Distribution and Genetic Diversity of the Amphibian Chytrid in Japan

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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Establishement of a national monitoring program based on environmental DNA for amphibians and the chytrid fungus Batrachochytrium dendrobatidis

ARPHA Conference Abstracts ◽

10.3897/aca.4.e65362 ◽

2021 ◽

Vol 4 ◽

Author(s):

Omneya Osman ◽

Johan Andersson ◽

Tomas Larsson ◽

Mats Töpel ◽

Alexander Eiler

Keyword(s):

Batrachochytrium Dendrobatidis ◽

National Level ◽

Monitoring Program ◽

12S Rrna ◽

Rrna Gene ◽

Chytrid Fungus ◽

Rana Arvalis ◽

Amphibian Species ◽

National Monitoring ◽

Wide Range

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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Impacts of thermal mismatches on chytrid fungus Batrachochytrium dendrobatidis prevalence are moderated by life stage, body size, elevation and latitude

10.1101/473934 ◽

2018 ◽

Author(s):

Jeremy M. Cohen ◽

Taegan A. McMahon ◽

Chloe Ramsay ◽

Elizabeth A. Roznik ◽

Erin L. Sauer ◽

...

Keyword(s):

Body Size ◽

Batrachochytrium Dendrobatidis ◽

Global Climate ◽

Global Analysis ◽

Life Stage ◽

Conservation Status ◽

Amphibian Declines ◽

Lower Latitude ◽

Infection Prevalence ◽

Chytrid Fungus

AbstractGlobal 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 hosts and lower-latitude hosts generally have slower acclimation times, we hypothesized that their disease susceptibility increases under “thermal mismatches”, or differences between baseline climate and the temperature during surveying. Here, we examined how thermal mismatches interact with body size, life stage, habitat, latitude, elevation, phylogeny, and IUCN conservation status to predict infection prevalence of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in a global analysis of 38,967 amphibian hosts. As hypothesized, we found that the susceptibility of larger hosts and hosts from lower latitudes was strongly influenced by thermal mismatches. Furthermore, hosts of conservation concern are more susceptible than others following thermal mismatches, suggesting that thermal mismatches might have contributed to recent amphibian declines.Data Accessibility StatementShould the manuscript be accepted, the data supporting the results will be archived in an appropriate public repository such as Dryad or Figshare and the data DOI will be included at the end of the article.

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Occurrence of Batrachochytrium dendrobatidis in Sweden: higher infection prevalence in southern species

Diseases of Aquatic Organisms ◽

10.3354/dao03502 ◽

2020 ◽

Vol 140 ◽

pp. 209-218

Author(s):

S Meurling ◽

S Kärvemo ◽

N Chondrelli ◽

M Cortazar Chinarro ◽

D Åhlen ◽

...

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Egg Laying ◽

Infection Prevalence ◽

Chytrid Fungus ◽

Generalist Species ◽

Green Toad ◽

Central Regions ◽

Bombina Bombina ◽

The Impact ◽

Southern Species

The chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused worldwide declines in amphibian populations. While Bd is widespread in southern and central Europe, its occurrence and distribution in northernmost Europe is mostly unknown. We surveyed for Bd in breeding anurans in Sweden by sampling 1917 amphibians from 101 localities and 3 regions in Sweden (southern, northern and central). We found that Bd was widespread in southern and central Sweden, occurring in all 9 investigated species and in 45.5% of the 101 localities with an overall prevalence of 13.8%. No infected individuals were found in the 4 northern sites sampled. The records from central Sweden represent the northernmost records of Bd in Europe. While the proportion of sites positive for Bd was similar between the southern and central regions, prevalence was much higher in the southern region. This was because southern species with a distribution mainly restricted to southernmost Sweden had a higher prevalence than widespread generalist species. The nationally red-listed green toad Bufotes variabilis and the fire-bellied toad Bombina bombina had the highest prevalence (61.4 and 48.9%, respectively). Across species, Bd prevalence was strongly positively, correlated with water temperature at the start of egg laying. However, no individuals showing visual signs of chytridiomycosis were found in the field. These results indicate that Bd is widespread and common in southern and central Sweden with southern species, breeding in higher temperatures and with longer breeding periods, having higher prevalence. However, the impact of Bd on amphibian populations in northernmost Europe remains unknown.

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Prevalence of the fungal pathogen Batrachochytrium dendrobatidis in amphibians of Costa Rica predated first-known epizootic

10.1101/482968 ◽

2018 ◽

Cited By ~ 1

Author(s):

Marina E. De León ◽

Héctor Zumbado-Ulate ◽

Adrián García-Rodríguez ◽

Gilbert Alvarado ◽

Hasan Sulaeman ◽

...

Keyword(s):

Costa Rica ◽

Fungal Pathogen ◽

Batrachochytrium Dendrobatidis ◽

Emerging Infectious Diseases ◽

Infection Prevalence ◽

Pcr Assay ◽

Local Data ◽

Amphibian Species ◽

Genetic Lineages ◽

Quantitative Pcr Assay

AbstractEmerging infectious diseases are a growing threat to biodiversity worldwide. Outbreaks of the infectious disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), have caused the decline and extinction of numerous amphibian species. In Costa Rica, a major decline event occurred in 1987, more than two decades before this pathogen was discovered. The loss of many species in Costa Rica is assumed to be due to Bd-epizootics, but there are few studies that provide data from amphibians in the time leading up to the proposed epizootics. In this study, we provide new data on Bd infection rates of amphibians collected throughout Costa Rica, in the decades prior to the epizootics. We used a quantitative PCR assay to test for Bd infection in 1016 specimens collected throughout Costa Rica. We found Bd-infected hosts collected as early as 1964, and a infection prevalence average per decade of just 4%. The infection prevalence remained relatively low and geographically constrained until the 1980s when epizootics are hypothesized to have occurred. After that time, infection prevalence increased three-fold and Bd-infected hosts we collected throughout the entire country. Our results, suggest that Bd may either have invaded Costa Rica earlier than previously known, and spread more slowly than previously reported, or that an endemic lineage of the pathogen may exists. To help visualize areas where future studies should take place, we provide a Bd habitat suitability model trained with local data. Studies that provide information on genetic lineages of Bd are needed to determine whether an endemic lineage of Bd or the Global Panzootic Lineage (identified from mass die off sites globally) was present in Costa Rica and responsible for the epizootics that caused amphibian communities to collapse.

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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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The Bacterially Produced Metabolite Violacein Is Associated with Survival of Amphibians Infected with a Lethal Fungus

Applied and Environmental Microbiology ◽

10.1128/aem.01294-09 ◽

2009 ◽

Vol 75 (21) ◽

pp. 6635-6638 ◽

Cited By ~ 115

Author(s):

Matthew H. Becker ◽

Robert M. Brucker ◽

Christian R. Schwantes ◽

Reid N. Harris ◽

Kevin P. C. Minbiole

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Plethodon Cinereus ◽

Chytrid Fungus ◽

Experimental Exposure ◽

Amphibian Species ◽

Mortality And Morbidity ◽

Antifungal Metabolite ◽

Microbial Species ◽

Skin Bacteria ◽

Janthinobacterium Lividum

ABSTRACT The disease chytridiomycosis, which is caused by the chytrid fungus Batrachochytrium dendrobatidis, is associated with recent declines in amphibian populations. Susceptibility to this disease varies among amphibian populations and species, and resistance appears to be attributable in part to the presence of antifungal microbial species associated with the skin of amphibians. The betaproteobacterium Janthinobacterium lividum has been isolated from the skins of several amphibian species and produces the antifungal metabolite violacein, which inhibits B. dendrobatidis. In this study, we added J. lividum to red-backed salamanders (Plethodon cinereus) to obtain an increased range of violacein concentrations on the skin. Adding J. lividum to the skin of the salamander increased the concentration of violacein on the skin, which was strongly associated with survival after experimental exposure to B. dendrobatidis. As expected from previous work, some individuals that did not receive J. lividum and were exposed to B. dendrobatidis survived. These individuals had concentrations of bacterially produced violacein on their skins that were predicted to kill B. dendrobatidis. Our study suggests that a threshold violacein concentration of about 18 μM on a salamander's skin prevents mortality and morbidity caused by B. dendrobatidis. In addition, we show that over one-half of individuals in nature support antifungal bacteria that produce violacein, which suggests that there is a mutualism between violacein-producing bacteria and P. cinereus and that adding J. lividum is effective for protecting individuals that lack violacein-producing skin bacteria.

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