Responses of olfactory receptor neurones to behaviourally important odours in gregarious and solitarious desert locust, Schistocerca gregaria

Recordings from antennal olfactory receptor neurones in young adult Schistocerca gregaria Forskal (Orthoptera: Acrididae) showed that behaviourally important odours are detected by receptor neurones present in morphologically identifiable sensillum types. Both nymph- and adult-produced aggregation pheromones activate receptor neurones housed in sensilla basiconica. The receptor neurones in this sensillum type in solitary-reared locusts display a higher sensitivity to aggregation pheromones and to some other behaviourally relevant odours than the same type of neurones in gregarious locusts. Receptor neurones present in sensilla coeloconica respond to green leaf odours, organic acids, and nymphal odours but are inhibited by mature adult-produced aggregation pheromones. Receptor neurones housed in sensilla trichodea respond to a possible sex pheromone. No phase differences were found in the response of coeloconic- or trichoid-associated receptor neurones.