Abstract
BackgroundThe adaptation of Anopheles gambiae to humans and its environment involves an ongoing speciation process that can be best demonstrated by the existence of various chromosomal forms adapted to different environments and of two molecular forms known as incipient taxonomic units.MethodsThe aim of this study was to compare the epidemiologic role of Anopheles arabiens is and the molecular forms M and S of Anopheles gambiae in the transmission of Plasmodium in a rural areas of southern Senegal, Dielmo. The sampling of mosquitoes was carried out monthly between July and December 2004, during the rainy season, by human volunteers and pyrethrum spray catches.ResultsAnopheles arabiensis, An. gambiae M and S forms coexisted during the rainy season with a predominance of the M form in September and the peak of density being observed in August for the S form. Similar parity rates were observed in An. arabiensis [70.9%] (n = 86), An. gambiae M form [68.7%] (n = 64) and An. gambiae S form [81.1%] (n = 156). The circumsporozoite protein (CSP) rates were 2.82% (n = 177), 3.17% (n = 315) and 3.45% (n = 405), with the mean anthropophilic rates being 71.4% (n = 14), 86.3% (n = 22) and 91.6% (n = 24) respectively for An. arabiensis and An. gambiae M and S forms. No significant difference was observed either in host preference or in Plasmodium falciparum infection rates between sympatric M and S populations.ConclusionNo difference was observed either in host preference or in Plasmodium falciparum infection rates between sympatric M and S populations, but they present different dynamics of population. These variations are probably attributable to different breeding conditions.
Highlights
The adaptation of Anopheles gambiae to humans and its environment involves an ongoing speciation process that can be best demonstrated by the existence of various chromosomal forms adapted to different environments and of two molecular forms known as incipient taxonomic units
Species diversity A total of 1,109 An. gambiae s.l. were caught during 72 collection nights between July and December 2004 (889 by night landing catches (NLC) and 220 by pyrethrum spray catches (PSC))
PCR for species identification was performed on 920 (83%) mosquitoes belonging to the gambiae complex, resulting in 177 An. arabiensis, 316 An. gambiae molecular form M, 405 An. gambiae molecular form S and 22 hybrids M/S (Table 1)
Summary
The adaptation of Anopheles gambiae to humans and its environment involves an ongoing speciation process that can be best demonstrated by the existence of various chromosomal forms adapted to different environments and of two molecular forms known as incipient taxonomic units. The adaptation of An. gambiae to humans and its environment involves an ongoing speciation process that can be best demonstrated by the existence of a number of incipient taxonomic units, characterized by the presence of paracentric inversions leading to different chromosomal arrangements [2]. This speciation process is primarily observed in West Africa, where five chromosomal forms of An. gambiae s.s. have been described and designated with a non-Linnean nomenclature: bamako, bissau, forest, mopti and savanna [3,4]. This revealed the existence of two genetic variants referred to as the molecular M and S forms [7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
