MOSQUITO-CONTROL IN DAR-ES-SALAAM .2. IMPACT OF EXPANDED POLYSTYRENE BEADS AND PYRIPROXYFEN TREATMENT OF BREEDING SITES ON CULEX-QUINQUEFASCIATUS DENSITIES

In two contrasting areas of Dar es Salaam (Ilala and Mikocheni) all en closed breeding sites of Culex quinquefasciatus, such as latrines and septic tanks, were treated with a floating layer of expanded polystyre ne beads. 7 months later checks in both study areas revealed only one site (from which the polystyrene had been removed during emptying) con taining immature stages of Cx quinquefasciatus. Open breeding sites su ch as areas of flooded land and blocked drains were treated with pyrip roxyfen (an insect growth regulator) at a concentration of 0.1 ppm. Em ergence of Cx quinquefasciatus adults from these sites was inhibited f or 4 weeks during the rainy season and for up to 11 weeks during the d ry season.The problem of mosquito breeding sites caused by bathroom su llage water was addressed through a combination of health education an d indirect pressure from the Urban Malaria Control Project (UMCP) via local community leaders. Households responsible for these sites were e ncouraged to eliminate them by diverting the water into an enclosed dr ainage structure, usually a pit latrine. After two weekly visits 64.7% of households had complied and 93.4% had complied after five visits. 5 months later, only 15.7% had reverted to allowing sullage water to c ollect into puddles. Densities of Cx quinquefasciatus adults dropped b y 76.7% in Mikocheni and by 46.2% in Ilala following intervention, but increased by 84.9% and 25.6% in two untreated comparison areas. The r easons for differential success of the combined interventions in the t wo treated areas are discussed.