关键词: 捕食, 根田鼠, 免疫能力, 球虫, 特征介导间接效应

Abstract: In natural ecosystems, different trophic levels can have a profound impact on ecosystem stability and population by trait-mediated indirect effects (TMIEs). However, at present, experimental studies on TMIEs are more common in invertebrates, fish, amphibians and reptiles. In this study, root voles (Microtus oeconomus) were used as experimental animals to establish two treatment populationsin field enclosures :: one in which predation was prevented and one in which predation was allowed to oocurWe then systematically examined thetypes of intestinal parasites, parasitic infection prevalence and intensity of infection by a modified McMaster method.. Phytohemagglutinin (PHA) response and white blood cell count were used to test the individual immunities of the different treatment populations to analyze the infection effect of predation risk on intestinal parasites in root voles. The results showed that the PHA response, leukocyte counts and lymphocyte counts of root voles exposed to predation treatment was significantly decreased compared to voles in which predation was prevented, while infection prevalence and intensity of infection of E. wenrichi were significantly increased. However, there were no significant changes in infection prevalence and intensity of infection of cestodes and nematodes and three other coccidias. It shows that predators can indirectly affect the intestinal parasites of prey by mediating the immune system and validated the hypothesis that the predation risk can increase the intestinal parasitic infection by decrease the immunocompetence of root voles.

Key words: Coccidia, Immunocompetence, Predation, Root voles, Trait-mediated indirect effects