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Chew A, West M, Berger L, Brannelly LA. The impacts of water quality on the amphibian chytrid fungal pathogen: A systematic review. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13274. [PMID: 38775382 PMCID: PMC11110485 DOI: 10.1111/1758-2229.13274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 04/06/2024] [Indexed: 05/25/2024]
Abstract
The pathogenic fungus Batrachochytrium dendrobatidis has caused declines of amphibians worldwide. Yet our understanding of how water quality influences fungal pathogenicity is limited. Here, we reviewed experimental studies on the effect of water quality on this pathogen to determine which parameters impacted disease dynamics consistently. The strongest evidence for protective effects is salinity which shows strong antifungal properties in hosts at natural levels. Although many fungicides had detrimental effects on the fungal pathogen in vitro, their impact on the host is variable and they can worsen infection outcomes. However, one fungicide, epoxiconazole, reduced disease effects experimentally and likely in the field. While heavy metals are frequently studied, there is weak evidence that they influence infection outcomes. Nitrogen and phosphorous do not appear to impact pathogen growth or infection in the amphibian host. The effects of other chemicals, like pesticides and disinfectants on infection were mostly unclear with mixed results or lacking an in vivo component. Our study shows that water chemistry does impact disease dynamics, but the effects of specific parameters require more investigation. Improving our understanding of how water chemistry influences disease dynamics will help predict the impact of chytridiomycosis, especially in amphibian populations affected by land use changes.
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Affiliation(s)
- Adeline Chew
- School of BiosciencesThe University of MelbourneParkvilleVictoriaAustralia
| | - Matt West
- School of BiosciencesThe University of MelbourneParkvilleVictoriaAustralia
| | - Lee Berger
- Melbourne Veterinary SchoolThe University of MelbourneWerribeeVictoriaAustralia
| | - Laura A. Brannelly
- Melbourne Veterinary SchoolThe University of MelbourneWerribeeVictoriaAustralia
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2
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Hopkins AP, Hoverman JT. Strobilurin fungicide increases the susceptibility of amphibian larvae to trematode infections. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 269:106864. [PMID: 38422928 DOI: 10.1016/j.aquatox.2024.106864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/14/2024] [Accepted: 02/16/2024] [Indexed: 03/02/2024]
Abstract
The global rise in fungal pathogens has driven the increased usage of fungicides, yet our understanding of their ecotoxicity remains largely limited to acute toxicity. While such data is critical for projecting the risk of fungicide exposure to individual species, the contamination of natural systems with fungicides also has the potential to alter species interactions within communities including host-parasite relationships. We examined the effects of the fungicide pyraclostrobin on the susceptibility of larval American bullfrogs (Rana catesbeiana) to trematode (echinostome) infections using a controlled laboratory experiment. Following a 2-wk exposure to 0, 1.0, 5.2, or 8.4 µg/L of pyraclostrobin, tadpoles were then exposed to parasites either in the 1) presence (continued/simultaneous exposure) or 2) absence (fungicide-free water) of pyraclostrobin. We found that when exposed to pyraclostrobin during parasite exposure, meta cercariae counts increased 4 to 8 times compared to control tadpoles. Additionally, parasite loads were approximately 2 times higher in tadpoles with continued fungicide exposures compared to tadpoles that were moved to fresh water following fungicide exposure. This research demonstrates that fungicides at environmentally relevant concentrations can indirectly alter host-parasite interactions, which could elevate disease risk. It also underscores the need for studies that expand beyond traditional toxicity experiments to assess the potential community and ecosystem-level implications of environmental contaminants.
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Affiliation(s)
- Andrew P Hopkins
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, United States.
| | - Jason T Hoverman
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, United States
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3
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Riascos-Flores LR, Bonilla J, Naranjo-Briceño L, Apunte-Ramos K, Reyes-Ortega GC, Cabrera M, Cáceres-Andrade JF, Carrera-Gonzalez A, Yánez-Galarza JK, Siavichay Pesántez F, Oyagata-Cachimuel LA, Goethals P, Celi J, Van der Heyden C, Ortega-Andrade HM. Field-based molecular detection of Batrachochytrium dendrobatidis in critically endangered Atelopus toads and aquatic habitats in Ecuador. PLoS One 2024; 19:e0299246. [PMID: 38484016 PMCID: PMC10939218 DOI: 10.1371/journal.pone.0299246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 02/06/2024] [Indexed: 03/17/2024] Open
Abstract
Batrachochytrium dendrobatidis (Bd) is a lethal fungal species that parasitizes vertebrates and is associated with the worldwide decline of amphibian populations. The development of sensitive, rapid detection methods, particularly DNA-based techniques, is critical for effective management strategies. This study evaluates the efficacy of DNA extraction and a portable PCR device in a mountable field laboratory setup for detecting Bd near the habitats of three critically endangered Atelopus toad species in Ecuador. We collected skin swabs from Atelopus balios, A. nanay, and A. bomolochos, and environmental DNA (eDNA) samples from streams in Andean and coastal regions of Ecuador. For eDNA, a comparison was made with duplicates of the samples that were processed in the field and in a standard university laboratory. Our findings revealed Bd detection in eDNA and swabs from 6 of 12 water samples and 10 of 12 amphibian swab samples. The eDNA results obtained in the field laboratory were concordant with those obtained under campus laboratory conditions. These findings highlight the potential of field DNA-based monitoring techniques for detecting Bd in amphibian populations and their aquatic habitats, particularly in remote areas. Furthermore, this research aligns with the National Action Plan for the Conservation of Ecuadorian Amphibians and contributes to the global effort to control this invasive and deadly fungus.
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Affiliation(s)
- Lenin R. Riascos-Flores
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Gent University, Gent, Belgium
- Escuela Superior Politécnica del Litoral, ESPOL/Facultad de Ciencias de la Vida, Centro de Investigaciones Biotecnológicas del Ecuador, Campus Gustavo Galindo Guayaquil, Guayaquil, Ecuador
| | - Julio Bonilla
- Escuela Superior Politécnica del Litoral, ESPOL/Facultad de Ciencias de la Vida, Centro de Investigaciones Biotecnológicas del Ecuador, Campus Gustavo Galindo Guayaquil, Guayaquil, Ecuador
| | - Leopoldo Naranjo-Briceño
- Applied Microbiology Research Group, Life Sciences Faculty, Universidad Regional Amazónica IKIAM, Tena, Ecuador
- Fungal Biotech Lab, Spora Biotech, Huechuraba, Santiago, Región Metropolitana, Chile
| | - Katherine Apunte-Ramos
- Molecular Biology and Biochemistry Lab, Universidad Regional Amazónica IKIAM, Tena, Ecuador
| | - Grace C. Reyes-Ortega
- Biogeography and Spatial Ecology Research Group, Life Sciences Faculty, Universidad Regional Amazónica IKIAM, Tena, Ecuador
| | - Marcela Cabrera
- Laboratorio Nacional de Referencia del Agua, Universidad Regional Amazónica Ikiam, Tena, Ecuador
- University of Valencia, Paterna, Spain
| | | | | | - Jomira K. Yánez-Galarza
- Applied Microbiology Research Group, Life Sciences Faculty, Universidad Regional Amazónica IKIAM, Tena, Ecuador
- Biogeography and Spatial Ecology Research Group, Life Sciences Faculty, Universidad Regional Amazónica IKIAM, Tena, Ecuador
| | | | | | - Peter Goethals
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Gent University, Gent, Belgium
| | - Jorge Celi
- Water and Aquatic Resources Research Group, School of Earth and Water Sciences, Universidad Regional Amazónica Ikiam, Tena, Ecuador
| | - Christine Van der Heyden
- Department of Biosciences and Industrial Technology, Health and Water Technology Research Centre, HOGENT—University of Applied Sciences and Arts, Gent, Belgium
| | - H. Mauricio Ortega-Andrade
- Biogeography and Spatial Ecology Research Group, Life Sciences Faculty, Universidad Regional Amazónica IKIAM, Tena, Ecuador
- Herpetology Division, Instituto Nacional de Biodiversidad, Quito, Pichincha, Ecuador
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4
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Chew A, West M, Brannelly LA. Comparison of methods for determining Batrachochytrium dendrobatidis zoospore viability. DISEASES OF AQUATIC ORGANISMS 2023; 155:141-146. [PMID: 37706644 DOI: 10.3354/dao03749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The emerging fungal pathogen Batrachochytrium dendrobatidis (Bd) threatens hundreds of amphibian species globally. During laboratory-based experiments it is often essential to quantify live Bd cells, but a comparison of the effectiveness of methods for counting and assessing the viability of the infectious zoospore life stage has not been done. A direct comparison of staining methods that assess viability will ensure that the most accurate and efficient method is used. Here, we compared the use of 2 relatively cheap common stains, trypan blue and methylene blue, and assessed their accuracy and precision for estimating the viability of Bd zoospores during both manual counting and colorimetric assays. We stained known proportions of killed Bd zoospores (0, 0.25, 0.50, 0.75, and 1.00) with each stain and estimated the proportion of stained (dead) and unstained (viable) cells in each sample using both manual counting and colorimetric assays. Trypan blue was found to be a much more effective stain than methylene blue for both microscopy and colorimetric assays. Additionally, counting zoospores via microscopy was both a more accurate and precise technique. We recommend using manual counts via microscopy using the trypan blue stain for assessing Bd zoospore viability.
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Affiliation(s)
- Adeline Chew
- School of Biosciences, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
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5
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Vasantha Raman N, Gsell AS, Voulgarellis T, van den Brink NW, de Senerpont Domis LN. Moving beyond standard toxicological metrics: The effect of diclofenac on planktonic host-parasite interactions. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 254:106370. [PMID: 36516501 DOI: 10.1016/j.aquatox.2022.106370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 12/01/2022] [Accepted: 12/04/2022] [Indexed: 06/17/2023]
Abstract
Pharmaceuticals are increasingly released into surface waters and therefore ubiquitous in aquatic systems. While pharmaceuticals are known to influence species interactions, their effect on host-parasite interactions is still underexplored despite potential ecosystem-level consequences. Here, we ask whether diclofenac, a widely used non-steroid anti-inflammatory drug, affects the interaction between a phytoplankton host (Staurastrum sp.; green alga) and its obligate fungal parasite (Staurastromyces oculus; chytrid fungus). We hypothesized that the effect of increasing diclofenac concentration on the host-parasite system depends on parasite exposure. We assessed acute and chronic effects of a wide range of diclofenac concentrations (0-150 mg/L) on host and parasite performance using a replicated long gradient design in batch cultures. Overall system response summarizing parameters related to all biotic components in an experimental unit i.e., number of bacteria and phytoplankton host cells along with photosynthetic yield (a measure of algal cell fitness), depended on diclofenac concentration and presence/absence of parasite. While host standing biomass decreased at diclofenac concentrations >10 mg/L in non-parasite-exposed treatments, it increased at ≥10 mg/L in parasite-exposed treatments since losses due to infection declined. During acute phase (0-48 h), diclofenac concentrations <0.1 mg/L had no effect on host net-production neither in parasite-exposed nor non-parasite-exposed treatments, but parasite infection ceased at 10 mg/L. During chronic phase (0-216 h), host net-production declined only at concentrations >10 mg/L in non-parasite-exposed cultures, while it was overall close to zero in parasite-exposed cultures. Our results suggest that chytrid parasites are more sensitive to diclofenac than their host, allowing a window of opportunity for growth of phytoplankton hosts, despite exposure to a parasite. Our work provides a first understanding about effects of a pharmaceutical on a host-parasite interaction beyond those defined by standard toxicological metrics.
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Affiliation(s)
- Nandini Vasantha Raman
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen, PB 6708, the Netherlands.
| | - Alena S Gsell
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen, PB 6708, the Netherlands
| | - Themistoklis Voulgarellis
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen, PB 6708, the Netherlands
| | - Nico W van den Brink
- Division of Toxicology, Wageningen University & Research, Stippeneng 4, Wageningen, WE 6708, the Netherlands
| | - Lisette N de Senerpont Domis
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen, PB 6708, the Netherlands; Aquatic Ecology and Water Quality Management Group, Wageningen University & Research, Wageningen, the Netherlands; Pervasive Systems Research Group, Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, the Netherlands; Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, University of Twente, the Netherlands
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6
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Efficacy of Plant-Derived Fungicides at Inhibiting Batrachochytrium salamandrivorans Growth. J Fungi (Basel) 2022; 8:jof8101025. [PMID: 36294589 PMCID: PMC9605044 DOI: 10.3390/jof8101025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/23/2022] [Accepted: 09/27/2022] [Indexed: 11/21/2022] Open
Abstract
The emerging fungal amphibian pathogen, Batrachochytrium salamandrivorans (Bsal), is currently spreading across Europe and given its estimated invasion potential, has the capacity to decimate salamander populations worldwide. Fungicides are a promising in situ management strategy for Bsal due to their ability to treat the environment and infected individuals. However, antifungal drugs or pesticides could adversely affect the environment and non-target hosts, thus identifying safe, effective candidate fungicides for in situ treatment is needed. Here, we estimated the inhibitory fungicidal efficacy of five plant-derived fungicides (thymol, curcumin, allicin, 6-gingerol, and Pond Pimafix®) and one chemical fungicide (Virkon® Aquatic) against Bsal zoospores in vitro. We used a broth microdilution method in 48-well plates to test the efficacy of six concentrations per fungicide on Bsal zoospore viability. Following plate incubation, we performed cell viability assays and agar plate growth trials to estimate the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of each fungicide. All six fungicides exhibited inhibitory and fungicidal effects against Bsal growth, with estimated MIC concentrations ranging from 60 to 0.156 μg/mL for the different compounds. Allicin showed the greatest efficacy (i.e., lowest MIC and MFC) against Bsal zoospores followed by curcumin, Pond Pimafix®, thymol, 6-gingerol, and Virkon® Aquatic, respectively. Our results provide evidence that plant-derived fungicides are effective at inhibiting and killing Bsal zoospores in vitro and may be useful for in situ treatment. Additional studies are needed to estimate the efficacy of these fungicides at inactivating Bsal in the environment and treating Bsal-infected amphibians.
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7
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Bernabò I, Guardia A, Macirella R, Sesti S, Tripepi S, Brunelli E. Tissues injury and pathological changes in Hyla intermedia juveniles after chronic larval exposure to tebuconazole. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 205:111367. [PMID: 32971454 DOI: 10.1016/j.ecoenv.2020.111367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/24/2020] [Accepted: 09/13/2020] [Indexed: 06/11/2023]
Abstract
Tebuconazole (TBZ), an azole pesticide, is one of the most frequently detected fungicides in surface water. Despite its harmful effects, mainly related to endocrine disturbance, the consequences of TBZ exposure in amphibians remain poorly understood. Here, we investigated the adverse and delayed effects of TBZ chronic exposure on a native anuran species, often inhabiting cultivated areas, the Italian tree frog (Hyla intermedia). To disclose the multiple mechanisms of action through which TBZ exerts its toxicity we exposed tadpoles over the whole larval period to two sublethal TBZ concentrations (5 and 50 μg/L), and we evaluated histological alterations in three target organs highly susceptible to xenobiotics: liver, kidney, and gonads. We also assessed morphometric and gravimetric parameters: snout-vent length (SVL), body mass (BM), liver somatic index (LSI), and gonad-mesonephros complex index (GMCI) and determined sex ratio, gonadal development, and differentiation. Our results show that TBZ induces irreversible effects on multiple target organs in H. intermedia, exerting its harmful effects through several pathological pathways, including a massive inflammatory response. Moreover, TBZ markedly affects sexual differentiation also by inducing the appearance of sexually undetermined individuals and a general delay of germ cell maturation. Given the paucity of data on the effects of TBZ in amphibians, our results will contribute to a better understanding of the environmental risk posed by this fungicide to the most endangered group of vertebrates.
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Affiliation(s)
- Ilaria Bernabò
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036, Rende, Cosenza, Italy.
| | - Antonello Guardia
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036, Rende, Cosenza, Italy
| | - Rachele Macirella
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036, Rende, Cosenza, Italy
| | - Settimio Sesti
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036, Rende, Cosenza, Italy
| | - Sandro Tripepi
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036, Rende, Cosenza, Italy
| | - Elvira Brunelli
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036, Rende, Cosenza, Italy.
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8
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Towards a food web based control strategy to mitigate an amphibian panzootic in agricultural landscapes. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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9
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Preuss JF, Greenspan SE, Rossi EM, Lucas Gonsales EM, Neely WJ, Valiati VH, Woodhams DC, Becker CG, Tozetti AM. Widespread Pig Farming Practice Linked to Shifts in Skin Microbiomes and Disease in Pond-Breeding Amphibians. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:11301-11312. [PMID: 32845628 DOI: 10.1021/acs.est.0c03219] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Farming practices may reshape the structure of watersheds, water quality, and the health of aquatic organisms. Nutrient enrichment from agricultural pollution increases disease pressure in many host-pathogen systems, but the mechanisms underlying this pattern are not always resolved. For example, nutrient enrichment should strongly influence pools of aquatic environmental bacteria, which has the potential to alter microbiome composition of aquatic animals and their vulnerability to disease. However, shifts in the host microbiome have received little attention as a link between nutrient enrichment and diseases of aquatic organisms. We examined nutrient enrichment through the widespread practice of integrated pig-fish farming and its effects on microbiome composition of Brazilian amphibians and prevalence of the globally distributed amphibian skin pathogen Batrachochytrium dendrobatidis (Bd). This farming system drove surges in fecal coliform bacteria, disturbing amphibian skin bacterial communities such that hosts recruited higher proportions of Bd-facilitative bacteria and carried higher Bd prevalence. Our results highlight previously overlooked connections between global trends in land use change, microbiome dysbiosis, and wildlife disease. These interactions may be particularly important for disease management in the tropics, a region with both high biodiversity and continually intensifying anthropogenic pressures on aquatic wildlife habitats.
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Affiliation(s)
- Jackson F Preuss
- Programa de Pós-Graduação em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS 93022-750, Brazil
- Departamento de Ciências da Vida, Universidade do Oeste de Santa Catarina, São Miguel do Oeste, SC 89900-000, Brazil
| | - Sasha E Greenspan
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Eliandra M Rossi
- Departamento de Ciências da Vida, Universidade do Oeste de Santa Catarina, São Miguel do Oeste, SC 89900-000, Brazil
| | - Elaine M Lucas Gonsales
- Departamento de Zootecnia e Ciências Biológicas, Universidade Federal de Santa Maria, RS 98300-000, Brazil
| | - Wesley J Neely
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Victor Hugo Valiati
- Programa de Pós-Graduação em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS 93022-750, Brazil
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts 02125, United States
| | - C Guilherme Becker
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Alexandro M Tozetti
- Programa de Pós-Graduação em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS 93022-750, Brazil
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10
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Cuco AP, Wolinska J, Santos JI, Abrantes N, Gonçalves FJM, Castro BB. Can parasites adapt to pollutants? A multigenerational experiment with a Daphnia × Metschnikowia model system exposed to the fungicide tebuconazole. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 226:105584. [PMID: 32795838 DOI: 10.1016/j.aquatox.2020.105584] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/05/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
There is increasing evidence about negative effects of fungicides on non-target organisms, including parasitic species, which are key elements in food webs. Previous experiments showed that environmentally relevant concentrations of fungicide tebuconazole are toxic to the microparasite Metschnikowia bicuspidata, a yeast species that infects the planktonic crustacean Daphnia spp. However, due to their short-term nature, this and other experimental studies were not able to test if parasites could potentially adapt to these contaminants. Here, we tested if M. bicuspidata parasite can adapt to tebuconazole selective pressure. Infected D. magna lineages were reared under control conditions (no tebuconazole) and environmentally realistic tebuconazole concentrations, for four generations, and their performance was compared in a follow-up reciprocal assay. Additionally, we assessed whether the observed effects were transient (phenotypic) or permanent (genetic), by reassessing parasite fitness after the removal of selective pressure. Parasite fitness was negatively affected throughout the multigenerational exposure to the fungicide: prevalence of infection and spore load decreased, whereas host longevity increased, in comparison to control (naive) parasite lineages. In a follow-up reciprocal assay, tebuconazole-conditioned (TEB) lineages performed worse than naive parasite lineages, both in treatments without and with tebuconazole, confirming the cumulative negative effect of tebuconazole. The underperformance of TEB lineages was rapidly reversed after removing the influence of the selective pressure (tebuconazole), demonstrating that the costs of prolonged exposure to tebuconazole were phenotypic and transient. The microparasitic yeast M. bicuspidata did not reveal potential for rapid evolution to an anthropogenic selective pressure; instead, the long-term exposure to tebuconazole was hazardous to this non-target species. These findings highlight the potential environmental risks of azole fungicides on non-target parasitic fungi. The underperformance of these microbes and their inability to adapt to such stressors can interfere with the key processes where they intervene. Further research is needed to rank fungicides based on the hazard to non-target fungi (parasites, but also symbionts and decomposers), towards more effective management and protective legislation.
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Affiliation(s)
- Ana P Cuco
- Department of Biology, University of Aveiro, Aveiro, Portugal; CESAM, University of Aveiro, Aveiro, Portugal; CBMA (Centre of Molecular and Environmental Biology), Department of Biology, University of Minho, Braga, Portugal; Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Braga, Portugal.
| | - Justyna Wolinska
- Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Joana I Santos
- Department of Biology, University of Aveiro, Aveiro, Portugal; CESAM, University of Aveiro, Aveiro, Portugal
| | - Nelson Abrantes
- CESAM, University of Aveiro, Aveiro, Portugal; Department of Environment and Planning, University of Aveiro, Aveiro, Portugal
| | - Fernando J M Gonçalves
- Department of Biology, University of Aveiro, Aveiro, Portugal; CESAM, University of Aveiro, Aveiro, Portugal
| | - Bruno B Castro
- CBMA (Centre of Molecular and Environmental Biology), Department of Biology, University of Minho, Braga, Portugal; Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Braga, Portugal
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11
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Zubrod JP, Bundschuh M, Arts G, Brühl CA, Imfeld G, Knäbel A, Payraudeau S, Rasmussen JJ, Rohr J, Scharmüller A, Smalling K, Stehle S, Schulz R, Schäfer RB. Fungicides: An Overlooked Pesticide Class? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3347-3365. [PMID: 30835448 PMCID: PMC6536136 DOI: 10.1021/acs.est.8b04392] [Citation(s) in RCA: 255] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 12/14/2018] [Accepted: 03/05/2019] [Indexed: 05/23/2023]
Abstract
Fungicides are indispensable to global food security and their use is forecasted to intensify. Fungicides can reach aquatic ecosystems and occur in surface water bodies in agricultural catchments throughout the entire growing season due to their frequent, prophylactic application. However, in comparison to herbicides and insecticides, the exposure to and effects of fungicides have received less attention. We provide an overview of the risk of fungicides to aquatic ecosystems covering fungicide exposure (i.e., environmental fate, exposure modeling, and mitigation measures) as well as direct and indirect effects of fungicides on microorganisms, macrophytes, invertebrates, and vertebrates. We show that fungicides occur widely in aquatic systems, that the accuracy of predicted environmental concentrations is debatable, and that fungicide exposure can be effectively mitigated. We additionally demonstrate that fungicides can be highly toxic to a broad range of organisms and can pose a risk to aquatic biota. Finally, we outline central research gaps that currently challenge our ability to predict fungicide exposure and effects, promising research avenues, and shortcomings of the current environmental risk assessment for fungicides.
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Affiliation(s)
- Jochen P. Zubrod
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
- Eußerthal
Ecosystem Research Station, University of
Koblenz-Landau, Birkenthalstraße
13, D-76857 Eußerthal, Germany
| | - Mirco Bundschuh
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
- Department
of Aquatic Sciences and Assessment, Swedish
University of Agricultural Sciences, Lennart Hjelms väg 9, SWE-75007 Uppsala, Sweden
| | - Gertie Arts
- Wageningen
Environmental Research, Wageningen University
and Research, Wageningen, The Netherlands
| | - Carsten A. Brühl
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
| | - Gwenaël Imfeld
- Laboratoire
d’Hydrologie et de Géochimie de Strasbourg (LHyGeS), Université de Strasbourg/ENGEES, CNRS, 1 rue Blessig, 67084 Strasbourg Cedex, France
| | - Anja Knäbel
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
| | - Sylvain Payraudeau
- Laboratoire
d’Hydrologie et de Géochimie de Strasbourg (LHyGeS), Université de Strasbourg/ENGEES, CNRS, 1 rue Blessig, 67084 Strasbourg Cedex, France
| | - Jes J. Rasmussen
- Aarhus
University, Dept. of Bioscience, Vejlsoevej 25, 8600 Silkeborg, Denmark
| | - Jason Rohr
- University
of South Florida, Department of Integrative
Biology, Tampa, Florida, United States
- Department
of Biological Sciences, Environmental Change Initiative, and Eck Institute
for Global Health, University of Notre Dame, Notre Dame, Indiana, United
States
| | - Andreas Scharmüller
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
| | - Kelly Smalling
- U.S.
Geological Survey, New Jersey Water Science
Center, Lawrenceville, New Jersey, United States
| | - Sebastian Stehle
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
- Eußerthal
Ecosystem Research Station, University of
Koblenz-Landau, Birkenthalstraße
13, D-76857 Eußerthal, Germany
| | - Ralf Schulz
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
- Eußerthal
Ecosystem Research Station, University of
Koblenz-Landau, Birkenthalstraße
13, D-76857 Eußerthal, Germany
| | - Ralf B. Schäfer
- Institute
for Environmental Sciences, University of
Koblenz-Landau, Fortstraße
7, D-76829 Landau, Germany
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12
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Fernández-Loras A, Martín-Beyer B, Garner TWJ, Bosch J. Itraconazole and thiophanate-methyl fail to clear tadpoles naturally infected with the hypervirulent lineage of Batrachochytrium dendrobatidis. DISEASES OF AQUATIC ORGANISMS 2018; 131:73-78. [PMID: 30324916 DOI: 10.3354/dao03282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The emerging infectious disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, is a major driver pushing many amphibian species to the brink of extinction. Substantial efforts to develop effective protocols that use antifungal drugs have had notable success. Here, we used the antifungal agents itraconazole and thiophanate-methyl, singly and in combination, in an attempt to treat common midwife toad Alytes obstetricans larvae naturally infected with the globalized hypervirulent lineage of B. dendrobatidis. Despite the successful use of itraconazole in a closely related species (A. muletensis), our results show that these antifungal treatments are not always effective and that full clearance of animals cannot be assumed following treatment.
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13
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Drawert B, Griesemer M, Petzold LR, Briggs CJ. Using stochastic epidemiological models to evaluate conservation strategies for endangered amphibians. J R Soc Interface 2018; 14:rsif.2017.0480. [PMID: 28855388 PMCID: PMC5582134 DOI: 10.1098/rsif.2017.0480] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 08/07/2017] [Indexed: 01/02/2023] Open
Abstract
Recent outbreaks of chytridiomycosis, the disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), have contributed to population declines of numerous amphibian species worldwide. The devastating impacts of this disease have led researchers to attempt drastic conservation measures to prevent further extinctions and loss of biodiversity. The conservation measures can be labour-intensive or expensive, and in many cases have been unsuccessful. We developed a mathematical model of Bd outbreaks that includes the effects of demographic stochasticity and within-host fungal load dynamics. We investigated the impacts of one-time treatment conservation strategies during the disease outbreak that occurs following the initial arrival of Bd into a previously uninfected frog population. We found that for all versions of the model, for a large fraction of parameter space, none of the one-time treatment strategies are effective at preventing disease-induced extinction of the amphibian population. Of the strategies considered, treating frogs with antifungal agents to reduce their fungal load had the greatest likelihood of a beneficial outcome and the lowest risk of decreasing the persistence of the frog population, suggesting that this disease mitigation strategy should be prioritized over disinfecting the environment or reducing host density.
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Affiliation(s)
- Brian Drawert
- Department of Computer Science, University of North Carolina Asheville, Asheville, NC 28804, USA
| | - Marc Griesemer
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
| | - Linda R Petzold
- Department of Computer Science, University of California, Santa Barbara, CA 93106, USA
| | - Cheryl J Briggs
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA
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14
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Rohr JR, Brown J, Battaglin WA, McMahon TA, Relyea RA. A pesticide paradox: fungicides indirectly increase fungal infections. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:2290-2302. [PMID: 28763165 PMCID: PMC5711531 DOI: 10.1002/eap.1607] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 04/21/2017] [Accepted: 07/11/2017] [Indexed: 05/17/2023]
Abstract
There 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 d 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 recolonizes, 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.
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Affiliation(s)
- Jason R. Rohr
- University of South Florida, Department of Integrative Biology, Tampa, FL 33620, USA
| | - Jenise Brown
- University of South Florida, Department of Integrative Biology, Tampa, FL 33620, USA
- SWCA Environmental Consultants, Pittsburgh, PA, 15017, USA
| | | | | | - Rick A. Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Inst., Troy, NY 12180, USA
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15
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Temperature modulates the interaction between fungicide pollution and disease: evidence from a Daphnia-microparasitic yeast model. Parasitology 2017; 145:939-947. [PMID: 29160185 DOI: 10.1017/s0031182017002062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Temperature is expected to modulate the responses of organisms to stress. Here, we aimed to assess the influence of temperature on the interaction between parasitism and fungicide contamination. Specifically, using the cladoceran Daphnia as a model system, we explored the isolated and interactive effects of parasite challenge (yeast Metschnikowia bicuspidata) and exposure to fungicides (copper sulphate and tebuconazole) at two temperatures (17 and 20 °C), in a fully factorial design. Confirming a previous study, M. bicuspidata infection and copper exposure caused independent effects on Daphnia life history, whereas infection was permanently suppressed with tebuconazole exposure. Here, we show that higher temperature generally increased the virulence of the parasite, with the hosts developing signs of infection earlier, reproducing less and dying at an earlier age. These effects were consistent across copper concentrations, whereas the joint effects of temperature (which enhanced the difference between non-infected and infected hosts) and the anti-parasitic action of tebuconazole resulted in a more pronounced parasite × tebuconazole interaction at the higher temperature. Thus, besides independently influencing parasite and contaminant effects, the temperature can act as a modulator of interactions between pollution and disease.
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16
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Antifungal treatment of wild amphibian populations caused a transient reduction in the prevalence of the fungal pathogen, Batrachochytrium dendrobatidis. Sci Rep 2017; 7:5956. [PMID: 28729557 PMCID: PMC5519715 DOI: 10.1038/s41598-017-05798-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/06/2017] [Indexed: 01/09/2023] Open
Abstract
Emerging infectious diseases can drive host populations to extinction and are a major driver of biodiversity loss. Controlling diseases and mitigating their impacts is therefore a priority for conservation science and practice. Chytridiomycosis is a devastating disease of amphibians that is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), and for which there is an urgent need to develop mitigation methods. We treated tadpoles of the common midwife toad (Alytes obstetricans) with antifungal agents using a capture-treat-release approach in the field. Antifungal treatment during the spring reduced the prevalence of Bd in the cohort of tadpoles that had overwintered and reduced transmission of Bd from this cohort to the uninfected young-of-the-year cohort. Unfortunately, the mitigation was only transient, and the antifungal treatment was unable to prevent the rapid spread of Bd through the young-of-the year cohort. During the winter, Bd prevalence reached 100% in both the control and treated ponds. In the following spring, no effects of treatment were detectable anymore. We conclude that the sporadic application of antifungal agents in the present study was not sufficient for the long-term and large-scale control of Bd in this amphibian system.
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17
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Cuco AP, Abrantes N, Gonçalves F, Wolinska J, Castro BB. Interplay between fungicides and parasites: Tebuconazole, but not copper, suppresses infection in a Daphnia-Metschnikowia experimental model. PLoS One 2017; 12:e0172589. [PMID: 28231278 PMCID: PMC5322920 DOI: 10.1371/journal.pone.0172589] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 02/07/2017] [Indexed: 11/23/2022] Open
Abstract
Natural populations are commonly exposed to complex stress scenarios, including anthropogenic contamination and their biological enemies (e.g., parasites). The study of the pollutant-parasite interplay is especially important, given the need for adequate regulations to promote improved ecosystem protection. In this study, a host-parasite model system (Daphnia spp. and the microparasitic yeast Metschnikowia bicuspidata) was used to explore the reciprocal effects of contamination by common agrochemical fungicides (copper sulphate and tebuconazole) and parasite challenge. We conducted 21-day life history experiments with two host clones exposed to copper (0.00, 25.0, 28.8 and 33.1 μg L-1) or tebuconazole (0.00, 154, 192 and 240 μg L-1), in the absence or presence of the parasite. For each contaminant, the experimental design consisted of 2 Daphnia clones × 4 contaminant concentrations × 2 parasite treatments × 20 replicates = 320 experimental units. Copper and tebuconazole decreased Daphnia survival or reproduction, respectively, whilst the parasite strongly reduced host survival. Most importantly, while copper and parasite effects were mostly independent, tebuconazole suppressed infection. In a follow-up experiment, we tested the effect of a lower range of tebuconazole concentrations (0.00, 6.25, 12.5, 25.0, 50.0 and 100 μg L-1) crossed with increasing parasite challenge (2 Daphnia clones × 6 contaminant concentrations × 2 parasite levels × 20 replicates = 480 experimental units). Suppression of infection was confirmed at environmentally relevant concentrations (> 6.25 μg L-1), irrespective of the numbers of parasite challenge. The ecological consequences of such a suppression of infection include interferences in host population dynamics and diversity, as well as community structure and energy flow across the food web, which could upscale to ecosystem level given the important role of parasites.
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Affiliation(s)
- Ana P. Cuco
- Department of Biology, University of Aveiro, Aveiro, Portugal
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal
| | - Nelson Abrantes
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal
- Department of Environment and Planning, University of Aveiro, Aveiro, Portugal
| | - Fernando Gonçalves
- Department of Biology, University of Aveiro, Aveiro, Portugal
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal
| | - Justyna Wolinska
- Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
- Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Bruno B. Castro
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Braga, Portugal
- * E-mail:
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18
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Jones DK, Dang TD, Urbina J, Bendis RJ, Buck JC, Cothran RD, Blaustein AR, Relyea RA. Effect of Simultaneous Amphibian Exposure to Pesticides and an Emerging Fungal Pathogen, Batrachochytrium dendrobatidis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:671-679. [PMID: 28001054 DOI: 10.1021/acs.est.6b06055] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Amphibian declines have been linked to numerous factors, including pesticide use and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Moreover, research has suggested a link between amphibian sensitivity to Bd and pesticide exposure. We simultaneously exposed postmetamorphic American toads (Anaxyrus americanus), western toads (A. boreas), spring peepers (Pseudacris crucifer), Pacific treefrogs (P. regilla), leopard frogs (Lithobates pipiens), and Cascades frogs (Rana cascadae) to a factorial combination of two pathogen treatments (Bd+, Bd-) and four pesticide treatments (control, ethanol vehicle, herbicide mixture, and insecticide mixture) for 14 d to quantify survival and infection load. We found no interactive effects of pesticides and Bd on anuran survival and no effects of pesticides on infection load. Mortality following Bd exposure increased in spring peepers and American toads and was dependent upon snout-vent length in western toads, American toads, and Pacific treefrogs. Previous studies reported effects of early sublethal pesticide exposure on amphibian Bd sensitivity and infection load at later life stages, but we found simultaneous exposure to sublethal pesticide concentrations and Bd had no such effect on postmetamorphic juvenile anurans. Future research investigating complex interactions between pesticides and Bd should employ a variety of pesticide formulations and Bd strains and follow the effects of exposure throughout ontogeny.
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Affiliation(s)
- Devin K Jones
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | | | | | - Randall J Bendis
- Department of Biological Sciences, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Julia C Buck
- Marine Science Institute, University of California Santa Barbara , Santa Barbara, California 93106, United States
| | - Rickey D Cothran
- Department of Biological Sciences, Southwestern Oklahoma State University , Weatherford, Oklahoma 73096, United States
| | | | - Rick A Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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19
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Bosch J, Sanchez-Tomé E, Fernández-Loras A, Oliver JA, Fisher MC, Garner TWJ. Successful elimination of a lethal wildlife infectious disease in nature. Biol Lett 2016; 11:rsbl.2015.0874. [PMID: 26582843 DOI: 10.1098/rsbl.2015.0874] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Methods to mitigate the impacts of emerging infectious diseases affecting wildlife are urgently needed to combat loss of biodiversity. However, the successful mitigation of wildlife pathogens in situ has rarely occurred. Indeed, most strategies for combating wildlife diseases remain theoretical, despite the wealth of information available for combating infections in livestock and crops. Here, we report the outcome of a 5-year effort to eliminate infection with Batrachochytrium dendrobatidis affecting an island system with a single amphibian host. Our initial efforts to eliminate infection in the larval reservoir using a direct application of an antifungal were successful ex situ but infection returned to previous levels when tadpoles with cleared infections were returned to their natal sites. We subsequently combined antifungal treatment of tadpoles with environmental chemical disinfection. Infection at four of the five pools where infection had previously been recorded was eradicated, and remained so for 2 years post-application.
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Affiliation(s)
- Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, Madrid 28006, Spain
| | - Eva Sanchez-Tomé
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, Madrid 28006, Spain
| | - Andrés Fernández-Loras
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, Madrid 28006, Spain
| | - Joan A Oliver
- Conselleria de Medi Ambient i Mobilitat, Govern de les Illes Balears, Gremi Corredors 10, Polígon Son Rossinyol, Palma 07009, Spain
| | - Matthew C Fisher
- Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Hospital, Norfolk Place, London W2 1PG, UK
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20
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Bernabò I, Guardia A, Macirella R, Sesti S, Crescente A, Brunelli E. Effects of long-term exposure to two fungicides, pyrimethanil and tebuconazole, on survival and life history traits of Italian tree frog (Hyla intermedia). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 172:56-66. [PMID: 26771902 DOI: 10.1016/j.aquatox.2015.12.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 12/14/2015] [Accepted: 12/26/2015] [Indexed: 06/05/2023]
Abstract
Over the last few years, the hazards associated with the extensive use of fungicides have become an issue of great concern but, at present, the effects of these substances on amphibians remain poorly understood. The goal of the present study was to assess the effects of two commonly used fungicides, tebuconazole and pyrimethanil, on Italian Tree Frog (Hyla intermedia), a species frequently found in agricultural areas. Tadpoles were exposed to fungicides from developmental Gosner stage 25 (GS 25) to completion of metamorphosis (GS 46) and the whole exposure period lasted 78 days. For both tested fungicides we used two concentrations (5 and 50μg/L) that are comparable to those detected in surface waters, near agricultural fields. A variety of sublethal effects-on growth, development, behavior, and physiology-may be used for evaluating alterations induced by pollutants in amphibians. We estimated whether pyrimethanil and tebuconazole exposure impacted on H. intermedia life history traits. For this purpose, survival, growth, development, initiation of metamorphosis, success and size at metamorphosis, time to metamorphosis, and frequency of morphological abnormalities were evaluated. We showed, for all considered endpoints, that the exposure to tebuconazole exerts more harmful effects on H. intermedia than does exposure to pyrimethanil. Before the onset of metamorphic climax we showed, for both fungicides, that the low concentrations (5μg/L) induced significantly greater effects than the higher ones (50μg/L) on survival and deformity incidence. During the metamorphic climax, a complete reversal of this nonlinear trend takes place, and the percentage of animals initiating metamorphosis was reduced in fungicide-exposed groups in a concentration-dependent manner. Furthermore, a strong correlation emerged between fungicide exposure and the incidence of morphological abnormalities such as tail malformations, scoliosis, edema, mouth and limb deformities. Exposure to tested fungicides also caused a reduction in developmental rates just prior to the onset of metamorphic climax, which translated to a significant delay in timing of metamorphosis. We detected a drastic decrease in the success at metamorphosis in all exposed groups, compared to control group (86.25%). In fact, the percentage of survived larvae to GS 46, in the high and low concentrations, respectively, was only 22.5% and 36.25% in tebuconazole-exposed groups and 43.75% (50μg/L) and 56.25% (5μg/L) in pyrimethanil-exposed groups. Our findings underscore the hazardous properties of these two fungicides for non-target species in the context of ecotoxicological risk assessment. No published studies have addressed the long-term effects of tebuconazole and pyrimethanil on amphibians. To date, this is one of only a few studies documenting the effects of fungicide exposure over the whole larval development.
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Affiliation(s)
- Ilaria Bernabò
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende (Cosenza), Italy
| | - Antonello Guardia
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende (Cosenza), Italy
| | - Rachele Macirella
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende (Cosenza), Italy
| | - Settimio Sesti
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende (Cosenza), Italy
| | - Antonio Crescente
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende (Cosenza), Italy
| | - Elvira Brunelli
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende (Cosenza), Italy.
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21
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Hanlon SM, Lynch KJ, Kerby JL, Parris MJ. The effects of a fungicide and chytrid fungus on anuran larvae in aquatic mesocosms. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:12929-12940. [PMID: 25913318 DOI: 10.1007/s11356-015-4566-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 04/19/2015] [Indexed: 06/04/2023]
Abstract
The amphibian disease chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), has been linked to significant amphibian declines over the past three decades. The most severe effects of the pathogen have been primarily observed in relatively pristine areas that are not affected by many anthropogenic factors.One hypothesis concerning improved amphibian persistence with Bd in disturbed landscapes is that contaminants may abate the effects of Bd on amphibians. Recent laboratory studies have shown that pesticides, specifically the fungicide thiophanate-methyl (TM), can kill Bd outside of hosts and clear Bd infections within hosts. Using aquatic mesocosms, we tested the hypothesis that TM (0.43 mg/L) would alter growth and development of Lithobates sphenocephalus (southern leopard frog) tadpoles and Bd-infection loads in infected individuals. We hypothesized that the scope of such alterations and infection clearing would be affected by aquatic community variables, specifically zooplankton. TM altered zooplankton diversity (reduced cladoceran and increased copepod and ostracod abundances) and caused mortality to all tadpoles in TM-exposed tanks. In TM-free tanks, Bd-exposed tadpoles in high-density treatments metamorphosed smaller than Bd-unexposed, effects that were reversed in low-density treatments. Our study demonstrates the potential adverse effects of a fungicide and Bd on tadpoles and aquatic systems.
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Affiliation(s)
- Shane M Hanlon
- Department of Biological Sciences, University of Memphis, Memphis, TN, 38152, USA,
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22
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Rumschlag SL, Boone MD. How Time of Exposure to the Amphibian Chytrid Fungus AffectsHyla chrysoscelisin the Presence of an Insecticide1. HERPETOLOGICA 2015. [DOI: 10.1655/herpetologica-d-13-00070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Buck JC, Hua J, Brogan WR, Dang TD, Urbina J, Bendis RJ, Stoler AB, Blaustein AR, Relyea RA. Effects of Pesticide Mixtures on Host-Pathogen Dynamics of the Amphibian Chytrid Fungus. PLoS One 2015; 10:e0132832. [PMID: 26181492 PMCID: PMC4504700 DOI: 10.1371/journal.pone.0132832] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 06/19/2015] [Indexed: 01/22/2023] Open
Abstract
Anthropogenic and natural stressors often interact to affect organisms. Amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. Although these factors often co-occur, their effects on amphibians are usually examined in isolation. We hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susceptibility to the fungus Batrachochytrium dendrobatidis (Bd), a pathogen that has contributed to amphibian population declines worldwide. We exposed five anuran species (Pacific treefrog, Pseudacris regilla; spring peeper, Pseudacris crucifer; Cascades frog, Rana cascadae; northern leopard frog, Lithobates pipiens; and western toad, Anaxyrus boreas) from three families to mixtures of four common insecticides (chlorpyrifos, carbaryl, permethrin, and endosulfan) or herbicides (glyphosate, acetochlor, atrazine, and 2,4-D) or a control treatment, either as tadpoles or as newly metamorphic individuals (metamorphs). Subsequently, we exposed animals to Bd or a control inoculate after metamorphosis and compared survival and Bd load. Bd exposure significantly increased mortality in Pacific treefrogs, spring peepers, and western toads, but not in Cascades frogs or northern leopard frogs. However, the effects of pesticide exposure on mortality were negligible, regardless of the timing of exposure. Bd load varied considerably across species; Pacific treefrogs, spring peepers, and western toads had the highest loads, whereas Cascades frogs and northern leopard frogs had the lowest loads. The influence of pesticide exposure on Bd load depended on the amphibian species, timing of pesticide exposure, and the particular pesticide treatment. Our results suggest that exposure to realistic pesticide concentrations has minimal effects on Bd-induced mortality, but can alter Bd load. This result could have broad implications for risk assessment of amphibians; the outcome of exposure to multiple stressors may be unpredictable and can differ between species and life stages.
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Affiliation(s)
- Julia C. Buck
- Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, Texas, United States of America
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jessica Hua
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - William R. Brogan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Trang D. Dang
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jenny Urbina
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
| | - Randall J. Bendis
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Aaron B. Stoler
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
| | - Rick A. Relyea
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
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24
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Hanlon SM, Lynch KJ, Kerby J, Parris MJ. Batrachochytrium dendrobatidis exposure effects on foraging efficiencies and body size in anuran tadpoles. DISEASES OF AQUATIC ORGANISMS 2015; 112:237-242. [PMID: 25590774 DOI: 10.3354/dao02810] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chytridiomycosis, the amphibian disease caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), is fatal to adults of many species. Bd is largely sublethal to amphibian larvae; however, it is known to reduce larval (i.e. tadpole) growth rates, with possible long-term effects on population dynamics and fitness. We conducted an experiment to test how Bd altered southern leopard frog Lithobates sphenocephalus tadpole mouthpart damage, percentage of food ingested, and subsequent body size. We examined our results using path analyses. We hypothesized that Bd would increase mouthpart damage, causing less food to be ingested, and ultimately reduce body size. In our model, both Bd exposure and increased mouthpart damage significantly reduced food ingested and subsequent body size. However, our study provides evidence against the long-standing hypothesis of mouthpart damage as a pathway for Bd-induced reductions in larval group. Here we provide evidence for reduced foraging efficiency (percentage of food ingested) as a mechanism for Bd-induced reductions in body size. This work highlights the importance of studying the sublethal effects of Bd on larval amphibians.
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Affiliation(s)
- Shane M Hanlon
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA
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25
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Wise RS, Rumschlag SL, Boone MD. Effects of amphibian chytrid fungus exposure on American toads in the presence of an insecticide. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:2541-2544. [PMID: 25099070 DOI: 10.1002/etc.2709] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/02/2014] [Accepted: 08/01/2014] [Indexed: 06/03/2023]
Abstract
Abiotic factors such as pesticides may alter the impact of a pathogen on hosts, which could have implications for host-pathogen interactions and may explain variation in disease outbreaks in nature. In the present laboratory experiment, American toad (Anaxyrus americanus) metamorphs were exposed to the amphibian chytrid fungal pathogen Batrachochytrium dendrobatidis (Bd) and environmentally relevant concentrations of the insecticide malathion to determine whether malathion altered the effects of Bd exposure on growth and survival of toad metamorphs. Exposure to Bd significantly decreased survival over the 51 d of the experiment, suggesting that Bd could reduce recruitment into the terrestrial life stage when exposure occurs at metamorphosis. Malathion did not impact survival, but a 12-h exposure at metamorphosis significantly reduced terrestrial growth. Toads that were exposed to both Bd and malathion showed a nonsignificant trend toward the smallest growth compared with other treatments. The present study suggests that Bd may pose a threat to American toads even though population declines have not been observed for this species; in addition, the presence of both the insecticide malathion and Bd could reduce terrestrial growth, which could have implications for lifetime fitness and suggests that environmental factors could play a role in pathogen impacts in nature.
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Affiliation(s)
- Rayona S Wise
- Department of Biology, Miami University, Oxford, Ohio, USA
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26
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Scheele BC, Hunter DA, Grogan LF, Berger L, Kolby JE, McFadden MS, Marantelli G, Skerratt LF, Driscoll DA. Interventions for reducing extinction risk in chytridiomycosis-threatened amphibians. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2014; 28:1195-1205. [PMID: 24975971 DOI: 10.1111/cobi.12322] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/21/2014] [Indexed: 06/03/2023]
Abstract
Wildlife diseases pose an increasing threat to biodiversity and are a major management challenge. A striking example of this threat is the emergence of chytridiomycosis. Despite diagnosis of chytridiomycosis as an important driver of global amphibian declines 15 years ago, researchers have yet to devise effective large-scale management responses other than biosecurity measures to mitigate disease spread and the establishment of disease-free captive assurance colonies prior to or during disease outbreaks. We examined the development of management actions that can be implemented after an epidemic in surviving populations. We developed a conceptual framework with clear interventions to guide experimental management and applied research so that further extinctions of amphibian species threatened by chytridiomycosis might be prevented. Within our framework, there are 2 management approaches: reducing Batrachochytrium dendrobatidis (the fungus that causes chytridiomycosis) in the environment or on amphibians and increasing the capacity of populations to persist despite increased mortality from disease. The latter approach emphasizes that mitigation does not necessarily need to focus on reducing disease-associated mortality. We propose promising management actions that can be implemented and tested based on current knowledge and that include habitat manipulation, antifungal treatments, animal translocation, bioaugmentation, head starting, and selection for resistance. Case studies where these strategies are being implemented will demonstrate their potential to save critically endangered species.
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Affiliation(s)
- Ben C Scheele
- ARC Centre of Excellence for Environmental Decisions, National Environmental Research Program Environmental Decisions Hub, Fenner School of Environment and Society, Forestry Building [48], Australian National University, Canberra, ACT 0200, Australia; NSW Office of Environment and Heritage, Queanbeyan, NSW 2620, Australia.
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27
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Gaietto KM, Rumschlag SL, Boone MD. Effects of pesticide exposure and the amphibian chytrid fungus on gray treefrog (Hyla chrysoscelis) metamorphosis. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:2358-2362. [PMID: 25044296 DOI: 10.1002/etc.2689] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/01/2014] [Accepted: 07/10/2014] [Indexed: 06/03/2023]
Abstract
Pesticides are detectable in most aquatic habitats and have the potential to alter host-pathogen interactions. The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been associated with amphibian declines around the world. However, Bd-associated declines are more prominent in some areas, despite nearly global distribution of Bd, suggesting other factors contribute to disease outbreaks. In a laboratory study, the authors examined the effects of 6 different isolates of Bd in the presence or absence of a pesticide (the insecticide carbaryl or the fungicide copper sulfate) to recently hatched Cope's gray treefrog (Hyla chrysoscelis) tadpoles reared through metamorphosis. The authors found the presence or absence of pesticides differentially altered the mass at metamorphosis of tadpoles exposed to different Bd isolates, suggesting that isolate could influence metamorphosis but not in ways expected based on origin of the isolate. Pesticide exposure had the strongest impact on metamorphosis of all treatment combinations. Whereas copper sulfate exposure reduced the length of the larval period, carbaryl exposure had apparent positive effects by increasing mass at metamorphosis and lengthening larval period, which adds to evidence that carbaryl can stimulate development in counterintuitive ways. The present study provides limited support to the hypothesis that pesticides can alter the response of tadpoles to isolates of Bd and that the insecticide carbaryl can alter developmental decisions.
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28
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Ghose SL, Donnelly MA, Kerby J, Whitfield SM. Acute toxicity tests and meta-analysis identify gaps in tropical ecotoxicology for amphibians. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:2114-2119. [PMID: 24934557 DOI: 10.1002/etc.2665] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/29/2013] [Accepted: 06/10/2014] [Indexed: 06/03/2023]
Abstract
Amphibian populations are declining worldwide, particularly in tropical regions where amphibian diversity is highest. Pollutants, including agricultural pesticides, have been identified as a potential contributor to decline, yet toxicological studies of tropical amphibians are very rare. The present study assesses toxic effects on amphibians of 10 commonly used commercial pesticides in tropical agriculture using 2 approaches. First, the authors conducted 8-d toxicity assays with formulations of each pesticide using individually reared red-eyed tree frog (Agalychnis callidryas) tadpoles. Second, they conducted a review of available data for the lethal concentration to kill 50% of test animals from the US Environmental Protection Agency's ECOTOX database to allow comparison with their findings. Lethal concentration estimates from the assays ranged over several orders of magnitude. The nematicides terbufos and ethoprophos and the fungicide chlorothalonil were very highly toxic, with evident effects within an order of magnitude of environmental concentrations. Acute toxicity assays and meta-analysis show that nematicides and fungicides are generally more toxic than herbicides yet receive far less research attention than less toxic herbicides. Given that the tropics have a high diversity of amphibians, the findings emphasize the need for research into the effects of commonly used pesticides in tropical countries and should help guide future ecotoxicological research in tropical regions.
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Affiliation(s)
- Sonia L Ghose
- Herpetology Department, California Academy of Sciences, San Francisco, California, USA
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29
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Hanlon SM, Parris MJ. The interactive effects of chytrid fungus, pesticides, and exposure timing on gray treefrog (Hyla versicolor) larvae. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:216-22. [PMID: 24259231 DOI: 10.1002/etc.2419] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 07/04/2013] [Accepted: 10/01/2013] [Indexed: 06/02/2023]
Abstract
Aquatic organisms are often exposed to a wide variety of perturbations in nature, including pathogens and chemical contaminants. Despite the co-occurrence of these 2 stressors, few studies have examined the effects of chemical contaminants on host-pathogen dynamics. The authors tested the individual and combined effects on gray treefrog (Hyla versicolor) tadpoles of 2 commonly used pesticides (Roundup® and Sevin®) and the pathogenic fungus Batrachochytrium dendrobatidis (Bd). A fully factorial design was used, and tadpoles were exposed to Bd, Roundup, or Sevin alone, or a combination of Bd and either pesticide at 3 points during larval development (early, mid, late). It was predicted that pesticides would mediate the effect of Bd on tadpoles and reduce the likelihood of negative consequences of infection and that timing of exposure would influence these effects. Tadpoles exposed to Bd at the mid point experienced higher survival through metamorphosis than those exposed to Bd at the early or late points, while tadpoles exposed to Sevin at the early point experienced reduced survival compared with those exposed to Roundup or no-pesticide control at the same exposure point. Roundup ameliorated the effects of Bd on survival compared with tadpoles exposed to Bd alone, while there was no interactive effect of Sevin on survival. In addition, Sevin reduced mass of new metamorphs compared with Roundup and reduced snout-vent length compared with all other treatments. The present study supports the hypothesis that pesticides can mitigate the effects of Bd on amphibian hosts and that such effects may depend on the timing of exposure.
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Affiliation(s)
- Shane M Hanlon
- Department of Biological Sciences, University of Memphis, Memphis, Tennessee, USA
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