DENSITY, SURVIVAL AND DISPERSAL OF ANOPHELES-GAMBIAE COMPLEX MOSQUITOS IN A WEST-AFRICAN SUDAN SAVANNA VILLAGE

To obtain information on adult populations of Afrotropical malaria vec tor mosquitoes, mark-release-recapture experiments were performed with Anopheles females collected from indoor resting-sites in a savanna ar ea near Ouagadougou, Burkina Faso, during September 1991 and 1992. Res ults were used to estimate the absolute population densities, daily su rvival rates, and dispersal parameters of malaria vectors in that area . In 1991 a total of 7260 female Anopheles were marked and released, o f which 106 were recaptured in the release village and 6 in the neighb ouring villages, a total recapture rate of 1.5%. The following year 13 ,854 female Anopheles were released and 116 recaptured in Goundri and 8 in the neighbouring villages, a total recapture rate of 0.9%. Recapt ures were found in three of eight villages near Goundri. Nearly all of the recaptured mosquitoes were An.gambiae s.l. Of these, molecular de termination revealed that An.gambiae s.s. and An.arabiensis were prese nt in a ratio of similar to 2:3. Two simple random models of dispersal were simulated and the parameters of the models determined by searchi ng for the least-squared fit between simulated and observed distributi ons. The mean distance moved by individual mosquitoes, estimated in th is way, ranged 350-650 m day(-1), depending on the model and the year considered. Population densities were estimated using the Lincoln Inde x, Fisher-Ford and Jolly's methods. The estimates of population size h ad high standard errors and were not particularly consistent. A 'conse nsus' value of 150,000-350,000 mosquitoes is believed to apply for the An.gambiae s.l. female population. Survival was estimated to be 80-88 % per day.