Distribution and Genetic Diversity of Aedes aegypti Subspecies across the Sahelian Belt in Sudan

Abstract

Aedes aegypti is the most important arboviral disease vector worldwide. In Africa, it exists as two morphologically distinct forms, often referred to as subspecies, Aaa and Aaf. There is a dearth of information on the distribution and genetic diversity of these two forms in Sudan and other African Sahelian region countries. This study aimed to explore the distribution and genetic diversity of Aedes aegypti subspecies using morphology and Cytochrome oxidase-1 mitochondrial marker in a large Sahelian zone in Sudan. An extensive cross-sectional survey of Aedes aegypti in Sudan was performed. Samples collected from eight locations were morphologically identified, subjected to DNA extraction, amplification, sequencing, and analyses. We classified four populations as Aaa and the other four as Aaf. Out of 140 sequence samples, forty-six distinct haplotypes were characterized. The haplotype and nucleotide diversity of the collected samples were 0.377–0.947 and 0.002–0.01, respectively. Isolation by distance was significantly evident (r = 0.586, p = 0.005). The SAMOVA test indicated that all Aaf populations are structured in one group, while the Aaa clustered into two groups. AMOVA showed 53.53% genetic differences within populations and 39.22% among groups. Phylogenetic relationships indicated two clusters in which the two subspecies were structured. Thus, the haplotype network consisted of three clusters.

Population Genetic Analysis of Aedes aegypti Mosquitoes From Sudan Revealed Recent Independent Colonization Events by the Two Subspecies

“…aegypti in Sudan is consistent with reports from parts of coastal East Africa dating back as far as the 1950s, based on morphology and habitats ( Mattingly, 1957 ), and later supported by genetic studies ( Brown et al, 2011 ; Gloria-Soria et al, 2016 ). These results are also in agreement with the findings from Abuelmaali et al , ( Abuelmaali et al, 2021 ), using the mitochondrial COI gene. The genetic differentiation observed between Sudan regions suggests there is little or no connectivity among populations of Eastern and Western Sudan, so it is not surprising that the two Ae.…”

“…aegypti revealed a broad range of genetic differentiation (F ST ) among mosquito populations across study sites, which is consistent with the findings from a recent study of Ae. aegypti in a large Sahelian zone in Sudan that used morphology and the Cytochrome oxidase-1 mitochondrial marker (CO1) ( Abuelmaali et al, 2021 ). Genetic differentiation between Ae.…”

“…Today, populations of Ae. aegypti in Africa can be found in urban habitats ( Paupy et al, 2008 ; Kamgang et al, 2013 ; Abuelmaali et al, 2021 ), even if they fall morphologically and genetically into Aaf. Aaf has been previously identified in African urban areas in Senegal ( Huber et al, 2008 ; Paupy et al, 2008 ; Sylla et al, 2009 ; Gloria-Soria et al, 2016 ).…”

“…Our findings are consistent with the conclusion from Brown et al ( Brown et al, 2011 ) suggesting multiple independent domestication events taking place in Africa, most probably as a response to expanding urbanization ( Gloria-Soria et al, 2016 ). The presence of Aaf and its association with human dwellings in Western Sudan suggests that Aaf might be the sole vector of arboviral diseases in this region ( Lewis, 1953 ; Abuelmaali et al, 2021 ).…”

“…( Tabachnick and Powell, 1979 ; Brown et al, 2011 ; Brown et al, 2014 ; Bennett et al, 2016 ; Gloria-Soria et al, 2016 ). In Sudan, however, little is known about the distribution and population genetics of the species ( Elnour et al, 2020 ; Abuelmaali et al, 2021 ). The current research aims to better understand the genetic composition, population structure, and ancestral origin of Ae.…”