HOW DO BLATTELLA GERMANICA (L.) AGGREGATE?

Abstract:
German cockroaches, Blattella germanica (L.), live in aggregates and are able to return to their resting sites. Stability of aggregates is ensured both by individual navigation abilities and by conspecific recognition. Naviga tion capacities (estimated by orientation angle of escape direction and by length of escape path) are due to two types of memorization processes: short-term memory with path integration cues learned during each trip and long-term memory of landmark cues in their home range. The different types of directional information used for homing are weighted and used in complement in relation to their reliability. To pinpoint their shelter, they use pheromonal cues to recognize conspecifics. Experiments revealed that cockroaches were able to discriminate and recognize the odour of members of their own strain and avoid odours of unknown strains and that cuticular hydrocarbons operate as a recognition signal allowing proximity tolerance between individuals, i.e. as an aggregation pheromone.