Salivary secretion in three species of tsetse flies (Glossinidae).

The study of the mechanism and process of salivation in tsetse flies is of paramount importance towards a fuller understanding of the transmission of trypanosomiasis and nagana diseases. Gordon, Crewe and Willett (1956) made direct observations, through a microscope, of the haustellum of G. morsitans as it penetrated into the ear of an anesthetised mouse and found that probing was accompanied by a copious but intermittent ejection of saliva from the hypopharynx. The outpouring of the saliva commenced during penetration of the stratum corneum and was maintained throughout probing of the tissues. During engorgement, blood is taken in through the labium while saliva was discharged from the hypopharynx at the same time. Besides this work, very little else seems to have been done on the salivary secretion by tsetse flies especially in relation to the hunger cycle of the fly and to the species of tsetse. These aspects were studied on three important species of tsetse and are reported upon in this paper.