18S rDNA as a tool for molecular characterization of mosquito species
from various regions within Limpopo.
Abstract
Anopheles mosquitos are the primary vectors for the rapid spread of
malaria in Limpopo, South Africa, negatively impacting all malaria
elimination agenda; particularly for a country with vector control as
one of the major malaria elimination strategies. The implementation of
vector control strategies, however, depends on the accurate
identification of mosquito vectors, which has been lacking in Limpopo as
a result of earlier studies that mainly relied on morphological
identification of vectors, which has numerous drawbacks that lead to
misidentification of mosquitoes, thus resulting in the development and
assignment of ineffective control strategies. All this together set back
elimination strategies and programs. The present study therefore aimed
to molecularly identify mosquitoes collected from various regions within
Limpopo province. This was accomplished by examining genetic composition
of mosquitos from different regions within Limpopo province, using
molecular genetics techniques such as 18S rDNA-based PCR analysis, 18S
rDNA sequencing, etc. This investigation was successful since 18S rDNA
was able to identify every one of the 42 mosquito samples that were
analysed, revealing that the samples belonged to 7 different Anopheles
species and the majority of the species were molecularly demonstrated to
have been misidentified morphologically. The outcomes of the molecular
analysis, which involved comparing the query sequences to the sequences
in GenBank, were supported by the close relationship among mosquitoes of
the same species in maximum likelihood trees and the presence of high to
100% bootstrap support values, giving confidence to conclude that
mosquitoes of the same species under study are genetically related. Due
to a number of constraints covered in this study, morphological
identification of mosquitoes is prone to misidentification of species,
hence genetic characterization is recommended to be used as a
confirmatory approach in the identification of the species.