The biting flies of the Kano Plains, Kenya: Part II. Larval habitats of common mosquito species (Dipt., Culicidae

Abstract

This paper describes the results of studies on the chemical and physical characteristics of terrestrial breeding habitats of common mosquito species in the Kano Plains of Kenya. The study was initiated following the decision by the Government of Kenya to establish in the Kano Plains in the near future a massive irrigation scheme for rice production. In order to determine to what extent irrigation would affect populations of the prevalent mosquito species, it seemed particularly important to undertake preliminary studied to establish the larval habitat preference of potential disease vectors. It was felt such studies would form a logical basis for the adoption of biological or cultural control methods concurrent with the construction of large-scale irrigation schemes. Six natural terrestrial mosquito breeding habitats were recognized in the Kano Plains of Kenya by their condition, i.e., temporary or permanent, presence or absence of emergent plants, and by the chemical and physical characteristics of their water. Between September 1968 and March 1970, 13 mosquito species were found breeding in these habitats. Most species were restricted to a few habitats; only four showed a wide occurrence, being found in at least four. Anopheles gambiae Giles and Culex annulioris Theo. exploited all the six habitats, suggesting that the characteristics studied were probably not critical to their selection of a breeding site. Mansonia and Coquillettidia spp. were restricted to habitats with some plants, indicating their dependence on such vegetation for respiration and protection. The indiscriminate selection of breeding sites by disease vectors, e.g. A. gambiae, A. pharoensis Theo. and Culex pipiens fatigans Wied., is worth noting in irrigation schemes.