The influence of age and season on dispersal and recapture of <i>Anopheles culicifacies</i> in Sri Lanka

Abstract

Abstract. 1. Three mark—release—recapture experiments with Anopheles culicifacies were carried out at different seasons in Sri Lanka. Blood fed females were collected daily in cattle baited huts, marked with fluorescent powder and released in the same village. In two of the experiments males and females were reared, marked when newly emerged, and released. The recapture rates were recorded in the same village and in a second village 2 km away. 2. The mosquitoes marked when already mature yielded an estimate that 2–7% of the mosquitoes in the second village had flown from the first. The recapture rate of reared mosquitoes in the first village was much lower than with those marked when already mature. This difference could be at least partly attributed to a tendency to disperse when young, as shown by the considerable number of recaptures of young mosquitoes in the second village. 3. By varying the colour used for marking, estimates were made of the amount of dispersal from hut to hut in the first village, the daily survival rate and the proportion of the wild population resting in the collecting huts each day. 4. Using the latter two estimates equations have been solved predicting the rate of build‐up of the proportion of recaptures. These predictions were compared with the observed results. The data on dispersal are discussed in relation to possible method for delaying the build‐up of insecticide resistance.