A comparison of the feeding behaviour of tsetse and stable flies.

In Zimbabwe, observations were made of the behaviour of individual stable flies (Stomoxys spp.) (Diptera: Muscidae) and tsetse (Glossina spp.) (Diptera: Glossinidae) feeding on cattle during the wet (Stomoxys and tsetse) and dry (tsetse only) seasons. For Stomoxys landing on adult cattle, only 27% took a full meal (mean feeding time = 147 s). Most Stomoxys left the host before completing their meal, largely due to disturbance by the host's defensive behaviour (24%, mean time = 59 s) or other flies (44%, 71 s). The probability of a Stomoxys leaving the host progressively increased with time. Simultaneous observations of tsetse showed that, compared to Stomoxys, their feeding success was lower (15%), feeding was interrupted earlier (33 s) and the time taken to complete a meal was shorter (109 s). Further studies of tsetse across different seasons and hosts showed that feeding success varied according to host age (adult = 7%; calf = 3%) and was negatively correlated with the frequency of host defensive behaviour and the relative abundance of non-biting Diptera. Disturbances were more often caused by host behaviour (69%) than other flies (31%) and the probability of tsetse leaving decreased with time on the host. Overall, these results suggest that tsetse and Stomoxys have different feeding strategies. In particular, tsetse appear to be more responsive to host defensive behaviour, which reduces their feeding success relative to Stomoxys. These behavioural differences are consistent with the respective life-history characteristics of Stomoxys and tsetse.