species – Cabot Institute for the Environment blog

Insects will struggle to keep pace with global temperature rise – which could be bad news for humans

Posted on October 4, 2022March 29, 2023 by janet.crompton

Animals can only endure temperatures within a given range. The upper and lower temperatures of this range are called its critical thermal limits. As these limits are exceeded, an animal must either adjust or migrate to a cooler climate.

However, temperatures are rising across the world at a rapid pace. The record-breaking heatwaves experienced across Europe this summer are indicative of this. Heatwaves such as these can cause temperatures to regularly surpass critical thermal limits, endangering many species.

In a new study, my colleagues and I assessed how well 102 species of insect can adjust their critical thermal limits to survive temperature extremes. We found that insects have a weak capacity to do so, making them particularly vulnerable to climate change.

The impact of climate change on insects could have profound consequences for human life. Many insect species serve important ecological functions while the movement of others can disrupt the balance of ecosystems.

How do animals adjust to temperature extremes?

An animal can extend its critical thermal limits through either acclimation or adaptation.

Acclimation occurs within an animal’s lifetime (often within hours). It’s the process by which previous exposure helps give an animal or insect protection against later environmental stress. Humans acclimate to intense UV exposure through gradual tanning which later protects skin against harmful UV rays.

One way insects acclimate is by producing heat shock proteins in response to heat exposure. This prevents cells dying under temperature extremes.

A ladybird drinking a speck of water on a narrow leaf. — Insects in warmer environments develop fewer spots to reduce heat retention.
mehmetkrc/Shutterstock

Some insects can also use colour to acclimate. Ladybirds that develop in warm environments emerge from the pupal stage with less spots than insects that develop in the cold. As darker spots absorb heat, having fewer spots keeps the insect cooler.

Adaptation occurs when useful genes are passed through generations via evolution. There are multiple examples of animals evolving in response to climate change.

Over the past 150 years, some Australian parrot species such as gang-gang cockatoos and red-rumped parrots have evolved larger beaks. As a greater quantity of blood can be diverted to a larger beak, more heat can be lost into the surrounding environment.

A colourful red-rumped parrot perched on a branch. — The red-rumped parrot has evolved a larger beak to cope with higher temperatures.
Alamin-Khan/Shutterstock

But evolution occurs over a longer period than acclimation and may not allow critical thermal limits to adjust in line with the current pace of global temperature rise. Upper thermal limits are particularly slow to evolve, which may be due to the large genetic changes required for greater heat tolerance.

Research into how acclimation might help animals survive exceptional temperature rise has therefore become an area of growing scientific interest.

A weak ability to adjust to temperature extremes

When exposed to a 1℃ change in temperature, we found that insects could only modify their upper thermal limit by around 10% and their lower limit by around 15% on average. In comparison, a separate study found that fish and crustaceans could modify their limits by around 30%.

But we found that there are windows during development where an insect has a greater tolerance towards heat. As juvenile insects are less mobile than adults, they are less able to use their behaviour to modify their temperature. A caterpillar in its cocoon stage, for example, cannot move into the shade to escape the heat.

Exposed to greater temperature variations, this immobile life stage has faced strong evolutionary pressure to develop mechanisms to withstand temperature stress. Juvenile insects generally had a greater capacity for acclimating to rising temperatures than adult insects. Juveniles were able to modify their upper thermal limit by 11% on average, compared to 7% for adults.

But given that their capacity to acclimate is still relatively weak and may fall as an insect leaves this life stage, the impact is likely to be limited for adjusting to future climate change.

What does this mean for the future?

A weak ability to adjust to higher temperatures will mean many insects will need to migrate to cooler climates in order to survive. The movement of insects into new environments could upset the delicate balance of ecosystems.

Insect pests account for the loss of 40% of global crop production. As their geographical distribution changes, pests could further threaten food security. A UN report from 2021 concluded that fall armyworm populations, which feed on crops such as maize, have already expanded their range due to climate change.

A damaged corn crop following an attack by fall armyworms. — The fall armyworm is a damaging crop pest which is spreading due to climate change.
Alchemist from India/Shutterstock

Insect migration may also carry profound impacts on human health. Many of the major diseases affecting humans, including malaria, are transmitted by insects. The movement of insects over time increases the possibility of introducing infectious diseases to higher latitudes.

There have been over 770 cases of West Nile virus recorded in Europe this year. Italy’s Veneto region, where the majority of the cases originate, has emerged as an ideal habitat for Culex mosquitoes, which can host and transmit the virus. Earlier this year, scientists found that the number of mosquitoes in the region had increased by 27%.

Insect species incapable of migrating may also become extinct. This is of concern because many insects perform important ecological functions. Three quarters of the crops produced globally are fertilised by pollinators. Their loss could cause a sharp reduction in global food production.

The vulnerability of insects to temperature extremes means that we face an uncertain and worrying future if we cannot curb the pace of climate change. A clear way of protecting these species is to slow the pace of climate change by reducing fossil fuel consumption. On a smaller scale, the creation of shady habitats, which contain cooler microclimates, could provide essential respite for insects facing rising temperatures.

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This blog is written by Hester Weaving, PhD Candidate in Entomology, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hester Weaving

Migration, mobilities and the ecological context

Posted on May 10, 2022April 16, 2023 by janet.crompton

In this special blog series, Migration Mobilities Bristol (MMB) and the Cabot Institute for the Environment bring together researchers from across the University of Bristol to explore connections between movement and the environment from a multi-disciplinary perspective. Their diverse approaches highlight the importance of developing frames that incorporate both migration and environment, and in so doing benefit our understandings of both.

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Migration can make you happy. When I see the first swifts arrive in the spring, I stop in my tracks and smile broadly at all and everyone. I have to restrain myself from telling people walking down the street that ‘they’ are back. Swifts are one of the wonders of the world – they make Concorde look clunky, they hurtle down streets in towns screaming wildly at dusk seemingly just for the fun of it, and scientists have calculated that the distance they fly over their lifetime is equivalent to flying to the moon and back seven times!

Dahlia (Bishop of Llandaff). Image credit: Jane Memmott

Migratory species like swifts have two homes and they are generally well regarded in both places. It’s a bit more touch and go whether alien species are welcome or not, and highly context dependent. For example, we deliberately introduce species from all around the world into our gardens without qualm – looking out the window onto my front garden, I’ve got honey bush and pineapple lilies from South Africa, Dahlias from Mexico, a Hebe from New Zealand, devil’s tobacco from Chile and foxgloves from seed collected down the road! In contrast, my local nature reserves are doing their best to remove Rhododendron, Cotoneaster and Himalayan balsam.

Context really is key here. Thus, gardens are grown for colour, relaxation, fruit, vegetables, and art (and I consider gardening as much of an art as a science) and they are highly managed and artificial habitats. In fact, they are increasingly considered as outdoor rooms in the media, and no one worries what countries their botanical furniture is from. In contrast, nature reserves are usually more natural settings where we want to capture natural patterns and processes, so there is an expectation that the species present should be native. And there is good evidence that while most alien species are harmless, some species (approximately 1%) can be very damaging to the environment and the economy.

Honey bush leaves (Melianthus major). Image credit: Jane Memmott

Migration is about mobility, and mobility is a key part of the scientific process. Thus, universities are ecosystems which provide intellectual homes to academics from all over the world. My own department is home to scientists from Africa, Germany, Brazil, Switzerland, Brazil, Italy and China and those are just the people I’ve bumped into over the last few days. COVID has put a bit of a spanner in the works on the mobility front, but mobility is so key to business that academics have quickly found other ways to be mobile. For example, in my own research group, we have been running a large project in a remote part of Nepal entirely by Zoom for the last two years. But, by dint of the internet and some incredible UK staff and amazing project partners in Nepal, we have trained field staff in ten remote villages in the Himalayas to collect diet data for both bees and villagers, using protocols that would have been very new to them. The data is then uploaded by the field staff to the internet and arrives on the computers the other side of the world as if by magic.

Mobility is such a large part of a scientist’s life that when it goes wrong it can feel shocking. I’ve had two encounters with mobility of scientists being blocked, one involving myself, another a visiting scientist. Mine was, I suspect, a straightforward random immigration check, but it did leave me rather shaken. I was travelling to Canada for the first time and got taken out of the queue and then grilled for 30 minutes on the nature of my visit. I was giving a plenary talk at a conference and had fortunately remembered to print out my letter of invitation. Unfortunately, I hadn’t actually read it for six months and so I probably did sound a bit suspicious. They did eventually let me in and it was an excellent trip thereafter. The second time was when a restoration ecologist from Latin America, who was visiting my research group for six months, went to Spain with his family for a weekend and upon return his whole family was issued with deportation papers. There is something deeply shocking about seeing the hostile environment process in action, especially when mobility is simply part of normal academic interchange. After some high-level work by an international lawyer this too was fixed. Restoration ecology is much more of a long-term process, but the restoration of mobility was much faster in this instance, if a lot more stressful.

Swift (Apus apus). Image credit: Wikimedia Commons.

Migration and mobility are everyday events in the environment. They can be natural such as the return of swifts each year, or they can be assisted such as the reintroduction programmes for species that have become extinct in the UK. One of the biggest reintroduction success stories is the red kite, a bird that you are almost guaranteed to see now if you drive down the M4 motorway or look out of the train window from Didcot to London. These are big and very beautiful predatory birds – imagine a paprika coloured swallow with a 6ft wingspan! My last few Saturdays have been spent driving from Bristol to a hospital in Hampshire to visit a sick relative and one of the things that has made this less stressful is counting the red kites along the motorway. Last Saturday was a 12-kite day, my highest count yet.

To end, migration, mobility and the environment are inextricably linked. There is both natural and human assisted movement of species in the environment. Species can be both welcome and unwelcome depending on the context. It’s complicated, but it’s the everyday bread and butter of ecologists around the world. With alien plants bringing colour and bizazz to our gardens and swifts bringing happiness as they return to their second homes in the UK, there is a lot to like about migration and mobility in the environment.

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This blog is written by Cabot Institute for the Environment member, Jane Memmott, Professor of Community Ecology in the School of Biological Sciences, University of Bristol. Her research interests include pollination ecology, invasion ecology, biological control and restoration ecology. In each case she considers how ecological networks can be used as a tool to answer environmental questions.

Professor Jane Memmott

Hollow: Bristol researchers engage with artists on 10,000 samples of wood

Posted on December 8, 2015April 12, 2023 by janet.crompton

Artist Katie Paterson invited the public to explore a collection of 10,000 samples of wood from almost every country in the world. Commissioned by the University of Bristol, Hollow will be a new permanent public artwork imagined by Katie in collaboration with scientists and researchers. Situations.org met with Cabot Institute researcher Jon Bridle to ask some questions about working with artists, his thoughts on the project, the evolution of species and the future of the planet.
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Hollow exhibition. L-r Katie Paterson and Jon Bridle. Image credit Situations.org

What’s your role at University of Bristol and why is it exciting?

I’m an Evolutionary Biologist, conducting research into how quickly populations can evolve to cope with changes in their environment, and so potentially avoid extinction. Such understanding is crucial for predicting how rapid climate change and habitat loss will affect the species and the ecosystems that we depend on for all human economies. Understanding these evolutionary processes also helps us to understand why one species splits into two, and so why life proliferates into so many diverse and beautiful forms.

What’s really exciting at the moment is that biologists suddenly have the tools to explore the genomic basis of these evolutionary responses. This revolution in genetic techniques could become as significant in transforming our understanding as when astronomers started to use the telescope in 16th Century Europe.

Tell us a little about commissioning a public artwork for the new Life Sciences building at University of Bristol…

The University of Bristol has demonstrated a huge commitment to Life Sciences through its investment in a building where we can do internationally leading research. This reflects how crucial the study of life is to addressing many of the acute challenges that face humanity this century, such as food security, biodiversity loss, and climate change.

Commissioning a public artwork to explore some of these themes is an exciting way to celebrate this, and to allow us to connect in new and previously unimagined ways with some of the beauty, complexity and depth of the natural world. It’s also absolutely fantastic for us as scientists, and for the wider community, to be able to engage with the work of an artist like Katie Paterson.

Jon Bridle at Hollow exhibition. Image credit Situations.org

Katie Paterson’s work often involves long and complex collaborations with researchers in different fields. What does it mean to put artists and scientists in the same room?

I think it’s very useful for both sides. The way I think about the world has certainly been shaped by art that has inspired me throughout my life. Sparks do fly but they’re usually very creative ones!

To me, scientists and artists share a huge amount in that they both have to always be prepared to revise their thinking, to see the unexpected, and to reexamine the familiar. Both cultures depend on curiosity, on confronting uncomfortable complexities, and on escaping any prejudices about how we might like things to be. Most of the artists I’ve known – and most of the historical ones I enjoy – have been fascinated by science, and the same applies to the scientists I know in relation to art.

The only resistance can come from the fear of looking foolish – or of asking naive questions – but that’s the whole point: science progresses by asking simple questions, and being wrong in clever ways that increase our understanding of the world. If you’re worried about being wrong, or being made to feel humble, the last thing you should be is a scientist! I find beauty when the world suddenly becomes more intricate – maybe even stranger – that I’d previously imagined. Both good art and good science takes me to these places. Incidentally, I also think the same is true of good comedy.

For Katie Paterson’s Open Studio, the public are invited to handle some of the extraordinary collection of tree samples and hear stories about each one. What do you hope people might take away from a close encounter with the collection?

Well, I’m sure the public will get inspiration from it in ways I can’t imagine, so all I can talk about is my response to the Open Studio. To me, it’s really helped me engage with the way that all life is connected at a profound level. This is both in terms of all life sharing a common (and in terms of trees, fairly recent) group of ancestors, with all these pieces of wood representing the living tips – or twigs – of this deeply rooted family tree.

In another sense all life is connected physically in that individuals and species come together and interact in ecosystems in real time. In trees, these interactions with pollinators, parasites, other plants, birds, fungi, bacteria and with each other (through sharing pollen, or through sharing space, or air) are clearly visible because they often bear their scars in their leaves and in the bark, and of course in their wood, which was once the living, growing part of the tree.

This physical relationship of the tree with the world around it is recorded even in the cut pieces of wood that now seem rather remote, and rudely removed from the forests where they once grew. Each piece of wood once had gallons of water being pulled through it that entered the soil from ancient rivers, powered by long-disappeared parts of our sun. It’s fun to think about this as we sit around a wooden table drinking coffee. For visitors to the studio, I hope the stories about human relationships with trees will help to unfold these broader truths about how all life is connected, and how we are all part of the biodiversity that the collection is testament to.

Hollow exhibition – wood samples from around the world. Image credit Situations.org

Rethinking our relationship to the natural environment seems increasingly significant for both artists and scientists. What are the key challenges ahead?

Yes – rethinking our relationship with nature is hugely important, especially when many governments seem to be sidestepping these profound challenges for fear of compromising short-term economic growth. This is why public engagement with things like the COP21 talks in Paris, and public awareness of the difference we can make by choosing how we consume are so important.

The challenges are enormous. There’s good evidence that we’ve lost 50% of the world’s biodiversity (and about half of the world’s forests) in the past 40 years, at precisely the time when overconsumption and climate change make that biodiversity increasingly important for the planet’s resilience. However, there is still time to tackle these issues. Unfortunately, the terrifying scale of the loss of this true wealth of our planet is not appreciated by most people, and is certainly not high up on the political agenda, perhaps because those most affected by it are the world’s poor and powerless, as well as our future unborn generations.

The difficult thing is how to accept these difficult truths without feeling powerless and overwhelmed. We need to start living on this planet as if we intend to stay here. And we need to ask ourselves whether overconsumption of the world’s resources, with all the profound consequences it entails, is really making us happy.

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This blog has been reposted with kind permission from Situations. View the original blog on their website.

The Open Studio ran from 4 – 6 December 2015.

Jon Bridle is based in the School of Biological Sciences at the University of Bristol. The Hollow art project also involved other Bristol researchers including Heather Whitney, Gary Foster and undergraduates during the open studio.