Diversity and transmissibility of RNA viruses in the small brown planthopper, Laodelphax striatellus.

While a considerable number of viruses have been recently discovered in hematophagous insects, there remains insufficient research on virus diversity and their association with phytophagous insect hosts. In this study, we conducted a systematic investigation of the RNA virome in the small brown planthopper (SBPH), Laodelphax striatellus, an important vector of plant viruses. We successfully identified a total of 22 RNA viruses, including 17 novel viruses, from various families. These viruses were prevalent and abundant in SBPH populations, originating from the lab or field, with +ssRNA viruses composing the core SBPH viruses. Subsequent analysis revealed that the overall abundance of RNA viruses in SBPH remained relatively consistent across different developmental stages of the insects, although the titers of individual viruses varied among different insect tissues. This indicates a delicate balance between the viruses and their insect hosts. Interestingly, cross-species experiments confidently indicated that certain SBPH viruses could successfully infect and replicate in two other rice planthopper species (the brown planthopper and the white-backed planthopper) through microinjection. In conclusion, this study provides valuable insights into the RNA virome and its adaptability in a phytophagous insect, contributing to a better understanding of the intimate relationship between viruses and host insects.

Importance: In the last decade, advances in the next-generation sequencing technology have unveiled a vast diversity of viruses in insects, particularly RNA viruses in hematophagous insects. However, research on virus diversity and their association with phytophagous insect hosts remains insufficient. This study presents a comprehensive analysis of the RNA virome in the small brown planthopper (SBPH), Laodelphax striatellus, a critical vector of plant viruses. The results indicated that the +ssRNA viruses, especially picorna-like viruses, comprised the core RNA viruses of SBPH that were prevalent in both laboratory and field populations. Moreover, a delicate balance was observed between the viruses and insect hosts. Significantly, some RNA viruses of SBPH could successfully infect and replicate in two other rice planthopper species belonging to different genera. This study provides valuable insights into the RNA virome and its adaptability in a phytophagous insect.