Salivary Secretion in wild Glossina pallidipes Austen. (Diptera, Glossinidae).

The salivation behaviour of wild G. pallidipes obtained from Lambwe Valley and Kbwezi was studied. Salivation was measured by counting the number of salivary drops secreted per minute and measuring the sizes of the stained saliva after drawing them with a camera lucida. The results confirmed observations obtained from laboratory bred flies. The quantity of saliva secreted by tsetse flies was significantly increased as the flies became hungrier. The proportion of flies salivating also increased with intensity of hunger. Female G. pallidipes secreted significantly more saliva than the males. There was no significant difference between the quantities of saliva secreted by infected and free tsetse flies; thus there is no evidence to support the suggestion that the presence of trypanosomes in the tsetse fly stimulated it to salivate copiously. Flies having trypanosome infection in their salivary glands discharge large numbers of mature parasites in their saliva. Flies with trypanosomes in their proboscis discharged relatively few mature and immature parasites in their saliva.