Antipredatory Behaviour of Feverish Tadpoles: Implications for Pathogen Transmission

Abstract

In 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.

Parasitized snails take the heat: a case of host manipulation?

“…Yet, interpreting cases of altered thermal choice are challenging, because parasites can also increase their host's thermal vulnerability (Fredensborg et al 2005;McDaniel 1969;Vernberg and Vernberg 1963). Thus, elevated thermal preferences may be tied to a decrease in host survivorship due to greater physiological costs, or indirectly, for example, by increasing malaise and enhancing predation risk (Lefcort and Eiger 1993).…”

Antipredator behavior of chytridiomycosis-infected northern leopard frog (Rana pipiens) tadpoles

“…For example, a typical ectothermic response to pathogens is for infected hosts to prefer warmer microhabitats, presumably to reduce pathogen proliferation within the host (i.e., behavioral fever; Kluger et al 1975). Bullfrog (Rana catesbeiana Shaw, 1802) tadpoles infected with Aeromonas bacteria prefer warmer aquatic temperatures (Lefcort and Eiger 1993), which slow bacterial growth. However, because warm conditions usually are in shallow water with high aquatic predator densities (Arnold and Wassersug 1978), predation risk may be enhanced for infected tadpoles.…”

Immune activation influences the trade-off between thermoregulation and shelter use

“…the type and dosage amount of pyrogen and the timing of measurement: Stahlschmidt & Adamo, 2013b) must be considered when determining its presence or absence. Although immune activation can also influence predator avoidance behaviour and shelter preference (Joop & Rolff, 2004;Lefcort & Eiger, 1993), experiments examining fever typically do not include shelter (Burns et al, 1996;Cich on, Chadzi nska, Ksią _ zek, & Konarzewski, 2002;Don et al, 1994;Ortega et al, 1991;Stahlschmidt & Adamo, 2013a;Zurovsky et al, 1987). Shelter is important for a plethora of behavioural processes, such as competition (Fero & Moore, 2014;Kintzing & Butler, 2014) and oviposition site selection (Stahlschmidt & Adamo, 2013a), and thus, it may be similarly important for behavioural fever.…”

“…Immune activation can also influence predator avoidance behaviour (e.g. cause an infected individual to react slower to predator attacks even at preferred temperature; Joop & Rolff, 2004;Lefcort & Eiger, 1993;Otti, Gantenbein-Ritter, Jacot, & Brinkhof, 2011;Rantala, Honkavaara, & Suhonen, 2010). The role of immune activation in the trade-off between thermoregulation and predator avoidance has been proposed (e.g.…”

“…We used the cornsnake, Pantherophis guttatus, to test our hypotheses because snakes utilize existing shelter (Hyslop, Cooper, & Meyers, 2009) and adjust their habitat selection to carefully regulate T b (Aïdam, Michel, & Bonnet, 2013;Blouin-Demers & Weatherhead, 2001;Lorioux, DeNardo, Gorelick, & Lourdais, 2012;Lourdais, Guillon, DeNardo, & BlouinDemers, 2013;McConnachie, Greene, & Perrin, 2011;Stahlschmidt et al, 2012). Like other animals (Johnson, 2002;Lefcort & Eiger, 1993), snakes may exhibit a shift in T b and increase shelter use due to immune activation; thus, we first hypothesized that immune activation influences thermoregulation and shelter use independently (sensu Kluger, 1986;Otti et al, 2011). Under this hypothesis, we predicted that snakes would undergo fever and increase their shelter use during an immune activation.…”