Although a large number of insect-specific viruses (ISVs) have recently been discovered from hematophagous insect, studies on ISV diversity and their association with phytophagous insect hosts were still insufficient. A systematic RNA virome investigation was performed for an important plant virus vector, small brown planthopper (SBPH), Laodelphax striatellus. A total number of 22 RNA viruses (including 17 novel viruses) belonging to various families were successfully identified and characterized. Subsequent analysis indicated that the overall RNA virus transcripts per million (TPM) in SBPH was relatively consistent throughout various different developmental stages of the insects, although the titers of individual viruses differ among different insect tissues, suggesting a delicate balance between ISVs and insect hosts. Moreover, analysis of virus-derived small interfering RNA (siRNA) demonstrated that siRNA mediated antiviral immune response of SBPH was activated in response to the replication of the discovered RNA viruses. Additionally, evaluation for potential cross-species ability of SBPH-ISVs showed that certain SBPH ISVs could successfully infect and replicate in another two rice planthoppers, the brown planthopper and the white-backed planthopper, through microinjection. In conclusion, the RNA virome and their adaptability in SBPH revealed in this study will contribute to a better understanding of the intimate relationship between ISVs and the host insects.

Diversity and adaptability of RNA viruses in rice planthopper, Laodelphax striatellus