Task-related variation of postpharyngeal and cuticular hydrocarbon compositions in the ant Myrmicaria eumenoides
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O R I GI N A L P A P E R
M. Kaib á B. Eisermann á E. Schoeters J. Billen á S. Franke á W. Francke
Task-related variation of postpharyngeal and cuticular hydrocarbon compositions in the ant Myrmicaria eumenoides Accepted: 19 August 2000 / Published online: 20 October 2000 Ó Springer-Verlag 2000
Abstract In the ant Myrmicaria eumenoides we investigated postpharyngeal and cuticular hydrocarbons. At eclosion the glands contained almost no hydrocarbons and there were no lipid inclusions in the glandular epithelium. During the ®rst 3 weeks of adult life the amount of hydrocarbons in the gland increased until day 5, and then remained constant while the lipid content in the epithelium increased steadily. Intracolonial hydrocarbon compositions were not uniform. Compositions of postpharyngeal and cuticular hydrocarbons in individual ants varied simultaneously, but in dierent manner depending on the tasks of the ant (brood-tenders, foragers, scouts). Variations on the cuticle were greater than in the gland, but they were strongly correlated. Independent of ants' age and task, cuticular hydrocarbon compositions were dominated by alkenes and alkadienes. Task-speci®c dierences in cuticular compositions were mainly in the amount of alkenes (high in foragers) and alkadienes (high in brood-tenders). Variation of hydrocarbons was low in ants up to 10 weeks old. Thereafter, ants fell into two groups: (1) ants that did not change their hydrocarbons and remained in the nest, and (2) ants that changed their hydrocarbon compositions and became foragers. These results contribute to an ongoing discussion of the dynamic relationship between postpharyngeal and cuticular hydrocarbons. Key words Gland ontogeny á Age á Task á Nestmate recognition á Colony label
M. Kaib (&) á B. Eisermann Lehrstuhl Tierphysiologie, UniversitaÈt Bayreuth, 95440 Bayreuth, Germany e-mail: [email protected] Tel.: +49-921-552482; Fax: +49-921-552794 E. Schoeters á J. Billen Zoological Institute, University of Leuven, Leuven, Belgium S. Franke á W. Francke Institut fuÈr Organische Chemie, UniversitaÈt Hamburg, Hamburg, Germany
Abbreviations BT brood-tenders á C cuticle á F foragers á PPG postpharyngeal gland á Sc scouts
Introduction In social insects, nestmate recognition allows the cohesiveness of a colony and denies access to alien conspeci®cs. Nestmate recognition has been studied in a number of ant species (e.g. HoÈlldobler and Michener 1980; Gadagkar 1985; Breed and Bennett 1987; Vander Meer and Morel 1998). During interaction between aliens, aggressive behaviour is initiated after an actual physical contact anywhere on the antagonist's body, which suggests that nestmate recognition cues come from chemicals associated with the cuticle (HoÈlldobler and Michener 1980; Bradshaw and Howse 1984). The cuticular lipids include fatty acids, alcohols, aldehydes, ketones, wax esters, and hydrocarbons (Lockey 1988). Hydrocarbons are the dominant chemicals found in most social insects. Their compositions vary between species and between conspeci®c colonies,
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