Insect-Specific RNA Viruses of Agricultural Pest Insects: Diversity, Evolution, Function, and Potential Applications

A vast diversity of RNA viruses has been uncovered in agricultural pest insects over the past decade through unbiased metatranscriptomics approaches. These viruses, known as insect-specific viruses (ISVs), are restricted to insects and cannot replicate in plant hosts. The discovery of plant virus–associated ISVs, along with endogenous viral elements derived from these viruses, offers valuable insights into the evolutionary relationships between ISVs, plant viruses, and their insect hosts. Moreover, ISVs may be pathogenic or influence host biology, potentially affecting vector competence and the virulence of other pathogens in their host insects. This finding has opened new possibilities for exploring nonbaculoviral ISVs as novel biological control agents for insect pests and plant viral diseases. This review offers a concise overview of ISVs, with a focus on insect RNA viruses in agricultural pest insects, and proposes guidelines for future research in this rapidly advancing field.