Antipredatory Behaviour of Feverish Tadpoles: Implications for Pathogen Transmission

Abstract

AbstractIn this paper we propose the hypothesis that pathogen-induced host defense responses result in altered host behaviors and enhanced predation. In particular we examine the effects of the acute phase response (whose effects include fever, reduced activity and malaise) on antipredatory behavior in bullfrog (Rana catesbeiana) tadpoles. This host response is associated with the preliminary stages of infection with many pathogens yet its behavioral effects have received little attention. Bullfrog tadpoles were injected with alcohol-killed bacteria to induce a response to infection and their ability to detect and avoid capture by predatory salamanders (Taricha granulosa) was explored. We predicted that acute phase responses increase tadpole vulnerability to predation by influencing thermoregulatory behavior and their ability to detect, and avoid capture by, salamanders. We found that the sterotypical effects of the acute phase response can lead to increased predation. Malaise affected the refuge seeking behavior of the tadpoles in the presence of salamanders. We suggest that for tadpoles provided with refuges, altered behaviors are a liability. This endogenous response may afford some parasites a potential pathway to their next host.