Lesser of two evils? Foraging choices in response to threats of predation and parasitism

PLoS One. 2015 Jan 30;10(1):e0116569. doi: 10.1371/journal.pone.0116569. eCollection 2015.

Abstract

Predators have documented post-encounter (density-mediated) effects on prey but their pre-encounter impacts, including behavioural alterations, can be substantial as well. While it is increasingly evident that this "ecology of fear" is important to understand for natural enemy-victim relationships, fear responses of hosts to the threat of infection by a parasite are relatively unknown. We examined larval amphibian (Lithobates pipiens) foraging choices by experimentally manipulating the presence of cues relating to predator (larval odonate) or parasite (the trematode Ribeiroia ondatrae) threats. Tadpoles avoided foraging where predator or parasite cues were present; however, they did not treat these as equal hazards. When both threats were simultaneously present, tadpoles strongly preferred to forage under the threat of parasitism compared to predation, likely driven by their relative lethality in our study. Our results indicate that altered spatial use is an important anti-parasite behaviour, and demonstrate that parasite avoidance can affect foraging in a manner similar to predators, warranting greater study of the pre-encounter effects of this enemy type.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avoidance Learning
  • Fear
  • Feeding Behavior*
  • Food Chain
  • Host-Parasite Interactions
  • Odonata / physiology
  • Predatory Behavior
  • Rana pipiens
  • Trematoda / physiology

Grants and funding

This study was supported by a Discovery Grant (386691-2010) to JK from the Natural Sciences and Engineering Research Council of Canada (http://www.nserc-crsng.gc.ca/index_eng.asp), and the Canada-Brazil Ciência Sem Fronteiras Scholarship Program to LP (http://www.cbie.ca/what-we-do/student-portal/brazil/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.