Species composition and diversity of malaria vector breeding habitats in Trincomalee District of Sri Lanka

Abstract

Introduction. Mosquito larval ecology is important in determining larval densities and species assemblage. This in turn influences malaria transmission in an area. Therefore, understanding larval habitat ecology is important in designing malaria control programs. Method. Larval surveys were conducted in 20 localities under five sentinel sites (Padavisiripura, Gomarankadawala, Thoppur, Mollipothana, and Ichchallampaththu) in Trincomalee District, Eastern Province of Sri Lanka, between June 2010 and July 2013. The relationship between seven abiotic variables (temperature, pH, conductivity, Total Dissolved Solid (TDS), turbidity, Dissolved Oxygen (DO), and salinity) was measured. Results. A total of 21,347 anophelines were recorded representing 15 species. Anopheles subpictus 24.72% (5,278/21,347) was the predominant species, followed by 24.67% (5,267/21,347) of An. nigerrimus and 14.56% (3,109/21,347) of An. peditaeniatus. A total of 9,430 breeding habitats under twenty-one categories were identified. An. culcicifacies was noted to be highest from built wells (20.5%) with high salinity (1102.3 ± 81.8 mg/L), followed by waste water collections (20.2%) having low DO levels (2.85 ± 0.03 mg/L) and high TDS (1,654 ± 140 mg/L). Conclusion. This study opens an avenue to explore new breeding habitats of malaria vectors in the country and reemphasizes the requirement of conducting entomological surveillance to detect potential transmission of malaria in Sri Lanka under the current malaria elimination programme.