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RNA interference (RNAi) is a promising technology for the development of next‐generation insect pest control products. Though RNAi is efficient and systemic in coleopteran insects, it is inefficient and variable in lepidopteron insects. In this study, we explored the possibility of improving RNAi in the fall armyworm (FAW),Spodoptera frugiperdaby conjugating double‐stranded RNA (dsRNA) with biodegradable chitosan (Chi). dsRNA conjugated with chitosan was protected from degradation by endonucleases present in Sf9 cell‐conditioned medium, hemolymph, and midgut lumen contents collected from the FAW larvae. Chi–dsRNA complexes showed reduced accumulation in the endosomes of Sf9 cells and FAW tissues. Exposing chitosan formulated dsRNA in Sf9 cells and the tissues induced a significant knockdown of endogenous genes. Chi–dsIAP fed to FAW larvae induced knockdown ofiapgene, growth retardation, and mortality. Processing of dsRNA into small interfering RNA was detected with chitosan‐conjugated³²P‐UTP‐labeled ds green fluorescent protein in Sf9 cells and FAW larval tissues. Overall, these data suggest that dsRNA conjugated with chitosan helps dsRNA escape from the endosomes and improves RNAi efficiency in FAW cells and tissues.

RNA interference (RNAi) is being developed for the management of pests that destroy crops. The twospotted Spider Mite (TSSM),Tetranychus urticaeis a worldwide pest due to its unique physiological and behavioral characteristics including extraordinary ability to detoxify a wide range of pesticides and feed on many host plants. In this study, we conducted experiments to identify target genes that could be used for the development of RNAi-based methods to control TSSM. Leaf disc feeding assays revealed that knockdown in the expression genes coding for proteins involved in the biosynthesis and action of juvenile hormone (JH) and action of ecdysteroids [Methoprene-tolerant (Met), retinoid X receptor β, farnesoic acid O-methyltransferase, and CREB-binding protein] caused 35–56% mortality. Transgenic tobacco plants expressing hairpin dsRNA targetingMetgene were generated and tested. About 48% mortality was observed in TSSM raised on transgenic tobacco plants expressing dsMet. These studies not only broaden our knowledge on understanding hormone action in TSSM but also identified target genes that could be used in RNAi-mediated control of TSSM.

Apoptosis has been widely studied from mammals to insects. Inhibitor of apoptosis (IAP) protein is a negative regulator of apoptosis. Recent studies suggest thatiapgenes could be excellent targets for RNA interference (RNAi)‐mediated control of insect pests. However, not much is known aboutiapgenes in one of the well‐known insect model species,Tribolium castaneum. The orthologues of fiveiapgenes were identified inT. castaneumby searching its genome at NCBI (https://www.ncbi.nlm.nih.gov/) and UniProt (https://www.uniprot.org/) databases usingDrosophila melanogasterandAedes aegyptiIAP protein sequences as queries. RNAi assays were performed inT. castaneumcell line (TcA) and larvae. The knockdown ofiap1gene induced a distinct apoptotic phenotype in TcA cells and induced 91% mortality inT. castaneumlarvae. Whereas, knockdown ofiap5resulted in a decrease in cell proliferation in TcA cells and developmental defects inT. castaneumlarvae which led to 100% mortality. Knockdown of the other threeiapgenes identified did not cause a significant effect on cells or insects. These data increase our understanding ofiapgenes in insects and provide opportunities for developingiap1andiap5as targets for RNAi‐based insect pest control.