Life Science

How biohacked insects would actually work

Backpack-wearing locusts may one day be bomb-sniffing heroes

January 22, 2021
image of a grasshopper on a stick
An American locust with a backpack strapped to its back and wires entering its brain. Scientists monitor smell data coming from the locust’s brain to measure the chemicals it has detected. [Credit: Joshua Hoehne | CC0 1.0]

A biohacked locust that can sniff out bomb chemicals is the latest in a long line of insect-machine hybrids to emerge from the workshops of creative engineers.

These designers say their inventions are not the stuff of nightmares, but simply attempts to take full advantage of the fact that some insect species have — over hundreds of millions of years — evolved useful skills that far surpass those of humans, including the ability to sniff out explosives, find dead bodies and scramble up rocky terrain. 

“Our tendency as humans is to think of ourselves as terribly clever, and engineers as terribly adept, and scientists as terribly smart. And it turns out that evolution can make all our science and engineering look pretty clunky,” says Jeffrey A. Lockwood, an entomologist-turned-creative writing professor at the University of Wyoming. Lockwood laid out the history of insects as tools in his book, “Six-Legged Soldiers,” noting that bugs have been used as instruments of war and torture as well as vectors to deliberately spread disease. 

The latest biohacked bugs and insect-mimicking robots can in some cases actually surpass the skills of naturally evolved insects, but their complexity and cost mean many of them won’t be deployed anytime soon. So far, they mostly exist as experimental prototypes. A few, however, are in wide use, including the commercially available cockroach biohacking kit RoboRoach, sold as a tool to teach neurotechnology.

The bomb-sniffing locusts were developed by a team of engineers at Washington University in St. Louis who implanted electrodes into the antennal lobes of locusts to tap into the insect’s naturally sophisticated smell receptors. 

Holding one of his biohacked locusts is his gloved left hand, the project’s lead researcher, biomedical engineer Barani Raman, explained the rationale behind his work in a web video: “We cannot create a sensor or a device as sophisticated as these guys, so can we take advantage of the biological olfaction but read out in the way we want it to be, and solve the practical challenges?”

The answer is yes, they can. In a newly released preprint of their study, posted on the server bioRxiv, Raman and his team say they have built and tested biohacked locusts that can serve as trained sentinels, reporting back to their human keepers whenever their sensitive olfactory systems detect a suspicious odor. While Raman and the rest of his team are declining comment until their study is published, they spell out the process in the web video, posted in 2016 on Washington University’s YouTube channel.

The idea of locusts as bomb detectors might seem outlandish, but locust experts think it could be possible. One such expert is Jeremy Niven, a zoologist who studies locusts at the University of Sussex. He helped publish a paper describing olfactory learning in desert locusts in 2011. 

“My understanding would be that it could actually be feasible,” Niven says. “You could have a little locust linked up to a computer, and that the olfactory system is just so sensitive that it could pick up on the trace of chemicals.” Locusts could not only sniff for bombs, Nivens says. They could also someday be used to detect drugs or identify unwanted chemicals in imported food. 

The Washington University project focused on training locusts to react to explosives because that’s the interest of its primary funder: the U.S. Navy, via the Office of Naval Research. But “more generally, what we’re after is to make a device that smells,” Raman says in the 2016 video.   

Their first step in making a bomb-sniffing locust was to teach it what to smell for. Using a form of classical conditioning, the researchers trained the insects to recognize and respond to the explosives dinitrotoluene (DNT) and trinitrotoluene (TNT) by wafting their scents to the locusts for four seconds at a time and repeating this ten times. Once the locusts knew what to smell for, researchers glued computer chips to the locusts’ backs and attached the backpacks to electrodes implanted in the locusts’ brains to access their neural information. The chip then recorded and interpreted each locust’s neural and olfactory activity and transmitted the data to the system’s human operator whenever the insect found something useful.

Engineers chose American locusts for the experiment for several reasons: They are big enough to carry the heavy load of the computer chip, have a well-studied olfactory system, can be classically conditioned to recognize certain odors and they have a relatively simple brain whose neural activity is easier to monitor. 

While the Washington University team reported success in training the locusts, there were some limitations. Data recording quality remained intact for only about seven hours, but that could be improved with regular feeding of the insects to keep their brains nourished, according to the researchers. Another limitation is that data collected from one locust can’t be used to understand what odor signals another locust picked up, as wires are inserted into each insect’s antennal lobe in different places. Since the insects are cheap and easy to train, though, researchers didn’t think those limitations posed much of a problem. 

Creative researchers have been harnessing insects’ powerful odor-detection capabilities for decades. In a 1988 paper, for example, University of Georgia entomologist Joe Lewis showed that parasitic wasps could be taught to react to specific odors just like humans and bloodhounds can. 

“That was quite a spectacular, you know, [there was] a lot of news interest and excitement about it,” recalls Lewis, who is now retired. He even produced a device called the Wasp Hound to show what wasps could do. 

Lewis built his Wasp Hound by installing a camera and a fan on one end of a piece of PVC pipe that’s three inches wide and about 10 inches long. On the other end, he put five trained wasps in a container that was sealed using a removable cap with a pinhole in it, allowing odors to enter the chamber. 

To train the wasps, Lewis and his team let the wasps smell a chemical for 10 seconds while simultaneously allowing them to drink sugar water, a favorite treat. They then repeated the process three times. It usually took five to 10 minutes to train the wasps to recognize a smell.  

“We ended up with some idiots, fast learners and slow learners,” Lewis says. One of the chemicals the wasps were taught to smell was 3-octanone, a chemical created by a toxic fungi that sickens corn and peanut plants. In previous studies, wasps also sniffed out 2,4-DNT — a breakdown product of TNT — as well as cadaverine, which is a chemical produced from decaying flesh. 

With trained wasps loaded into the Wasp Hound, someone could walk around holding the tube as a fan circulates air into the wasps’ holding chamber. If the wasps detect the scent they were trained to pick up, they’ll crowd around the pinhole, hoping for sugar water. Seeing that, whoever was holding the Wasp Hound would know they got a hit. 

Lewis says he tried to take his Wasp Hound invention into the real world, but there was no demand for it. “What we encountered here was a whole new technology, but it’s so new, there’s nowhere to deliver it,” he says. Theaters and hotels were interested in the Wasp Hound for bed bug detection, but Lewis says that nothing ever panned out due to financial concerns. 

In addition to being a detection device, Lewis’ invention showed that olfactory learning could have come from an ancient evolutionary adaptation. “Parasitic wasps were doing the same kind of thing that we knew that occurred in humans and other primates and higher animals — that the nose learns from the mouth,” Lewis says. 

Biohacking, in which machined devices are fused directly to live animals — including humans — is an emerging frontier in insect engineering. “Biohacking is a way of exploiting millions of years of natural selection to shortcut what would take decades, or perhaps centuries, for us to engineer anything that’s as sophisticated as a fly with regard to energy systems, a navigation system and an aerodynamic system,” Lockwood says. “We’re so far away from that right now that it’s just incredible.”

There have, however, been nuclear-powered cyborg beetles created for espionage use, thanks to funding from the U.S. Defense Advanced Research Projects Agency. The agency also studied sex-starved moths as a potential way to track bank robbers, and even has a whole branch called Insect Allies that investigates how insects can essentially vaccinate crops from harmful diseases or other insects. 

Insect-inspired robots that are entirely machines are another hot area of research. In collaboration with Tsinghua University, in China, mechanical engineer Liwei Lin and his team at the University of California, Berkeley, created a robot that looks and moves like a cockroach. If you step on it, the robo-roach can withstand up to one million times its weight — another trait adopted from the humble roach. The robot could help in search-and-rescue endeavors that would normally endanger humans or dogs. Lin says the robot hasn’t been used in the field yet, as he and his team are still working on its controls. Now, he’s studying the movements of tigers and leopards for ideas about how his robots could make quicker turns. 

While robot movement typically uses wheels or tracks, those usually require a flat surface, Lin says. Insects, by contrast, have mastered how best to move over challenging surfaces with their six dynamic legs. Using these natural techniques to inform robotic engineering allows the creations to move more easily, which is why Lin says he thinks “this biological animal would actually be a very, very good model if we want to improve the artificial robots’ performance.”

Despite all the attention that these insect-inspired robots and biohacked hybrids are getting, there are relatively few examples in wide commercial use so far. Demand is still limited and development costs are high. Though organizations like the U.S. Navy continue to research biohacked bugs, this bug technology has not yet achieved the ease, cost and utility needed for implementation into everyday life. In addition, as author and entomologist Lockwood notes, insects’ learning capacities are limited and their crushable bodies make them fragile technologies, even if their uses exceed current limitations of human engineering. 

Even so, engineers are still dreaming, and are convinced that at least some of their creepy-crawly dreams will someday become reality. The temptation to utilize the assets of these species may be too strong for us to resist, according to Lockwood. 

Humans are not humble creatures, he says, but we’re smart enough to eventually “realize that wheeled vehicles and tiny flying jets might not be nearly as viable as taking seriously those aspects of biology that we can sort of mimic rather than reinvent.”

About the Author

M.K. Manoylov

MK Manoylov likes covering trees, the environment, microbes, and all things bugs. MK was the former opinion editor for The Red & Black newspaper and moved to Brooklyn to pursue science journalism. When not writing, you can find MK editing videos or drawing comics.

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