Adaptation of male moth antennal neurons in a pheromone plume is associated with cessation of pheromone-mediated flight

Recordings of the firing rates of single antennal neurons when Agrotis segetum antennac were placed 70 cm downwind of a pheromone source revealed that cells sensitive to the most volatile component adapted rapidly in a plume from a high-concentration source known from previous studies to cause in-flight arrestment of progress towards the source. No adaptation was found in response to lower-concentration plumes known to promote high levels of sustained flight to the source with little premature arrestment. Adaptation was not observed in antennal neurons of a second species, Heliothis virescens, when they were placed in plumes of this species' sex pheromone blend, regardless of the concentration. In flight-tunnel tests these same pheromone sources evoked high levels of source location with little arrestment. These results indicate that adaptation or attenuation of antennal neuronal burst frequencies in response to rapidly arriving pheromone filaments in a plume may be important peripheral determinants of whether or not prolonged upwind flight and successful pheromone source location occurs.