A) The head and antennae of a male Heliothis virescens moth (B) single segment of Heliothis virescens male noth antenna (C) Heliothis virescens
On the moth antennae are microscopic olfactory hairs with neurons that pick up both sex pheromones (in the case of male moths) and plant odors. Baker and his colleagues devised a method to cut off the tip of a hair and install an electrode on it, allowing them to “listen” to the neurons, which send signals to the brain.
“So we have thousands of neurons attuned to sex pheromones going to one site on the brain, and those attuned to crop odors going to another site.” Baker says. “And we’ve been able to actually train the moth antennae to pick up certain odors.”
Baker’s team developed an instrument called a biosensor, which uses insect antennae that respond to plumes emanating from different odor sources. In field studies, his team has shown that the biosensor can discriminate among and locate different odor sources in the field, locating a hidden odor source from as much as thirty meters away. “We’re excited about the biosensor,” Baker says, “ because of what it’s revealing to us about odor plumes and insects’ olfactory capabilities, as well as its potential for detecting and locating agents of harm, such as drugs or unexploded land mines.”
The biosensor’s ability to detect odors outdoors signifies the next frontier in chemical ecology. “We’d really like to take more of our studies outdoors,” says Jack Schultz. “There’s a lot we can do in the lab—we put the plant in a bottle, collect the air, and identify the volatiles being emitted. We can concentrate plant volatiles, pipe them to another plant, and watch what happens. But we can’t stick a machine outside and detect those same volatiles in the very low concentrations in which plants emit them. There’s no instrument that sensitive. So the ecologist in us wants to see all this in action outdoors, in an ecological setting, the way it works in the laboratory. That’s our next challenge."
Faculty and staff referenced in this article are Heidi Appel; Tom Baker, professor of entomology in the college and the Huck Institutes of the Life Sciences; John Carlson, associate professor of molecular genetics and director of the Schatz Center for Tree Molecular Genetics, School of Forest Resources; Consuelo De Moraes, assistant professor of entomology; Chris Frost, postdoctoral scholar in entomology; Mark Mescher, research associate and assistant professor of entomology; Jack Schultz; and Jim Tumlinson, Ralph O. Mumma professor of entomology in the college and the Huck Institutes of the Life Sciences.