US boffins have come up with a device that uses trained sniffer wasps, rather than dogs, to detect chemicals such as explosives and illegal drugs.

The trained hymenoptera are held in a cup-sized device, called a 'Wasp Hound', developed by the University of Georgia and US Department of Agriculture (USDA).

It is capable of sounding an alarm or triggering a visual signal, such as a flashing light, when the insects encounter a target odour.

According to the researchers, the sensor is cheaper to use than trained dogs and more sensitive than some sophisticated chemical detection methods, including electronic noses.

They believe the 'Wasp Hound' has the potential to be used to detect cancer, plant diseases and even buried bodies.

The idea of using unconventional biological sensors to detect target odours is not unprecedented, according to study leaders Glen C. Rains, a biological engineer with the University of Georgia, and W. Joe Lewis, a research entomologist with the USDA's Agricultural Research Service.

They point out that honeybees, fish and even yeast strains have all been used experimentally to detect various explosives or toxins.

"We have now developed a prototype device that puts the idea of using chemical-sensing wasps into a practical framework and its possibilities are astounding," said Rains, who believes that the device could be ready for commercial use in five to 10 years.

In the current study, the researchers used a species of tiny parasitic wasp that can be trained to detect certain odours by associating them with a food reward.

The Wasp Hound comprises a ventilated device, composed of PVC piping, which holds a small cartridge containing five trained wasps.

The wasps in the experimental unit have been trained to detect 3-octanone, a chemical produced by certain toxic fungi that infect corn and peanut crops. The presence of the fungi can result in costly crop losses.

The device contains a tiny camera linked to a computer to record the movement of the wasps. This movement can be translated into an alarm signal to indicate the presence of a toxic plant fungus, the scientists explained.

Besides detecting plant diseases, the device has a wide variety of other applications. In previous studies, the researchers demonstrated that they also could train the wasps to detect 2,4-dinitrotoluene, a chemical used in certain explosives.

The wasps can also be used to detect chemical odours associated with certain human diseases, including lung cancer, skin cancer and stomach ulcers.