Meeting Abstract

55.8  Tuesday, Jan. 6  Combined impact of parasites and predators on wood frog tadpoles BELDEN, L.K.*; WOJDAK, J.M.; Virginia Tech; Radford University belden@vt.edu

Predators can have important impacts on host-parasite dynamics in natural systems. Some predators are hosts that become infected after consuming infected prey. In other cases, predators that are not themselves hosts can reduce transmission by removing the most heavily infected individuals from the population. Less is known about how predators might influence parasite dynamics in systems where the parasite relies on vectors or numerous different host species to complete their life-cycle. Digenetic trematodes are a diverse group of parasitic flatworms with complex life-cycles typically involving three host species. They can infect all vertebrate classes, and are common parasites in freshwater systems containing aquatic snails, which serve as obligate first intermediate hosts. In this study, we examined the impact of two trematode species (Echinostoma trivolvis and Ribeiroia ondatrae) and predatory larval salamanders (Ambystoma jeffersonianum) on short-term survival of larval wood frogs (Rana sylvatica). Both parasites and predators significantly reduced tadpole survival in experimental outdoor pools. After six days, tadpole survival was reduced from 100% in control pools to a mean of 46% in pools containing infected snails and a mean of 49% in pools containing predators. In pools containing both infected snails and predators, tadpole survival was further reduced to a mean of just 5%. These dramatic results suggest that non-host tadpole predators could potentially limit transmission of trematode parasites in systems with intense predation. In addition, the parasites themselves may cause substantial mortality to second intermediate hosts which could also limit transmission to the next host.