Olfactory discrimination conditioning in the moth Spodoptera littoralis.

We used a proboscis extension reflex (PER) to study the olfactory discrimination capability in the moth Spodoptera littoralis. Already after a single experience, moths were capable to discriminate a rewarded from an unrewarded odor. In the first experiment, when rewarded and unrewarded odors were substituted for each other, moths were able to undergo reversal conditioning already after two experiences. Both shorter and longer inter-trial intervals (ITIs) supported high degrees of learning. In a second experiment, moths could solve both feature-positive and -negative discrimination tasks. Two hypotheses for the way in which these associations exert their discrimination performance are considered. The moth's olfactory physiology has been extensively studied. This animal thus provides a powerful system in which to study the neurobiology of olfactory discrimination and odor recognition.