Judith REINHARD-1, Manfred KAIB-2
1-Bundesanstalt für Materialforschung und -prütung,
D-12200 Berlin, Germany
2-Lehrstuhl Tierphysiologie, Universität Bayreuth,
D-95440 Bayreuth, Germany
Chemical signals from secretions of different exocrine glands modulate a variety of behavioural patterns in termite societies. During food exploitation workers of the African termite Schedorhinotermes lamanianus Sjöstedt (Isoptera: Rhinotermitidae) release the secretion of their labial gland directly onto the food. The secretion carries a signal, which stimulates feeding and leads to aggregations of gnawing workers at feeding sites [1,2].
The paired labial gland of the French termite Reticulitermes santonensis Sjöstedt (Isoptera: Rhinotermitidae) is located in the meso- and metathorax. In the head, the gland ducts join with the ducts of the nearby located water sacs. In a feeding bioassay, workers of R. santonensis had to choose between two semicircles of moist filterpaper as food. The termites significantly preferred one of the semicircles, if labial gland secretion was applied on it. That is, the labial gland secretion of R. santonensis carries a feeding stimulating signal as well. The content of the water sacs is not active in this context. The feeding stimulating signal proved to be extremely polar (soluble in water only), heat-resistant up to 100ºC for at least 24h and thus to be very persistent These chemical properties point to e.g. salts or saccharides as signal substances.
Apart from its own secretion, the labial gland secretions of 8 further termite species from 5 different families, including S. lamanianus, all proved to have this feeding stimulating effect on R. santonensis. This points towards a chemically similar or even identical principle in the labial gland secretion of termites.
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