Determination and silencing optimization of the main components in the Reticulitermes flavipes (Kollar) peritrophic matrix

The peritrophic matrix is a non-cellular structure that lines the gut of most insects. Because of its close involvement in digestive processes and its role as a barrier against pathogens and toxins, the peritrophic matrix is an attractive target for pest management strategies. The objectives of this study were to (1) identify and characterize the genes that encode for either structural proteins or enzymes that synthesize the main components of Reticulitermes flavipes peritrophic matrix and (2) to reduce the expression of those genes by means of interference RNA (RNAi). After sequence identification, analysis and expression profiles of potential candidates, a chitin synthase B (RfCHSB) gene and two peritrophins (RfPMP2-III, RfPMP3-IV) were selected as targets for RNAi. In order to determine the most effective dsRNA delivery technique, the silencing efficacy of force feeding and injection was compared. Moreover, the most efficient type of dsRNA was determined by comparing the silencing efficacy of long dsRNAs and siRNAs. Force feeding termites with long dsRNAs, targeting the chitin synthase and the peritrophin gene RfPMP3-IV, resulted in the highest gene silencing efficiency. RfCHSB expression was reduced by 8-fold, whereas the transcript level of RfPMP3-IV was decreased by 10-fold. Although force feeding of a long dsRNA reduced the expression of RfPMP2-III by 3-fold, the highest silencing efficiency for this gene was obtained by injection of a long dsRNA (6.8-fold). This results are a vital step in testing the viability of the R. flavipes peritrophic matrix as a target in termite pest management.