THE INTERACTION OF TASTE AND HEAT ON THE BITING RESPONSE OF THE TSETSE-FLY GLOSSINA-FUSCIPES-FUSCIPES

Tsetse flies probe more on a heated surface with a trace of uric acid than on one without. Uric acid is one of the components of human sweat and it elicits spike responses from taste hairs on the flies' legs. I n this paper it is examined how heat from the surface and taste intera ct to affect the biting behaviour of Glossina fuscipes fuscipes Newste ad 1910 (Diptera: Glossinidae) over successive days of food deprivatio n. The biting behaviour consists of bouts of probing, both ambulatory and stationary, intercalated with short hops of flight. The number of bouts increases over successive days, whereas the average bout duratio n does not. Although uric acid alone could not induce the flies to pro be, in combination with surface heat it affected the flies greatly Ave rage bout duration was two-fold that on a heated surface not treated w ith uric acid. The frequency of bouts was not affected by uric acid. T hese experiments and auxiliary ones on mechanoreceptive input and odou rs lead to the insight that the factors which affect biting behaviour can be viewed as a hierarchy. The hierarchy extends from those that af fect the onset of biting to those that affect its course.