RNA interference (RNAi) is a sequence-specific down-regulation in the expression of a particular gene, induced by double-stranded RNA (dsRNA). Feeding of dsRNA either directly or through transgenic plants expressing dsRNA of insect genes has been proven successful against lepidopteran and coleopteran pests, establishing an additional alternative to control insect pests. Lepidopteran crop pests including (Fabricius) (Noctuidae), (Swinhoe) (Crambidae), (Linnaeus) (Plutellidae), and (Fabricius) (Pyralidae) are the devastating pests of a variety of crops. To tap the potential of RNAi against insect pests, a gene coding for the key enzyme in chitin biosynthesis in arthropods, the (), has been targeted through an exogenous delivery of dsRNA and plant-mediated RNAi. The introduction of caused "Half ecdysis" and "Black body" type lethal phenotypes and a significant reduction in larval body weight. Subsequent RT-qPCR analysis demonstrated the down-regulation of gene transcripts from 1.38- to 8.33-fold in the four target species. Meanwhile, when larvae fed with leaves of transgenic tobacco plants expressing , the mRNA abundance of gene was significantly decreased resulting in lethal phenotypes like "Double head formation," "Half ecdysis," and "Black body." In addition, abnormalities in pupal-adult and adult stage were also documented, strongly suggesting the RNAi effect of gene at late developmental stages. Overall, the results demonstrated that gene expression in Lepidopteran crop pests could be suppressed by application of dsRNA either as feeding or through transgenic crop plants.