Browsing by Author "Chibwana, Fred Demetrius"

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    Digeneans of snails and birds in lake Victoria and mindu dam, with reference to the life cycle of diplostomids infecting clarias gariepinus (clariidae) in Tanzania
    (University of Dar es Slaam, 2014) Chibwana, Fred Demetrius
    Diplostomids comprise a large and diverse group of digeneans whose metacercariae are important arasites that may exert serious impact in wild and cultured freshwater fish. However, our understanding of their diversity and life cycle in Africa remains incomplete. The present study was carried out to determine the diversity of digeneans infecting some freshwater snails and fish eating birds in the Mwanza Gulf, Lake Victoria and Mindu dam with a view to determining the life cycle of diplostomid species infecting the cranial cavity of the catfish Clarias gariepinus in their natural environment. Both conventional and molecular methods i.e. cytochrome c oxidase subunit I (CO1) and ribosomal DNA (ITS1-5.8S-ITS2) were employed. Out of 9194 snails (Biomphalaria pfeifferi, Bulinus spp and Radix natalensis) collected from Mindu dam and the Mwanza gulf, 678 (7.34%) were infected with the larvae of 13 digenean species: 3 xiphidiocercariae, 6 furcocercariae, l gymnocephalous, 1 amphistome, 2 echinostome and 1 unidentified metacercaria. From 152 piscivorous birds (Phalacrocorax carbo,Leptoptilos crumeniferus, Ardea cinerea, Egretta alba, Scopus umbretta and Ceryle rudis) examined, 91 (59.87%) were infected with digenean from 4 families: Echinostomatidae, Strigeidae, Diplostomidae and Cyathocotylidae. Although both morphological and molecular techniques revealed the presence of 10 possible species digeneans, only Holostephanus dubinini (Cyathocotylidae), Apharyngostrigea pipientis (Strigeidae) and Tylodelphys mashonense (Diplotomidae) from Phalacrocorax carbo, Ardea cinerea and Egretta alba, respectively, were precisely identified to species level. It is also revealed that Bulinus spp serve as the first intermediate hosts for T. mashonense and E. alba as its new definitive host supplementary to A. cinerea. However, the occurrence of T. mashonense in A. cinerea in Tanzania is a new geographical record. Lastly, based on cercarial features of Diplostomum mashonense and topological position in the phylogenies based on both ITS and CO1 sequences, D. mashonense is reallocated to Tylodelphys mashonense Sudarikov, 1971. As such, the three diplostomid metacercariae found in the cranial cavity of catfish C. gariepinus are Tylodelphys