Conservation translocations for amphibian species threatened by chytrid fungus: A review, conceptual framework, and recommendations

National monitoring programs provide the basis for evaluating the integrity of ecosystems, their responses to disturbances, and the success of actions taken to conserve or recover biodiversity. In this study, we successfully established a national program for the invasive chytrid fungus Batrachochytrium dendrobatidis (Bd) based on dual TaqMan assays. Amphibian diversity based on metabarcoding of the mitochondrial 12S rRNA gene was also performed. Assays were optimized for sensitive detection of target species from a wide range of amphibian ponds with variable potential of inhibitions for eDNA based detection. An amphibian mock community of 5 species was used to validate the metabarcoding approach while internal standards were used in the case of the dual TaqMan assays. First sampling of over 170 ponds in Norway resulted in Bd detection in 12 environmental samples and one swab sample taken over multiple years indicating the establishment of Bd in Norway. Five amphibian species Bufo bufo, Lissotriton vulgaris, Triturus cristatus, Rana arvalis and Rana temporaria as predicted from data in long-term citizen science reporting systems were widely detected in the collected eDNA samples. Our large scale-monitoring program indicates a low risk of a Bd outbreak and amphibian decline caused by chytridiomycosis but continued monitoring is recommended in the future. These findings indicate that eDNA is an effective method to detect invasive species, and to monitor endangered amphibian species. Still, several shortcomings (such as PCR inhibitors and sample volume) were identified that need to be addressed to improve eDNA-based monitoring at the national level.

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Environmental DNA sampling in a terrestrial environment: methods to detect a critically endangered frog and a global pathogen

10.1101/2020.03.01.968693 ◽

2020 ◽

Author(s):

Thomas J. Burns ◽

Nick Clemann ◽

Anthony R. van Rooyen ◽

Ben C. Scheele ◽

Andrew R. Weeks ◽

...

Keyword(s):

Field Experiments ◽

Survey Methods ◽

Environmental Dna ◽

Wash Water ◽

Critically Endangered ◽

Chytrid Fungus ◽

Amphibian Skin ◽

Natural Habitats ◽

Amphibian Species ◽

Terrestrial Environment

AbstractEnvironmental DNA techniques have become established as a useful tool for biological monitoring and are used extensively to determine species presence in aquatic systems. However, their application in terrestrial systems has been more limited, likely in part due to difficulties in choosing where to sample and ensuring that collected DNA reflects current species presence. We developed methods to sample eDNA in the terrestrial environment and trialled them under controlled and field conditions. We targeted three species, an elusive critically endangered frog, an abundant non-threatened frog, and the globally distributed amphibian skin pathogen chytrid fungus, which has been implicated in the decline of over 500 amphibian species. We used a sandpaper-sampling surface to ‘trap’ DNA. After sampling, we washed the surface and filtered the wash water to gather material for DNA extraction and subsequent qPCR. Our controlled condition experiments demonstrated that frog and chytrid fungus DNA was detectable after as few as five contacts between a frog and the sampling surface. Furthermore, this DNA remained detectable after two weeks in cool, shaded, outdoor conditions. Our field experiments demonstrated that these techniques were transferable to natural habitats, where we detected both the common and rare amphibian target species, as well as chytrid fungus. Field sampling eDNA results were broadly consistent with those derived from conventional survey methods. Our methods have potential application in non-invasive sampling of amphibians and other species in terrestrial systems, broadening the applicability of eDNA techniques for species detection and monitoring.

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Mosquitoes as a potential vector for the transmission of the amphibian chytrid fungus

Zoology and Ecology ◽

10.35513/21658005.2019.1.5 ◽

2019 ◽

Vol 29 (1) ◽

pp. 39-44 ◽

Cited By ~ 1

Author(s):

John Gould ◽

Jose W. Valdez ◽

Michelle P. Stockwell ◽

Simon Clulow ◽

Michael J. Mahony

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Agar Plate ◽

Insect Host ◽

Chytrid Fungus ◽

Amphibian Species ◽

Potential Vector ◽

Amphibian Chytrid Fungus ◽

And Control ◽

Zoospore Suspension

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is an infectious disease responsible for the worldwide decline of amphibian species. To mitigate these declines, it is necessary to identify the various vectors by which the fungus can be transmitted between individuals and populations. The objective of this study was to determine whether adult female mosquitoes can carry and transfer Bd fungal cells. Mosquitoes were exposed to netting soaked in a live Bd zoospore suspension to determine whether they are able to externally acquire the fungus. Another group was placed into containers with a sterile and Bd-inoculated agar plate to determine whether mosquitoes could transfer Bd between these surfaces. Bd DNA was found to be present on mosquito legs exposed to inoculated netting and agar plates suggesting that Bd can be transmitted by the mosquito over short distances. This is the first study to demonstrate that an insect host may be a mechanical vector of Bd and suggests that we should begin to consider the role of mosquitoes in the dissemination and control of the fungus.

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Single infection with Batrachochytrium dendrobatidis or Ranavirus does not increase probability of co-infection in a montane community of amphibians

Scientific Reports ◽

10.1038/s41598-020-78196-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Jaime Bosch ◽

Camino Monsalve-Carcaño ◽

Stephen J. Price ◽

Jon Bielby

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Disease Outbreaks ◽

Single Infection ◽

Chytrid Fungus ◽

Population Declines ◽

Emerging Pathogens ◽

Amphibian Species ◽

Management Interventions ◽

Amphibian Chytrid Fungus ◽

Common Situation

AbstractUnderstanding the occurrence and consequence of co-infections can be useful in designing disease management interventions. Amphibians are the most highly threatened vertebrates, and emerging pathogens are a serious threat to their conservation. The amphibian chytrid fungus and the viruses of the Ranavirus genus are already widely distributed, causing disease outbreaks and population declines worldwide. However, we lack information about the occurrence and consequences of coinfection with these pathogens across age-classes of amphibian hosts. Here, we analyze the occurrence of infection of the amphibian chytrid fungus and ranaviruses during one season in two susceptible amphibian species at two different locations at which outbreaks have occurred. We found that the co-occurrence of both pathogens in a particular host is not common except in highly susceptible life-stages, and that single infections are the most common situation. Moreover, we found that the occurrence of one pathogen in a particular host did not predict the occurrence of the other. We attribute these results to the niches in which both pathogens proliferate in amphibian hosts.

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Inhibition of Batrachochytrium dendrobatidis Caused by Bacteria Isolated from the Skin of Boreal Toads, Anaxyrus (Bufo) boreas boreas, from Grand Teton National Park, Wyoming, USA

Microbiology Insights ◽

10.4137/mbi.s13639 ◽

2014 ◽

Vol 7 ◽

pp. MBI.S13639 ◽

Cited By ~ 13

Author(s):

Shawna T. Park ◽

Amanda M. Collingwood ◽

Sophie St-Hilaire ◽

Peter P. Sheridan

Keyword(s):

National Park ◽

Batrachochytrium Dendrobatidis ◽

Chytrid Fungus ◽

Bacterial Isolates ◽

Skin Microbiota ◽

Amphibian Species ◽

Bufo Boreas ◽

Grand Teton National Park ◽

Boreal Toads

The chytrid fungus Batrachochytrium dendrobatidis is a significant cause of the worldwide decline in amphibian populations; however, various amphibian species are capable of coexisting with B. dendrobatidis. Among them are boreal toads ( Anaxyrus ( Bufo) boreas boreas) located in Grand Teton National Park (GTNP) in Wyoming, USA. The purpose of this study was to identify cultivable bacterial isolates from the skin microbiota of boreal toads from GTNP and determine if they were capable of inhibiting B. dendrobatidis in vitro, and therefore might be a factor in the toad's coexistence with this pathogen. Isolates from 6 of 21 genera tested were found to inhibit the growth of B. dendrobatidis. These bacteria represent diverse lineages such as the Gammaproteobacteria, the Betaproteobacteria, and the Bacteroidetes/Chlorobium groups. We propose that these bacteria compete via microbial antagonism with B. dendrobatidis.

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Mosquitoes as a Potential Vector for the Transmission of the Amphibian Chytrid Fungus

10.20944/preprints201903.0234.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

John Gould ◽

Jose Valdez ◽

Michelle Stockwell ◽

Simon Clulow ◽

Michael Mahony

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Agar Plate ◽

Insect Host ◽

Chytrid Fungus ◽

Amphibian Species ◽

Potential Vector ◽

Amphibian Chytrid Fungus ◽

And Control ◽

Zoospore Suspension

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is an infectious disease responsible for the worldwide decline of amphibian species. To mitigate these declines, it is necessary to identify the various vectors by which the fungus can be transmitted between individuals and populations. The objective of this study was to determine whether adult female mosquitoes can carry and transfer Bd fungal cells. Mosquitoes were exposed to net soaked in a live Bd zoospore suspension to determine whether they are able to externally acquire the fungus. Another group was placed into containers with a sterile and Bd-inoculated agar plate to determine whether mosquitoes could transfer Bd between these surfaces. Bd DNA was found to be present on mosquito legs exposed to inoculated netting and agar plates suggesting that Bd can be transmitted by the mosquito over short distances This is the first study to demonstrate that an insect host may be a mechanical vector of Bd and suggests that we should begin to consider the role of mosquitoes in the dissemination and control of the fungus.

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Host Species is Linked to Pathogen Genotype for the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis)

10.1101/2021.11.24.469827 ◽

2021 ◽

Author(s):

Allison Q Byrne ◽

Anthony W Waddle ◽

Veronica Saenz ◽

Michel Ohmer ◽

Jef R Jaeger ◽

...

Keyword(s):

United States ◽

Host Species ◽

Batrachochytrium Dendrobatidis ◽

The United States ◽

Ancestral Population ◽

Chytrid Fungus ◽

Species Identity ◽

Amphibian Species ◽

Host Pathogen ◽

Amphibian Chytrid Fungus

Host-pathogen specificity can arise from certain selective environments mediated by both the host and pathogen. Therefore, understanding the degree to which host species identity is correlated with pathogen genotype can help reveal historical host-pathogen dynamics. One animal disease of particular concern is chytridiomycosis, typically caused by the global panzootic lineage of the amphibian chytrid fungus ( Batrachochytrium dendrobatidis , Bd), termed the Bd-GPL. This pathogen lineage has caused devastating declines in amphibian communities around the world. However, the origin of Bd-GPL and the fine-scale transmission dynamics of this lineage have remained a mystery. This is especially the case in North America where Bd-GPL is widespread, but disease outbreaks occur sporadically. Herein, we use Bd genetic data collected throughout the United States from amphibian skin swab and cultured isolate samples to investigate Bd genetic patterns. We highlight two case studies in Pennsylvania and Nevada where Bd-GPL genotypes are strongly correlated with host species identity. Specifically, in some localities bullfrogs ( Rana catesbeiana ) are infected with Bd-GPL lineages that are distinct from those infecting other sympatric amphibian species. Overall, we reveal a previously unknown association of Bd genotype with host species and identify the eastern United States as a Bd diversity hotspot and potential ancestral population for Bd-GPL.

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Populations of a Susceptible Amphibian Species Can Grow despite the Presence of a Pathogenic Chytrid Fungus

PLoS ONE ◽

10.1371/journal.pone.0034667 ◽

2012 ◽

Vol 7 (4) ◽

pp. e34667 ◽

Cited By ~ 48

Author(s):

Ursina Tobler ◽

Adrian Borgula ◽

Benedikt R. Schmidt

Keyword(s):

Chytrid Fungus ◽

Amphibian Species

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Distribution and Genetic Diversity of the Amphibian Chytrid in Japan

Journal of Fungi ◽

10.3390/jof7070522 ◽

2021 ◽

Vol 7 (7) ◽

pp. 522

Author(s):

Koichi Goka ◽

Jun Yokoyama ◽

Atsushi Tominaga

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Limited Area ◽

Infection Prevalence ◽

Chytrid Fungus ◽

Amphibian Species ◽

Okinawa Island ◽

Dna Variation ◽

The Status ◽

Long Time ◽

Pcr Method

While research on frog chytrid fungus Batrachochytrium dendrobatidis (Bd), an infectious disease that threatens amphibian diversity, continues to advance worldwide, little progress has been made in Japan since around 2010. The reason for this is, which we pointed out in 2009, that the origin of frog chytrid fungus may be in the East Asian region, including Japan based on the Bd ITS-DNA variation, and as few cases of mass mortality caused by this fungus have been observed in wild amphibian populations in Japan, the interest of the Japanese government and the general public in Bd has waned. However, we believe that organizing the data obtained so far in Japan and distributing the status of frog chytrid fungus in Japan to the world will provide useful insight for future risk management of this pathogen. We collected more than 5500 swab samples from wild amphibians throughout Japan from 2009 to 2010. Then, we investigated the infection status using the Nested-PCR method. We sequenced the obtained DNA samples and constructed a maximum-parsimony (MP) tree to clarify the phylogenetic diversity of Bd. We detected Bd infection in 11 (nine native and two alien) amphibian species in Japan and obtained 44 haplotypes of Bd ITS-DNA. The MP tree showed a high diversity of Bd strains in Japan, suggesting that some strains belong to Bd-GPL and Bd-Brazil. Except for local populations of the Japanese giant salamanders Andrias japonicus in Honshu Island and the sword tail newts Cynops ensicauda in Okinawa Island, the Bd infection prevalence in native amphibian species was very low. The alien bullfrog Aquarana catesbeiana had high Bd infection rates in all areas where they were sampled. No Bd infection was detected in other native amphibians in the areas where giant salamanders, sword tail newts, and bullfrogs were collected, suggesting that many native amphibians are resistant to Bd infection. The sword tail newt of Okinawa Island had both the highest infectious incidence and greatest number of haplotypes. The giant salamanders also showed relatively high infection prevalence, but the infected strains were limited to those specific to this species. These two Caudata species are endemic to a limited area of Japan, and it was thought that they may have been refugia for Bd, which had been distributed in Japan Islands for a long time.

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Evaluation of the Amphibian Fauna of the Semi-arid and Arid Grassland Habitats in and around the Mayureshwar, Rehekuri, and Karmala Wildlife Sanctuaries in Maharashtra, India

Reptiles & Amphibians ◽

10.17161/randa.v27i2.14023 ◽

2020 ◽

Vol 27 (2) ◽

pp. 129-136

Author(s):

Nikhil Dandekar ◽

Varun Kherr ◽

Chaitanya Risbud ◽

Mayuresh Kulkarni ◽

Makarand Ketkar ◽

...

Keyword(s):

Chytrid Fungus ◽

Population Status ◽

Amphibian Species ◽

Semiarid Environments ◽

Preliminary Study ◽

Surrounding Areas ◽

Bodies Of Water ◽

Grassland Habitats ◽

Semi Arid ◽

Arid And Semiarid

Few studies document amphibian species composition from arid and semiarid environments. Scatteredbodies of water in the semi-arid and arid landscape around Pune, Maharashtra, India, could be viable amphibian habitats; however; information on amphibians using these bodies of water is not available. In a preliminary study, we assessed the amphibian diversity and population status in three wildlife sanctuaries and surrounding areas near Pune. We also compared the use of artificial and natural ponds by amphibians and surveyed the amphibians for the presence of the chytrid fungus.

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