Meeting Abstract

P3.1  Sunday, Jan. 6  Host life history influences parasite encystment location and tolerance in tadpoles SEARS, BF*; ROHR, JR; Univ. of South Florida; Univ. of South Florida bsears@mail.usf.edu

Larval trematodes, called cercariae, frequently parasitize anuran tadpoles that can resist or tolerate these infections. We have previously demonstrated that encystment location of cercariae can be affected by anesthesia; therefore, we experimentally infected tadpoles with armatae-type cercariae, which encyst throughout the skin, to determine whether behavior in non-anesthetized tadpoles can actively influence location of parasite encystment. Tadpoles were exposed to parasites for 1 hour while anesthetized or not anesthetized, as well as for 24 hours while not anesthetized. Encystment location of cercariae did not vary within or among species between anesthesia treatments, but did vary among species when hosts were exposed to cercariae for 24 hours. Strikingly, encystment location was strongly correlated with host species and life history. Cercariae infected the head and body of small, rapidly developing (“fast-paced”) tadpole species but infected the tail of large, slowly developing (“slow-paced”) species. Furthermore, slow-paced, tail-infected species had better tolerance of their infections, exhibiting less mass loss post-infection, than fast-paced species. This pattern of encystment location suggests that slow-paced hosts, which are more likely to encounter trematode parasites, might shunt parasites to the least deleterious location. Conversely, the parasites themselves might seek different body regions in different host species in order to maximize the likelihood of transmission to the definitive host. Patterns of trematode infection should be further investigated to assess whether encystment location affects sensory systems (head) and locomotion (tail), which might impact survival in the presence of predators and/or definitive hosts.