Insect Gut Bacterial Diversity Determined by Environmental Habitat, Diet, Developmental Stage, and Phylogeny of Host

TLDR

Insects are the most abundant animals on Earth, and their gut microbiota mediate beneficial and pathological interactions with hosts. The study comprehensively characterized gut bacteria of 305 insects across 218 species and 21 orders using 454 pyrosequencing of 16S rRNA genes. The authors generated 174,374 16S rRNA sequence reads, yielding 9,301 OTUs with an average of 84.3 per sample. Proteobacteria and Firmicutes dominated the gut microbiota (62.1% and 20.7% of reads, respectively), and the study found that anaerobe abundance varied with habitat, diet, developmental stage, and phylogeny, with omnivorous insects exhibiting significantly higher bacterial diversity than stenophagous insects.

Abstract

Insects are the most abundant animals on Earth, and the microbiota within their guts play important roles by engaging in beneficial and pathological interactions with these hosts. In this study, we comprehensively characterized insect-associated gut bacteria of 305 individuals belonging to 218 species in 21 taxonomic orders, using 454 pyrosequencing of 16S rRNA genes. In total, 174,374 sequence reads were obtained, identifying 9,301 bacterial operational taxonomic units (OTUs) at the 3% distance level from all samples, with an average of 84.3 (± 97.7) OTUs per sample. The insect gut microbiota were dominated by Proteobacteria (62.1% of the total reads, including 14.1% Wolbachia sequences) and Firmicutes (20.7%). Significant differences were found in the relative abundances of anaerobes in insects and were classified according to the criteria of host environmental habitat, diet, developmental stage, and phylogeny. Gut bacterial diversity was significantly higher in omnivorous insects than in stenophagous (carnivorous and herbivorous) insects. This insect-order-spanning investigation of the gut microbiota provides insights into the relationships between insects and their gut bacterial communities.