Anopheles arabiensis larval habitats characterization and Anopheles species diversity in water bodies from Jozini, KwaZulu-Natal Province.

Abstract

<title>Abstract</title> <bold>Introduction:</bold> The South African government is now implementing winter larviciding as a supplementary vector control tool. To achieve effective larviciding programme there is a need to understand the distribution of the larval habitats of vectors and their corresponding ecology. This study aimed to determine larval breeding habitats of anophelines and characterize the physicochemical properties of water that promote the proliferation of <italic>Anopheles arabiensis</italic>immature stages of this species. <bold>Methods:</bold> A desktop survey of water bodies was carried out followed by a physical search of potential <italic>Anopheles</italic>breeding habitats. Anopheline larvae were sampled from water habitats in January and April 2021. At each positive habitat, physicochemical characteristics of the water including pH, electrical conductivity, total dissolved solids and salinity were measured. The collected <italic>Anopheles</italic> larvae were reared to adults and identified to genus and species level using morphological and molecular techniques. Factors associated with the presence of <italic>Anopheles arabiensis</italic>larvae in the breeding habitats were determined. <bold>Results: </bold>Desktop survey identified 72 potential water bodies and only 38 were physically identified as potential anopheline larval habitats. Of these 84% (n=32/38)<italic> </italic>were positive for <italic>Anopheles</italic> larvae. A total of 598 <italic>Anopheles</italic> larvae collected, of which 59.4% (n=355/598) emerged into adults. Morphological identification of these adults, showed that the <italic>Anopheles gambiae</italic>complex accounted for 70% (n=250/355) of the collections. Polymerase chain reaction species of the <italic>Anopheles gambiae</italic>complex showed predominance of <italic>Anopheles merus</italic> 56% (n=83/147) in January, and predominance of <italic>Anopheles arabiensis</italic> in April, 91% (n=80/88). All physicochemical parameters differed significantly between the breeding sites (p&lt;0.05 in all instances), except for electrical conductivity (p =0.07). The aquatic habitats surveyed showed that the impermanency of the breeding sites, neutral to alkaline pH, moderate salinity and low total dissolved solids were associated with the occurrence of <italic>Anopheles arabiensis</italic> larvae. <bold>Conclusion:</bold> This study showed that <italic>Anopheles arabiensis</italic> primarily breed in small temporary water habitats characterized by neutral pH. Larviciding that targets <italic>Anopheles arabiensis </italic>should focus on temporary water bodies with neutral, moderate salinity and low total dissolved solids.