Non-stinging wasps called Microplitis croceipes are trained to smell certain odors such as TNT, marijuana, or chemicals associated with dead bodies through associative learning. While they feed on sugar water, a target smell wafts through the cage. Very quickly — in only about 20 — seconds the wasps learn to associate that smell with food.

Once trained, they can smell a rat, so to speak, by acting in concert to create a conspicuous indicator. A group of wasps in a container called a Wasp Hound is waved over a suspicious parcel or person. If the target smell is in the vicinity, the insects will crowd around a small hole in the container where the scent enters the holding cell.

“But as they don’t get positive feedback — their much-favored sugar water — when used in the field, they start unlearning immediately,” said Rains. Thus, the insects can only be used a limited number of times before they figure out that the smell no longer means a tasty treat.

Dogs, of course, have the advantage of longer attention spans, wider utility, and longer life spans than the wasps, which live about two weeks. On the other hand, said Rains, “wasps are a cheaper, quicker alternative to a highly trained and expensive dog.” For these reasons, he added, “the Department of Defense has expressed interest in the Wasp Hound and the uses are multiple for food-safety issues as well.”

Probably the best application for the wasps, said Rains, is the detection of aflatoxin, given that existing alternatives are cumbersome, expensive, and of limited utility. Produced by the fungus Aspergillus flavus, this compound can destroy corn and peanut crops, is a known carcinogen, and also has implications for bioterrorism. Because aflatoxin is toxic both to animals and humans if introduced into food or drinking water in high enough quantities, it was manufactured en masse by several foreign powers in the 1980s and ’90s as a potential biological weapon.

For more information contact Glenn Rains at grains@uga.edu.