Population increases in Culex pipiens fatigans Wiedemann. A review of present knowledge

The author reviews the growing body of evidence that urban populations of Culex pipiens fatigans have increased extensively during recent years in both Africa and Asia. Two main factors seem to be responsible-the spread of urbanization, providing favourable habitats for this essentially urban mosquito; and the increasing use of residual insecticides, leading to disregard of conventional sanitary measures and a consequent proliferation of suitable culicine breeding-places. In addition, it is possible that the use of insecticides may be bringing about a selective destruction of less resistant competitors of C. fatigans.Present knowledge of this species is too exiguous to allow of a full understanding of the reasons for its increase, to assess its significance in relation to disease transmission, or definitively to adopt economical and practicable control methods. However, a number of possible lines of approach to this problem are suggested.