Bomb-Sniffing Cyborg Locusts Can Now Successfully Detect Explosives

Research funded by the U.S. Navy could spell the end of bomb-sniffing dogs

Photo: Baran Lab via The Washington Post

The bad guys wanted to blow something up — but they forgot about the cyborg bugs.

Scientists funded by the United States Navy have revealed they have successfully augmented locusts and hijacked their ability to sense a wide range of chemical odors, including explosives.

According to a preprint research paper published on February 11 in BioRxiv, the insects have been used to detect gases released by substances like ammonium nitrate, commonly used by terrorist groups for bomb-making, and the military explosives TNT and RDX. Individual locusts were able to successfully sniff out incendiary material, but the results improved when the scientists compiled data from seven or more locusts, where the detection capability was distributed across a mini-swarm.

The researchers, from Washington University in St. Louis, declined to comment for this story. But their paper describes how they transformed the bugs into would-be bomb detectors by implanting electrodes into the insects’ brains. That allowed researchers to analyze the neural activity of the locusts when they encountered certain substances.

Four years ago, the U.S. Office of Naval Research allocated $750,000 in funding for the project, but at the time, it was not clear whether the plan to turn locusts into bomb detection agents would actually work. The new paper suggests that some version of a biohacked locust could one day be deployed into the field.

The Washington University scientists cocooned the locusts in tiny wheeled robots that could be positioned at will.

The researchers chose to work with American locusts because they are “sturdy” and “can carry heavy payloads,” the preprint paper reveals. The real challenge was finding a way to read the locusts’ minds without subjecting them to extensive surgery. The procedure involved making a “minor” incision in the locusts’ heads that allowed the insects to continue moving their mouthparts and antennae freely afterward.

But for these cyborg locusts to be useful, operators must be able to physically control their movement. To do this, the Washington University scientists cocooned the locusts in tiny wheeled robots that could be positioned at will. (The researchers are also finalizing work on silk-based “nanotattoo” implants that will allow operators to move the insects remotely without using a vehicle.)

The robot-bound locusts were exposed to five different explosives and a few other chemicals. Within 500 milliseconds of exposure to each substance, a discernible and distinct pattern of activity appeared in the insects’ brains.

This speed can be chalked up to locust biology: Their tiny antennae are packed with around 50,000 olfactory neurons. That’s what makes the critters so good at sensing a wide range of substances — better than any artificial sensors humans currently know how to make.

Because it would be challenging to process data from that many neurons, the team focused on a “bottleneck” in the locust brain itself — a compact region of about only 800 neurons that processes information from the antennae. Signals there revealed what the insects were sensing, allowing the scientists to effectively eavesdrop on the locust brains.

Good-quality signals can be picked up by the electrodes for around seven hours after locusts receive their implants but fade beyond that, the researchers write. They note, however, that this period could likely be lengthened by feeding the insects regularly and by refining the surgical technique used to augment them.

Previous studies have demonstrated that it’s possible to reveal neural responses to different odors in various insect brains. Thomas Nowotny at the University of Sussex in the U.K. and colleagues showed in 2014 that this could be done with fruit flies.

Developing a cyborg-like, mobile system with a wheeled robot is a step forward, argues Nowotny.

“We just said, ‘Look, we can use insects to detect this stuff,’ but we never built anything with it,” he says. “They seem to have put it together.”

He adds, however, that there are still practical challenges in keeping the augmented locusts alive. In his view, it may make more sense to extract the relevant sensory mechanisms from the locust antennae and build those into a different cyborg system rather than retaining the whole animal.

Maintaining the health of living, mechanically augmented animals could present problems in real-world settings, cautions Alper Bozkurt at North Carolina State University, who has also experimented with cyborg insects. Nevertheless, he thinks Barani Raman and his colleagues have made an important contribution to the field. “This is very exciting work,” he adds.