, Volume 159, Issue 2, pp 447–454 | Cite as

Parasites, info-disruption, and the ecology of fear

  • Jason R. Rohr
  • Autumn Swan
  • Thomas R. Raffel
  • Peter J. Hudson
Behavioral Ecology - Original Paper


There is growing interest in the ecological consequences of fear, as evidenced by the numerous studies on the nonconsumptive, trait-mediated effects of predators. Parasitism, however, has yet to be fully integrated into research on the ecology of fear, despite it having direct negative and often lethal effects on hosts and being the most common life history strategy on the planet. This might at least be partly due to the traditional, but untested, assumption that anti-parasite responses are weak relative to anti-predator responses. To test this hypothesis, we quantified the activity and location responses of Bufo americanus tadpoles to one of six chemical cues: water; cercariae of Echinostoma trivolvis, a trematode which infects and can kill amphibians; a snail releasing E. trivolvis cercariae; an uninfected snail; food; or conspecific alarm chemicals signaling predation. There is also literature encouraging research on the context dependency and pollution-induced disruption of fear responses. Consequently, before quantifying responses to the chemical cues, half of the B. americanus were exposed to the herbicide atrazine (201 μg/l for 4 days), a reported inhibitor of fear responses in fish. Tadpoles were attracted to food, were indifferent to an uninfected snail, avoided alarm chemicals, and exhibited avoidance and elevated activity in response to a snail shedding cercariae and cercariae alone. Atrazine had no detectable effects on B. americanus’ responses to the tested cues despite the use of a higher concentration and longer exposure duration than has been repeatedly shown to inhibit chemical cue detection in fish. The magnitude of anti-parasite and anti-predator responses were qualitatively similar, suggesting that the fear of disease and its ecological consequences could be comparable to that of predation. Consequently, we call for a greater integration of parasites into research on the ecology of fear and trait-mediated indirect effects.


Alarm chemical Atrazine Bufo americanus Trait-mediated indirect effects Trematode 



We thank two anonymous reviewers for comments and suggestions and Lauren Fayish, Alexis Jesikiewicz, Alyssa Putman, and Hee Young Seo for helping with video analysis. Funds were provided by a National Science Foundation (DEB 0516227) grant to J. R. R. and P. J. H., a US Department of Agriculture (NRI 2006-01370) grant to J. R. R., and a US Environmental Protection Agency STAR grant to J. R. R. and T. R. R. (R833835). A. S. was supported through Penn State University’s Summer Research Opportunity Program for minorities in science. These experiments comply with current laws of the United States of America.


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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Jason R. Rohr
    • 1
  • Autumn Swan
    • 2
  • Thomas R. Raffel
    • 1
  • Peter J. Hudson
    • 3
  1. 1.Department of BiologyUniversity of South FloridaTampaUSA
  2. 2.Hartwick College, Department of BiologyJohnstone Science CenterOneontaUSA
  3. 3.Center for Infectious Disease Dynamics and Department of Biology, Mueller LaboratoryPennsylvania State UniversityUniversity ParkUSA

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