The Analysis of Mortality and Survival Rates in Wild Populations of Mosquitoes

Abstract

Methods are described for the analysis of survival data. The re-analysis of survival data for wild populations of 11 tropical spp. of mosquitoes [Aedes aegypti, Anopheles gambiae, A. funestus, A. arabiensis, A. flavirostris, A. farauti, A. albimanus, A. darlingi, A. vagus, Culex quinquefasciatus and Mansonia uniformis] revealed that in most of these populations the adult female mortality rates were not independent of age, as had commonly been supposed, but increased with age. The patterns of mortality of most of the populations were well described by the Gompertz function, according to which the rate of mortality increases with age in such a manner that its logarithm is directly proportional to age. The epidemiological implications of these findings were examined by calculating the longevity factor, which is a component of vectorial capacity, for 7 of these populations. Considerable differences were obtained in estimates of the longevity factor when the Gompertz model of mortality was substituted, in appropriate cases, for the widely used exponential model.