CHARACTERIZATION OF SURFACE LAYER MICROBIAL COMMUNITIES OF ANOPHELES GAMBIAE COMPLEX LARVAL HABITATS IN BURKINA FASO

Afro-tropical malaria vectors of the Anopheles gambiae complex represents a remarkable example of adaptive radiation thought to be driven by ecological divergence operating predominantly on the larval stages. Some ecological factors involved in larval niche partitioning, such as different ability to escape predators or tolerate abiotic stress, have been identified. Little is known, however, about the role in this process of environmental microbial communities occurring in the larval habitats. Thus, we tested the hypothesis that members of the An. gambiae complex are preferentially associated with different microbial communities.To this aim, we sampled An. gambiae s.l. larvae and the surface layer of 63 randomly chosen water collections in the village of Goundry (Burkina Faso). The microbiological profile of each site was obtained by PCR amplification using consensus primers flanking the V6-V8 region of bacterial 16S rDNA, and subsequent sequencing by Illumina Miseq. Paired-end reads were taxonomically analysed using the two bioinformatic pipelines BioMaS, for identification at species level, and QIIME, for OTU based analysis. The relative frequencies of mosquito species occurring in the larval sites (i.e. An. arabiensis, An. gambiae, and An. coluzzii) were associated to the inferred bacterial composition by Canonical Correspondence Analysis (CCA).Preliminary analysis of a subsample of 37 breeding sites based on 1,620 molecularly-identified mosquitoes (45% An. coluzzii, 38% An. arabiensis, 17% An. gambiae) showed that bacterial composition accounted for 6% of the total variance in larval relative frequencies. The first two canonical axes, which accounted for ~75% of the explained variance, separated the three species and associated bacterial communities.The results indicate that microbial communities occurring in larval habitats can be informative about the composition of sympatricspecies of the An. gambiae complex, supporting the hypothesis that particular environmental bacteria may represent an ecological marker of niche partitioning for these malaria vector species.