Relationship between sex pheromone elicited behaviour and response of single olfactory receptor neurones in a wind tunnel

Abstract:
Responses from pheromone-specific receptor neurones in male Agrotis segetum (Denis & Schiffermuller) (Lepidoptera: Noctuidae) were recorded in a laboratory wind tunnel. Stimuli were: (1) rubber septum dispensers loaded with single components or a four-component pheromone blend, (2) excised glands from female A. segetum, (3) constrained A. segetum females with extruded glands. Dose-response curves for three neurone-types with different specificity were established. The neurones were specifically tuned to respond to either one of the two pheromone components (Z)-5-decenyl acetate and (Z)-7-dodecenyl acetate, or to the behavioural antagonist (Z)-5-decenol. In parallel, a behavioural dose-response curve with males flying upwind to a four-component pheromone blend was established. There was a clear correlation between behavioural arrestment of upwind flight and maximum spiking activity in ZS-10:OAc-specific neurones. The pheromone release rates of individual females and synthetic dispensers were compared. A load of 50-200 ng of ZS-10:OAc on a rubber septum elicited approximately the same neural response as one female gland.