TORONTO -- Scientists have found a way to turn locusts into explosive-sniffing cyborgs by hijacking the insects' sense of smell, according to a new study funded by the U.S. Navy.
Researchers from Washington University in St. Louis have managed to program locusts to detect gases released by substances such as TNT, DNT, RDX, PETN and ammonium nitrate by implanting electrodes into their brains.
By examining which neurons were firing when different odors were detected by the bugs' senses, researchers found that these signals allowed the locusts to distinguish between explosive vapors and non-explosive chemicals.
"We didn't know if they'd be able to smell or pinpoint the explosives because they don't have any meaningful ecological significance," Barani Raman, Washington University biomedical engineering professor and lead author of the study, said in a press release.
"It was possible that they didn't care about any of the cues that were meaningful to us in this particular case."
The findings were published in a pre-print research paper on Aug. 6 in the journal Biosensors and Bioelectronics: X. The U.S. Office of Naval Research granted the team US$750,000 back in 2016 to conduct the research.
The locusts were exposed to five different explosives, and researchers reported that it only took 500 milliseconds of exposure for a distinct pattern of activity to appear in the locusts' brains.
According to the study, it is the first time a biological system used for smelling was successfully "hijacked to develop a cyborg chemical sensing approach."
However, the enhanced locusts were able to go beyond detecting different explosives. The insects were also able to identify from which direction the odour was being emitted.
"You know when you're close to the coffee shop, the coffee smell is stronger, and when you're farther away, you smell it less? That's what we were looking at," Raman said.
The explosive vapors were injected into a hole in a box where the locust sat in a tiny, wheeled vehicle. As the locust was driven around and sniffed different concentrations of vapors, researchers studied its odor-related brain activity. The signals in the bugs' brains reflected those differences in vapor concentration.
"Most surprisingly, we could clearly see the neurons responded differently to TNT and DNT, as well as these other explosive chemical vapors," Raman said.
Researchers chose to work with locusts because their antennae contain almost 50,000 olfactory neurons. Additionally, their strength and sturdiness allows them to carry heavy loads – specifically the implanted electrodes -- attached to their bodies. Researchers said the electrodes were attached using a new surgical procedure that did not hinder the locusts' movement.
The research demonstrates both the ability to control the locusts and the ability to read their brains, according to Raman. He added that the cyborg locusts could one day be used by Homeland Security to help search for bombs.
"Now we can implant the electrodes, seal the locust and transport them to mobile environments," Raman said.
However, Raman acknowledged that the use of animals or insects to detect the presence of toxic gases is not a new concept.
"This is not that different from in the old days, when coal miners used canaries. People use pigs for finding truffles. It's a similar approach -- using a biological organism -- this is just a bit more sophisticated," he said.
