RNA interference in symbiotic protists of the termite Coptotermes formosanus (Isoptera: Rhinotermitidae) through ingestion of siRNA by the host termite.

This study investigated RNA interference (RNAi) in symbiotic protists via voluntary feeding on small interfering RNA (siRNA) by the host termite, Coptotermes formosanus. The 21 nucleotide siRNAs designed for endoglucanases of the symbiotic protists Pseudotrichonymphagrassii (PgEG), Holomastigotoides mirabile (HmEG), and Spirotrichonympha leidyi (SlEG) were used to silence the protist genes . Disorganization of P. grassii and H. mirabile occurred within a few days in the hindgut of the termites that had ingested PgEG and HmEG siRNAs, respectively. These results provide the first examples of protisticidal effects from siRNA ingestion by a host termite. Additionally, these results contribute to the development of novel RNAi-based termiticides because elimination of P. grassii and H. mirabile leads to starvation of the host termite.