Gene silencing by RNA interference in the ectoparasitic mite, Psoroptes ovis

The presence of components of the RNA interference (RNAi) pathway in Psoroptes ovis, an ectoparasitic mite responsible for psoroptic mange, was investigated through interrogation of the P. ovis genome. Homologues of transcripts representing critical elements for achieving effective RNAi in the mite, Tetranychus urticae and the model organisms Caenorhabditis elegans and Drosophila melanogaster were identified and, following the development of a non-invasive immersion method of double stranded RNA delivery, gene silencing by RNAi was successfully demonstrated in P. ovis. Significant reductions in transcript levels were achieved for three target genes which encode the Group 2 allergen (Pso o 2), mu-class glutathione S-transferase (PoGST-mu1) and beta-tubulin (Poβtub). This is the first demonstration of RNAi in P. ovis and provides a mechanism for mining transcriptomic and genomic datasets for novel control targets against this economically important ectoparasite.