Elevated temperature clears chytrid fungus infections from tadpoles of the midwife toad, Alytes obstetricans

Abstract

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is sensitive to high temperature. Hence, exposing amphibians to high temperature may be a method to clear Bd infection. However, the effect of exposure to elevated temperature has never been tested in larval stages or temperate species.We experimentally exposed tadpoles of the toad Alytes obstetricans to low, medium and high temperatures and found that most, but not all, tadpoles lost the infection when exposed to temperatures higher than 26•C for 5 days. Thus, exposure to elevated temperatures can be used to treat tadpoles against Bd infection. Abstract. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is sensitive to high temperature. Hence, exposing amphibians to high temperature may be a method to clear Bd infection. However, the effect of exposure to elevated temperature has never been tested in larval stages or temperate species. We experimentally exposed tadpoles of the toad Alytes obstetricans to low, medium and high temperatures and found that most, but not all, tadpoles lost the infection when exposed to temperatures higher than 26 • C for 5 days. Thus, exposure to elevated temperatures can be used to treat tadpoles against Bd infection.

Context‐dependent amphibian host population response to an invading pathogen

“…It is interesting to speculate that, in warmer years, the proportion of time that Torrent des Ferrerets is exposed to Bd-optimal temperatures will increase, with the likelihood that the dichotomous responses seen between these two populations will be exacerbated. Expanding our model to take into account temperature-dependent recovery using an experimentally determined equation (Geiger et al 2011) and using the different temperature profiles of the two sites enabled the reproduction of both differing trends. This is consistent with temperature as the factor driving the different host population responses to invasion by Bd through its effects on the physiology of Bd or the host.…”

“…Recent experimental work in the congener A. obstetricans described a relationship between temperature and probability of remaining infected (Geiger et al 2011) …”

Treatment of amphibians infected with chytrid fungus: learning from failed trials with itraconazole, antimicrobial peptides, bacteria, and heat therapy

“…Successful trials have been documented in peer-reviewed journals. These reports include treatment with elevated temperature (Woodhams et al 2003, Chatfield & Richards-Zawacki 2011, Geiger et al 2011, treatment with salt (White 2006), and also treatments with different antifungals (Hadfield & Whitaker 2005, Garner et al 2009a, Bowerman et al 2010, Martel et al 2011. Unfortunately, information about unsuccessful trials is scarce (Berger et al 2009).…”

Mitigating Disease Impacts in Amphibian Populations: Capitalizing on the Thermal Optimum Mismatch Between a Pathogen and Its Host

“…In the terrestrial environment of adults, on the other hand, animals live dispersed, so that heating up their entire habitat is obviously absolutely impossible. Decreasing canopy cover around ponds and streams may lead to elevated temperatures and thereby provide sufficiently warm thermal refuges in many environments (Raffel et al, 2010;Geiger et al, 2011;Heard et al, 2014), but the approach of felling or pruning trees and shrubs may often not be an acceptable measure due to the collateral damage inflicted, especially so in protected areas, and removal of shading vegetation may simply not elevate temperatures to a sufficient extent in many others.…”