Comparative study of Anopheles gambiae larval habitats and larval densities in relation to physicochemical parameters in three urban sites in Abidjan district.

Abstract

The knowledge of Anopheles gambiae s.l larval habitats is important in order to choose an appropriate malaria control strategy. The purpose of this study is to identify potential mosquito breeding sites in the district of Abidjan and analysed the relationship between environmental factors and larval abundance. Abiotic characteristics such as temperature, pH, dissolved oxygen, salinity, conductivity and biotic characteristics (larval density) of Anopheles gambiae s.l. larval habitats were examined from January to November 2021 in three areas of the Abidjan district. The larval collection was performed using dippers and pipettes. During the rainy season, the proportion of breeding site was more important in NDotre and in the port area of Treichville in contrast to 43rd BIMA, where furrows predominated. On the other hand, during the dry season, the proportion of breeding sites was higher in 43rd BIMA area, followed by the port area with and NDotre with. The proportions of breeding sites were highly significant between the two seasons in each site. Mean larval densities varied significantly between sites ({chi}2 = 108.9, df=2, p < 0.001. In Port area and NDotre, temperature was positively correlated with larval density (r=0.2, p < 0.001). In the 43rd BIMA, conductivity (r=0.8, p < 0.001), pH (r=0.64, p < 0.001) and salinity (r=0.2, p < 0.001) were positively correlated with larval density, while dissolved oxygen was negatively correlated in in port area, 43rd BIMA and NDotre (r = -0.01, p < 0.001; r = -0.53, p < 0.001; r = -0.3, p < 0.001) respectively. This study revealed that the larval habitats of An. gambiae s.l. were not very diverse in these areas. These larval habitats were mainly affected by human activity. These data may shed light on malaria control strategies in the cities.