Microbiota, Gut Physiology, and Insect Immunity

This chapter aims to visualize insect gut as a life-sustaining organ that is resilient yet interactive with the changing environment to maintain its immunological and physiological homeostasis. As in all metazoans, insect gut is where the organism interacts most actively with the external ecosystem. A healthy gut epithelium properly controls incoming foodborne microbes as well as microbiota while maintaining its structural and functional integrity. Novel insights into gut immunity and physiology have been made using the fruit fly Drosophila melanogaster as a model system. Here, we begin our discussion with the gut architecture and the microbial environment the gut faces. Then, we review the current understanding of the immune responses of the gut epithelium involving the immune deficiency and dual oxidase pathways to restrict unwanted microbial colonization. We also discuss how the gut epithelium maintains its functionality by utilizing controlled proliferation and differentiation of intestinal stem cells despite damage-causing gut environment.