Characterization of Anopheles gambiae (Giles) Breeding Sites in Gokwe South, Zimbabwe

Abstract

Anopheles gambiae Giles larval breeding habitats were characterized in Gokwe South district in Zimbabwe to determine the ecological parameters of Anopheles breeding sites and identify their associations with larval density. This was also done to determine abundance, distribution and extent of cohabitation of the anophelines and to identify them to species level. Larval abundance in swamps, drainage channels, a dam and a pool of water were determined through sampling conducted using the dipping technique. Sampled larvae were then reared to adults and identified to species level using morphological characters. Habitats were characterized based on vegetation, water quality, habitat permanence, pH, conductivity, turbidity, dissolved oxygen, temperature, salinity, total dissolved solids, calcium, nitrates and chlorides. Anophelines were found breeding in swamps primarily populated with Typha species. The water in the breeding sites was dirty and organically polluted with decaying plant and animal waste. Data analysis using variable selection by stepwise regression followed by multiple regressions of larval densities with significant variables showed that the abundance of mosquito larvae was positively correlated with salinity. Larval density was not affected by pH, conductivity, turbidity, total dissolved solids, dissolved oxygen, temperature, calcium, nitrates and chlorides. Three members of the An. gambiae complex were identified: An. arabiensis, An. merus and An. quadriannulatus. While An. arabiensis was the most abundant and widely distributed species, An. merus was predominant at Masakadza where breeding sites had high levels of salinity. On the other hand, An. quadriannulatus occurred in low densities but in association with An. arabiensis.