Insects Trained to Sniff Out Poisons, Explosives
TIFTON, Ga. – Trained wasps could someday replace dogs for sniffing out drugs, bombs and bodies. No kidding.
Scientists say a species of non-stinging wasps can be trained in only five minutes and are just as sensitive to odors as man's best friend, which can require up to six months of training at a cost of about $15,000 per dog.
With the use of a handheld device that contains the wasps but allows them to do their work, researchers have been able to use the insects to detect target odors such as a toxin that grows on corn and peanuts, and a chemical used in certain explosives.
"There's a tremendous need for a very flexible and mobile chemical detector," said U.S. Department of Agriculture entomologist Joe Lewis, who has been studying wasps since the 1960s. "Our best devices that we have currently are very cumbersome, expensive and highly fragile."
The "Wasp Hound" research by Lewis and University of Georgia agricultural engineer Glen Rains is part of a larger government project to determine if insects and even reptiles or crustaceans could be recruited for defense work. That project has already resulted in scientists refining the use of bees as land-mine detectors.
Through the years, Lewis and a USDA colleague, J.H. Tumlinson, discovered that a tiny, predatory wasp known as microplitis croceipes had relied on odors to locate nectar for food and hosts for its eggs — caterpillars that damage crops.
While they don't sting humans, the female wasps use their stingers to deposit eggs inside caterpillars, producing larvae that eventually kill the caterpillars.
The scientists also discovered that plants being attacked by the caterpillars give off SOS scents to attract the all-black wasps and that the quarter-inch-long insects could be trained to associate other odors with food and prey.
"They have to be good detectors, because their whole survival depends on it," Lewis said.
Rains said the wasps can be trained to detect a specific odor very quickly. The researchers expose hungry wasps to the target odor, then let them feed on sugar water for 10 seconds and then give them a one-minute break. After three repetitions of sniffing and feeding, the wasps associate the odor with feeding.
Since the scientists couldn't put leashes on their trained wasps, they needed a way to contain them while monitoring their reactions to odors.
Enter the Wasp Hound — a 10-inch-long plastic cylinder made of PVC pipe with a hole in one end and a small fan on the other. Inside is a Web camera that connects to a laptop computer for monitoring the behavior of five wasps housed in a transparent, ventilated capsule.
When the wasps detect a target odor, they converge around the vent, creating a mass of dark pixels on the computer screen. Otherwise, they just hang out inside the capsule.
They can work for as long as 48 hours, and then they're released to live out their remainder of their two-to three-week life span.
"What we have ... is a technology-free organism that you can quickly program and use in a highly mobile way," said Lewis, who believes the Wasp Hound could be used to search for explosives at airports, locate bodies, monitor crops for toxins and detect diseases such as cancer from the odors in a person's breath.
"They're very cheap to produce and very sensitive," Rains said of the wasps. "Dogs take months to train and they need a specific handler. Wasps can be trained on the spot."
Rains believes the Wasp Hound could be available for sale in three to five years. He and Lewis are still exploring ways to breed more wasps and to train hundreds simultaneously.
"We've done enough on it to know it's technically feasible to do that," Lewis said. "It's just a matter of completing and refining the methodology."
Lewis believes many other types of invertebrates — bees, other types of parasitic insects, even water bugs — can be trained to sniff out trouble.
"It's opened a whole new resource for invertebrates as biological sensors," he said.
Other scientists also are working to harness the sniffing power of insects.
In 2002, the Pentagon considered fitting sniffer bees with transmitters the size of a grain of salt to locate explosives and relay that information wirelessly to laptop computers.
A British firm, Inscentinel Ltd., sells trained bees and mini-hives where the insects' response to scents from natural and man-made chemicals can be monitored. The company says the system can be used to screen for explosives, drugs, chemical weapons, land mines and for food quality control.
Jerry Bromenshenk, a research professor at Montana State University, is using bees for mine detection. The bees congregate over mines or other explosives and their locations are mapped using laser-sensing technology.
"Insects and their antennae have an olfactory system that is pretty much on a par with a dog," Bromenshenk said. "They're a whole lot more plentiful and a lot less expensive to come by."
Bromenshenk said bees may be more appropriate for open areas, while the Wasp Hound may be better in buildings.
"The difference is that we let our bees free fly," he said. "That's not good in confined areas like an airport."