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Evaluating a predator–prey interaction in the field: the interaction between beetle larvae (predator) and tadpoles (prey)


Michael J. Rubbo. Current address: Department of Biology, 2125 Derring Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA. Tel: 540-231-2715. Email:


The larval amphibian community of temporary pond ecosystems has served as a model for studies in community ecology, with a majority of this work being conducted in mesocosms. Recent research has suggested that mesocosms may overestimate ecological effects; therefore, experimental studies conducted under field conditions are required to gauge the results of mesocosm studies. To assess a species interaction under more natural conditions, we conducted a series of field experiments examining the predator–prey interaction between beetle larvae (Dytiscus sp.; predator) and larval wood frogs Rana sylvatica (prey) in central Pennsylvania, USA. Quantitative sampling of woodland ponds indicated that beetle larvae of the genus Dytiscus were the most common predator of tadpoles. In a field enclosure experiment, dytiscids were effective predators of tadpoles in the pond environment. Moreover, tadpoles avoided areas in a pond containing caged dytiscids, demonstrating that tadpoles recognize the chemical stimuli of predators in complex environments. The results of this study are consistent with data from prior laboratory and mesocosm studies and suggest that these venues can produce reliable interpretations of predator–prey dynamics in this community.