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Abstract Batrachochytrium dendrobatidis(Bd), an aquatic pathogenic fungus, is responsible for the decline of hundreds of amphibian species worldwide and negatively impacts biodiversity globally. Prophylactic exposure to the metabolites produced by Bd can provide protection for naïve tree frogs and reduce subsequent Bd infection intensity.Here, we used a response surface design crossing Bd metabolite prophylaxis concentration and exposure duration to determine how these factors modulate prophylactic protection against Bd in Pacific chorus frog (Pseudacris regilla) tadpoles (5 × 5 surface design) and metamorphs (3 × 3 surface design). We exposed individuals every weekday to one of five Bd metabolite concentrations or a water control for 1–5 weeks, after which all animals were challenged with live Bd to evaluate their susceptibility.Exposure to the Bd metabolite prophylaxis reduced Bd load and prevalence compared to the control for both the tadpoles and metamorphs. Increasing Bd metabolite prophylaxis concentration did not confer additional protection for either life stage, but increasing duration of exposure did benefit metamorphs by decreasing Bd prevalence but not Bd load.On average, control tadpoles and metamorphs had 66.2% and 99.4% higher Bd loads, respectively, than tadpoles and metamorphs exposed to any Bd metabolite prophylaxis.Additionally, Bd metabolite prophylaxis reduced Bd prevalence relative to controls in both tadpoles (20.5% vs. 56.3%, respectively) and metamorphs (21.9% vs. 87.5%, respectively).Synthesis and applications: The efficacy of short‐term exposures of relatively low concentrations of Bd metabolites at reducing Bd infections suggests that this approach has the potential to be scaled up to field use to aid in disease mitigation and conservation. Our results, combined with additional research on Bd metabolite prophylaxis for other amphibian species, suggest that this strategy may represent a broadly useful tool to protect at‐risk amphibian populations.
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Freshwater snails and the green algae Cladophora are probably not hosts of Batrachochytrium dendrobatidis
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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- Award ID(s):
- 1754862
- PAR ID:
- 10454402
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Freshwater Biology
- Volume:
- 66
- Issue:
- 3
- ISSN:
- 0046-5070
- Page Range / eLocation ID:
- p. 582-586
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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