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Dr David Horsell

APEX Award holder 2018-2020

University of Exeter

Hot fuzz: Bumble bee hair as a thermal metamaterial

Thermal image of the APEX Award team at the University of Exeter (clockwise from top left: Dr James Cresswell, Dr Steve Hepplestone, Dr David Horsell).

What is your research project about?

My research lies mostly in the area of electrical and thermal conduction in novel materials, which includes layered materials such as graphene. In recent years, I have been collaborating more and more with colleagues from other disciplines, particularly on biological systems, searching for ways to apply and adapt techniques from my research to such systems.

Our project is to take a materials science approach to look at how bumblebees exchange energy with their environment. For a bee, efficiently sourcing energy and then either storing it or releasing it to incubate the next generation is key to its survival. From a physics perspective, evolutionary solutions the bee has found to this problem are of interest in terms of how structures on the outer layers of the bee have been designed to conserve or release heat. In particular, a distinctive characteristic of the bumblebee, in contrast to almost all other insects, is its dense covering of hair. One of the main things we are investigating is how features of this hair might help to control heat exchange.

What attracted you to apply for the APEX Award? What were the challenges that influenced you to seek support?

The attraction of the APEX Award was very much its cross-disciplinary focus. It is rare that traditional funding routes offer true opportunities like this for such research.

Our research team involves an ecologist (Dr James Cresswell), a theoretical physicist (Dr Steve Hepplestone) and an experimental physicist (myself). For some time before the APEX Award, we had been working on bumblebees together on and off between teaching and other research commitments. We had a common interest in how energy enters systems (a bee or its nest, in this case) and how that energy is subsequently lost. The APEX Award came at the perfect time, as we were beginning to identify some clear, tractable experimental questions we could collectively answer but needed some time away from teaching and a little extra equipment to start to do so properly.

What are some benefits of working across disciplines and with collaborators?

In academia, it is all too easy to specialise in a subject to such an extent that it becomes difficult to consider techniques and subject matter from other areas of science. What is particularly beneficial of opening up to cross-disciplinary research is that there is enormous scope for knowledge exchange. For instance, before meeting the ecologist on our team, I had little appreciation of how critical energy exchange was to a bumblebee. Yet the challenges the bee faces are more or less identical to the technological challenges we often look to address in materials research.

In 2013, the University of Exeter began a Natural Sciences degree programme with the aim to bring the traditional scientific disciplines, mathematics and computer science together. From the start, I was involved with this programme and had the chance to work with a wide variety of researchers. The need to create cross-disciplinary teaching materials and projects for students has led to many new research collaborations I would never have considered possible before this programme began. The news headlines are now full of scientific challenges that appear tailor-made for multi-disciplinary research teams to tackle and I am delighted that the APEX Award has given me the chance to be part of this emergent era of research.

Describe the impact your research has had or might have in the future.

There are two significant outcomes our research could have. By understanding more about the energy and habitat requirements of bumblebees, we will be in a better position to address their conservation. If the outer body structure is a thermal adaptation, then we can not only use it as an indicator for changes in the climate or environment but also start to identify places where populations are likely to be healthy or declining. This, of course, has follow on consequences for crop and wild flower pollination.

The other impact will be in finding ways to adapt these evolutionary solutions to practical uses in our own society. We are becoming ever more aware that our throw-away society is not sustainable, and one of the most precious things we are throwing away is energy in the form of waste heat. By finding ways to efficiently absorb, store and release heat we can address this problem. Bees, as well as other animal species whose survival critically depends on heat exchange, may hold the answer.

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