BACKGROUND: Scientists from the University of Georgia and the USDA Agricultural Research Service are training wasps to detect the telltale odors of concealed explosives, drugs and human remains, and possibly one day certain diseases like cancer. They are now investigating whether it is possible to train mosquitoes as living odor detectors as well, and plan to eventually study other insects with excellent sniffing ability, like honeybees and moths.
HOW IT WORKS: The Georgia scientists have built a device they call the Wasp Hound: an odor-detection device that costs around $60. It is made of a small PVC tube containing five wasps that can be trained to detect any target odor within minutes. The device has a fan at the top, which draws odors into the tube through a filter. If the wasps catch a whiff of whatever they've been trained to smell, they crowd around a hole in the filter. A web cam inside the tube is attached to a computer, which alerts the operator to the wasps' reaction with a beep or a flashing light. The Wasp Hound could be used by farmers to monitor crops for diseases and pests; to check for explosives in airport security applications; to help doctors monitor diseases, or even by defense forces searching for buried land mines.
ADVANTAGES: Unlike dogs and the electronic sensors more commonly used today, wasps are cheap and disposable. It costs pennies and takes minutes to train them: Feed them sugar water while introducing them to a target smell for 10 seconds; give them a 30-second break, repeat the process twice more, and they are completely trained to track that single scent.
ABOUT WASPS: Wasps have olfactory sensors on their antennae that they use to stay alive. For instance, one strain of wasp lays its eggs inside a specific variety of caterpillar. The insects are attracted to the caterpillars by chemicals released by plans as the caterpillars much on them -- a type of SOS signal from the plants. This is also how wasps attract mates. Wasps can sense chemicals in concentrations as tiny as a few parts per billion in the air ý the same range to which dogs and chemical sensors are sensitive. Some species can pick up scents at concentrations as low as one part in a thousand billion, which is a hundred thousand times weaker that the concentrations detectable by commercial "electronic noses."