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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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This content will become publicly available on April 1, 2026
Ecological niche models based on occurrence records of the amphibian chytrid fungus overestimate lethal chytridiomycosis risk
Abstract Ecological niche models (ENMs) have been used frequently to predict the distribution and future spread of the pathogenic chytrid fungusBatrachochytrium dendrobatidis(Bd). Based on the assumption that chytridiomycosis outbreaks are most likely to occur where the conditions are ideal for Bd, many studies have identified high‐risk areas for chytridiomycosis and its associated mortality risk using only known Bd occurrences. However, the presence of a pathogen does not necessarily indicate high infection, disease or associated mortality.We used the BIOMOD2 package implemented in R, 19 bioclimatic variables, and 267 locality records, covering three levels of infection progress (occurrence, high infection loads and disease‐associated mortality), to calculate the potential areas where: (1) Bd is likely to be present, (2) amphibians are prone to harbour high infections and (3) chytridiomycosis‐related mortalities are likely to occur. We evaluate discrepancies among the three potential areas projected by the models, encompassing their spatial extent and associated environmental conditions.When all the Bd occurrences were used, the predicted area subjected to Bd risk covered 17% of the study area. However, when just mortality records were used, the predicted area decreased three‐fold. Notably, the three predicted areas only overlapped in 3% of the total study area, suggesting that the region at risk of mortality plus high infections constituted only one‐fifth of the predicted area for Bd presence. Mean temperature during the wettest and warmest 3 months of the year together with isothermality emerged as the most robust negative predictors in each of the three models.Synthesis and applications. Ecological niche models (ENMs) based on the presence data ofBatrachochytrium dendrobatidis(Bd) can overestimate the mortality risk of chytridiomycosis because the environmental conditions suitable for Bd presence do not always correspond to those conducive to significant host mortality. Distribution modelling can be a powerful tool when used correctly, and this study highlights the significance of careful data selection to ensure alignment with intended objectives. Considering the widespread use of ENMs to inform policy, meticulous design and comprehensive evaluation are imperative.
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- Award ID(s):
- 2109293
- PAR ID:
- 10585511
- Publisher / Repository:
- British Ecological Society
- Date Published:
- Journal Name:
- Journal of Applied Ecology
- Volume:
- 62
- Issue:
- 4
- ISSN:
- 0021-8901
- Page Range / eLocation ID:
- 995 to 1006
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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