Molecular Characterization Of Malaria Vectors In Gonjasame District: The Impact Of Insecticide Treated Net Interventions

ABSTRACT

An entomological survey was conducted in the lowland and highland of Gonja Maore and Bombo villages respectively in Same District north - eastern Tanzania. The aim of this survey was to estimate the malaria vectors abundance and to determine the malaria vector composition of Anopheles gambiae and Anopheles funestus sibling species. Mosquitoes were collected from two identified villages with houses preferred for mosquito resting. In each of the selected village, twelve houses were provided with CDC light traps and mosquito magnet traps to collect indoor and outdoors mosquitoes respectively. The collected mosquitoes were sorted morphologically and identified by using dichotomous taxonomic key followed by preservation for molecular genotyping. DNA extraction was done using modified Bender buffer method whereby each mosquito was treated individually. The DNA were analyzed by polymerase chain reaction and the resulting amplified DNA was run in the 2% agarose gel electrophoresis parallel with ladder marker and photographed in the ultraviolet trans-illuminator light (UVP) to visualize the bands which stained by ethidium bromide. The results of this study indicate that, An. arabiensis were predominant sibling species of the An. gambiae complex in the study area, followed by Anopheles rivulorum and Anopheles leesoni for the malaria vectors. Furthermore, it was found that there has been a marked change in sibling species composition whereby Anopheles gambiae s.s. changed from being the most abundant in the past, to become the most rare species and An. arabiensis had changed to become the most common species in the study area. It is concluded that the decline in population of An. gambiae complex has excessively affected the most important malaria vector and thus reducing its role in the transmission of malaria in the study areas. It is recommended to carry out longitudinal study which will provide more information on malaria vectors composition of the sibling species and seasonal variation of the vectors.