Mosquito control in Dar es Salaam. I. Assessment of Culex quinquefasciatus breeding sites prior to intervention.

In preparation for a trial polystyrene beads and pyriproxyfen for the control of Culex quinquefasciatus mosquitoes, surveys of their breeding were carried out in two contrasting areas of Dar es Salaam, Mikocheni and Ilala, during the dry season. Sanitation structures (latrines, soakage pits, septic tanks and cess pits) were the most profilic breeding places, totalling 780 in Mikocheni and 1544 in Ilala. Those in Mikocheni were estimated to contain about 1.4 times more mosquito pupae, per site, than in such structures in Ilala. This was both because a higher proportion of sites contained visible water and because sites with water were more likely to contain pupae in Mikocheni. The relative importance of the different types of structure, in terms of productivity, was the same in both areas. Although septic tanks and cess pits made up only 10.5% of the on-site sanitation structures in Ilala, they contained 53% of the total number of pupae in enclosed sites; they were therefore particularly important targets for treatment with polystyrene beads. A survey during the rainy season of sites in Ilala revealed little change in the proportion that were wet, or in the frequency of breeding in those with visible water. The number, type and area of open breeding sites varied greatly between the two study areas. In Mikocheni the area of open breeding sites was 100 times greater than in Ilala, with 97% of the 13,000 m2 being flooded grassland. In Ilala all but four of the sixty-six open breeding sites were puddles of sullage water derived from bathrooms.(ABSTRACT TRUNCATED AT 250 WORDS)