Species Composition, Diversity, and Distribution of Mosquitoes (Diptera: Culicidae) in Kalutara District, Sri Lanka

Abstract

Mosquitoes are evolutionary more successful organisms and they play an important role in disease transmission. Due to the lack of data on mosquito diversity, this study was designed to evaluate the relative abundance (RA), diversity, and distribution (C) of mosquito larvae in Kalutara district, Sri Lanka. The larval survey was carried out every two months from January 2019 to December 2021 with 13 Medical Officers of Health areas in the district. Standard dipping, pipetting and well netting methods were used as sampling methods. Species diversity was calculated by the Shanon Weiner diversity index (H), Simpson index of diversity (1-D), and Simpson index of dominance (D). A total of 24,344 mosquito larvae belonging to 13 genera (Aedes, Anopheles, Armigeres, Culex, Ficalbia, Heizmania, Hodgesia, Lutzia, Malaya, Mansonia, Toxorhynchites, Tripteroides and Uranotaenia) and 57 species were identified. The highest diversity of mosquito larvae was found in stream margins (H=2.14, 1-D=0.86) and Ae. albopictus (RA=47.6) was the most prevalent mosquito species in the district. In addition, Ae. vittatus, Ae. albopictus, Ar. subalbatus, Cx. quinquefasciatus, and Tripteroides sp.1 were constantly distributed (C>80%). One-way ANOVA showed that there was no significant seasonal variation in mosquito larvae in terms of species richness (P=0.984), D (P=0.728), 1-D (P=0.728), and H (P=0.871). However, two potential vectors of malaria; An. vagus, (n=11; RA=0.0; C=15%), An. varuna (n=50; RA=0.2; C=8%), two vectors of dengue and chikungunya; Ae. aegypti (n=715; RA=2.9; C=54%), Ae. albopictus (n=11,591; RA=47.6; C=100%), vector of bancriftian filariasis; Cx. quinquefasciatus (n=2,393; RA=9.8; C=100%), one vector of brugian filariasis; Ma. annulifera (n=1; RA=0.0; C=8%), and three vectors of Japanese encephalitis; Cx. tritaeniorhynchus (n=432; RA=1.8; C=69%), Cx. gelidus (n=54; RA=0.2; C=8%) and Cx. fuscocephala (n=53; RA=0.2; C=15%) were identified in different aquatic habitats. Therefore, studies on the diversity and distribution of mosquito fauna should be reinforced to cope with the potential challenges of mosquito-borne diseases.