| Flying Noses |
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25 November 2005, for Science Hunting for dead bodies or hidden explosives? A tube of wasps may be the answer. In the wild, the tiny parasitic wasp Microplitis croceipes can smell not only nectar but also airborne chemical signals from plants being eaten by its host caterpillar. Entomologist W. Joe Lewis of the U.S. Department of Agriculture's Agricultural Research Service found he could train the wasps to link many scents with a sugar-water reward. But "you can't put a wasp on a leash and take it around" like a bomb-sniffing dog, he says. So engineer Glen Rains of the University of Georgia, Tifton, designed a portable "Wasp Hound": a device outfitted with a fan that pulls air through a cartridge holding five wasps. When they catch a whiff of a target scent, say, 2,4-dinitrotoluene from explosives, they crowd around the air holes, looking for a reward. In a recent test using five different smells, the device far outperformed an electronic nose and was as good as a dog, the researchers report in an upcoming issue of Biotechnology Progress. But wasps are cheaper than bloodhounds and need only 5 minutes of training, Lewis says. Now, Rains and Lewis are working on a mass wasp-training regimen and on new applications including finding dead bodies from scents such as cadaverine and putrescene. Bees are also joining the olfactory workforce. Bee specialist Mathilde Briens, of Inscentinel in Harpenden, U.K., says they're working on a system in which bees stick out their tongues in response to a scent. |