Thrips tabaci is a severe pest of onion and cotton. Due to lack of information on its genome or transcriptome, not much is known about this insect at the molecular level. To initiate molecular studies in this insect, RNA was sequenced; de novo transcriptome assembly and analysis were performed. The RNAseq data was used to identify reference and RNAi pathway genes in this insect. Additionally, feeding RNAi was demonstrated in T. tabaci for the first time. From the assembled transcriptome, 27,836 coding sequence (CDS) with an average size of 1236 bp per CDS were identified. About 85.4% of CDS identified showed positive Blast hits. The homologs of most of the core RNAi machinery genes were identified in this transcriptome. To select reference genes for reverse-transcriptase real-time quantitative PCR (RT-qPCR) experiments, 14 housekeeping genes were identified in the transcriptome and their expression was analyzed by (RT-qPCR). UbiCE in adult, 28s in nymphs and SOD under starvation stress were identified as the most stable reference genes for RT-qPCR. Feeding dsSNF7 and dsAQP caused 16.4- and 14.47-fold reduction in SNF7 and AQP mRNA levels respectively, when compared to their levels in dsGFP fed control insects. Feeding dsSNF7 or dsAQP also caused 62 and 72% mortality in T. tabaci. Interestingly, simultaneous feeding of dsRNAs targeting SNF7 or AQP and one of the RNAi pathway genes (Dicer-2/Aubergine/Staufen) resulted in a significant reduction in RNAi of target genes. These data suggest the existence of robust RNAi machinery in T. tabaci. The current research is the first report of the assembled, analyzed and annotated RNAseq resource for T. tabaci, which may be used for future molecular studies in this insect. Reference genes validated across stages and starvation stress provides first-hand information on stable genes in T. tabaci. The information on RNAi machinery genes and significant knockdown of the target gene through dsRNA feeding in synthetic diet confirms the presence of efficient RNAi in this insect. These data provide a solid foundation for further research on developing RNAi as a method to manage this pest.

中文翻译：

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RNA测序，参考基因的选择和烟粉虱（Thipsoptera：Thripidae）的RNAi饲养示范。

烟蓟马是洋葱和棉花的严重害虫。由于缺乏有关其基因组或转录组的信息，因此在分子水平上对该昆虫知之甚少。为了对该昆虫进行分子研究，对RNA进行了测序。进行从头转录组组装和分析。RNAseq数据用于鉴定该昆虫中的参考基因和RNAi途径基因。此外，首次在烟粉虱中证明了喂食RNAi。从组装的转录组中，鉴定出27,836个编码序列（CDS），每个CDS的平均大小为1236 bp。大约85.4％的CDS被鉴定为Blast阳性。在此转录组中鉴定出大多数核心RNAi机械基因的同源物。要选择参考基因进行逆转录酶实时定量PCR（RT-qPCR）实验，在转录组中鉴定了14个管家基因，并通过（RT-qPCR）分析了它们的表达。成年人UbiCE，若虫28s和饥饿压力下的SOD被确定为RT-qPCR最稳定的参考基因。与饲喂dsGFP的对照昆虫相比，饲喂dsSNF7和dsAQP分别导致SNF7和AQP mRNA水平降低16.4和14.47倍。饲喂dsSNF7或dsAQP也导致烟粉虱的死亡率分别为62％和72％。有趣的是，同时饲喂靶向SNF7或AQP的dsRNA和一种RNAi途径基因（Dicer-2 / Aubergine / Staufen）导致靶基因RNAi显着降低。这些数据表明在烟粉虱中存在强大的RNAi机制。目前的研究是烟粉虱的组装，分析和注释RNAseq资源的第一份报告，可用于该昆虫的未来分子研究。经过阶段和饥饿压力验证的参考基因为烟粉虱中的稳定基因提供了第一手信息。有关RNAi机器基因的信息以及通过在合成饮食中饲喂dsRNA显着抑制目标基因的信息，证实了这种昆虫中存在有效的RNAi。这些数据为进一步研究开发RNAi作为控制这种有害生物的方法奠定了坚实的基础。