Next-generation sequencing sheds light on intricate regulation of insect gut microbiota

Next-generation sequencing (NGS) technologies are getting cheaper and easier and hence becoming readily accessible for many researchers in biological disciplines including ecology. In this issue of Molecular Ecology, Sudakaran et al. (2012) show how the NGS revolution contributes to our better and more comprehensive understanding of ecological interactions between gut symbiotic microbiota and the host organism. Using the European red firebug Pyrrhocoris apterus as a model system, they demonstrated that the gut microbiota consists of a small number of major bacterial phylotypes plus other minor bacterial associates. The major bacteria are localized in a specific anoxic section of the midgut and quantitatively account for most of the gut microbiota irrespective of host's geographic populations. The specific gut microbiota is established through early nymphal development of the host insect. Interestingly, the host feeding on different food, namely linden seeds, sunflower seeds or wasp larvae, scarcely affected the symbiont composition, suggesting homoeostatic control over the major symbiotic microbiota in the anoxic section of the midgut. Some of the minor components of the gut microbiota, which conventional PCR/cloning/sequencing approaches would have failed to detect, were convincingly shown to be food-derived. These findings rest on the robust basis of high-throughput sequencing data, and some of them could not be practically obtained by conventional molecular techniques, highlighting the significant impact of NGS approaches on ecological aspects of host-symbiont interactions in a nonmodel organism.