony die-offs are likely to be a ‘canary in the coalmine’ that is mirrored by many wild pollinator species. ̽��ֱ��attention on honeybees may help raise awareness, but action must also be directed towards our threatened species,” said Geldmann.

“ ̽��ֱ��past decade has seen an explosion in research on honeybee loss and the dangers posed to crops. Yet little research has been done to understand wild native pollinator declines, including the potential negative role of managed honeybees.”

Geldmann and González-Varo recommend policies to limit the impact of managed honeybees, including hive size limits, the moving of colonies to track the bloom of different crops, and greater controls on managed hives in protected areas.

“Honeybees may be necessary for crop pollination, but beekeeping is an agrarian activity that should not be confused with wildlife conservation,” they write.

Contrary to public perception, die-offs in honeybee colonies are an agricultural not a conservation issue, argue Cambridge researchers, who say that manged honeybees may contribute to the genuine biodiversity crisis of Europe’s declining wild pollinators.

Honeybees are artificially-bred agricultural animals similar to livestock such as pigs and cows

Juan P. González-Varo

Eric Ward

Commercial honeybee hives in the Teide National Park, Tenerife, Spain.

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Virus attracts bumblebees to infected plants by changing scent

fpjl2 — Thu, 11 Aug 2016 18:05:25 +0000

Plant scientists at the ̽��ֱ�� of Cambridge have found that the cucumber mosaic virus (CMV) alters gene expression in the tomato plants it infects, causing changes to air-borne chemicals – the scent – emitted by the plants. Bees can smell these subtle changes, and glasshouse experiments have shown that bumblebees prefer infected plants over healthy ones.

Scientists say that by indirectly manipulating bee behaviour to improve pollination of infected plants by changing their scent, the virus is effectively paying its host back. This may also benefit the virus: helping to spread the pollen of plants susceptible to infection and, in doing so, inhibiting the chance of virus-resistant plant strains emerging.

̽��ֱ��authors of the new study, published today in the journal PLOS Pathogens, say that understanding the smells that attract bees, and reproducing these artificially by using similar chemical blends, may enable growers to protect or even enhance yields of bee-pollinated crops.

“Bees provide a vital pollination service in the production of three-quarters of the world’s food crops. With their numbers in rapid decline, scientists have been searching for ways to harness pollinator power to boost agricultural yields,” said study principal investigator Dr John Carr, Head of Cambridge’s Virology and Molecular Plant Pathology group.

“Better understanding the natural chemicals that attract bees could provide ways of enhancing pollination, and attracting bees to good sources of pollen and nectar – which they need for survival,” Carr said.

He conducted the study with Professor Beverley Glover, Director of Cambridge ̽��ֱ�� Botanic Garden, where many of the experiments took place, and collaborators at Rothamsted Research.

CMV is transmitted by aphids – bees don’t carry the virus. It’s one of the most prevalent pathogens affecting tomato plants, resulting in small plants with poor-tasting fruits that can cause serious losses to cultivated crops.

Not only is CMV one of the most damaging viruses for horticultural crops, but it also persists in wild plant populations, and Carr says the new findings may explain why:

“We were surprised that bees liked the smell of the plants infected with the virus – it made no sense. You’d think the pollinators would prefer a healthy plant. However, modelling suggested that if pollinators were biased towards diseased plants in the wild, this could short-circuit natural selection for disease resistance,” he said.

“ ̽��ֱ��virus is rewarding disease-susceptible plants, and at the same time producing new hosts it can infect to prevent itself from going extinct. An example, perhaps, of what’s known as symbiotic mutualism.”

̽��ֱ��increased pollination from bees may also compensate for a decreased yield of seeds in the smaller fruits of virus-infected plants, say the scientists.

̽��ֱ��findings also reveal a new level of complexity in the evolutionary ‘arms race’ between plants and viruses, in which it is classically believed that plants continually evolve new forms of disease-resistance while viruses evolve new ways to evade it.

“We would expect the plants susceptible to disease to suffer, but in making them more attractive to pollinators the virus gives these plants an advantage. Our results suggest that the picture of a plant-pathogen arms race is more complex than previously thought, and in some cases we should think of viruses in a more positive way,” said Carr.

Plants emit ‘volatiles’, air-borne organic chemical compounds involved in scent, to attract pollinators and repulse plant-eating animals and microbes. Humans have used them for thousands of years as perfumes and spices.

̽��ֱ��researchers grew plants in individual containers, and collected air with emissions from CMV-infected plants, as well as ‘mock-infected’ control plants.

Through mass spectrometry, researchers could see the change in emissions induced by the virus. They also found that bumblebees could smell the changes. Released one by one in a small ‘flight arena’ in the Botanic Gardens, and timed with a stopwatch by researchers, the bees consistently headed to the infected plants first, and spent longer at those plants.

“Bees are far more sensitive to the blends of volatiles emitted by plants and can detect very subtle differences in the mix of chemicals. In fact, they can even be trained to detect traces of chemicals emitted by synthetic substances, including explosives and drugs,” said Carr.

Analysis revealed that the virus produces a factor called 2b, which reprograms genetic expression in the tomato plants and causes the change in scent.

Mathematical modelling by plant disease epidemiologist Dr Nik Cunniffe, also in the Department of Plant Sciences at Cambridge, explored how the experimental findings apply outside the glasshouse. ̽��ֱ��model showed how pollinator bias for infected plants can cause genes for disease-susceptibility to persist in plant populations over extremely large numbers of generations.

̽��ֱ��latest study is the culmination of work spanning almost eight years (and multiple bee stings). ̽��ֱ��findings will form the basis of a new collaboration with the Royal Horticultural Society, in which they aim to increase pollinator services for cultivated crops.

With the global population estimated to reach nine billion people by 2050, producing enough food will be one of this century’s greatest challenges. Carr, Glover and Cunniffe are all members of the Cambridge Global Food Security Initiative at Cambridge, which is involved in addressing the issues surrounding food security at local, national and international scales.

̽��ֱ��use of state-of-the-art experimental glasshouses at Cambridge Botanic Garden, and equipment at Cambridge and Rothamsted, was funded by the Leverhulme Trust.

Study of bee-manipulating plant virus reveals a “short-circuiting” of natural selection. Researchers suggest that replicating the scent caused by infection could encourage declining bee populations to pollinate crops – helping both bee and human food supplies.

Modelling suggested that if pollinators were biased towards diseased plants in the wild, this could short-circuit natural selection for disease resistance

John Carr

John Carr/Alex Murphy

Researcher Sanjie Jiang inside the 'flight arena' in the glasshouse of the Cambridge ̽��ֱ�� Botanic Garden.

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Flowers tone down the iridescence of their petals and avoid confusing bees

jeh98 — Thu, 25 Feb 2016 17:04:02 +0000

Iridescent flowers are never as dramatically rainbow-coloured as iridescent beetles, birds or fish, but their petals produce the perfect signal for bees, according to a new study published today in Current Biology.

Bees buzzing around a garden, looking for nectar, need to be able to spot flower petals and recognise which coloured flowers are full of food for them. Professor Beverley Glover from the ̽��ֱ�� of Cambridge’s Department of Plant Sciences and Dr Heather Whitney from the ̽��ֱ�� of Bristol found that iridescence – the shiny, colour-shifting effect seen on soap bubbles – makes flower petals more obvious to bees, but that too much iridescence confuses bees’ ability to distinguish colours.

Whitney, Glover and their colleagues found that flowers use more subtle, or imperfect, iridescence on their petals, which doesn’t interfere with the bees’ ability to distinguish subtly different colours, such as different shades of purple. Perfect iridescence, for example as found on the back of a CD, would make it more difficult for bees to distinguish between subtle colour variations and cause them to make mistakes in their flower choices.

“In 2009 we showed that some flowers can be iridescent and that bees can see that iridescence, but since then we have wondered why floral iridescence is so much less striking than other examples of iridescence in nature,” says Glover. “We have now discovered that floral iridescence is a trade-off that makes flower detection by bumblebees easier, but won’t interfere with their ability to recognise different colours.”

Bees use ‘search images’, based on previously-visited flowers, to remember which coloured flowers are a good source of nectar.

“On each foraging trip a bee will usually retain a single search image of a particular type of flower,” explains Glover, “so if they find a blue flower that is rich in nectar, they will then visit more blue flowers on that trip rather than hopping between different colours. If you watch a bee on a lavender plant, for example, you’ll see it visit lots of lavender flowers and then fly away – it won’t usually move from a lavender flower to a yellow or red flower.”

This colour recognition is vital for both the bees and the plants, which rely on the bees to pollinate them. If petals were perfectly iridescent, then bees could struggle to identify and recognise which colours are worthwhile visiting for nectar – instead, flowers have developed an iridescence signal that allows them to talk to bees in their own visual language.

̽��ֱ��researchers created replica flowers that were either perfectly iridescent (using a cast of the back of a CD), imperfectly iridescent (using casts of natural flowers), or non-iridescent. They then tested how long it took for individual bees to find the flowers.

They found that the bees were much quicker to locate the iridescent flowers than the non-iridescent flowers, but it didn’t make a difference whether the flowers were perfectly or imperfectly iridescent. ̽��ֱ��bees were just as quick to find the replicas modelled on natural petals as they were to find the perfectly iridescent replicas.

When they tested how fast the bees were to find nectar-rich flowers amongst other, similarly-coloured flowers, they found that perfect iridescence impeded the bees’ ability to distinguish between the flowers – the bees were often confused and visited the similarly-coloured flowers that contained no nectar. However, imperfect iridescence, found on natural petals, didn’t interfere with this ability, and the bees were able to successfully locate the correct flowers that were full of nectar.

“Bees are careful shoppers in the floral supermarket, and floral advertising has to tread a fine line between dazzling its customers and being recognisable,” says Lars Chittka from Queen Mary ̽��ֱ�� of London, another co-author of the study.

“To our eyes most iridescent flowers don’t look particularly striking, and we had wondered whether this is simply because flowers aren’t very good at producing iridescence,” says Glover. “But we are not the intended target – bees are, and they see the world differently from humans.”

“There are lots of optical effects in nature that we don’t yet understand. We tend to assume that colour is used for either camouflage or sexual signalling, but we are finding out that animals and plants have a lot more to say to the world and to each other.”

Glover and her colleagues are now working towards developing real flowers that vary in their amount of iridescence so that they can examine how bees interact with them.

“ ̽��ֱ��diffraction grating that the flowers produce is not as perfectly regular as those we can produce on things like CDs, but this 'advantageous imperfection' appears to benefit the flower-bee interaction,” says Whitney.

Reference: Whitney, Heather et al “Flower Iridescence Increases Object Detection in the Insect Visual System without Compromising Object Identity” Current Biology (2016). DOI: https://dx.doi.org/10.1016/j.cub.2016.01.026

Professor Glover will be giving the talk 'Can we improve crop pollination by breeding better flowers?' at the Cambridge Science Festival on Sunday 20 March 2016. More information can be found here: http://www.sciencefestival.cam.ac.uk/events/can-we-improve-crop-pollinat...

Inset images: Iridescent flower (Copyright Howard Rice); Bee on non-iridescent flower (Edwige Moyroud); Bee on non-iridescent flower (Edwige Moyroud).

Latest research shows that flowers’ iridescent petals, which may look plain to human eyes, are perfectly tailored to a bee’s-eye-view.

There are lots of optical effects in nature that we don’t yet understand... we are finding out that animals and plants have a lot more to say to the world and to each other

Beverley Glover

Bee on a non-iridescent flower

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̽��ֱ��Life and Death of the Queen Bumblebee

amb206 — Wed, 23 Sep 2015 09:43:16 +0000

Scroll to the end of the article to listen to the podcast.

Each autumn, colonies of bumblebees die. All, that is, apart from the gravid (egg-carrying) queens who survive the winter in tiny burrows in the ground. Early in the spring, the queen emerges to start making a nest in which to lay her eggs. To do so, she needs the energy provided by nectar and pollen. If she can’t find enough flowers from which to gather these resources, she will die – and the next generation she is carrying will die too.

Bumblebees are among the UK’s estimated 1,500 species of wild pollinators and play a vital role in the environment. They transfer pollen from plant to plant – and thus ensure that plants reproduce. An estimated 75% of the crops we eat depend on pollination. Bumblebees are particularly important pollinators of beans, raspberries and tomatoes. Uniquely, they are capable of ‘buzz pollination’, producing a high-pitched buzz which releases pollen from pollen-containing tubes inside some flowers. Tomatoes are pollinated like this.

Over the past 80 years or so, there has been a dramatic decline in the distributions of some bumblebee species. Two of the 26 species of bumblebee once common in the UK are now extinct. Scientists think that the factors behind this decline are several and interconnected. Most obvious is the loss of wild flower meadows which have disappeared as farming has become more intensive and fields made larger by the removal of hedgerows. Although many British gardens burst with flowers, many of the showy favourites (such as pansies and begonias) produce little pollen or nectar.

A recent report by Dr Lynn Dicks (Department of Zoology) and staff at Natural England makes an important contribution to the development of nation-wide strategies to halt – and reverse – the loss of wild pollinators such as bumblebees. In 2013, a rare and time-limited opportunity opened up for scientists to contribute to the development of an ‘agri-environment package’ for wild pollinators as part of the new Countryside Stewardship scheme, launched earlier this year.

As an expert in the ecology of flower-visiting insects, Dicks used this ‘policy window’ to bring together a wide range of available information and ask key questions about wild pollinators and their relationship with the farmed environment. In providing tentative answers to these questions, her paper provides ballpark figures on aspects of land management that determine population levels of wild pollinators, including bumblebees, and bolsters arguments for policies that encourage farmers to sow a mix of wild flowers.

“An agri-environment package is a bundle of management options that supply sufficient resources to support a target group of species. Data from a similar package, aimed at helping farmers provide resources for species of birds known to be declining, are not yet publically available. But some of the measures in the package are known to have led to an upturn in numbers of six target species – including skylarks and yellowhammers – which is most encouraging,” says Dicks.

“We depend on pollinators for food production so it’s in our interests to halt drops in numbers. If species are declining, it’s because they lack specific resources – or because other factors are reducing their numbers faster than they can reproduce. Some risks to pollinators – notably pesticides and climate change – are difficult to quantify and politically challenging. An alternative is to focus policy on providing the resources that are lacking – such as nectar-rich flowers.”

̽��ֱ��most critical period for bumblebee survival is March and April when the queens that have hibernated over the winter need access to enough nectar and pollen to raise their first batch of workers within an estimated 1km radius of their nests. ̽��ֱ��first batch of eggs laid by the queen become female workers whose role is to feed the new colony by visiting flowers to gather nectar. Throughout the summer the queen will produce further batches of eggs, seldom leaving the nest. She will eventually control a nest of as many as 400 individuals, including new queens. Honeybee hives, in comparison, typically contain around 50,000 bees.

Many commercial crops flower several weeks after the queen bumblebees are most in need of nectar. Oil seed rape, for example, produces its bright yellow flowers in May and June. Nectar and pollen provided by these crops are valuable to later batches of bumblebees. However, the first batch of bumblebees relies on plants that flower in early spring – including those associated with rough land (such as comfrey and white deadnettle) and hedgerow species (such as willow, hawthorn and blackthorn).

Recent research revealed that wild pollinators provide a much more important service to commercial crops than previously thought. Dicks’ report identifies opportunities for enhancing the environment for six species of wild bee including three species of bumblebee by sowing wild flowers and providing environments for nests.

She compiled and analysed data from a number of wildlife conservation and research organisations, including the Bumblebee Conservation Trust, to build an overall picture of the resources that these insects need to flourish.

By calculating the pollen demands of individual bees, and the resulting demand for flowers, Dicks has come up with some approximate figures in terms of the percentage of land and hedgerow needed to resource a healthy population of selected wild pollinators. Using a 100-hectare block of land as the basis for calculations, she estimates that the provision of a 2% flower-rich habitat and 1km flowering hedgerow will supply the six pollinator species with enough pollen to feed their larvae.

“We suggest that farmers sow headlands, field corners and other areas with mixes that will flower in the summer months, but they also need to manage hedgerows, woodland edges, margins and verges to enhance early and late flowering species and provide nesting and hibernating opportunities,” says Dicks. “It’s really important that the packages offered to farmers through the Countryside Stewardship scheme are easy to implement and well supported by financial incentives and advice. Because we are learning more all the time about the interaction between wild pollinators and the environment, schemes also need to have built-in flexibility.”

Next in the Cambridge Animal Alphabet: R is for an animal that is often found among the pages of children's literature.

Have you missed the series so far? Catch up on Medium here.

Inset images: Bombus pascuorum (Joan Chaplin); Bombus lapidarius (Tessa Bramall).

The Cambridge Animal Alphabet series celebrates Cambridge's connections with animals through literature, art, science and society. Here, Q is for Queen Bumblebee, one of the UK's 1,500 species of wild pollinators that play a vital role in the environment and food production.

We depend on pollinators for food production so it’s in our interests to halt drops in numbers

Lynn Dicks

Linda Peall

Bombus pascuorum

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Translating science for conservation: bees benefit first

bjb42 — Wed, 08 Sep 2010 00:00:00 +0000

For the first time, scientific knowledge and experience about how to conserve wild bees around the world has been brought together by conservation scientists led by Professor William J. Sutherland and Dr Lynn Dicks at the ̽��ֱ�� of Cambridge.

̽��ֱ��synopsis of evidence on bee conservation is meant to inform people taking action or spending money to help wild bees - anyone from farmers to international NGOs - about what works and what doesn't. It is part of a project called Conservation Evidence, which aims to make conservation practice more science-based.

Bees are the most important pollinators globally, and their decline has received much publicity. "There are more than 25,000 species of bee worldwide," says Dr Simon G. Potts, an expert on pollinator conservation from the ̽��ֱ�� of Reading who advised on the development of the bee synopsis. "In areas where good quality data are available, severe declines in many species have been documented." In response, governments and international organisations are now investing in pollinator conservation.

̽��ֱ��bee synopsis, developed in partnership with an international group of bee experts, lists 59 different actions you could take to benefit wild bees. They range from providing nest boxes or planting flowers to training beekeepers to keep native species. For each intervention, evidence is summarised in plain English.

In some cases, the evidence tells a clear story. Leaving strips at the edge of crop fields untreated with herbicides and pesticides does not help bumblebees, for example - two replicated trials in the UK have found no more bees on these strips than in ordinary crop fields. But there is evidence from many parts of the world that providing nest boxes on agricultural land can benefit solitary bees. Twenty-nine studies show that solitary bees, including endangered species, will use nest boxes and three studies show numbers of nesting bees can double over three years with repeated nest box provision.

Bees can be problematic in places where they are not native, and there is some evidence about how to reduce the impacts of invasive bee species. A concerted effort to eradicate European buff-tailed bumblebees from small patches of Japanese countryside, for example, increased numbers of native bumblebees, but did not remove the invaders altogether.

"This synopsis is a great step forward in providing a clear evidence base for anyone setting out to conserve wild bees, from conservation agencies to individuals," says Professor Andrew Bourke, a bumblebee expert from the ̽��ֱ�� of East Anglia, UK, and member of the Advisory Board for the bee synopsis. He was surprised by the often low success rate of artificial nest boxes for bumblebees. "This work highlights how much more there is to learn about bees," he says.

As well as helping to inform decisions about bee conservation, the synopsis shows where there are gaps in our knowledge. There is no direct evidence to show whether increasing the amount of natural habitat in farmed areas can help bees, for example, and very little evidence for the effects of restricting pesticide use on bees, although conservationists often advocate these actions. "Habitat preservation and the proper application and use of insecticides are the most important issues in bee conservation now," says Peter Kwapong, of the International Stingless Bee Centre in Ghana, a member of the Advisory Board. Clearly, these are areas where research should focus.

̽��ֱ��Conservation Evidence project also has an open access journal where conservationists can document their experience and an online database of evidence published elsewhere, relating to conservation interventions. ̽��ֱ��series of synopses, of which Bee Conservation is the first, will cover other major species groups, habitat types and issues. Synopses are already being prepared for birds, butterflies, grassland and farmland.

" ̽��ֱ��bee synopsis brings together, for the first time, a systematic overview of conservation practices that can really help protect bees," says Potts. " ̽��ֱ��challenge now is for policymakers to take up these actions."

A project to make conservation science accessible and relevant to conservationists and policymakers launches its first major synopsis of evidence, on bee conservation.

In areas where good quality data are available, severe declines in many species have been documented

Dr Simon G. Potts

rumpleteaser from Flickr

Bee in flight

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