Chytrid fungus Batrachochytrium dendrobatidis has nonamphibian hosts and releases chemicals that cause pathology in the absence of infection

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 1; pp. 210 - 215
• Main Authors: McMahon, Taegan A., Brannelly, Laura A., Chatfield, Matthew W. H., Johnson, Pieter T. J., Joseph, Maxwell B., McKenzie, Valerie J., Richards-Zawacki, Corinne L., Venesky, Matthew D., Rohr, Jason R.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences 02.01.2013; National Acad Sciences
• Subjects: Amphibians; Animal, plant and microbial ecology; Animals; Applied ecology; Aquatic ecosystems; Astacoidea - microbiology; Biological and medical sciences; Biological Sciences; Chemicals; Chytridiomycota - chemistry; Chytridiomycota - physiology; Colorado - epidemiology; Conservation, protection and management of environment and wildlife; Crayfish; Cyprinodontiformes; Fish; Fish Diseases - epidemiology; Fish Diseases - microbiology; Fish Diseases - transmission; Fundamental and applied biological sciences. Psychology; Fungi; Gastrointestinal Contents - microbiology; Gastrointestinal tract; Gills - microbiology; Infections; Inoculum; Louisiana - epidemiology; Mortality; Mycoses - epidemiology; Mycoses - transmission; Mycoses - veterinary; Parasite hosts; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Pathogens; Pathology; Prevalence; Proportional Hazards Models; Reptiles & amphibians; Sporangia; Tadpoles; Zoospores; Louisiana; Colorado; United States; North America; America; field correlation; Secretion; Parasite; Zoopathogen; Bd toxin; Macrura; Crustacea; Mycoparasite; Toxin; Alternative host; alternative hosts; vectors; Arthropoda; Pathogenic; Orconectes virilis; Decapoda; Invertebrata; Animal conservation; Environmental monitoring
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1200592110

Batrachochytrium dendrobatidis , a pathogenic chytrid fungus implicated in worldwide amphibian declines, is considered an amphibian specialist. Identification of nonamphibian hosts could help explain the virulence, heterogeneous distribution, variable rates of spread, and persistence of B. dendrobatidis in freshwater ecosystems even after amphibian extirpations. Here, we test whether mosquitofish (Gambusia holbrooki) and crayfish (Procambarus spp. and Orconectes virilis), which are syntopic with many amphibian species, are possible hosts for B. dendrobatidis . Field surveys in Louisiana and Colorado revealed that zoosporangia occur within crayfish gastrointestinal tracts, that B. dendrobatidis prevalence in crayfish was up to 29%, and that crayfish presence in Colorado wetlands was a positive predictor of B. dendrobatidis infections in cooccurring amphibians. In experiments, crayfish, but not mosquitofish, became infected with B. dendrobatidis , maintained the infection for at least 12 wk, and transmitted B. dendrobatidis to amphibians. Exposure to water that previously held B. dendrobatidis also caused significant crayfish mortality and gill recession. These results indicate that there are nonamphibian hosts for B. dendrobatidis and suggest that B. dendrobatidis releases a chemical that can cause host pathology, even in the absence of infection. Managing these biological reservoirs for B. dendrobatidis and identifying this chemical might provide new hope for imperiled amphibians.