Crunchy on the outside

By Susie Glover, HOPE Learning Officer

We have an ambitious project underway at the Museum, to preserve a unique and scientifically important collection of over one million British insects. It’s called HOPE for the Future, after the Hope Entomological Collections, and we are keen to shout about how these specimens can help us understand biodiversity, habitats and ecologies.

The learning team behind the project are today launching a new blog for young people interested in entomology. Intriguingly, it’s called Crunchy on the Outside, but please don’t confuse this with the similar, but fundamentally different, mid-’90s advertising campaign for the Dime bar.

A high magnification image of an insect, face-on, showing large proboscis and brown body.
One of many weird and wonderful specimens from our collection, the Acorn Weevil (Curculio glandium).
Here is a peek at some of the tools of the trade, used to move and mend specimens like this moth.

Crunchy will be crammed full of interesting insect info, fun things to make and do, a peek behind the scenes at the Museum, and news from people, past and present, who work in the field of entomology. The odd bad joke may also worm its way in (What do butterflies sleep on? Cater-pillows).

The blog will also be a platform for young people to have their say, about the topics covered on Crunchy itself, as well as on the activity of the Museum. It will give them first dibs on access to related events too. You can check it out, follow, and share at crunchyontheoutside.com.

HOPE for the Future is funded by the National Lottery Heritage Fund.

Bees use shark ‘supersense’ to help find food

This article is taken from European research magazine Horizon as part of our partnership to share natural environment science stories with readers of More than a Dodo.

Armed with sensitive antennae and wide-angled compound eyes, bees have a sophisticated set of senses to help them search out pollen and nectar as they buzz from flower to flower.

But new research is revealing that bumblebees may employ another hidden sense that lets them detect when a flower was last visited by another insect.

Professor Daniel Robert, an expert in animal behaviour and senses at the University of Bristol, UK, has discovered that bumblebees have the ability to sense weak electrostatic fields that form as they fly close to a flower.

‘A bee has a capacity, even without landing, to know whether a flower has been visited in the past minutes or seconds, by measuring the electric field surrounding the flower,’ Prof. Robert explained.

The discovery is one of the first examples of electroreception in air. This sense has long been known in fish such as sharks and rays, which can detect the weak electrical fields produced by other fish in the water. Water-dwelling mammals such as platypus and dolphins have also been found to use electric fields to help them hunt for prey.

But rather than hunting for fish, bees appear to use their ability to sense electrical fields to help them find flowers that are likely to be rich in pollen and nectar.

Charge
Bees develop an electrostatic charge because as they fly they lose electrons due to the air rubbing against their bodies, leading to a small positive electric charge. The effect is a bit like rubbing a party balloon against your hair or jumper, except the charge the bees accumulate is around 10,000 times weaker.

Flowers, by comparison, are connected to the ground, a rich source of electrons, and they tend to be negatively charged.

These electrostatic charges are thought to help bees collect pollen more easily. Negatively charged pollen sticks to the positively charged bee because opposite charges attract. Once the pollen sticks to the bee, it too becomes more positively charged during flight, making it more likely to stick to the negatively charged female part of a flower, known as a stigma.

Bees develop a positive electric charge as they fly, which helps them to collect pollen from negatively charged flowers. Image credit – Pxfuel.com/DMCA

But Prof. Robert and his colleagues wondered whether there could be more to this interaction. When they put an electrode in a flower, they detected a current flowing through the plant whenever a bumblebee approached in the air. Their study revealed that the oppositely charged flower and bee generate an electrostatic field between them that exerts a tiny attractive force. 

To study whether the bees are aware of this electrostatic field, they then offered bumblebees discs with or without sugar rewards. Those with sugar also had 30 volts of electricity flowing through them to create an electrical field. They showed that the bees could sense electrical field and learn that it was associated with a reward. Without the charge, bees were no longer able to correctly identify the sugary disc.

Research by another group published shortly after Prof. Robert’s own work also showed that honey bees are also able to detect an electrical field. But exactly how the insects were able to do this remained a mystery, leading Prof. Robert to set up the ElectroBee project.

Very few animals have the capacity to read the stars and use it to find, north, south, east or west.
Professor Eric Warrant, Lund University, Sweden

Hairs
He has discovered that fine hairs on the bees’ bodies move in the presence of weak electrical fields. Each of these hairs has nerves at its base that are so sensitive they can detect tiny movements – as little as seven nanometres – caused by the electrical field.

Prof. Robert believes that when a bee visits a flower, it may cancel out some of the negative charge and so reduce the electrostatic field that forms when bees approach. This change in the strength of the electrostatic field could allow other bees flying past to work out whether a flower is worth visiting before they land, helping to save time and energy.

Other signals, such as changes in the colour and smell of flowers, happen in minutes or hours, while switches in electric potential occurs within seconds.

Prof. Robert and his team are now testing their theory that the electric field helps bees know which flowers to visit by counting visits by bumblebees to flowers in a meadow this summer and measuring electric fields around the flowers.

Their findings could help scientists better understand the relationship between plants and pollinating insects, which may prove crucial for improving the production of many vital fruit crops that rely upon bees for pollination.

Prof. Robert is also investigating whether bumblebees use their electrostatic charge to communicate to their nest sisters about the best places to fly for pollen.

But while bumblebees use their extraordinary sensory power to find food just a few kilometres from their nests, another insect is using another hidden sense to make far longer journeys.

The Bogong moth can travel more than 1,000km to hibernate in caves during the Australian summer. Image credit – Lucinda Gibson & Ken Walker, Museum Victoria/Wikimedia, licenced under CC BY-SA 3.0

In Australia, Bogong moths (Agrotis infusa) flitter steadily from various parts of the country and make their way towards the Snowy Mountains in the southeast. They fly for many days or even weeks to reach the high alpine valleys of the highest mountain range in the country, sometimes travelling over 1,000km. Once there, the insects hibernate in caves typically above 1,800m for the Australian summer, before making the return journey.

The only other insect known to migrate so far is the monarch butterfly in North America. But while the monarch butterfly relies in part on the sun’s position for navigation, the moths fly by night. Professor Eric Warrant, a zoologist at Lund University in Sweden, has been fascinated with how these insects, just a couple of centimetres in length, managed such a feat ever since he was a student in Canberra, Australia.

Moth mystery
He suspected that the moths might use the Earth’s magnetic field to find their way, so his team tethered moths to a stalk that allowed them to fly and turn in any direction before surrounding them with magnetic coils to manipulate Earth’s magnetic field.

For two years, experiments failed. While the moths did appear to be influenced by the magnetic field, they were using something else to navigate too – their vision.

‘It is a little like how we would go hiking,’ said Prof. Warrant, who is trying to unravel how the moths sense the Earth’s magnetic fields in his project MagneticMoth. ‘We’d take a reading from a compass, then look for something to walk towards in that direction, a tree or mountain peak.’

His research has already shown that the moths check their internal compass every two or three minutes and continue to make for a visual cue ahead. But what are the insects able to see at night?

Further research revealed something remarkable. When Prof. Warrant downloaded an open source planetarium programme called Stellarium and projected the Australian night sky above the moths, he discovered they were using the stars.

‘Very few animals have the capacity to read the stars and use it to find, north, south, east or west,’ said Prof. Warrant. ‘We (humans) learnt how to do it. Some birds do it.’

But insect eyes of bogongs mean they don’t simply follow one guiding star. Rather they are sensitive to panoramic scenes.

‘In the southern hemisphere, the Milky Way is much more distinct than it is here in the northern hemisphere,’ said Prof. Warrant. ‘It really is a stripe of pale light in which there are interspersed very bright stars.’ He believes that the moths are at least in part guided to their cool alpine caves by the light of the Milky Way.

Prof. Warrant believes that Bogong moths naviagte in part by using the Milky Way as a guide. Image credit – Dave Young/Flickr, licenced under CC BY 2.0

The discovery could also lead to the development of new types of navigation for our own species too. GPS, for example, relies upon a constellation of satellites that are vulnerable to disruption. Prof. Warrant believes studying an insect capable of flying 1,000km to a cave using a brain the size of a rice grain, could help us find alternatives too.

‘Animals seem to solve complex problems with little material and low amounts of energy,’ Prof Warrant said.

The research in this article was funded by the EU. If you liked this article, please consider sharing it on social media.

This post Bees use shark ‘supersense’ to help find food was originally published on Horizon: the EU Research & Innovation magazine | European Commission.

Top image: Fine hairs on bees’ bodies can sense tiny changes in electrostatic fields, enabling them to sense whether another bee has visited a flower before them. Image credit – Unsplash/George Hiles, licenced under Unsplash licence

Understanding beeswax

By Tuuli Kasso, PhD in Science Fellow at the Natural History Museum of Denmark, University of Copenhagen. Tuuli is a visiting researcher, who has used the Museum’s collection to help her understanding of beeswax. 

When working on the dissertation for my MSc in Archaeological Science last year, I explored the medieval craftsmanship of sealing wax. I was interested in the way the medieval wax seals had flaked, as the beeswax dried out. Drawing on my previous education in conservation techniques, I began a close investigation of the prestigious material, beeswax.

Medieval craftsmen used a range of dangerous materials to make sealing wax. The red pigment cinnabar, a mercury (II) sulphide, and red lead, are now known to be extremely poisonous.

Although some of the ingredients of sealing wax are very hazardous, there is nothing dangerous in beeswax… except the bees! Produced by honey bees, Apis mellifera, honey and beeswax were important commodities in the Middle Ages. Beekeeping was a skilful profession, housing colonies in woven hives, known as skeps. Colonies were carefully selected to overwinter for the next season.

Manuscript illuminations provide detailed information on the types and construction of beehives in the Middle Ages.England, 13th century. British Library Royal 12 C XIX f. 45.

Beeswax was also important in the Middle Ages for lighting, and beeswax candles were preferred for their pleasant smell. After the Protestant Reformation in the 16th and 17th centuries, the religious use of candles decreased, so demand for beeswax declined.

Even today, the Catholic and Orthodox Churches still require the candles they use to contain a proportion of beeswax.

On my quest to understand the degradation of beeswax in sealing wax and write my disseration, I was very lucky to use some samples from the entomological collections from the Oxford University Museum of Natural History. After some early mornings spent amongst the Westwood collection, I found the perfect specimens of natural honeycombs, from the 19th century. The old hand-written labels were also a lovely encounter when exploring the historical collections.

I compared the samples to modern beeswax and medieval seal samples, and learned that the degradation of beeswax is caused by multiple factors, triggered also by storage conditions. The composition of beeswax is very complex, and there are differences caused by the age of the bee in addition to geographical provenance.

A selection of bee specimens from the Museum’s collection.

The recent catastrophic decline of bee populations has drawn focus to save the bees, and in my PhD research (University of Copenhagen and University of Cambridge) I will explore the recovery of ancient DNA and proteins of bees from beeswax, to cast light on the health of bee populations over time.

From pin to paper

Katherine Child, image technician in the Museum’s Life collections, doesn’t just use photography to capture the beauty of specimens. She is also an artist and has been trying out innovative techniques for her paintings. You may remember her amazing moth illustrations created with deposits of verdigris on pinned insects and she’s now using that technique to explore Museum staff’s favourite insect specimens.

Verdigris is a green corrosion often found on old pins within entomology collections (as well as elsewhere, on things like statues and copper pipes). Last year, after learning that the substance was once used as a pigment, I decided to try and make my own paint.

A clearwing moth before conservation, showing verdigris spreading where metal reacts with insect fats, or lipids.

Verdigris forms when copper or a copper alloy reacts with water, oxygen, carbon dioxide or sulphur. While a beautiful shade of green, the substance is damaging in natural history collections, where it can actually develop inside specimens and if left, split them irreversibly. So as part of the conservation of the Hope Entomological Collections, verdigris is removed.

I started to collect up the substance as it was cleaned from specimens and after about three years (you only get a little bit per pin) I was ready to make my paint! After my first moth project, the only question was, what to paint next…?

Attelabid_small
Byctiscus populi or ‘The Attelabid that changed my life’, chosen by Zoë (collections manager) who said ‘I saw a pink version of this species in the Natural History Museum in London and that’s when I decided I wanted to study entomology’.

With an estimated 6 million insects and arachnids in the entomology collections, it’s very easy to feel overwhelmed. You can pull open any one of thousands of draws and find astonishing specimens. While I have favourites, my first inclinations as to what to paint still felt a little arbitrary. After mulling over various possibilities, I decided to get help!

Chosen by DPhil student Leonidas, Agalmatium bilobum is a little bug which lays its eggs on tree bark, then covers them with mud to protect them.

I asked my co-workers what their favourite insects were, then opened the question out to regular volunteers and visitors of the Life collections. I loved finding out why people chose the things they did. Answers varied from ‘It was the first spider I ever looked at under a microscope aged 12’ to ‘Because they’re cool’ to ‘Because they have an ingenious way of manipulating spiders!’

Nuctenea_small
One of arachnologist Russell’s favourite spiders: Nuctenea umbratica. Though common in the UK, umbratica is Latin for “living in the shadows”, and it often hides away during the day. The slight transparency of the paint lends itself to a spider’s glittering eyes.

 

Painting this live African Mantis Sphodromantis lineola (chosen by conservator Jackie) was made slightly more challenging by the fact that the subject thought Katherine’s pencil might be tasty.

Most of the subjects I painted were based on specimens from the Museum’s collections or specimens individuals had brought in from their own collections, but one favourite was a live African Mantis, housed in the department to help with education and outreach. When I began to draw her she was intrigued by the movement of my pencil and came to the front of the tank, to follow every mark I made with her intimidating gaze.

A detail from the final painting

Attelabid that...
Katherine’s fabulous finished painting, which will be framed and displayed in the Life collections department.

Though time consuming, the painting was loads of fun to research and do. It’s fantastic to be surrounded not only by extremely knowledgeable people, but also by people with a genuine passion for what they do and a love for the insects (and spiders) they study.

Why do we need pinned insect specimens?

Since we posted about ten-year-old Sarah’s amazing beetle discovery, we’ve had lots of queries as to why the insect needed to be caught and pinned. It’s a question we’re often asked, so here’s Darren Mann, Head of Life Collections at the Museum, to explain the value of ‘voucher specimens’.

The Museum’s collection houses over five million insect specimens, amassed over the past 300 years. This collection is, in effect, a biodiversity database, but unlike virtual databases, each data point has an associated ‘voucher specimen’ that was caught, pinned and labelled.

Although technical advances in digital macro-photography do reduce the need for some collecting, it is impossible to dissect an image to confirm an identification. So for many groups, even the best photograph in the world is inadequate for identification purposes.

Shingle CrawlerD18 (Psammoporus insularis Pittino, 2006) one of our few endemic insects.

Unlike plants and birds, many insects can only be identified with the aid of a microscope, to study tiny features that distinguish closely-related species. Some groups even require the dissection of minuscule genitalia to really tell them apart.

Entomologists take voucher specimens to enable this correct identification and these are later deposited in museum collections, making them available for further study in years to come. From an entomologist’s point of view, we believe we need to know what a species is, where it occurs and as much about it as possible, so we can inform biodiversity conservation.

The conservation assessment of UK insects by Natural England in their Species Status Reviews has only been possible with the data provided by entomologists, generated from collecting and identifying voucher specimens.

Entomologists follow a Code of Conduct for responsible collecting, which ensures they don’t remove too many species or damage the environment during their work .

There are numerous examples of the value and use of insect collections in contemporary science, including the discovery of previously unknown species in the UK and population genetics for butterfly conservation. Recently a species believed extinct in the UK was rediscovered. This was only made possible by checking the identification of several thousand museum specimens.

Museum collections also contain numerous examples of species now considered extinct in the UK. Without voucher specimens much of this research would be impossible and our understanding of insect distribution patterns, ecology and conservation would be significantly diminished.

Large Tortoiseshell butterflies, now considered to be extinct in the UK. The voucher specimens act as record in time of its occurrence in the UK.

What is rare?
Sarah’s False Darkling Beetle (Anisoxya fuscula) has been described as ‘rare’, but what does that mean in reality? For most invertebrates when we talk about a rare species we are not talking about a tiny number of individuals. This conservation status is based on their known distribution and the level of threat they face. A species can be rare if it is only found at one or two locations, but at those locations there may be many thousands of individuals.

The greatest threats to biodiversity are well known and include habitat loss, fragmentation and degradation and pollution, such as pesticides and light. Taking a small number of voucher specimens to confirm the identification of species has negligible impact on its population. But if we don’t know it’s there because we couldn’t identify it, then a housing development destroys its entire habitat… well you get the picture!

Further Reading
Ask an Entomologist
Entomological Collections
Natural England Species Status Reviews
To Kill or Not to Kill That is the Question Part 1
To Kill or Not to Kill That is the Question Part 2
To Kill or Not to Kill That is the Question Part 3
– Austin, J. J., & Melville, J. (2006). Incorporating historical museum specimens into molecular systematic and conservation genetics research. Molecular Ecology Notes, 6(4), 1089-1092.
– Colla, S.R., Gadallah, F., Richardson, L., Wagner, D., & Gall, L. (2012). Assessing declines of North American bumble bees (Bombus spp.) using museum specimens. Biodiversity and Conservation, 21(14), 3585-3595.
– Short, A. E. Z., Dikow, T., & Moreau, C. S. (2018). Entomological collections in the age of big data. Annual review of entomology, 63, 513-530.
– Suarez, A.V., & Tsutsui, N.D. (2004). The value of museum collections for research and society. AIBS Bulletin, 54(1), 66-74. Abstract available here
– Wandeler, P., Paquita, Hoeck, E.A. & Keller, L.F. (2007). Back to the future: museum specimens in population genetics. Trends in Ecology & Evolution 22.12, 634-642.

One in a million find

By Rachel Parle, Public Engagement Manager

The Museum’s collection of British insects already houses over a million specimens, and now it boasts one more special insect.

Ten-year-old Sarah Thomas of Abbey Woods Academy in Berinsfield, Oxfordshire discovered a rare beetle in her school grounds while taking part in a Museum outreach session. To Sarah’s excitement, the beetle is so important that it has now become part of the collections here at the Museum – and it is the first beetle of its kind to be added to the historically important British Insect Collection since the 1950s.

Sarah Thomas examines her beetle under the microscope with Darren Mann, entomologist and Head of Life Collections at the Museum

Sarah’s class took part in a HOPE Discovery Day, where they were visited by a professional entomologist, learnt about insect anatomy and how to identify and classify specimens, and went on the hunt for insects in the school grounds. HOPE – Heritage, Outreach and Preservation of Entomology – is reaching out to students in state primary schools across Oxfordshire, using the Museum’s British Insect Collection to spark curiosity and foster a love of natural history. It’s all part of a bigger project at the Museum, supported by the Heritage Lottery Fund, to safeguard this important Collection for the future and engage people with natural heritage.

Sarah brought her family to the Museum to see her beetle in the British Insect Collection.

After some searching, Sarah spotted a 5mm insect lurking under a leaf. To the untrained eye it looked rather like any other tiny shiny beetle, but luckily Darren Mann, Head of the Museum’s Life Collections, was visiting as part of the HOPE team. Darren spotted it as something unusually and took it back to the Museum to get a closer look under the microscope. He was then able to identify it as a False Darkling Beetle.

It’s Anisoxya fuscula, which is rated as Nationally Scarce in Great Britain. We seldom see these outside old forest habitats and this is the first beetle of its kind to be added to the collections for around 70 years.

– Darren Mann, Head of Life Collections

The False Darkling Beetle under the microscope and labelled in the Museum’s British Insect Collection as found by Sarah Thomas

The tiny beetle has been labelled with Sarah’s name and the location of her find, and added to the British Insect Collection. Though she’s very excited to have her specimen in the collections, Sarah admits that she hasn’t always been a big fan of insects:

Before Project Insect I didn’t really like insects, but now I really do.

– Sarah Thomas

Everyone at the Museum is really pleased with Sarah’s fantastic find and we hope it spreads the word to inspire others to become budding young entomologists too.

The beetle Sarah discovered will be stored in this drawer in the British Insect Collection.