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They're a lot cheaper to rear than bloodhounds, take just a few minutes to train, and they don't bark, slobber or smell. But will wasps one day replace dogs for sniffing out bombs — or even harmful food contaminants? Hear the buzz in this ScienCentral News video report.
Biological brains
A new device for detecting suspicious odors has an unusual component. Its brain consists of five tiny trained wasps. Their trainer, agricultural engineer Glen Rains, admits the idea may sound far-fetched at first.
"I initially thought some people would kind of look at it like some kind of a flea circus type thing," says Rains, associate professor at the University of Georgia. But as he wrote in the journal Biotechnology Progress, the sensor is cheaper to use than trained dogs and more sensitive than some electronic noses.
"We were trying to come up with ways to improve their efficiency for foraging… it turned out that they use their sense of smell to find food and hosts, filter out all this information they find in the field very, very efficiently," Rains says. Further study showed that the wasps actually learn odors in the field as they get positive or negative reinforcement.
"We got a request from the Department of Defense, interested in how possibly these wasps could be trained to detect odors," says Rains. "We didn't know if they would learn odors that weren't in their natural habitat and we didn't know if they would even respond with any kind of behavior that would indicate that they had detected an odor."
He found he could train the wasps to seek out almost any odor of concern — from explosives to marijuana to clandestinely buried corpses — by exposing them to the smell while giving them sugar water. It only takes a few minutes to program the wasps, he says,"We let them feed for 10 seconds, remove them for 30 seconds to a minute, repeat that two times and basically they've imprinted that odor in their brains."
Loading the Wasp Hound cartridge.
Since the wasps don't sit up or bark, Rains invented the "Wasp Hound," a handheld device to contain and watch them. It's a plastic pipe into which Rains inserts a cartridge containing trained wasps. The cartridge has a small hole in the center though which air is pumped by a small fan. A simple camera that takes black and white images four times per second is focused on the hole, and is attached to a laptop that displays the images in real time. A light sensor controls the lighting. "The idea is, we control the environment the wasps are in by keeping them enclosed in the Wasp Hound and we observe what they're doing with a camera and read it with a computer to tell us when they've detected an odor," Rains explains.
If the target odor is not present, the wasps just wander around the cartridge. But when they sense the scent they've been trained to respond to, "then they all start crowding around the hole to try to get at what they think is food coming in," Rains says.
Rains thinks the Wasp Hound would be a better detector of the natural poison aflatoxin in stored food crops like corn, peanuts and cotton seed. The toxin, which recently contaminated pet food in 23 states, can also cause liver cancer in people.
"Right now the current sampling methods are not really adequate to get a good feel for the actual contamination because they're sampling parts of the grain or corn or peanuts," Rains says. "So what we're hoping is trying to develop a method by which we're just looking at… a whole wagon of peanuts or a storage area of corn and get an indication of whether there's actually toxin in that whole area… as opposed to just a sample that you have to assume is representative of a whole area."
"The wasp hound can be used to detect toxin in a wagonload probably in about 25 seconds," he explains.
Rains found it takes five wasps to get a reliable reading — showing that a few bugs in the system can sometimes be a good thing. But one bug he's working to eliminate is the flea-circus aspect. Right now the researchers train the wasps by hand, "so although it's very easy to rear thousands of them — we rear about 4,000 a week here — it's still tedious to train them because we're training them one at a time," he says. So they're working on automating the process. Then Rains thinks the Wasp Hound might fly as a product.
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