The development of the nematode Syncuaria squamata (Linstow, 1883), a gizzard parasite of cormorants, was experimentally studied in the ostracod Notodromas monacha. After the eggs of this nematode have been swallowed by the ostracod, the toothed first-stage larvae of the parasite are released and penetrate through the intestinal wall into the haemocoel of the crustacean. Before attaining the infective third stage, the larvae moult twice in the body of the intermediate host (9-11 and 13-15 days after infection at water temperatures of 20-22° C). The fishes Alhumaides hipunctatus, Noemacheilus barbatulus, Oncor-hynchus mykiss and Poecilia reticulata were for the first time recorded as suitable experimental paratenic hosts of S. squamata third-stage larvae in which a slight growth of larvae may occur. The first recorded natural paratenic host of this nematode was tench, Tinca tinea, originating from a South-Bohemian pond where cormorants occur. Paratenic hosts are apparently the main source of S. squamata infection for cormorants.
Three species of planktonie crustaceans, Cyclops strenuus and Macrocyclops alhidus (Copcpoda) and Notodromas monacha (Ostracoda), were experimentally infected with the eggs and second-stage larvae of the swimbladder nematode Anguillicola crassus originating from eels from Neusiedler Lake in Austria. At 20-22°C, third-stage larvae of the parasite developed in all these invertebrate hosts within 16-20 days p.i. Ostracods harbouring the nematode third-stage larvae (33 days p.i.) were fed to small eels (Anguilla anguilla), while infected copepods (20 days p.i.) to seven other fish species. By these experiments, the larvae from ostracods proved to be infective for the definitive host and the ostracod was thus confirmed as a true intermediate host of Anguillicola crassus. Notodromas monacha represents a new experimental intermediate host of A. crassus and the second known invertebrate other than a copepod in which the larval development of this nematode up to the infective stage takes place. Five species of fish, cyprinids Tinca tinea, Alhumus alburnus, Gobio gobio and Albumoides bipunctatus (the latter representing a new host record), and guppy, Poecilia reticulata, were found to serve as experimental paratenic hosts for A. crassus, in which the live nematode infective larvae were recorded 49 days p.i.