THE GUT BACTERIA OF INSECTS: Nonpathogenic Interactions

Abstract

The diversity of the Insecta is reflected in the large and varied microbial communities inhabiting the gut. Studies, particularly with termites and cockroaches, have focused on the nutritional contributions of gut bacteria in insects living on suboptimal diets. The indigenous gut bacteria, however, also play a role in withstanding the colonization of the gut by non-indigenous species including pathogens. Gut bacterial consortia adapt by the transfer of plasmids and transconjugation between bacterial strains, and some insect species provide ideal conditions for bacterial conjugation, which suggests that the gut is a "hot spot" for gene transfer. Genomic analysis provides new avenues for the study of the gut microbial community and will reveal the molecular foundations of the relationships between the insect and its microbiome. In this review the intestinal bacteria is discussed in the context of developing our understanding of symbiotic relationships, of multitrophic interactions between insects and plant or animal host, and in developing new strategies for controlling insect pests.

Integrating nutrition and immunology: A new frontier

“…Gut microbes also play a role in invertebrate biology (Dillon and Dillon, 2003) and digestive process [Brune, 2011 [Lundgren, 2010, and recently the composition of microbe gut populations has been described in a variety of insect species, including bees (Jeyaprakash et al, 2003;Mohr and Tebbe, 2006), beetles (Egert et al, 2005;Lehman et al, 2009;Nardi et al, 2006;Zhang and Jackson, 2008), flies (Cox and Gilmore, 2007;Ren et al, 2007;Ryu et al, 2008;Shin et al, 2011;Wong et al, 2011), lepidopterans (Pauchet et al, 2010;Xiang et al, 2006) and termites (Hongoh et al, 2003). In Drosophila, the microbiome regulates host metabolic homeostatic and developmental programs by modulating the insulin/insulin-like growth factor (Shin et al, 2011).…”

Bacterial strategies to overcome insect defences

“…ability to colonize and persist in insect species might have resulted from horizontal gene transfer (HGT) of plasmid-borne persistence genes in S. entomophila (afp-encoding genes) and in M. ulcerans (mycolactone biosynthetic genes). A role for HGT in the evolution of entomopathogens is also revealed by the distribution of genes that encode similar toxins in unrelated genera 50,77,78 , which suggests that the insect gut constitutes an environment that is favourable for gene transfer 79 .…”

Community Structure of the Mediterranean Fruit Fly Microbiota: Seasonal and Spatial Sources of Variation

“…The digestive system of insects is a major bacterial habitat and a wellstudied microbial environment (reviewed by Dillon and Dillon, 2004). Most of the data obtained on insect gut bacterial diversity is derived from traditional microbial methods such as viable plate counts and phenetic taxonomy.…”