askST: What are the ethical concerns of using animals such as insects in cyborg technology?

SINGAPORE – The Nanyang Technological University (NTU), together with the Home Team Science and Technology Agency (HTX) and Klass Engineering and Solutions,

has been developing cyborg cockroaches

– part organism, part electronic – which could be used in disasters to find survivors during search and rescue operations within the next two to three years.

The Madagascar hissing cockroaches, averaging 6cm in length when fully grown, wear “backpacks” with built-in sensors and a small infrared camera that can detect life by picking up temperature signatures.

Each backpack also carries a microcomputer that can control the insect’s movements through electrical signals sent to its nervous system.

In a building collapse, the cyborg cockroaches can crawl through rubble, and into crevices and confined spaces, to find survivors – a task which is dangerous for humans – and provide front-line responders with critical information.

Seeing the potential for using cyborgs in such search and rescue operations, HTX collaborated with NTU and Klass Engineering to enhance the technology, making the cyborgs fully autonomous when they search for survivors.

HTX directed The Straits Times to Professor Hirotaka Sato, the provost’s chair in mechanical and aerospace engineering at NTU, for answers to questions regarding the ethical considerations of the technology.

Prof Sato said that he and his research team are serious about developing cyborg insects to save humans.

Most medical researchers use live animals such as mice for the purpose of curing human diseases. His team carries out research with the same aspirations as medical researchers, using live insects to save humans from disasters, he added.

Published in May 2023 in the journal Advanced Intelligent Systems, the research paper by Prof Sato and his team stated that the cockroaches were fed various vegetables weekly.

The researchers kept the insects in plastic containers with a system that pumped clean air throughout their living space and kept the temperature in the containers at 25 deg C.

The containers were washed every week. The researchers limited the number of cockroaches to just five per container, giving them plenty of space to move around.

It was also stated in the paper that “the use of the cockroach(es) was permitted by the National Environment Agency”.

ST spoke with experts in biological and animal behavioural science to understand the science and ethics behind using animals, especially insects, in technology that allows for the direct control of the animals’ nervous system.

Q. What are some advantages of deploying insects in scientific research?

The very traits that make them unpopular – resilience and adaptability – make cockroaches valuable research subjects.

Assistant Professor Eunice Tan of the Department of Biological Sciences at the National University of Singapore said that insects such as cockroaches have evolved over millions of years, and their biological structures or processes can inspire research in non-biological science and technology.

“The rapid reproduction of insects and their abundance also make them good test beds for use in research,” Prof Tan added.

Mr Foo Maosheng, entomologist at Lee Kong Chian Natural History Museum, said: “It is a testament to how capable and useful cockroaches are to humans, in contrast to the general stigma that cockroaches are disgusting pests which should be exterminated.”

However, author Lars Chittka, who wrote the book The Mind Of A Bee, said the potential benefits of using insects in search and rescue should be balanced against the ethical concerns of doing undue harm to them in the process.

The sensory and behavioural ecology professor at Queen Mary University of London said: “If you think about malaria-transmitting mosquitoes, there is a very good reason why we do research on them, as there are clear benefits to humans.

“For the mitigation of infectious diseases, it wouldn’t be defensible to actually abandon such research. And likewise, if there are good reasons to suggest that these cyborg insects might be beneficial to saving human lives, then that’s at least worth considering.”

Q. Do insects feel pain?

At the nub of the question is whether the technology would cause insects unnecessary suffering. Vertebrates, such as mammals, reptiles and birds, can feel pain, and this is evident from their ability to learn and avoid the repetition of stimuli that result in a negative experience.

It is thought that insects – which make up the largest group of invertebrates – do not feel pain, but have a sense of nociception – the ability to detect potentially harmful stimuli in the environment.

This ability is distinct from pain, as it is a reflexive response controlled by neurons relaying signals from nociceptors – specialised nerve endings that respond directly to noxious stimuli – to the spinal cord and back again.

It prompts withdrawal from the stimulus without necessarily involving the conscious experience of pain.

But Professor Chittka, who is also the founder of the Research Centre for Psychology at Queen Mary University of London, said it is not possible to say with absolute certainty that insects do not feel pain. Instead, he points to “reasons to be sufficiently worried that insects might not be the sort of machine-like living things that many people think that they are”.

A review by his team of hundreds of studies was published in Advances In Insect Physiology in 2022.

To assess if insects feel pain, the researchers evaluated six insect groups based on an established set of criteria that has been used to indicate pain. 

University of Pennsylvania postdoctoral researcher Matilda Gibbons, the primary author of the review, said the review found strong evidence for pain in the insect orders that include adult flies, mosquitoes, cockroaches and termites.

She added that pain is a subjective, personal experience that changes between individuals, and many criteria need to be used to evaluate pain. Taken together, these suggest that some orders of insects could feel pain.

Prof Chittka said that while the approach used by the team in the review does not amount to formal proof, the many pieces of evidence add up to either a high or a low probability.

“We just looked at multiple indicators, both psychological ones, neurophysiological ones and so on, to see where the probability is for various types of insects, and at least it looks quite high for a number of taxa, including flies, cockroaches and bees as well. But we’re not saying we’ve identified a formal proof.”

Using fruit flies as an example of an insect species that fulfils many criteria for the capacity to feel pain, Dr Gibbons said that fruit flies possess the necessary nervous system components such as nerves to detect painful stimuli, as well as interconnected neurons that can send signals to their brains.

She said that fruit flies also have the neural circuitry for painkillers, and research has shown that analgesic drugs work to reduce their response to painful stimuli. Finally, fruit flies will actively avoid painful stimuli, and will remember to avoid them in the future.

“This evidence suggests that fruit flies have the neural ability to detect potentially painful stimuli, and care about avoiding them, suggesting that potentially painful stimuli are negative to them,” she said.

Prof Chittka’s research on bees also suggests that there is evidence that insects can choose to bear discomfort for a better reward.

A stereotype about insects is that their response to noxious stimuli is hardwired and therefore predictable.

In contrast, one of the hallmarks of pain in humans is that they do not have a hardwired response to noxious stimuli and thus have the ability to choose whether to bear the discomfort, said Prof Chittka.

“We were interested in whether a bee could actually suppress a reflex-like response to withdraw from a source of heat if there was an appropriate gain.”

The animal behavioural scientist and his team found that given a choice, bees could suppress their default response to withdraw from a more unpleasant stimulus – an artificial flower that was heated to 55 deg C – and land on it to get a sweeter reward than could be found on another surface.

“And it’s this kind of plasticity that, while again it’s not on its own a formal proof of a pain-like response, shows a similar flexibility there as you might see in humans – where you can modulate when it’s to your own advantage your responses to pain, or injurious or unpleasant stimuli.”

Q. What are some considerations researchers should take into account when developing cyborg animals?

A major factor to consider would be the ratio of the mass of the device attached to the animal to its body mass.

A best-practice recommendation for scientific research is that devices borne by animals, such as birds and dogs, should weigh less than 3 per cent to 5 per cent of their body mass.

The average weight of each

Madagascar hissing cockroach developed by HTX, NTU and Klass Engineering and Solutions

is about 23g, which means that the 5.5g backpack would be an estimated 24 per cent of the insect’s body weight.

Prof Tan said: “Sensors that are too bulky or heavy will impede the cockroach’s movement and ability to navigate disaster sites and reach survivors.”

Mr Foo said a device that is too heavy could cause the animal to expend a significant amount of energy to move as usual.

“Researchers won’t want the device to impair the animal as that will defeat the intended outcome,” he added.

Other factors that researchers should take into consideration would be the stress on the insect from having its movements dictated by an external force and the amount of voltage used to control the insect. 

“Every step it takes, it encounters a new thing to escape from, which is an obviously stressful life to live. The cockroach has no control over its movement and is thrust into situations it would likely never put itself into,” said Dr Gibbons.

There might not be research as to the physical effects of passing a current through the cockroach’s body, but multiple studies show that cockroaches and other insects will avoid areas where they have received electric shocks, she added.

Q. What are other animals that have been developed into cyborgs?

In 2017, research and development company Draper and the Howard Hughes Medical Institute collaborated to develop a drone piloted by dragonflies. 

Dubbed DragonflEye, the technology used optical electrodes to deliver steering commands directly to the dragonfly’s nervous system, which had been genetically modified to respond to these light signals. 

In 2013, a team of researchers at the University of Tokyo built a robot that could be steered by a silkworm moth towards a target scented with female moth sex pheromones. The moth walked on a special ball that controls the robot’s direction. Sensors tracked the ball’s movement and steered the robot accordingly.

Researchers at the Korea Advanced Institute of Science and Technology developed cyborg mice which wore special headgear that had a fibre-optic thread penetrating the skull. It stimulated the part of the brain which drives them to pursue an object dangling in front of them that is always just out of reach. 

When the male mouse travels through a maze, signals are sent to its brain to cause it to chase after the object dangling in front of it, ignoring distractions such as food and a female mouse.

Their work was published in the journal Nature Neuroscience in 2018.

Q. What principles should researchers consider when designing cyborg animals?

They could consider the “3Rs” framework, which was first defined by scientists W.M.S. Russell and R.L. Burch in their book, The Principles Of Humane Experimental Technique, published in 1959.

Most researchers working in the biosciences field, including entomologists, would be familiar with the framework.

The core principles of the “3Rs” have not changed much since they were introduced, although there have been some refinements in emphasis and definition over the years.

They are as follows:

Replacement: Animals believed to have the ability to experience feelings and sensations should not be used if animals without such ability are available.

Reduction: If animals have to be used, then the research has to be designed and analysed for the minimum number of animals to be used.

Refinement: Researchers must implement measures to mitigate any potential pain, suffering or distress experienced by the animals.

In response to whether any of the “3Rs” could be applied in this area of research, Prof Chittka suggested replacing live insects with robotics.

“Drones are already being used by some for surveying disaster areas. And the question would be – could you not replace insects, for example, with relatively small robots that you could build to crawl into tiny crevices? Much more efficient than trying to manipulate the nervous system of a live insect.”

While Prof Chittka is not advocating for the complete abandonment of any invasive insect work, he is encouraging researchers to at least take welfare concerns seriously and to minimise suffering where possible.