Genetic relatedness of Diplostomum species (Digenea: Diplostomidae) infesting nile tilapia (Oreochromis niloticus L.) in western Kenya

Abstract

Diplostomum species metacercariae are trematode parasites that pose serious economic threats to aquaculture practice globally. Identification of Diplostomum at metacercariae stage has remained equivocal, hence lack of elucidation of the actual role of these species in fish population. 21 Diplostomoid metacercariae obtained from eyes of Nile tilapia were characterized using 18S and ITS rDNA (ITS1-5.8S-ITS2) genes. Phylogenetic analyses of ITS rDNA gene dataset in the metacercariae revealed close relationship to Diplostomum mashonense and D. baeri. Molecular identification using 18S rDNA sequences revealed close relationship to D. compactum, D. phoxini and D. spathaceum. Overall, genetic analyses in this study depicted a significant unrecognized genetic diversity among Diplostomum species. Successful differentiation of Diplostomum genera in this study using ribosomal markers suggested that 18S and ITS rDNA genes are effective genetic markers for inter-species phylogenetic analysis and should be employed in future for identification of diplostomoidea.