Abstract:Symbiotic bacteria can protect their insect hosts against pathogens by producing antimicrobial substances, regulating host immune-related genes, and competing with exotic pathogens for resources. To maintain the symbiotic relationship, insects have evolved fine-tuned regulatory mechanisms to avoid overactive immune responses to symbiotic bacteria, and the latter reduce or evade the damage from the host immune system via immune recognition signal polymorphisms or chemical mimicry. In this paper, we analyzed the function of symbiotic bacteria on host immunity and the mechanism and then explored the precise regulation of immune response by the host and the coevolution of the symbiotic system, hoping to provide a reference for further research on the influence of symbiotic bacteria on host immunity.