Water quality and immatures of the M and S forms of Anopheles gambiae s.s. and An. arabiensis in a Malian village

Frances E Edillo,Charles E Taylor,Frederic Tripét,Yeya T Touré,Gregory C Lanzaro,Guimogo Dolo

doi:10.1186/1475-2875-5-35

Abstract

IntroductionThe associations between the immatures of Anopheles gambiae s.s. (Diptera: Culicidae), its M and S forms, and Anopheles arabiensis among and within larval breeding habitats in Banambani, Mali were investigated under varying conditions of water quality and rainfall. The intent was to elucidate on niche partitioning of these taxa.MethodsImmatures of An. arabiensis, An. gambiae s.s., and its M and S forms were sampled every alternate day for a month in mid-rainy season from three sampling sites in each of the larval breeding habitats (rock pools, swamp, and puddles). Water quality was characterized by alkalinity, conductivity, dissolved oxygen (D.O.), nitrate, orthophosphate, pH, temperature, total dissolved solids (TDS), and turbidity. A type 3 analysis of the GENMOD model was used to examine the associations between the proportional frequencies of young (first and second instar larvae) and old (third and fourth instar larvae and pupae) or total immatures of species or forms among sampling sites within and among larval breeding habitats during a category of rainfall as influenced by water quality.ResultsOf the 4,174 immatures sampled, 1,300 were molecularly identified to species and forms. Significant association between the proportional frequencies of young larvae of An. arabiensis, An. gambiae s.s., its M and S forms was found among sampling sites within habitats but not among larval breeding habitats. The proportional frequencies of young larvae of M and S forms varied daily perhaps due to recruitment, mortality, and dispersal within habitats. Conductivity and TDS had significant effects when the proportional frequencies of young larvae of M and S forms among sampling sites within habitats were significantly associated. Alkalinity, D.O., orthophosphate, pH, nitrate, temperature and turbidity had no effects on niche partitioning of species and forms among sampling sites within habitats. Rainfall did not affect the frequencies of these immatures.ConclusionConductivity and TDS have significant effects on niche partitioning of young larvae of M and S forms among sampling sites within habitats in Banambani, Mali.

Highlights

The associations between the immatures of Anopheles gambiae s.s. (Diptera: Culicidae), its M and S forms, and Anopheles arabiensis among and within larval breeding habitats in Banambani, Mali were investigated under varying conditions of water quality and rainfall
Macrogeographic studies of habitat usage across sub-Saharan Africa generally find that An. gambiae s.s. and An. arabiensis differ principally along axes of warm-cool and dry-wet, though there is more to differences than just climate [711]
Conductivity and total dissolved solids (TDS) varied among the three puddle sites and among two sampling sites in the swamp and rock pools

Summary

Introduction

The associations between the immatures of Anopheles gambiae s.s. (Diptera: Culicidae), its M and S forms, and Anopheles arabiensis among and within larval breeding habitats in Banambani, Mali were investigated under varying conditions of water quality and rainfall. (Diptera: Culicidae), its M and S forms, and Anopheles arabiensis among and within larval breeding habitats in Banambani, Mali were investigated under varying conditions of water quality and rainfall. Arabiensis, are broadly sympatric but there are areas where only one or the other may be found [6]. Macrogeographic studies of habitat usage across sub-Saharan Africa generally find that An. gambiae s.s. and An. arabiensis differ principally along axes of warm-cool and dry-wet, though there is more to differences than just climate [711]. Less is known about macrogeographic differences across sub-Saharan Africa in habitat usage among chromosomal or molecular forms of An. gambiae s.s. though Touré et al [12] reported that they exist. In west Africa, the M form seems able to exploit man-made habitats that are otherwise available only to An. arabiensis in dry areas [5]

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