Studies on some of the physical and biological factors affecting the abundance of the Aedes simpsoni (Diptera: Culicidae) complex-larvae and pupae in plant axils

Some physical and biological factors affecting the abundance of larvae and pupae of the Aedes simpsoni (Theobald) complex, in leaf axils of different plants at several locations in Uganda, were investigated during the rainy and dry seasons. The mean number of axils per plant, axils containing larvae and pupae, and the mean number of larvae and pupae per ml of axil water all varied between seasons and locations. The percentage of axils containing larvae and pupae increased with volume of water in the axils of the different plants. The mean number of larvae and pupae per axil containing water also increased with water content of the axils. There was more water in the axils during the rainy than during the dry seasons. The mean temperature of water was lower in Xanthosorna sagittifoliurn (20.4°C) and Colocasia esculentum (22.1°–22.7°C) than in those of banana (25.0°–27.2°C) and this affected developmental rates of larvae and pupae. The indices of association between larvae and pupae of the A. simpsoni complex and Malaya taeniarostris (Theobald) did not indicate competition and there was some habitat segregation between them. The volume and temperature of water in the axils appeared to be the major factors affecting larval and pupal abundance of A. simpsoni in the axils.