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Abstract Batrachochytrium dendrobatidis(Bd) is a pathogenic fungus that has devastated amphibian populations globally by causing the disease chytridiomycosis.Batrachochytrium dendrobatidisis capable of infecting non‐amphibian hosts, such as crayfish, and has been detected on reptile and bird species. Given the taxonomic heterogeneity in the known hosts and vectors of Bd, it is likely that there is a diversity of undiscovered non‐amphibian hosts of the fungus.Here, we investigated whether Bd could survive on freshwater snails (Physella acuta) andCladophoraalgae. We exposed small and large snails (n = 15 snails/size category),Cladophoraalgae (n = 5), and artificial spring water controls (ASW;n = 5) to live Bd. We also maintained Bd‐free control snails (n = 5 snails/size category) in ASW. All treatments were maintained for 7 weeks at 18°C. Mortality was checked three times a week, snails were weighed every 2 weeks, and 7 weeks after exposure, the snails, algae, and water were tested for Bd using quantitative polymerase chain reaction.We found that Bd did not grow on live snails, algae, or ASW long term. Additionally, live snails (n = 20) collected from Bd‐positive ponds in California were all negative for Bd, as well. Given that we found no Bd on the experimentally exposed or field swabbed snails, snails are probably not a reservoir host of Bd.While negative results are often not published, Bd is one of the deadliest pathogens on earth; it is essential to know what is and is not capable of maintaining Bd for well‐designed disease models.
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Impacts of thermal mismatches on chytrid fungus Batrachochytrium dendrobatidis prevalence are moderated by life stage, body size, elevation and latitude
Abstract Global climate change is increasing the frequency of unpredictable weather conditions; however, it remains unclear how species‐level and geographic factors, including body size and latitude, moderate impacts of unusually warm or cool temperatures on disease. Because larger and lower‐latitude hosts generally have slower acclimation times than smaller and higher‐latitude hosts, we hypothesised that their disease susceptibility increases under ‘thermal mismatches’ or differences between baseline climate and the temperature during surveying for disease. Here, we examined how thermal mismatches interact with body size, life stage, habitat, latitude, elevation, phylogeny and International Union for Conservation of Nature (IUCN) conservation status to predict infection prevalence of the chytrid fungusBatrachochytrium dendrobatidis(Bd) in a global analysis of 32 291 amphibian hosts. As hypothesised, we found that the susceptibility of larger hosts and hosts from lower latitudes toBdwas influenced by thermal mismatches. Furthermore, hosts of conservation concern were more susceptible than others following thermal mismatches, suggesting that thermal mismatches might have contributed to recent amphibian declines.
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- Award ID(s):
- 1754868
- PAR ID:
- 10460682
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ecology Letters
- Volume:
- 22
- Issue:
- 5
- ISSN:
- 1461-023X
- Page Range / eLocation ID:
- p. 817-825
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Batrachochytrium dendrobatidis(Bd) has been associated with massive amphibian population declines worldwide. Wildlife vaccination campaigns have proven effective for mitigating damage from other pathogens, and there is evidence that adult frogs can acquire resistance to Bd when exposed to killed Bd zoospores and the metabolites they produced.Here, we investigated whether Cuban treefrogs tadpolesOsteopilus septentrionaliscan gain protection from Bd through exposure to a prophylaxis treatment composed of killed zoospores or soluble Bd metabolites. We used a 2 × 2 factorial design, crossing the presence or absence of killed zoospores with the presence or absence of Bd metabolites. All hosts were subsequently exposed to live Bd to evaluate susceptibility.Exposure to killed zoospores did not induce a protective response. However, tadpoles exposed to Bd metabolites had significantly lower Bd intensity and prevalence than tadpoles that were not exposed to metabolites.The metabolites Bd produce pose no risk of Bd infection and therefore make an epidemiologically safe prophylaxis treatment, protecting tadpoles against Bd. This work provides a promising potential for protecting amphibians in the wild as a disease management strategy for controlling Bd‐associated declines.more » « less
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Abstract Environmental temperature is a crucial abiotic factor that influences the success of ectothermic organisms, including hosts and pathogens in disease systems. One example is the amphibian chytrid fungus,Batrachochytrium dendrobatidis(Bd), which has led to widespread amphibian population declines. Understanding its thermal ecology is essential to effectively predict outbreaks. Studies that examine the impact of temperature on hosts and pathogens often do so in controlled constant temperatures. Although varying temperature experiments are becoming increasingly common, it is unrealistic to test every temperature scenario. Thus, reliable methods that use constant temperature data to predict performance in varying temperatures are needed. In this study, we tested whether we could accurately predictBdgrowth in three varying temperature regimes, using a Bayesian hierarchical model fit with constant temperatureBdgrowth data. We fit the Bayesian hierarchical model five times, each time changing the thermal performance curve (TPC) used to constrain the logistic growth rate to determine how TPCs influence the predictions. We then validated the model predictions usingBdgrowth data collected from the three tested varying temperature regimes. Although all TPCs overpredictedBdgrowth in the varying temperature regimes, some functional forms performed better than others. Varying temperature impacts on disease systems are still not well understood and improving our understanding and methodologies to predict these effects could provide insights into disease systems and help conservation efforts.more » « less
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