Double-stranded RNA binding protein, Staufen, is required for the initiation of RNAi in coleopteran insects

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 is 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 dsRNA to siRNA. RNAi resistant cells selected by exposing Lepd-SL1 to the inhibitor of apoptosis 1 dsRNA for multiple generations showed lower levels of StaufenC expression when compared to 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 paper will help to improve RNAi in non-coleopteran insects and manage RNAi resistance in coleopteran insects.