Host Parasite Manipulation
Michelle Greenfield ’18
Department of Ecology and Evolutionary Biology
Host manipulation occurs when parasites alter the behavior of their host organisms in order to increase their overall fitness. Melanoides tuberculata is the first intermediate host in the life cycle of the trematode Centrocestus formosanus (pictured). In this lifecycle, free-swimming cercariae release from an infected snail host and swim to find their second intermediate fish host. Studies have demonstrated that C. formosanus cercariae exhibit a positive phototaxic response, however, there is no sign of manipulation in the snail’s phototaxic preference. This suggests that the manipulation of the snail with respect to light may not be important in the successful completion of this trematode lifecycle and perhaps other manipulations, such as a chemotaxis response, are more significant in increasing parasite fitness.