The impact of environmental habitats and diets on the gut microbiota diversity of true bugs (Hemiptera: Heteroptera)

Insects are generally associated with gut bacterial communities that benefit the hosts with respect to diet digestion, limited resource supplementation, pathogen defense and ecological niche expansion. Heteroptera (true bugs) represents one of the largest and most diverse insect lineages and are comprised of species consuming different diets and inhabit in various ecological niches of even extended to below the water. However, the bacterial symbiotic associations were characterized for those basically restricted to herbivorous stink bugs of the infraorder Pentatomomorpha. The gut microbiota associated with the megadiverse heteropteran lineages and the implications with ecological and diet variance remains largely unknown. Here, we conducted a bacterial 16S rRNA amplicons sequencing of the gut microbiota across 30 species of true bugs representative for different ecological niches and diets. It was revealed that Proteobacateria and Firmicute were the predominant bacterial phyla. Environmental habitats and diets coordinately contributed to the diversity of gut bacterial community of true bugs. True bugs living in aquatic environment harbor multiple bacterial taxa that are not present in their terrestrial counterparts. Carnivorous true bugs possessed distinct gut microbiota comparing to phytophagous species. Particularly, assassin bugs of the family Reduviidae possessed a characterized gut microbiota predominantly comprised of one Enterococcus and/or another Proteobacteria, implying a specific association between gut bacteria and host. Overall, our findings highlight the importance of comprehensive surveillance of gut microbiota association with true bugs for understanding of molecular mechanisms underpinning insect-bacteria symbiosis.<br>