Experimental infection of Telorchis and Echinostoma trematode in the green frog, Rana clamitans
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Two species of trematode common in North American aquatic ecosystems are Telorchis and Echinostoma. These trematodes were experimentally infected in the green frog, Rana clamitans under two different experimental conditions. The first of these investigates the parasitic infection affect on growth rate and activity level of the frog, while the other examines whether vegetation abundance affects the infection rate. Results were largely opposite to hypothesis. In the growth rate experiment, growth rate did not differ among treatments. The stage of development, however, did differ among the treatments, where the Echinostoma-infected tadpoles ended at about 2 Gosner stages more advanced than the control and Telorchis. The activity levels of the tadpoles did differ between individual tadpoles, but did not differ between treatment groups. The tadpoles in the habitat complexity experiment were cleared and stained at the end of the experiment, to determine the infection concentration. Echinostoma-mfected tadpoles had metacercaria cysts in each treatment, including controls, suggesting previous infection of Echinostoma prior to capture and use in the experiment. Telorchis-infected tadpoles had no visible metacercaria cysts in each treatment. Green frogs may have evolved a resistance to the parasite. Other studies have shown that increased infection levels and lower activity levels occurs if there is stress in the environment.