ROLE OF CUTICULAR LIPIDS IN NESTMATE RECOGNITION OF THE EUROPEAN HORNET VESPA-CRABRO L. (HYMENOPTERA, VESPIDAE)

In order to elucidate nestmate recognition in the European hornet Vesp a crabro L. (Hymenoptera, Vespidae) the behavioral response of workers towards dead nestmates and non-nestmates was tested in a bioassay. Th e testing arena was integrated in a socially and physically intact nes t, in an effort to ensure natural behavior of the extremely sensitive wasps. The hornets responded to dead non-nestmates with aggressive beh avior, whereas dead nestmates were tolerated or ignored. Solvent extra ction of non-nestmate dummies resulted in significant decrease of agon istic behavior of the responding workers. Their behavior towards extra cted non-nestmate dummies was no longer statistically distinguishable from the behavior towards nestmate dummies treated in the same way. Tr eatment of extracted nestmate dummies with cuticular extracts of non-n estmates induced aggressive behavior in the responding workers, wherea s treatment of the extracted non-nestmate dummies with cuticular extra cts of nestmates lead to a significant decrease of agonistic behavior, when compared with untreated non-nestmates. A statistical comparison of the two colonies with regard to the chemical composition of the cut icular extracts revealed that relative peak areas of 5 monoenes, 4 met hyl branched alkanes, 1 terpenoid ester, and 2 n-alkanes differed sign ificantly. The chemical analysis of the Dufour's gland revealed that a ll 16 compounds identified in the gland were also present in the cutic ular extracts. The results strongly indicate that particular mixtures of cuticular lipids play an important role in nestmate recognition of crabro.