COCKROACH AGGREGATION - DISCRIMINATION BETWEEN STRAIN ODORS IN BLATTELLA-GERMANICA

Behavioural experiments on gregariousness in larval German cockroaches , Blattella germanica (L.), confirmed that this species deposits an ag gregation pheromone by body contact. Choice tests with groups of larva e indicated that they were preferentially attracted to papers conditio ned by the odour of their conspecifics, although they were able to agg regate on clean paper in the absence of cockroach odour. Individual la rvae were able to recognize the odour of their own population or strai n in the absence of conspecifics. The odour was produced and perceived by larvae at all developmental stages. We report, for the first time, experiments comparing the relative attractiveness of odours of strain s from different locations: larval cockroaches were able to discrimina te and recognize the odour of members of their own strain. Our results showed that different strains have variations of a specific odour. Al l experimental strains had similar discriminatory capacities and all p referred the odour of their own strain. When larvae were presented wit h a choice between odours from two unfamiliar strains, they appeared t o avoid these odours. (C) 1998 The Association for the Study of Animal Behaviour.