Wasps to the Rescue

Wasps usually elicit squeals and a mad dash for bug spray. But now a team of Agricultural Research Service scientists and cooperators has found a new job for wasps--as chemical detectors.

ARS scientists Joe Lewis in Tifton, Ga., and Jim Tumlinson in Gainesville, Fla., and University of Georgia researcher Glen Rains have found parasitic wasps can be used to detect chemicals, such as those associated with foodborne toxins.

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Lewis’ team is using a model system to demonstrate the detection of chemicals associated with aflatoxins, which are naturally occurring mycotoxins produced by certain types of mold, such as Aspergillus flavus and A. parasiticus. Some strains of these Aspergillus species produce aflatoxins, and others don’t. Parasitic wasps can differentiate between toxin- and non-toxin-producing molds and could prove useful in testing harvested peanuts and corn for the toxin-producing ones. Current methods to test for aflatoxins are limited, time-consuming and expensive.

Wasps can be trained to detect any chemical by using their natural instincts to find food by scent. Mimicking nature, scientists feed sugar water to wasps while exposing them to the chemical scent to be tracked. During this process, wasps learn to link this chemical scent to food. This mechanism is called "typical associative learning."

To test for chemicals, wasps are placed in a container with a small hole, and air is passed over the wasps. If the wasps detect the target chemical, they go into the hole hoping to find a food source associated with the chemical scent. When they move into the hole, they trip a buzzer that indicates aflatoxins are present.

Although certain airborne vapors are associated with aflatoxin, the specific chemicals are unknown. The research team’s next step is to determine the particular chemical in aflatoxin that attracts the wasps. This will allow the development of a portable machine that acts as a flexible biosensor.

The Defense Advanced Research Projects Agency also provided funding for this research. ARS is the chief scientific research agency of the U.S. Department of Agriculture.