Chilo suppressalis is one of the most prevalent and damaging rice pests, causing significant economic losses each year. Chemical control is currently the primary method of controlling C. suppressalis. However, the indiscriminate use of chemical insecticides increases pest resistance, pollutes the environment and poses a significant health threat to humans and livestock, highlighting the need to find safer, more pest-specific and more effective alternatives to pest control. Plant-mediated RNA interference (RNAi) is a promising agricultural pest control method that is highly pest-specific and has less of an impact on the environment. Using multi-sgRNAs/Cas9 technology to delete Fatty acyl-CoA reductase (FAR) of C. suppressalis in the G0 generation, we show that downregulating FAR transcription may significantly increase the mortality rate and darken the epidermis of C. suppressalis compared with the control. Subsequently, we developed dsFAR transgenic rice lines using Agrobacterium-mediated genetic transformation and then screened three strains expressing dsFAR at high levels using transcriptional level analysis. Using transgenic rice stems, a laboratory feeding bioassay indicated that at least one line (L#10) displayed a particularly high level of insect resistance, with an insect mortality rate of more than 80%. In the field trials, dsFAR transgenic rice displayed high levels of resistance to C. suppressalis damage. Collectively, these results suggest the potential of a new environment-friendly, species-specific strategy for rice pest management.

The most important physiological processes in insects are those related to reproduction and development. Ecdysone is an essential hormone in insects that controls various physiological processes, including reproduction and development. E74A, a subtype of the essential ecdysone‐induced transcription factor E74, affects the reproductive systems of many insects. Uncertainty exists regarding the molecular mechanism of E74A in non‐model insect reproduction processes. Using bioinformatics analysis, we determined that Chilo suppressalis E74A shared the highest homology with E74 in Ostrinia furnacalis which belongs to the ETS superfamily. By characterizing the spatiotemporal expression profile of CsE74A from different developmental stages and tissues, we found that CsE74A expression levels were highest in female pupae on the 4th day and in the head of female pupa. Knockdown of CsE74A resulted in delayed oocyte maturation and reduced yolk deposition. Additionally, the expression level of vitellogenin (Vg), βFTZ‐F1, and E93, which are associated with vitellogenesis and the ecdysone pathway, were also downregulated in the E74A silencing group. Collectively, our findings demonstrate that CsE74A not only plays a critical role in the reproductive processes of C. suppressalis but may also participate in the transcriptional regulation of genes involved in the ecdysone pathway.

Juvenile hormone (JH) is a major endocrine hormone that mediates development, metamorphosis, and reproduction in insects. It binds directly to its methoprene-tolerant receptor and recruits a heterodimer partner to form the JH–receptor complex that then activates a JH-inducible gene known as the Krüppel homolog 1 (Kr-h1). There is evidence that this gene is a downstream factor mediating both physiological and biochemical processes; however, the functional mechanism of Kr-h1 is largely unknown. Using the economically important rice (Oryza sativa L.) pest Chilo suppressalis (Walker) (Lepidoptera: Crambidae) as a model, we used a combination of RNA interference (RNAi), high-throughput RNA sequencing, and real-time quantitative polymerase chain reaction (RT-qPCR) to identify candidate transcription factor (TF) genes that are regulated by Kr-h1. RNAi knockdown of Krh1 identified the Zinc finger proteins, ZBTB, THAP, PAX, MYB, HSF, Homeobox, HMG, CSD, basic helix-loop-helix, STAT, RHD, and MBD families as regulated by Kr-h1. RT-qPCR confirmed the transcription levels of these putative TFs and indicated that knockdown of Kr-h1 can induce or suppress the expression of these proteins in C. suppressalis. These results provide the basic information required for in-depth research on the TFs regulated by Kr-h1 in C. suppressalis and other insects.