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

Hettyey, Attila; Ujszegi, János; Herczeg, Dávid; Holly, Dóra; Vörös, Judit; Schmidt, Benedikt R.; Bosch, Jaime

doi:10.3389/fevo.2019.00254

Cited by 29 publications

(23 citation statements)

References 187 publications

(260 reference statements)

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“…This life cycle requires temperatures between approximately 2-27 °C in vitro, with an optimal temperature range between 15 and 25 °C and a drop in reproduction and viability above 27 °C [51,66,73,78]. Because increases in Bd loads correlate with the severity of chytridiomycosis [72,74], exposure to temperatures above the Bd thermal maximum that negatively affect Bd growth and reproduction may decrease infection intensities and slow disease progression [23,26,62].…”

Section: Introductionmentioning

confidence: 99%

Daily fluctuating temperatures decrease growth and reproduction rate of a lethal amphibian fungal pathogen in culture

2020

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Background: Emerging infectious diseases (EIDs) are contributing to species die-offs worldwide. We can better understand EIDs by using ecological approaches to study pathogen biology. For example, pathogens are exposed to variable temperatures across daily, seasonal, and annual scales. Exposure to temperature fluctuations may reduce pathogen growth and reproduction, which could affect pathogen virulence, transmission, and environmental persistence with implications for disease. We examined the effect of a variable thermal environment on reproductive life history traits of the fungal pathogen Batrachochytrium dendrobatidis (Bd). Bd causes chytridiomycosis, an emerging infectious disease of amphibians. As a pathogen of ectothermic hosts, Bd can be exposed to large temperature fluctuations in nature. To determine the effect of fluctuating temperatures on Bd growth and reproduction, we collected temperature data from breeding pools of the Yosemite toad (Anaxyrus canorus), a federally threatened species that is susceptible to chytridiomycosis. We cultured Bd under a daily fluctuating temperature regime that simulated Yosemite toad breeding pool temperatures and measured Bd growth, reproduction, fecundity, and viability. Results: We observed decreased Bd growth and reproduction in a diurnally fluctuating thermal environment as compared to cultures grown at constant temperatures within the optimal Bd thermal range. We also found that Bd exhibits temperature-induced trade-offs under constant low and constant high temperature conditions. Conclusions: Our results provide novel insights on variable responses of Bd to dynamic thermal conditions and highlight the importance of incorporating realistic temperature fluctuations into investigations of pathogen ecology and EIDs.

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Section: Introductionmentioning

confidence: 99%

Daily fluctuating temperatures decrease growth and reproduction rate of a lethal amphibian fungal pathogen in culture

2020

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“…One exception is the case of the chytridiomycosis, a disease responsible for the decline of hundreds of amphibian species, with new reports accruing [17]. An enormous body of literature bears witness to the research that has revealed the ecological and evolutionary drivers of disease [18,19], but only a relatively sparse publication list provides recommendations on how to respond to the threat chytrid fungi pose to amphibian biodiversity [20][21][22][23][24][25][26][27][28]. Even more sparse is the collection of published studies reporting the outcomes of attempts at mitigating infections and disease in nature, none of which presents a scalable and transferable solution [5,[29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Significant reductions of host abundance weakly impact infection intensity of Batrachochytrium dendrobatidis

et al. 2020

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Infectious diseases are considered major threats to biodiversity, however strategies to mitigate their impacts in the natural world are scarce and largely unsuccessful. Chytridiomycosis is responsible for the decline of hundreds of amphibian species worldwide, but an effective disease management strategy that could be applied across natural habitats is still lacking. In general amphibian larvae can be easily captured, offering opportunities to ascertain the impact of altering the abundance of hosts, considered to be a key parameter affecting the severity of the disease. Here, we report the results of two experiments to investigate how altering host abundance affects infection intensity in amphibian populations of a montane area of Central Spain suffering from lethal amphibian chytridiomycosis. Our laboratory-based experiment supported the conclusion that varying density had a significant effect on infection intensity when salamander larvae were housed at low densities. Our field experiment showed that reducing the abundance of salamander larvae in the field also had a significant, but weak, impact on infection the following year, but only when removals were extreme. While this suggests adjusting host abundance as a mitigation strategy to reduce infection intensity could be useful, our evidence suggests only heavy culling efforts will succeed, which may run contrary to objectives for conservation.

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“…Bd has already caused the extinction of over a hundred amphibian species, and remains a major threat to global biodiversity (Scheele et al 2019). Hettyey et al (2019) recently argued that current mitigation methods are not yet suitable for in situ application, and proposed that the creation of microhabitats with elevated temperatures may be the best countermeasure to Bd in terms of practicality and minimization of collateral damage to ecosystems. Microhabitat manipulation, however, hinges on the assumption that amphibians will use warm spots if provided them.…”

Section: Discussionmentioning

confidence: 99%

Infection Status as the Basis for Habitat Choices in a Wild Amphibian

Barrile

Chalfoun

Walters

2021

The American Naturalist

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Animals challenged with disease may select specific habitat conditions that help prevent or reduce infection. Whereas pre-infection avoidance of habitats with a high risk of disease exposure has been documented in both captive and free-ranging animals, evidence of postinfection habitat switching to conditions that promote the clearing of infection is limited to laboratory experiments. The extent to which wild animals proximately modify habitat choices in response to infection status therefore remains unclear. We investigated pre-infection behavioral avoidance and post-infection habitat switching using wild, radio-tracked boreal toads (Anaxyrus boreas boreas) in a population challenged with Batrachochytrium dendrobatidis (Bd); a pathogenic fungus responsible for a catastrophic panzootic affecting hundreds of amphibian species worldwide. Boreal toads did not preemptively avoid microhabitats with conditions conducive to Bd growth. Infected individuals, however, selected warmer, more open habitats, which were associated with elevated body temperature and the subsequent clearing of infection. Our results suggest that disease can comprise an important selective pressure on animal habitat and space use. Habitat selection models therefore may be greatly improved by including variables that quantify infection risk and/or the infection status of individuals through time.

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

Cited by 29 publications

References 187 publications

Daily fluctuating temperatures decrease growth and reproduction rate of a lethal amphibian fungal pathogen in culture

Daily fluctuating temperatures decrease growth and reproduction rate of a lethal amphibian fungal pathogen in culture

Significant reductions of host abundance weakly impact infection intensity of Batrachochytrium dendrobatidis

Infection Status as the Basis for Habitat Choices in a Wild Amphibian

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