Integration of behaviourally relevant odours at the central nervous level in solitary and gregarious third instar locusts, Schistocerca gregaria

Integration of behaviourally relevant odours at the central nervous level o f 3rd instar nymphal desert locusts, Schistocerca gregaria, showed phase- a nd (developmental) stage-dependent characteristics which correlated with di fferences in the number of olfactory sensilla. Antennal lobe (AL) neurons o f gregarious locusts generally responded more frequently and showed a highe r sensitivity to the tested stimuli. However, AL neurons of solitary locust s responded significantly more frequently to phenylacetonitril, the major c omponent of the adult aggregation pheromone. Pheromone-specific, plant-spec ific and pheromone-plant generalist neurons were found in both phases. The response spectra of pheromone-specific neurons correlated with the potentia l behavioural significance of attractant chemical cues in the environment. Neurons of both phases responded specifically to stage-specific aggregation -pheromone components and to other chemical cues that may be involved in th e location of suitable roosting and foraging sites. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.