Bacterial communities associated with culex mosquito larvae and two emergent aquatic plants of bioremediation importance.

Dagne Duguma,Michael W Hall,Michael G Kaufman,Josh D Neufeld,Paul Rugman-Jones,Richard Stouthamer,William E Walton

doi:10.1371/journal.pone.0072522

Abstract

Microbes are important for mosquito nutrition, growth, reproduction and control. In this study, we examined bacterial communities associated with larval mosquitoes and their habitats. Specifically, we characterized bacterial communities associated with late larval instars of the western encephalitis mosquito ( Culex tarsalis ), the submerged portions of two emergent macrophytes (California bulrush, Schoenoplectus californicus and alkali bulrush, Schoenoplectus maritimus ), and the associated water columns to investigate potential differential use of resources by mosquitoes in different wetland habitats. Using next-generation sequence data from 16S rRNA gene hypervariable regions, the alpha diversity of mosquito gut microbial communities did not differ between pond mesocosms containing distinct monotypic plants. Proteobacteria, dominated by the genus Thorsellia (Enterobacteriaceae), was the most abundant phylum recovered from C . tarsalis larvae. Approximately 49% of bacterial OTUs found in larval mosquitoes were identical to OTUs recovered from the water column and submerged portions of the two bulrushes. Plant and water samples were similar to one another, both being dominated by Actinobacteria, Bacteroidetes, Cyanobacteria , Proteobacteria and Verrucomicrobia phyla. Overall, the bacterial communities within C . tarsalis larvae were conserved and did not change across sampling dates and between two distinct plant habitats. Although Thorsellia spp. dominated mosquito gut communities, overlap of mosquito gut, plant and water-column OTUs likely reveal the effects of larval feeding. Future research will investigate the role of the key indicator groups of bacteria across the different developmental stages of this mosquito species.

Highlights

Recent studies have focused on understanding the role of microorganisms in mosquito biology and ecology, with the prospect of designing effective control strategies for species that vector debilitating diseases [1,2,3]
We addressed the following objectives: 1) characterize bacterial communities within the larvae of the western encephalitis mosquito sampled from semi-natural habitats; 2) characterize the bacterial communities found in the water column from which the mosquitoes were sampled, and, 3) detect evidence for larval grazing by comparing the epiphytic bacterial composition of two aquatic plants of phytoremediation importance to larval mosquito gut communities
A total of 12,177,876 sequences aligned to the bacterial small subunit models and were used in the analysis, which resulted in a total of 123,814 bacterial operational taxonomic units (OTUs)

Summary

Introduction

Recent studies have focused on understanding the role of microorganisms in mosquito biology and ecology, with the prospect of designing effective control strategies for species that vector debilitating diseases [1,2,3] Among these microorganisms, Bacteria play an important role, as major components of larval diet [4,5], and in generating volatiles that attract mosquitoes for oviposition [3,6]. Most genera of Bacteria found in the gut of larval C. tarsalis were found in the adults, with the exception of Aerobacter, Escherichia, and Flavobacterium [8,9] These studies were based on laboratory-reared mosquitoes, and it is difficult to extrapolate the bacterial composition of the gut of this mosquito species in the natural habitat. The extent to which Culex species feed on the biofilm attached to these substrates is unknown

Methods

Results

Conclusion