Nov. 7, 2005 — A new biological sensor that relies on wasps to detect chemical odors could one day be used to sense explosives, dead bodies, illegal drugs and even disease.

The cup-sized device, named the Wasp Hound, employs trained wasps whose movement triggers an alarm system.

The sniffer is 70 to 100 times more sensitive than electronic noses and thousands of dollars cheaper to use than trained dogs. The wasps can also be trained in about five minutes to respond to a specific scent.

"You might have a situation where you want to respond to something immediately, but you don't know if the dog or electronic nose can respond to it. You can just do a quick training with the wasps," said Glen Rains, a biological engineer at the University of Georgia who, along with W. Joe Lewis, a research entomologist at the USDA's Agricultural Research Service, reported their device in a study that will appear in the January/February issue of Biotechnology Progress.

These wasps, known as Microplitis croceipes, have an ability to adapt to the chemical odor that best leads them to food and larvae host — in their natural setting, caterpillars.

In the lab, Rains can easily manipulate a wasp's flexible aptitude to associate different odors with food.

First, he puts a small filter paper soaked in the desired chemical compound inside a foil-covered jar, poking holes into the foil to allow the chemical scent to escape.

Then he places a sugar-soaked filter paper on top of the foil.

Finally, Rains allows the wasps to feed for 10 seconds on the sugary filter paper before removing them for 30 seconds. He repeats this process about three times and in less than five minutes, has a trained wasp hound.

Five wasp hounds are placed into a clear, ventilated, disc-shaped cartridge. The cartridge is placed into the bottom of the Wasp Hound canister, near an air hole. A fan at the top of the device pulls air into the canister through the air inlet.

If the air contains the chemical signature of the odor the wasps have been trained to recognize, they congregate near the air hole.

A tiny Web camera affixed to the top of the canister records their movement and transmits it to a nearby computer, which analyzes the goings-on and initiates an alarm when the wasps gather around the air inlet.

"I think the approach Rains is taking is becoming more and more realistic as time passes because of improvements in technological capabilities," said associate professor Raj Raman, a biosystems engineer at the University of Tennessee.

To date, the wasps have been trained to detect the chemical odor given off by a hard-to-spot toxic fungi that infects corn and peanuts and can be carcinogenic in humans.

By placing a large tarp over a wagon of peanuts, any chemical odor emanating from the toxic fungi will become trapped in the space above the wagon.

The air can then be easily and quickly sensed with a wasp-filled canister.

Rains is working on fine tuning the wasp's sensing abilities and believes the device could be ready for the market in five to 10 years.

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