Insect infestations are usually spotted by the symptoms they leave on plants. But often the destruction starts invisibly within trees, plants, and roots--and shows up only when damage is far advanced. Now researchers think that they've found a way to get the jump on these bugs: by listening for the tiny vibrations made by beetle grubs, Indian meal moth larvae, or termites as they chow down.
Physicist-turned-entomologist Richard W. Mankin and colleagues at the U.S. Department of Agriculture's lab at the University of Florida, Gainesville, are developing ways to eavesdrop on unseen pests via sensors that are pushed into soil, clamped onto a plant stem or tree trunk, or attached to a food container. The vibrations given off by the insects are fed into amplifiers. Mankin has developed software that can identify the sound "fingerprints" of different species. In field tests, researchers are now trying to detect weevils in citrus groves and in the pots of ornamentals. Lab tests are focused on finding Indian meal moths in dry pet food packages and exotic insect pests in endangered bromeliads in Florida. "Ultimately," says Mankin, "we hope to develop an acoustic system that could easily detect insects in packages without opening them."
Cornell University entomologist Cole Gilbert says that this work "can be especially useful for assessing the population density of hidden insects"--once the technical bugs, such as interference from natural background noises, are under control.