Croissance des trachees au cours de l'evolution de la physogastrie chez la reine des Termites superieurs (Isoptera : Termitidae)

Abstract

The evolution of tracheae and tracheoles during the development of the queen's physogastry has been studied in 2 species of higher termites : Cubitermes fungifaber (Termitinae) in which the queen's physogastry is limited, and Bellicositermes natalensis (Macrotermitinae) in which the queen's physogastry is very important. The tracheae of the alate adults are similar to those of other insects. They do not show structural sexual dimorphism. In those without endocuticle tracheae, the presence of chitin poses a problem which is discussed. In the young imago queen the development of the tracheae is caused by a double cellular activation, which determines the growth of the tracheal epithelium by cellular multiplication, and the transformation of the intima by cuticular secretion; the latter leads to an exceptionally thick and partially sclerotized intima. The taenidial spiral in the physogastric queen is due to the transformation of the taenidial spiral of the alate adult; there are no new taenidial folds. The development of the intima involves growth of the epicuticle. This growth is carried out at a distance from the epithelial cells, by transport of dense maiterial visible in electron microscopy. The tracheae of the physogastric queen seem to assume a supplementary function of supporting the aerated organs.