Abstract:  A stable intestinal microbial internal environment is the result of the interaction between intestinal microbes and intestinal immune response. During the continuous feeding, the species and number of insect intestinal microbes constantly change, so a complex and dynamic homeostatic mechanism is formed between intestinal microbes and intestinal epithelial cells. Insect intestinal epithelial cells can sense beneficial and harmful conditions and use immunoregulatory pathways for dynamic regulation of microbial population homeostasis, such as the dual oxidase-reactive oxygen species (Duox-ROS) system and immunodeficiency (Imd) signaling pathways, which can sense the changes in the number of intestinal microbies and participate in the regulation of intestinal microbial homeostasis. In addition, the intestinal microbes can also indirectly play a role in homeostatic regulation by releasing corresponding effectors to regulate the behavior of the flora through quorum sensing (QS). Thus, in this article, we reviewed the roles of physical defense, immune signaling pathways and QS in the maintenance of insect intestinal microbial homeostasis, which will deepen the understanding of the interactions between intestinal tissues and intestinal microbes. In the future, we will continue to reveal the regulatory mechanisms of microbial homeostasis in more species of insects and the relationship between the regulatory mechanisms. In addition, new pesticides will be designed and developed to alter the homeostasis of intestinal microbes based on the regulatory mechanisms, which will provide new targets and ideas for the pest control.

Key words: Intestinal microbes, intestinal immune, homeostasis, Duox-ROS signaling pathway, quorum sensing