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Glen Rains knew that parasitic wasps
could be trained to pick up a scent and stick to it as well as any bloodhound.
But wasps don't respond to commands like "sic 'em" or "stop." They
can't fly well with little leashes, either.
Rains needed a way to keep them focused, contained and mobile outside the lab.
So, he and a colleague invented the "Wasp Hound."
The Wasp Hound is a 3-inch PVC pipe about 10 inches long. A fan and a Web camera
closes one end. Inside, a tray places four or five wasps over the tiny pinhole
in the removable white cap that covers the other end.
This portable nose can monitor the behavior of wasps trained to respond to
a particular scent or volatile compound, he said.
"Volatile compounds are released by all organisms, either directly or
by chemical reaction with other materials," said Rains, an engineer with
the University of Georgia College of Agricultural and Environmental Sciences.
The premise of the Wasp Hound is based on the work of Joe Lewis, a U.S. Department
of Agriculture entomologist. Over the past two decades, Lewis has learned that
parasitic wasps can smell nearly anything and can be taught to respond to smell.
Rains and Lewis use wasps that have been bred in a lab on the UGA Tifton, Ga.,
campus. Thousands can be produced each week. There is nothing particularly
unique about the wasps when they're born.
But through conditioning them to link a certain smell to food -- in this case,
sugar water -- they become like little bloodhounds. It takes 5 to 10 minutes
to train them. It can take months to train a dog to consistently pick out one
scent.
The conditioned wasps are loaded into the Wasp Hound. The fan sucks air through
the pinhole in the cap. If the scent they've been trained to recognize whiffs
through, they will crowd around the pinhole. If the scent's not there, they
just hang out.
Through a USB wire, the Web camera sends an image of the wasps to a computer.
There, software analyzes the amount of dark space created around the pinhole
by the wasps against the white background of the cap.
The software creates a graph that shows the level of crowding, or the wasps'
response to the odor they were trained to detect. It doesn't take long for
the Wasp Hound handler to get the answer.
"This adds objectivity to the process," Rains said. "In about
30 seconds, we can know if the wasps picked up anything."
Forensic entomologists have asked Rains if wasps can be trained to help investigators
find clandestine grave sites. He thinks they can.
The wasps can also be trained to detect explosives, he said.
Once a dog is trained to a scent, it's tough to train it to go after another.
The wasps in the Wasp Hound can't be trained to respond to another scent, either,
he said. But wasps are cheap to produce and are beneficial to farmers.
"Once you're through with the wasps," he said, "you can just
let them go."
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University
of Georgia scientist Glen Rains uses the Wasp Hound, a portable device that
can be used to monitor the behavior of wasps trained to respond to a particular
scent or volatile compound. It was developed by researchers with the University
of Georgia and the U.S. Department of Agriculture.
