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

Abstract

Increases in arbovirus outbreaks in Sudan are vectored by Aedes aegypti, raising the medical importance of this mosquito. We genotyped 12 microsatellite loci in four populations of Ae. aegypti from Sudan, two from the East and two from the West, and analyzed them together with a previously published database of 31 worldwide populations to infer population structure and investigate the demographic history of this species in Sudan. Our results revealed the presence of two genetically distinct subspecies of Ae. aegypti in Sudan. These are Ae. aegypti aegypti in Eastern Sudan and Ae. aegypti formosus in Western Sudan. Clustering analysis showed that mosquitoes from East Sudan are genetically homogeneous, while we found population substructure in West Sudan. In the global context our results indicate that Eastern Sudan populations are genetically closer to Asian and American populations, while Western Sudan populations are related to East and West African populations. Approximate Bayesian Computation Analysis supports a scenario in which Ae. aegypti entered Sudan in at least two independent occasions nearly 70–80 years ago. This study provides a baseline database that can be used to determine the likely origin of new introductions for this invasive species into Sudan. The presence of the two subspecies in the country should be consider when designing interventions, since they display different behaviors regarding epidemiologically relevant parameters, such as blood feeding preferences and ability to transmit disease.

Microsatellite‐based analysis revealsAedes aegyptipopulations in the Kingdom of Saudi Arabia result from colonization by both the ancestral African and the global domestic forms

“…The STRUCTURE and ABC analyses indicated genetic admixture between the two genetic groupings originating from Africa or the global population in the intervening geographic regions of Sahil and the Jazan region. The mixing of these two distinct genetic forms of A. aegypti has also recently been inferred to have occurred in Sudan (Elnour et al, 2022).…”

“…To investigate the evolutionary history and test the hypothesis of genetic admixture within Saudi Arabia of the ancestral African and pantropical global forms, population samples from Thailand and Uganda were also included to represent these potential source populations (Table 1). Use of a single population to represent each form is reasonable given that there is far greater genetic differentiation between the forms than there is between populations within the forms (Elnour et al., 2022; Gloria‐Soria et al., 2016).…”

Biology and Behaviour of Aedes aegypti in the Human Environment: Opportunities for Vector Control of Arbovirus Transmission

“…However, the ease with which the forms are separable here is rare and not in any way typical of Africa. The complexity is increased by the reintroductions of Aaa in the African continent [ 206 ] and by the presence of domestic populations in West Africa [ 4 , 5 ]. The real picture is one of complexity and variation, as many of the useful morphological characters are rarely exclusive to one form and differentiation or determining “which form is present or predominant” at any particular study site, is far from straightforward.…”

The insupportable validity of mosquito subspecies (Diptera: Culicidae) and their exclusion from culicid classification

“…In Sudan, Abuelmaali et al (2021) and Elnour et al (2022) both reported geographically separated populations of a. formosus (in the west) and a. aegypti (in the east). Elnour et al (2022) wrote that "Analysis supports a scenario in which Ae. aegypti entered Sudan on at least two independent occasions nearly 70-80 years ago."…”