FALKENBACH, J.J.*; RUBBO, M.J.; BELDEN, L.K.; KIESECKER, J.M.; Pennsylvania State University; Pennsylvania State University; Virginia Polytechnic Institute and State University; Pennsylvania State University: Effects of trematode infection on the behavior of wood frogs in post-infection life history stages

In addition to hindering growth and development, parasites have been shown to affect an organism�s behavior. However, the influence of parasitism on behavior has predominately been documented in the life-history stage in which infection occurred. To examine the influence of parasitic infection on the behavior of organisms in post-infection stages, we exposed wood frog (Rana sylvatica) tadpoles to trematode cercariae (family: Teleorchidae). Wood frogs were exposed to either 0 (control), 20 (low infection), or 100 (high infection) trematode cercariae for 24 h. Tadpoles were then reared in the absence of infection for the remainder of their larval period. After metamorphosis, the juvenile frogs were tested in both lab and field environments to determine if infection had an effect on their response to the chemical cues of predatory garter snakes (Thamnophis sirtalis) and non-predatory iguanas (Iguana iguana). The tests monitored frogs� location with respect to cue-soaked paper towels versus water-soaked paper towels. In the laboratory, uninfected frogs showed an avoidance response to chemical stimuli from both snakes and iguanas, whereas the infected frogs did not avoid either cue. We then tested avoidance of snake cue (versus water blank) in meter square field enclosures. As in the laboratory, uninfected individuals in the field avoided snake cues, while infected individuals did not. These results suggest that parasitic infection in one life-history stage can influence behavior in later stages, and could potentially lead to an increased susceptibility to predators.