Abstract:  Reactive oxygen species (ROS) is a general term for a class of oxygen-containing free radicals formed due to incomplete oxidation of oxygen molecules, or peroxides that are easy to form oxygen free radicals. When insects are invaded by pathogens, the ROS defense system mediated by dual oxidase (DUOX) will respond quickly to produce a large amount of ROS to resist the invasion of pathogenic bacteria, and then play a role in regulating the immune defense process of insects. However, high level of ROS can damage the biological macromolecules such as proteins, DNA and lipids in cells, causing damage to insect cells and affecting the normal development of insects. In order to avoid damage from excessive oxidative stress, insects have formed a complete antioxidant defense system mainly composed of antioxidant enzymes and small molecule antioxidants to prevent excessive damage from occurring. It is interesting that changes in ROS levels in cells can play completely different roles in regulating insect lifespan: for certain insects the accumulation of a large amount of ROS could lead to a shortened lifespan, while for some other insects the presence of high physiological levels of ROS could also induce diapause and prolong their lifespan. Studies on the regulatory mechanisms of ROS in insect lifespan have achieved a lot of progress in recent years. Therefore, in this article, we comprehensively reviewed the sources and influencing factors of insect ROS, the defense mechanisms mediated by ROS, and for the first time made a summary and outlook on the specific roles of ROS in regulating insect lifespan, so as to provide a reference for subsequent research on ROS-related topics.

Key words: Insects, reactive oxygen species, immune defense, lifespan, diapause