Morphological and Molecular Identification of Mosquitoes species from Kosti region (White Nile State)

Abstract

Mosquitoes play an important role as potent vectors of pathogenic micro-organisms namely protozoans, arboviruses and filarial worms. They are able to transmit human malaria and other diseases like yellow fever, dengue, filariasis and encephalitis to humans and animals. The main aim of the study was to identify the main mosquitos' species in the study areas. The current study was undertaken in September, October and November 2015 and August 2016 in ten different sites A (Almrabie, Alnsr, Alskahdeed and Alia), B (Kadugli, Block 32 and Alraba) and C (Alshati, Block 26 and Althwrat) in Kosti district. Mosquitoes were collected by hand collection (HC) and spray sheet collection (SC). The collected mosquitoes were morphologically identified as 18.7% An. gambiae complex, 0.8% An. pharoensis, 40.3% Cx. quinquefasciatus, 39.8% Cx. univittatus, and 0.4% Cx. pipiens. Anopheles and Culex spp were found throughout the study period, but Culex spp were the most abundant. A trial was made to study the cytogenetics of mosquitoes in the area. The polytene chromosomes were prepared from the ovarian nurse cells of both Anophelines and Culicine mosquitoes. In order to solve the problem of morphological similarities in the same species, and to confirm the morphological identification results, a molecular analysis was carried out. To this end, DNA extraction and PCR were performed for molecular identification of An. gambiae complex, using UN and GA oligonucleotide primers. The species-specific PCR identification using UN and AR oligonucleotide primers revealed that An. arabiensis was the only member of the An. gambiae complex present in the study areas. In addition, Internal transcribed spacer (ITS-2) – PCR was used on Culicine samples to characterize the species, the result of which revealed different band size amplified by different mosquito species. There was a significant variation in the distribution of the different mosquitos’ species within the 10 different localities in Kosti district. These findings are of importance in the planning and implementation of vector control strategy in the Kosti region, White Nile State.