New insect species mimics dead leaves for camouflage

A new species of bushcricket which mimics dead leaves to the point of near invisibility and sings so loud humans can hear it has been examined for the first time using advanced technologies to reveal the unusual acoustic properties of its wings.

Zoology student Andrew Baker, from Market Harborough, has investigated the newly-described species, named Typophyllum spurioculis in reference to the vivid orange eye spots on its legs and its necrotic-looking wings, and found that when the males sing the entire wing resonates at the frequency of the call – something which does not happen in other species of bushcrickets.

Usually the resonating call of a bushcricket is localised to the region where the sound originates, and is created by a plectrum on the right wing being plucked by a tooth-covered file on the left wing to produce sound vibrations. The plectrum is connected to a drum-like structure that works as a speaker to radiate and amplify the signal.

In-situ-male-and-female

Significantly, the research team from the University of Lincoln, UK, found that in Typophyllum spurioculis, it is actually the whole wing, which resonates and amplifies the generated sound signals – and that song is so loud it is audible to humans.

The scientists also found that the females are larger than the males and also remain silent, with only the males employing their unusual acoustic abilities. Both sexes have wing regions that resemble damaged, discoloured leaves which provide excellent camouflage in the dense foliage of the South American rain forests, and are almost impossible to spot.

In another twist on the conventional rules of nature, researchers also found that the bright orange spots, which sit at the base of the bushcricket’s legs, are not to deter predators, but instead are likely to be involved in visual communication between the sexes. This is to be examined in future studies.

To uncover the biophysical properties, behaviour and ecology of the species for the first time, undergraduate Zoology student Andrew produced the anatomical description of the species using illustrations to infer the arrangement of veins in the insect’s wing, and examined the sound producing structures of the wings in the males using advanced bioacoustics research techniques.

Andrew said: “During the 3rd year overseas field trip to Ecuador while I was conducting a research project on frog biodiversity, I became friends with the academic leading the trip, Dr Fernando Montealegre-Z, and took some photographs of these bushcrickets.

“Afterwards, he came to the lab with the strange bushcricket specimens, and we determined it was likely a species new to science. He kindly gave me the opportunity to describe the species in a research article and I of course jumped at the chance. It was a bit of a dream come true.

“Since then, I’ve been to a conference at the Natural History museum where I presented the relevant poster at the Orthopterists’ meeting of the Royal Entomological Society.”

The study was led by entomologist Dr Montealegre-Z from the University of Lincoln’s School of Life Sciences. He said: “We wanted to find out more about this species, and we were very pleased to find an abundance of both sexes in the Cloud Forest of Colombia and Ecuador, something we had not been able to find before.

“To do this, we needed a keen ear and eye, and finding the animals proved to be particularly troublesome, so by listening to the males calling in the night and then locating them with a headtorch, we knew we were close to the females as well.

“We had to have a great deal of luck and patience as the females don’t sing, but we eventually managed to uncover three females as they are attracted by the calls of the males and will walk towards them. These three females then finally gave us the missing data to be able to properly describe these amazing animals as a new species.

“The unusual whole-wing-resonance might partly explain why the male’s song is particularly loud and also in the range audible to the human ear, while its closest relatives are all singing at higher frequencies which we cannot detect with our ears.

“Using a combination of tools from classical morphology to the-state-of-the-art bioacoustics and laser Doppler vibrometry, we have now been able to describe this species for the first time, and our approach gives fresh air to classical taxonomy.”

The findings have been published in the Journal of Comparative Zoology.

Hearing capabilities of bushcrickets and mammals

A new review paper detailing the functional mechanics of katydid (bushcricket) hearing has been published in an international journal.

Dr Fernando Montealegre-Z, from the School of Life Sciences, University of Lincoln, UK, together with Professor Daniel Robert from the University of Bristol, aim to present in detail the functional mechanics of katydid hearing, drawing a parallel between the ear of the bushcricket and tetrapods.

The paper has been published in a special issue of the Journal of Comparative Physiology dedicated to research in insect hearing.

In the animal kingdom many species must identify environmental sounds to increase their chance of survival. Therefore, animals have evolved a vast diversity of mechanisms to detect sounds. Acoustic communication occurs in many groups of animals. Yet, due to their biological diversity, insect species constitute a large percentage of the acoustic community – particularly cicadas, crickets, katydids and grasshoppers. In these groups, males sing to attract females. The Tettigoniidae (or bushcrickets) ear has evolved in the context of intraspecific communication and predator detection.

Dr Montealegre-Z said: “Some insects, like katydids, have evolved biophysical mechanisms for auditory processing that are remarkably equivalent to those of mammals. Located on their front legs, katydid ears are small, yet capable of performing several of the tasks usually associated with mammalian hearing. These tasks include air-to-liquid impedance conversion, signal amplification, and frequency analysis.

“Katydids and tetrapods have evolved remarkably different structural solutions to common biophysical problems. This paper discusses the biophysics of hearing in katydids and the variations observed across different species.”

In 2014 Dr Montealegre-Z was awarded a grant of £250,000 from The Leverhulme Trust to further his study how katydids evolved incredible ultrasonic hearing abilities.

A cochlear organ for frequency selectivity was thought to be unique to hearing in mammals until Dr Montealegre-Z led the team that discovered a similar mechanism for frequency analysis in the ears of bushcrickets in South American rainforests two years ago.

Scientists believe the discovery of this previously unidentified hearing organ could pave the way for technological advancements in bio-inspired acoustic sensors, including medical imaging devices and hearing aids.

The new research project aims to develop an integrated understanding of the evolution of ultrasonic hearing in bushcrickets; specifically how they developed cochlear-like systems in response to changing evolutionary pressures over millions of years.

Fernando Montealegre-Z, Daniel Robert ‘Biomechanics of hearing in katydids’ Journal of Comparative Physiology http://link.springer.com/article/10.1007/s00359-014-0976-1

BBC One documentary features academic’s research

​Research into the hearing abilities of bushcrickets by the School of Life Sciences Dr Fernando Montealegre-Z has been featured by the BBC.

Brought forward from its original transmission date, Super Senses: The Secret Power of Animals was screened by BBC One at 8pm on Tuesday, 26th August.

The series explores the hidden world that animals experience through their senses. The ‘Sound’ episode featured research by Dr Montealegre-Z, who studies how bushcrickets or ‘ katydids’ evolved incredible ultrasonic hearing abilities.

A cochlear organ for frequency selectivity was thought to be unique to hearing in mammals until a similar mechanism for frequency analysis was found in the ears of bushcrickets in South American rainforests two years ago.

Scientists believe the discovery of this previously unidentified hearing organ could pave the way for technological advancements in bio-inspired acoustic sensors, including medical imaging devices and hearing aids.

Dr Montealegre-Z has recently been awarded a £250,000 research grant from The Leverhulme Trust, to further develop an integrated understanding of the evolution of ultrasonic hearing in bushcrickets; specifically how they developed cochlear-like systems in response to changing evolutionary pressures over millions of years.

The episode can be seen here on BBC iPlayer, with the segment on Fernando’s research starting at 50 minutes. It can be viewed until 9th September, 2014.

 

Scientists to explore how insects evolved ultrasonic hearing

A grant of £250,000 from The Leverhulme Trust has been awarded to a team of scientists led by the University of Lincoln, UK, to study how a group of insects evolved incredible ultrasonic hearing abilities.

A cochlear organ for frequency selectivity was thought to be unique to hearing in mammals until a similar mechanism for frequency analysis was found in the ears of bushcrickets in South American rainforests two years ago.

Scientists believe the discovery of this previously unidentified hearing organ could pave the way for technological advancements in bio-inspired acoustic sensors, including medical imaging devices and hearing aids.

The new research project, funded by The Leverhulme Trust, aims to develop an integrated understanding of the evolution of ultrasonic hearing in bushcrickets; specifically how they developed cochlear-like systems in response to changing evolutionary pressures over millions of years.

Project lead Dr Fernando Montealegre-Z, from the School of Life Sciences, University of Lincoln, UK, led the team who discovered the previously unidentified hearing organ in bushcrickets.

He explained: “We will study these hearing systems and their variation in many species of bushcrickets. There are around 7,000 living species of these insects, but what we know about cochlear mechanisms has been investigated in only two or three. Therefore we expect to find enormous amount of variation across species. Through data from fossils and existing species, we aim to unveil major changes in sensory ecological niches and in the auditory ecology of species which have evolved from a single ancestral species.”

Bushcrickets are among the first terrestrial animals to have evolved acoustic communication. The sound emitted by crickets is produced by the stridulatory organ, a large vein running along the bottom of one wing, covered with “teeth”, which is rubbed against a plectrum on the other wing. The ears, located on their forelegs, are used in mating and predator avoidance.

Nearly 70 per cent of the living species, measured with ultrasound-sensitive equipment, produce acoustic signals in the ultrasonic range. However, their ancestors communicated at much lower frequencies. Modern bushcrickets emerged some 55-60 million years ago. Since bats arose at about the same time, the group hypothesise that bushcrickets might have evolved ultrasonic communication and elaborate hearing organs in response to acoustic predators, such as echolocating bats.

For the first time, the group will reconstruct changes in shape and function of fossil bushcrickets’ auditory and stridulatory organs throughout the recorded history of this group, from the Triassic onwards. This will enable them to understand the selective pressures that drove the evolution of cochlear systems in mammals and insects.

The work will enable the construction of a series of biophysical models that will simulate and predict tympanal vibrations and wing resonances in extinct bushcrickets, plus the acoustic reconstruction of the bushcricket community that lived in the long-gone forests of the Triassic and Jurassic eras.

Dr Montealegre-Z said: “Findings will help to comprehend the multiple origins and diversity of auditory mechanisms in mammals and insects. Results will also open up our understanding of the acoustic ecology of extinct environments where other auditory animals lived, and not only provide insights into the lives of singing insects, but that of their prey and predators. Studying fossil insects advances our general understanding of both behavioural and physical ecologies of the forests of the distant past.

“The research encompasses several disciplines including paleontology, biophysics, physiology and engineering. The integration of these disciplines is original and innovative and will open up new opportunities to enhance the current knowledge of sensory mechanisms in living organisms, including humans.”

Samples of fossil material
Samples of fossil material

Research showcased at Royal Society national science exhibition

Two pioneering research projects involving scientists from the School of Life Sciences are featured in a major public exhibition by The Royal Society.

The Royal Society’s prestigious Summer Science Exhibition, which runs from 1st July to 6th July, 2014, is the organisation’s premier public engagement event of the year, showcasing cutting-edge science and technology research in accessible and exciting ways.

Academics will be revealing their ground-breaking work into insect sensory biology and the training of working dogs.

Dr Fernando Montealegre-Zapata from the University of Lincoln and Professor Daniel Robert from the University of Bristol are showcasing their research into the complex hearing mechanisms of insects.

Together with colleagues from Bristol, Dr Montealegre-Z discovered a previously unidentified hearing organ in the South American bushcrickets’ ear. This breakthrough could pave the way for technological advancements in bio-inspired acoustic sensors research, including microphones and cochlear implants.

Their exhibition allows visitors to experience how a Jurassic-era cricket used to sing and a hands-on demonstration will also enable people to hear what a cricket actually hears.

Dr Montealegre-Z said: “This exhibit will allow us to immerse visitors in the world of insect hearing, giving them the opportunity to find out how hearing works at the micro-scale, what exactly it is that insects hear, and how this helps them to find their prey, avoid predators and attract mates.”

Professor Daniel Mills and Helen Zulch, from the School of Life Sciences, and Dr Emile van der Zee from the School of Psychology, are partners in a project with The Open University. Their exhibit focusses on dog-friendly interactive technology used to support or enhance the performance of working dogs which help humans.

Increasingly dogs are humans’ trusted working partners in a wide range of important jobs, such as assisting disabled people, playing crucial roles in military operations, detecting and managing life-threatening medical conditions, or rescuing stranded and injured people.

The Open University Animal-Computer Interaction Lab is currently focussed on designing interactive technologies from a canine perspective. The exhibit showcases prototypes of technologies such as an electronic light-switch designed for assistance dogs; an interface allowing cancer detection dogs to express levels of confidence when assessing biological samples; and an alarm system allowing medical alert dogs to summon help for their assisted humans. Dogs from research partners Dogs for the Disabled and Medical Detection Dogs are also demonstrating the technologies.

Professor Mills said: “This exhibit is a great example of truly interdisciplinary science that has a real impact on society. Dogs were the first species to be domesticated and their partnership with humans is unique. Our work shows how we can use modern technology to help maximise the potential of the partnership and the value that dogs can bring to society.”

 

Technology for Dogs
Technology for Dogs
Helen Zulch at the Technology for Dogs exhibit
Helen Zulch at the Technology for Dogs exhibit
Dr Emile van der Zee at the Technology for Dogs exhibit
Dr Emile van der Zee at the Technology for Dogs exhibit
Dr Emile van der Zee and Helen Zulch
Dr Emile van der Zee and Helen Zulch
3D model of a bushcricket
3D model of a bushcricket
Insect Ear exhibit
Insect Ear exhibit
Insect ear exhibit
Insect ear exhibit

 

Dr Fernando Montealegre-Zapata at the Insect Ear exhibit
Dr Fernando Montealegre-Zapata at the Insect Ear exhibit