Comparison of the RNA interference effects triggered by dsRNA and siRNA in Tribolium castaneum

Even though both dsRNA and siRNA have been widely used in laboratory studies to knock down target genes, it has been found that siRNA rarely triggers phenotypic changes for intact insects. In this study, Tribolium castaneum was used as a model species to compare dsRNA and siRNA and select the more efficient of these for insect RNAi.

Four dsRNAs and ten siRNAs targeting the same three genes were tested by checking the suppression of target genes and the deformation of treated insects. The results showed that dsRNAs could reduce the expression of target genes by 55-75% for more than 7 days and deformed 78.8-87.0% of the larvae tested. Injection of their corresponding siRNAs targeting the same gene did yield about 45% silencing of target genes, but only in a short time period (from day 2 to day 4), and it did not trigger any phenotypic changes.

SiRNAs were less efficient than their corresponding dsRNAs. Most of them could hardly trigger any phenotypic changes owing to the temporary silencing effect on target genes. Meanwhile, the efficiency of different siRNAs varied with their matching sequence, and careful selection was necessary for proper use.