The significance of mosquito longevity and blood-feeding behaviour in the dynamics of arbovirus infections.

Mosquito longevity and blood-feeding behaviour are very important but neglected factors in the dynamics of arbovirus infections as changes in them affect transmission rates exponentially. Some mosquito species feed on a narrow range of vertebrates, some on a wide range, both influenced by host-availability and other environmental and behavioural factors. Only those which feed on maintenance hosts contribute to maintenance of the infection. Some species change their feeding pattern with season. The frequency of blood-feeding depends inter alia on environmental temperature. Longevity is perhaps most important: the majority of mosquitoes infected probably do not survive long enough to become infective; it is influenced by relative humidity, temperature and predation. Longevity, feeding frequency and the extrinsic incubation period are all temperature dependent and are therefore important rate determinants in seasonal epizootics or epidemics. Equally, their relative stability in the tropics contributes to the equilibrium of an enzootic or endemic.