Nestmate recognition in Parischnogaster striatula (Hymenoptera Stenogastrinae), visual and olfactory recognition cues

The recognition of nestmates from alien individuals is a well known phenome non in social insects. In the stenogastrine wasp Parischnogaster striatula, we investigated the ability of females to recognize nestmates and the cues on which such recognition is based. Recognition of nestmates was observed in naturally occurring interactions between wasps approaching a nest and th e resident females on that nest. This recognition was confirmed in experime nts in which nestmates or alien conspecifics were presented to resident fem ales. In naturally occurring interactions, nestmates generally approach the ir nest with a direct flight, while aliens usually hover in front of the ne st before landing. In experiments in which the presented wasps were placed close to the nest in a direct manner, antennation of the presented wasp gen erally occurred, indicating that chemical cues are involved. Experiments in which dead alien individuals, previously washed in hexane, and then reappl ied with extracts were recognized by colonies giving further evidence that chemical cues mediate nestmate recognition. Epicuticular lipids, known to b e nestmate recognition cues in social insects, were chemically analysed by GC-MS for 44 P. striatula females from two different populations (13 differ ent colonies). Discriminant analysis was performed on the data for the lipi d mixture composition. The discriminant model showed that, in the samples f rom these two populations, 68.2% and 81.9% of the specimens could be correc tly assigned to their colony. (C) 2001 Elsevier Science Ltd. All rights res erved.