With the rapid development of high-throughput sequencing technology and bioinformatics algorithms, great progress has been made in the field of noncoding RNA (ncRNA) in the last decade.  RNA molecules have been regarded only as a messenger between DNA and protein for decades, but now they have new roles in the biological process as ncRNAs.  A growing number of ncRNAs have been identified in insects from the RNA-Seq data of small RNA libraries or transcriptomes.  ncRNAs have varied regulatory functions at the epigenetic, transcriptional, or post-transcriptional levels, and participate in almost all types of biological processes.  Here, we review the research progress of four kinds of ncRNAs, including microRNA (miRNA), Piwi-interacting RNA (piRNA), circular RNA (circRNA), and long noncoding RNA (lncRNA) in insects.  The discovery, biogenesis mechanisms, and regulatory functions of these ncRNAs are presented here to provide a comprehensive understanding of insect ncRNAs and to promote the application of ncRNAs in insect pest control. 

Small brown planthopper (SBPH, Laodelphax striatellus Fallén) is an important vector of major crop pathogen rice stripe virus (RSV).  Controlling SBPH population is an efficient approach to control RSV.  Long non-coding RNAs (lncRNA) have been reported to block virus replication in hosts.  However, the function of lncRNAs in RSV infection and replication is still unknown.  Here, we aimed to study regulatory mechanisms of lncRNA in an immune system during RSV infection.  First, lncRNA genes were predicted from SBPH transcriptomes using a bioinformatics pipeline based on characteristics of lncRNA.  We identified 4 786 lncRNA genes corresponding to 5 790 transcripts in SBPH from an RNA-Seq dataset of 15 transcriptomes.  Differential expression analysis indicated that 3, 11, and 25 lncRNA genes were highly expressed in gut, salivary gland, and ovary, respectively, of viruliferous SBPH (Student’s t-test, P<0.05).  We randomly selected eight lncRNAs for expression validation using quantitative real-time PCR, confirming the differential expression of these lncRNAs between viruliferous and non-viruliferous SBPH.  In summary, we present evidence that the expression of lncRNA genes was induced by RSV infection, suggesting that RSV might be involved in the antivirus immune system in SBPH and participate in regulating the RSV replication mechanism.  These data provide helpful information for future investigations of the interaction between lncRNA and RSV.