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RNA interference (RNAi) is being used to develop methods to control pests and disease vectors. RNAi is robust and systemic in coleopteran insects but is quite variable in other insects. The determinants of efficient RNAi in coleopterans, as well as its potential mechanisms of resistance, are not known. RNAi screen identified a double-stranded RNA binding protein (StaufenC) as a major player in RNAi. StaufenC homologs have been identified in only coleopteran insects. Experiments in two coleopteran insects, Leptinotarsa decemlineata and Tribolium castaneum , showed the requirement of StaufenC for RNAi, especially for processing of double-stranded RNA (dsRNA) to small interfering RNA. RNAi-resistant cells were selected by exposing L. decemlineata , Lepd-SL1 cells to the inhibitor of apoptosis 1 dsRNA for multiple generations. The resistant cells showed lower levels of StaufenC expression compared with its expression in susceptible cells. These studies showed that coleopteran-specific StaufenC is required for RNAi and is a potential target for RNAi resistance. The data included in this article will help improve RNAi in noncoleopteran insects and manage RNAi resistance in coleopteran insects. 

Abstract 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.