Four small RNA (sRNA) libraries derived from Laodelphax striatellus were constructed in our previous study that were infected with rice black-streaked dwarf virus (RBSDV) or rice stripe virus (RSV), doubly infected with RBSDV and RSV, or virus free.In this study, unique sRNA sequences of each library were assembled into contigs using Velvet and the assembled contigs were used as queries for BLASTN searches against the viral genomes database available in the NCBI database.A large number of contigs showed high identities (e-value < 10-10) to the genome sequence of an insect dicistrovirus, himetobi P virus (HiPV) and the presence of HiPV in L.striatellus was confirmed by RTPCR.In addition, HiPV-derived sRNAs were further characterized in this study.In all libraries, the vast majority of HiPV sRNAs were derived from the positive-strand genome (93% ~95% of total viral sRNAs), whilst the antisense sRNAs were predominantly 21 and 22 nt.Interestingly, HiPV sRNAs had a wide size distribution, and were relatively abundant throughout the 18 ~30 nt size range with only a slight peak at 22 nt.HiPV sRNAs do not have the typical features of PIWI-interacting RNAs.Logo analysis indicated that both the 5and 3ends of HiPV sense sRNAs were most frequently cleaved between dinucleotides UU, UA or AA.In contrast, such a pattern was not observed for HiPV antisense sRNA sequences or for those of RBSDV and RSV sRNAs, showing that this preferential cleavage is a distinct characteristic of HiPV sense sRNAs.Our data suggest that HiPV sRNAs may be derived both from activities of the RNA interference pathway and from cleavage of the viral genome by other host RNases.