scholarly journals A pesticide paradox: Fungicides indirectly increase fungal infections

2017 ◽  
Author(s):  
Jason R. Rohr ◽  
Jenise Browna ◽  
William A. Battaglin ◽  
Taegan A. McMahon ◽  
Rick A. Relyea
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Crop Yields ◽  
Insect Pests ◽  
Disease Risk ◽  
Fungal Infections ◽  
Pathogenic Fungus ◽  
Pathogen Resistance ◽  
Amphibian Declines ◽  
Unintended Consequences ◽  
Tree Frog

AbstractThere are many examples where the use of chemicals have had profound unintended consequences, such as fertilizers reducing crop yields (paradox of enrichment) and insecticides increasing insect pests (by reducing natural biocontrol). Recently, the application of agrochemicals, such as agricultural disinfectants and fungicides, has been explored as an approach to curb the pathogenic fungus, Batrachochytrium dendrobatidis (Bd), which is associated with worldwide amphibian declines. However, the long-term, net effects of early-life exposure to these chemicals on amphibian disease risk have not been thoroughly investigated. Using a combination of laboratory experiments and analysis of data from the literature, we explored the effects of fungicide exposure on Bd infections in two frog species. Extremely low concentrations of the fungicides azoxystrobin, chlorothalonil, and mancozeb were directly toxic to Bd in culture. However, estimated environmental concentrations of the fungicides did not reduce Bd on Cuban tree frog (Osteopilus septentrionalis) tadpoles exposed simultaneously to any of these fungicides and Bd, and fungicide exposure actually increased Bd-induced mortality. Additionally, exposure to any of these fungicides as tadpoles resulted in higher Bd abundance and greater Bd-induced mortality when challenged with Bd post-metamorphosis, an average of 71 days after their last fungicide exposure. Analysis of data from the literature revealed that previous exposure to the fungicide itraconazole, which is commonly used to clear Bd infections, made the critically endangered booroolong frog (Litoria booroolongensis) more susceptible to Bd. Finally, a field survey revealed that Bd prevalence was positively associated with concentrations of fungicides in ponds. Although fungicides show promise for controlling Bd, these results suggest that, if fungicides do not completely eliminate Bd or if Bd re-colonizes, exposure to fungicides has the potential to do more harm than good. To ensure that fungicide applications have the intended consequence of curbing amphibian declines, researchers must identify which fungicides do not compromise the pathogen resistance mechanisms of amphibians.

scholarly journals The emerging amphibian pathogen Batrachochytrium dendrobatidis globally infects introduced populations of the North American bullfrog, Rana catesbeiana

2006 ◽  
Vol 2 (3) ◽  
pp. 455-459 ◽  
Author(s):  
Trenton W.J Garner ◽  
Matthew W Perkins ◽  
Purnima Govindarajulu ◽  
Daniele Seglie ◽  
Susan Walker ◽  
...  
Keyword(s):  
North American ◽  
Disease Transmission ◽  
Batrachochytrium Dendrobatidis ◽  
Rana Catesbeiana ◽  
Pathogenic Fungus ◽  
Amphibian Declines ◽  
Eastern Canada ◽  
The North ◽  
Introduced Populations ◽  
Global Threat

Batrachochytrium dendrobatidis is the chytridiomycete fungus which has been implicated in global amphibian declines and numerous species extinctions. Here, we show that introduced North American bullfrogs ( Rana catesbeiana ) consistently carry this emerging pathogenic fungus. We detected infections by this fungus on introduced bullfrogs from seven of eight countries using both PCR and microscopic techniques. Only native bullfrogs from eastern Canada and introduced bullfrogs from Japan showed no sign of infection. The bullfrog is the most commonly farmed amphibian, and escapes and subsequent establishment of feral populations regularly occur. These factors taken together with our study suggest that the global threat of B. dendrobatidis disease transmission posed by bullfrogs is significant.

scholarly journals Chytridiomycosis-induced mortality in a threatened anuran

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241119
Author(s):  
Andrea J. Adams ◽  
Allan Pessier ◽  
Peggy Cranston ◽  
Robert L. Grasso
Keyword(s):  
Sierra Nevada ◽  
Batrachochytrium Dendrobatidis ◽  
Disease Risk ◽  
Amphibian Declines ◽  
Ex Situ ◽  
Source Population ◽  
Sierra Nevada Mountains ◽  
Selection For ◽  
Source Populations ◽  
Two Populations

Effectively planning conservation introductions involves assessing the suitability of both donor and recipient populations, including the landscape of disease risk. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has caused extensive amphibian declines globally and may hamper reintroduction attempts. To determine Bd dynamics in potential source populations for conservation translocations of the threatened California red-legged frog (Rana draytonii) to Yosemite National Park, we conducted Bd sampling in two populations in the foothills of the Sierra Nevada Mountains, California, U.S.A. At one of two sites, we observed lethally high Bd loads in early post-metamorphic life stages and confirmed one chytridiomycosis-induced mortality, the first such report for this species. These results informed source population site selection for subsequent R. draytonii conservation translocations. Conservation efforts aimed at establishing new populations of R. draytonii in a landscape where Bd is ubiquitous can benefit from an improved understanding of risk through disease monitoring and ex situ infection studies.

scholarly journals Primer registro de Saprolegnia sp. en una población de anfibios en Colombia.

2011 ◽  
Vol 16 (3) ◽  
pp. 234 ◽  
Author(s):  
Luis Daniel Prada-Salcedo ◽  
Marcela Franco-Correa ◽  
Andrés Rymel Acosta-Galvis
Keyword(s):  
Rainbow Trout ◽  
North America ◽  
Batrachochytrium Dendrobatidis ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Amphibian Declines ◽  
Blue Staining ◽  
Amphibian Species ◽  
Saprolegnia Ferax ◽  
The World

<p><strong> </strong></p> <p><strong>Objective: </strong><strong>Most </strong>research related to the decline of amphibians has been focused on the detection of the pathogenic fungus <em>Batrachochytrium dendrobatidis</em>. This fungus is the main pathogen detected around the world. However, research has shown the presence of another fungus, <em>Saprolegnia ferax</em>, as a cause of mortality in amphibians in North America. Our study suggests a possible interspecific transmission caused by the presence of rainbow trout; thus, amphibian declines may not be attributable only to the presence of a single pathogen, but to other organisms and factors. <strong>Materials and methods: </strong>Our study revealed the presence of <em>Saprolegnia</em> sp. in the Andean frog <em>Atelopus mittermeieri</em> using the imprinting technique with lactophenol blue staining, which allowed the typical structures of this fungus to be observed. <strong>Results:</strong> The importance of this discovery is the presence of two pathogenic fungi, <em>B. dendrobatidis </em>and <em>Saprolegnia</em>, which affecting simultaneously a population of amphibians. This finding brings attention to the eventual presence of other microorganisms that might be involved individually or collectively in the decline of amphibian species. <strong>Conclusions:</strong> This record suggests a possible transmission between rainbow trout (<em>Oncorhynchus mykiss</em>), an introduced species in the highlands of Colombia, which shares the same habitats with different species of amphibians in the Sanctuary of Flora and Fauna Guanentá in the upper river Fonce in the mid Cordillera Oriental of Colombia.</p> <p><strong>Key words: </strong>decline, Amphibians,<em> Saprolegnia</em>, Fishes, <em>Atelopus</em>, Colombia.</p> <p> </p> <p><strong> </strong></p><br />

GROWTH INHIBITORY ACTIVITIES OF THE RHIZOME CRUDE EXTRACT OF Curcuma longa ON THE HUMAN PATHOGENIC FUNGUS Mucor circinelloides

2020 ◽  
Vol 65 (10) ◽  
pp. 82-91
Author(s):  
Phuong Nguyen Anh ◽  
Mai Le Thi Tuyet ◽  
Trung Trieu Anh
Keyword(s):  
Antifungal Activity ◽  
Crude Extract ◽  
Fungal Infections ◽  
Early Stage ◽  
Curcuma Longa ◽  
Pathogenic Fungus ◽  
Mucor Circinelloides ◽  
Antifungal Drugs ◽  
Diffusion Method ◽  
Dilution Method

Mucormycosis is an uncommon but life-threatening invasive fungal infection, mostly occurs in immunocompromised patients. Lacking the appropriate antifungal drugs is one of the reasons that lead to difficulties in the management of mucormycosis. Curcuma longa has been used traditionally and widely to treat various diseases, including fungal infections. In the search for novel antifungal compounds from natural resources, we evaluated the effect of rhizome crude extract of C. longa on Mucor circinelloides – a causal agent of mucormycosis. The results of screening, using broth dilution method and agar-well diffusion method, showed that the C. longa extract exhibited promising antifungal activity against the fungus M. circinelloides. In liquid medium, C. longa extract decreased the ability of spore germination and the speed of hyphae formation of M. circinelloides decreased by up to approximately 70% and 90%, respectively. Besides, in a solid medium, the crude extract presented similar activity with amphotericin B (400 μg\mL) in decreasing the growth of M. circinelloides by nearly 77%. Moreover, the extract of C. longa also likely to induce the yeast-like type of growth of the dimorphic M. circinelloides in the early stage. These results suggest the plant could be a potential source for further study on biochemical components and the mechanism of its antifungal activity.

Legume seed flavonoids and nitrogenous metabolites as signals and protectants in early seedling development

2003 ◽  
Vol 30 (7) ◽  
pp. 729 ◽  
Author(s):  
Patrick A. Ndakidemi ◽  
Felix D. Dakora
Keyword(s):  
Amino Acids ◽  
Crop Yields ◽  
Insect Pests ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Effective Control ◽  
Plant Seeds ◽  
Plant Pest ◽  
The Family ◽  
Early Seedling

Flavonoids and nitrogenous metabolites such as alkaloids, terpenoids, peptides and amino acids are major components of plant seeds. Conjugated forms of these compounds are soluble in water, and therefore, are easily released as chemical signals following imbibition. Once in the soil, these metabolites are first in line to serve as eco-sensing signals for suitable rhizobia and arbuscular mycorrhizal (AM) fungal partners required for the establishment of symbiotic mutualisms. They may also serve as defence molecules against pathogens and insect pests, as well as playing a role in the control of parasitic members of the family Scrophulariaceae, especially Striga, a major plant pest of cereal crops in Africa. Seed metabolites such as flavonoids, alkaloids, terpenoids, peptides and amino acids define seedling growth and, ultimately, crop yields. Thus, an improvement in our understanding of seed chemistry would permit manipulation of these molecules for effective control of pathogens, insect pests, Striga and destructive weeds, as well as for enhanced acquisition of N and P via symbioses with soil rhizobia and AM fungi.

scholarly journals Fungal infection, decline and persistence in the only obligate troglodytic Neotropical salamander

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9763
Author(s):  
Mizraim Olivares-Miranda ◽  
Vance T. Vredenburg ◽  
Julio C. García-Sánchez ◽  
Allison Q. Byrne ◽  
Erica B. Rosenblum ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Infection Intensity ◽  
Sampling Technique ◽  
Sympatric Species ◽  
Amphibian Declines ◽  
Small Range ◽  
Museum Specimens ◽  
Amphibian Species ◽  
Extant Population ◽  
Epidemic Wave

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is implicated in global mass die-offs and declines in amphibians. In Mesoamerica, the Bd epidemic wave hypothesis is supported by detection of Bd in historic museum specimens collected over the last century, yet the timing and impact of the early stages of the wave remain poorly understood. Chiropterotriton magnipes, the only obligate troglodytic Neotropical salamander, was abundant in its small range in the decade following its description in 1965, but subsequently disappeared from known localities and was not seen for 34 years. Its decline is roughly coincident with that of other populations of Neotropical salamanders associated with the invasion and spread of Bd. To determine the presence and infection intensity of Bd on C. magnipes and sympatric amphibian species (which are also Bd hosts), we used a noninvasive sampling technique and qPCR assay to detect Bd on museum specimens of C. magnipes collected from 1952 to 2012, and from extant populations of C. magnipes and sympatric species of amphibians. We also tested for the presence of the recently discovered Batrachochytrium salamandivorans (Bsal), another fungal chytridiomycete pathogen of salamanders, using a similar technique specific for Bsal. We did not detect Bd in populations of C. magnipes before 1969, while Bd was detected at low to moderate prevalence just prior to and during declines. This pattern is consistent with Bd-caused epizootics followed by host declines and extirpations described in other hosts. We did not detect Bsal in any extant population of C. magnipes. We obtained one of the earliest positive records of the fungus to date in Latin America, providing additional historical evidence consistent with the Bd epidemic wave hypothesis. Genotyping results show that at least one population is currently infected with the Global Panzootic Lineage of Bd, but our genotyping of the historical positive samples was unsuccessful. The lack of large samples from some years and the difficulty in genotyping historical Bd samples illustrate some of the difficulties inherent in assigning causality to historical amphibian declines. These data also provide an important historical baseline for actions to preserve the few known remaining populations of C. magnipes.

scholarly journals Habitat fragmentation in the Brazilian Atlantic Forest is associated with erosion of frog immunogenetic diversity and increased fungal infections

2021 ◽  
Author(s):  
Anat Belasen ◽  
Kevin Amses ◽  
Rebecca Clemons ◽  
Guilherme Becker ◽  
Felipe Toledo ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Atlantic Forest ◽  
Batrachochytrium Dendrobatidis ◽  
Fungal Infections ◽  
Emerging Infectious Diseases ◽  
Genetic Erosion ◽  
Population Level ◽  
Brazilian Atlantic Forest ◽  
Frog Species ◽  
Mhc Iib

Habitat fragmentation and infectious disease threaten amphibians globally, but little is known about how these two threats interact. In this study, we examined the effects of Brazilian Atlantic Forest habitat fragmentation on frog genetic diversity at an immune locus known to affect disease susceptibility in amphibians, the MHC IIB locus. We used a custom high-throughput assay to sequence the MHC IIB locus across six focal frog species in two regions of the Atlantic Forest. We also used a molecular assay to quantify infections by the fungal pathogen Batrachochytrium dendrobatidis (Bd). We found that habitat fragmentation is associated with genetic erosion at the MHC IIB locus, and that this erosion is most severe in frog species restricted to intact forests. Significant Bd infections were recovered only in one Atlantic Forest region, potentially due to the relatively higher elevation. In this region, forest specialists showed an increase in both Bd prevalence and loads in fragmented habitats. We also found that reduced population-level MHC IIB diversity was associated with increased Bd infection risk. On the individual-level, MHC IIB heterozygotes (by allelic genotype as well as supertype) exhibited a reduced risk of Bd infection. Our results suggest that habitat fragmentation increases infection susceptibility in amphibians, mediated at least in part through loss of immunogenetic diversity. Our findings have implications for the conservation of fragmented populations in the face of emerging infectious diseases.

scholarly journals The Opportunistic Human Pathogenic Fungus Aspergillus fumigatus Evades the Host Complement System

2007 ◽  
Vol 76 (2) ◽  
pp. 820-827 ◽  
Author(s):  
Judith Behnsen ◽  
Andrea Hartmann ◽  
Jeannette Schmaler ◽  
Alexander Gehrke ◽  
Axel A. Brakhage ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Complement System ◽  
Developmental Stages ◽  
Fungal Infections ◽  
Alternative Pathway ◽  
Pathogenic Fungus ◽  
Factor H ◽  
Human Sera ◽  
Human Pathogenic Fungus ◽  
Complement Regulators

ABSTRACT The opportunistic human pathogenic fungus Aspergillus fumigatus causes severe systemic infections and is a major cause of fungal infections in immunocompromised patients. A. fumigatus conidia activate the alternative pathway of the complement system. In order to assess the mechanisms by which A. fumigatus evades the activated complement system, we analyzed the binding of host complement regulators to A. fumigatus. The binding of factor H and factor H-like protein 1 (FHL-1) from human sera to A. fumigatus conidia was shown by adsorption assays and immunostaining. In addition, factor H-related protein 1 (FHR-1) bound to conidia. Adsorption assays with recombinant factor H mutants were used to localize the binding domains. One binding region was identified within N-terminal short consensus repeats (SCRs) 1 to 7 and a second one within C-terminal SCR 20. Plasminogen was identified as the fourth host regulatory molecule that binds to A. fumigatus conidia. In contrast to conidia, other developmental stages of A. fumigatus, like swollen conidia or hyphae, did not bind to factor H, FHR-1, FHL-1, and plasminogen, thus indicating the developmentally regulated expression of A. fumigatus surface ligands. Both factor H and plasminogen maintained regulating activity when they were bound to the conidial surface. Bound factor H acted as a cofactor to the factor I-mediated cleavage of C3b. Plasminogen showed proteolytic activity when activated to plasmin by urokinase-type plasminogen activator. These data show that A. fumigatus conidia bind to complement regulators, and these bound host regulators may contribute to evasion of a host complement attack.

scholarly journals Sensitivity of histology for the detection of the amphibian chytrid fungus Batrachochytrium dendrobatidis

2019 ◽  
Vol 31 (2) ◽  
pp. 246-249 ◽  
Author(s):  
Claudio Borteiro ◽  
Francisco Kolenc ◽  
José Manuel Verdes ◽  
Claudio Martínez Debat ◽  
Martín Ubilla
Keyword(s):  
Skin Disease ◽  
Batrachochytrium Dendrobatidis ◽  
Pathogenic Fungus ◽  
Chytrid Fungus ◽  
Clinically Normal ◽  
Frog Species ◽  
Amphibian Chytrid Fungus

Histology is often underappreciated for the detection of the amphibian pathogenic fungus Batrachochytrium dendrobatidis, the cause of the potentially lethal skin disease chytridiomycosis. We evaluated the sensitivity of histology to detect chytrids in 20 wild specimens of 2 frog species from Uruguay that were clinically normal, but confirmed by PCR to be infected by B. dendrobatidis. We detected maturing and sporulated sporangia in 15 of 20 (75%) frogs, which is more sensitive than previously reported for histology. The effort needed to identify chytrids in histologic skin sections of Physalaemus henselii and Pleurodema bibroni required examination of 3.2 and 8.7 mm of skin sections for each frog species, respectively.

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