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O'Keeffe KR, Halliday FW, Jones CD, Carbone I, Mitchell CE. Parasites, niche modification and the host microbiome: A field survey of multiple parasites. Mol Ecol 2021; 30:2404-2416. [PMID: 33740826 DOI: 10.1111/mec.15892] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 02/04/2021] [Accepted: 03/15/2021] [Indexed: 01/04/2023]
Abstract
Parasites can affect and be affected by the host's microbiome, with consequences for host susceptibility, parasite transmission, and host and parasite fitness. Yet, two aspects of the relationship between parasite infection and host microbiota remain little understood: the nature of the relationship under field conditions, and how the relationship varies among parasites. To overcome these limitations, we performed a field survey of the within-leaf fungal community in a tall fescue population. We investigated how diversity and composition of the fungal microbiome associate with natural infection by fungal parasites with different feeding strategies. A parasite's feeding strategy affects both parasite requirements of the host environment and parasite impacts on the host environment. We hypothesized that parasites that more strongly modify niches available within a host will be associated with greater changes in microbiome diversity and composition. Parasites with a feeding strategy that creates necrotic tissue to extract resources (necrotrophs) may not only have different niche requirements, but also act as particularly strong niche modifiers. Barcoded amplicon sequencing of the fungal ITS region revealed that leaf segments symptomatic of necrotrophs had lower fungal diversity and distinct composition compared to segments that were asymptomatic or symptomatic of other parasites. There were no clear differences in fungal diversity or composition between leaf segments that were asymptomatic and segments symptomatic of other parasite feeding strategies. Our results motivate future experimental work to test how the relationship between the microbiome and parasite infection is impacted by parasite feeding strategy and highlight the potential importance of parasite traits.
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Affiliation(s)
- Kayleigh R O'Keeffe
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Fletcher W Halliday
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Corbin D Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ignazio Carbone
- Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Charles E Mitchell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Environment, Ecology and Energy Program, University of North Carolina, Chapel Hill, NC, USA
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2
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Ghosh PN, Brookes LM, Edwards HM, Fisher MC, Jervis P, Kappel D, Sewell TR, Shelton JM, Skelly E, Rhodes JL. Cross-Disciplinary Genomics Approaches to Studying Emerging Fungal Infections. Life (Basel) 2020; 10:E315. [PMID: 33260763 PMCID: PMC7761180 DOI: 10.3390/life10120315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/15/2020] [Accepted: 11/19/2020] [Indexed: 11/16/2022] Open
Abstract
Emerging fungal pathogens pose a serious, global and growing threat to food supply systems, wild ecosystems, and human health. However, historic chronic underinvestment in their research has resulted in a limited understanding of their epidemiology relative to bacterial and viral pathogens. Therefore, the untargeted nature of genomics and, more widely, -omics approaches is particularly attractive in addressing the threats posed by and illuminating the biology of these pathogens. Typically, research into plant, human and wildlife mycoses have been largely separated, with limited dialogue between disciplines. However, many serious mycoses facing the world today have common traits irrespective of host species, such as plastic genomes; wide host ranges; large population sizes and an ability to persist outside the host. These commonalities mean that -omics approaches that have been productively applied in one sphere and may also provide important insights in others, where these approaches may have historically been underutilised. In this review, we consider the advances made with genomics approaches in the fields of plant pathology, human medicine and wildlife health and the progress made in linking genomes to other -omics datatypes and sets; we identify the current barriers to linking -omics approaches and how these are being underutilised in each field; and we consider how and which -omics methodologies it is most crucial to build capacity for in the near future.
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Affiliation(s)
- Pria N. Ghosh
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Lola M. Brookes
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- Institute of Zoology, Zoological Society of London, London NW1 4RY, UK
- Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK
| | - Hannah M. Edwards
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Matthew C. Fisher
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Phillip Jervis
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- Institute of Zoology, Zoological Society of London, London NW1 4RY, UK
- Department of Chemistry, University College London, London WC1H 0AJ, UK
| | - Dana Kappel
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Thomas R. Sewell
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Jennifer M.G. Shelton
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- UK Centre for Ecology & Hydrology, Wallingford OX10 8BB, UK
| | - Emily Skelly
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Johanna L. Rhodes
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
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3
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Severns PM, Sackett KE, Farber DH, Mundt CC. Consequences of Long-Distance Dispersal for Epidemic Spread: Patterns, Scaling, and Mitigation. PLANT DISEASE 2019; 103:177-191. [PMID: 30592698 DOI: 10.1094/pdis-03-18-0505-fe] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Epidemics caused by long-distance dispersed pathogens result in some of the most explosive and difficult to control diseases of both plants and animals (including humans). Yet the factors influencing disease spread, especially in the early stages of the outbreak, are not well-understood. We present scaling relationships, of potentially widespread relevance, that were developed from more than 15 years of field and in silico single focus studies of wheat stripe rust spread. These relationships emerged as a consequence of accounting for a greater proportion of the fat-tailed disease gradient that may be frequently underestimated in disease spread studies. Leptokurtic dispersal gradients (highly peaked and fat-tailed) are relatively common in nature and they can be represented by power law functions. Power law scale invariance properties generate patterns that repeat over multiple spatial scales, suggesting important and predictable scaling relationships between disease levels during the first generation of disease outbreaks and subsequent epidemic spread. Experimental wheat stripe rust outbreaks and disease spread simulations support theoretical scaling relationships from power law properties and suggest that relatively straightforward scaling approximations may be useful for projecting the spread of disease caused by long-distance dispersed pathogens. Our results suggest that, when actual dispersal/disease data are lacking, an inverse power law with exponent = 2 may provide a reasonable approximation for modeling disease spread. Furthermore, our experiments and simulations strongly suggest that early control treatments with small spatial extent are likely to be more effective at suppressing an outbreak caused by a long-distance dispersed pathogen than would delayed treatment of a larger area. The scaling relationships we detail and the associated consequences for disease control may be broadly applicable to plant and animal pathogens characterized by non-exponentially bound, fat-tailed dispersal gradients.
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Affiliation(s)
- Paul M Severns
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Kathryn E Sackett
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Daniel H Farber
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Christopher C Mundt
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
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4
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Carlson CJ, Getz WM, Kausrud KL, Cizauskas CA, Blackburn JK, Bustos Carrillo FA, Colwell R, Easterday WR, Ganz HH, Kamath PL, Økstad OA, Turner WC, Kolstø AB, Stenseth NC. Spores and soil from six sides: interdisciplinarity and the environmental biology of anthrax (Bacillus anthracis). Biol Rev Camb Philos Soc 2018; 93:1813-1831. [PMID: 29732670 DOI: 10.1111/brv.12420] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 03/27/2018] [Accepted: 04/03/2018] [Indexed: 12/11/2022]
Abstract
Environmentally transmitted diseases are comparatively poorly understood and managed, and their ecology is particularly understudied. Here we identify challenges of studying environmental transmission and persistence with a six-sided interdisciplinary review of the biology of anthrax (Bacillus anthracis). Anthrax is a zoonotic disease capable of maintaining infectious spore banks in soil for decades (or even potentially centuries), and the mechanisms of its environmental persistence have been the topic of significant research and controversy. Where anthrax is endemic, it plays an important ecological role, shaping the dynamics of entire herbivore communities. The complex eco-epidemiology of anthrax, and the mysterious biology of Bacillus anthracis during its environmental stage, have necessitated an interdisciplinary approach to pathogen research. Here, we illustrate different disciplinary perspectives through key advances made by researchers working in Etosha National Park, a long-term ecological research site in Namibia that has exemplified the complexities of the enzootic process of anthrax over decades of surveillance. In Etosha, the role of scavengers and alternative routes (waterborne transmission and flies) has proved unimportant relative to the long-term persistence of anthrax spores in soil and their infection of herbivore hosts. Carcass deposition facilitates green-ups of vegetation to attract herbivores, potentially facilitated by the role of anthrax spores in the rhizosphere. The underlying seasonal pattern of vegetation, and herbivores' immune and behavioural responses to anthrax risk, interact to produce regular 'anthrax seasons' that appear to be a stable feature of the Etosha ecosystem. Through the lens of microbiologists, geneticists, immunologists, ecologists, epidemiologists, and clinicians, we discuss how anthrax dynamics are shaped at the smallest scale by population genetics and interactions within the bacterial communities up to the broadest scales of ecosystem structure. We illustrate the benefits and challenges of this interdisciplinary approach to disease ecology, and suggest ways anthrax might offer insights into the biology of other important pathogens. Bacillus anthracis, and the more recently emerged Bacillus cereus biovar anthracis, share key features with other environmentally transmitted pathogens, including several zoonoses and panzootics of special interest for global health and conservation efforts. Understanding the dynamics of anthrax, and developing interdisciplinary research programs that explore environmental persistence, is a critical step forward for understanding these emerging threats.
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Affiliation(s)
- Colin J Carlson
- National Socio-Environmental Synthesis Center (SESYNC), University of Maryland, Annapolis, MD 21401, U.S.A.,Department of Biology, Georgetown University, Washington, DC 20057, U.S.A
| | - Wayne M Getz
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, U.S.A.,School of Mathematical Sciences, University of KwaZulu-Natal, PB X 54001, Durban 4000, South Africa
| | - Kyrre L Kausrud
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316, Oslo, Norway
| | - Carrie A Cizauskas
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, U.S.A
| | - Jason K Blackburn
- Spatial Epidemiology & Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, U.S.A.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, U.S.A
| | - Fausto A Bustos Carrillo
- Department of Epidemiology & Department of Biostatistics, School of Public Health, University of California, Berkeley, CA 94720-7360, U.S.A
| | - Rita Colwell
- CosmosID Inc., Rockville, MD 20850, U.S.A.,Center for Bioinformatics and Computational Biology, University of Maryland Institute for Advanced Computer Studies, University of Maryland, College Park, MD 20742, U.S.A.,Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - W Ryan Easterday
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316, Oslo, Norway
| | - Holly H Ganz
- UC Davis Genome Center, University of California, Davis, CA 95616, U.S.A
| | - Pauline L Kamath
- School of Food and Agriculture, University of Maine, Orono, ME 04469, U.S.A
| | - Ole A Økstad
- Centre for Integrative Microbial Evolution and Section for Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, N-0316, Oslo, Norway
| | - Wendy C Turner
- Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, U.S.A
| | - Anne-Brit Kolstø
- Centre for Integrative Microbial Evolution and Section for Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, N-0316, Oslo, Norway
| | - Nils C Stenseth
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316, Oslo, Norway
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5
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Hagerty CH, Graebner RC, Sackett KE, Mundt CC. Variable competitive effects of fungicide resistance in field experiments with a plant pathogenic fungus. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:1305-1316. [PMID: 28266146 DOI: 10.1002/eap.1524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 01/26/2017] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
Classic evolutionary theory suggests that mutations associated with antimicrobial and pesticide resistance result in a fitness cost in the absence of the selective antimicrobial agent or pesticide. There is experimental evidence to support fitness costs associated with resistance to anti-microbial compounds and pesticides across many biological disciplines, including human pathology, entomology, plant sciences, and plant pathology. However, researchers have also found examples of neutral and increased fitness associated with resistance, where the effect of a given resistance mutation depends on environmental and biological factors. We used Zymoseptoria tritici, a model evolutionary plant pathogenic fungus, to compare the competitive ability of fungicide-resistant isolates to fungicide-sensitive isolates. We conducted four large-scale inoculated winter wheat experiments at Oregon State University agriculture experiment stations. We found a significant change in the frequency of fungicide resistance over time in all four experiments. The direction and magnitude of these changes, however, differed by experimental location, year of experiment, and inoculum resistance treatment (fungicide-resistant, resistant/sensitive mixture, and fungicide-sensitive). These results suggest that the competitive ability of resistant isolates relative to sensitive isolates varied depending upon environmental conditions, including the initial frequency of resistant individuals in the population.
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Affiliation(s)
- Christina H Hagerty
- Columbia Basin Agricultural Research Center, Oregon State University, 48037 Tubbs Ranch Road, Adams, OR, 97801, USA
| | - Ryan C Graebner
- Hermiston Agricultural Research and Extension Center, Oregon State University, 2121 S 1st St, Hermiston, OR, 97838, USA
| | - Kathryn E Sackett
- Department of Botany and Plant Pathology, Oregon State University, Cordley Hall, 2701 SW Campus Way, Corvallis, OR, 97331, USA
| | - Christopher C Mundt
- Department of Botany and Plant Pathology, Oregon State University, Cordley Hall, 2701 SW Campus Way, Corvallis, OR, 97331, USA
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6
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Borer ET, Laine AL, Seabloom EW. A Multiscale Approach to Plant Disease Using the Metacommunity Concept. ANNUAL REVIEW OF PHYTOPATHOLOGY 2016; 54:397-418. [PMID: 27296140 DOI: 10.1146/annurev-phyto-080615-095959] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Plant disease arises from the interaction of processes occurring at multiple spatial and temporal scales. With new tools such as next-generation sequencing, we are learning about the diversity of microbes circulating within and among plant populations and often coinhabiting host individuals. The proliferation of pathogenic microbes depends on single-species dynamics and multispecies interactions occurring within and among host cells, the spatial organization and genetic landscape of hosts, the frequency and mode of transmission among hosts and host populations, and the abiotic environmental context. Here, we examine empirical evidence from these multiple scales to assess the utility of metacommunity theory, a theoretical framework developed for free-living organisms to further our understanding of and assist in predicting plant-pathogen infection and spread. We suggest that deeper understanding of disease dynamics can arise through the application of this conceptual framework at scales ranging from individual cells to landscapes. In addition, we use this multiscale theoretical perspective to synthesize existing knowledge, generate novel hypotheses, and point toward promising future opportunities for the study of plant pathogens in natural populations.
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Affiliation(s)
- Elizabeth T Borer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108; ,
| | - Anna-Liisa Laine
- Centre of Excellence in Metapopulation Biology, Department of Biosciences, University of Helsinki, FI-00014, Finland;
| | - Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108; ,
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7
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Döring TF, Vieweger A, Pautasso M, Vaarst M, Finckh MR, Wolfe MS. Resilience as a universal criterion of health. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2015; 95:455-465. [PMID: 24343565 DOI: 10.1002/jsfa.6539] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 12/06/2013] [Accepted: 12/11/2013] [Indexed: 06/03/2023]
Abstract
To promote and maintain health in agricultural and food systems, appropriate criteria are needed for the description and assessment of the health of soils, plants, animals, humans and ecosystems. Here we identify the concept of resilience as a universally applicable and fundamentally important criterion of health in all relevant areas of agriculture. We discuss definitions of resilience for soils, plants, animals, humans and ecosystems, and explore ways in which resilience can be applied as a criterion of health in different agricultural contexts. We show how and why resilience can be seen as a key criterion of health. Based on this, we discuss how resilience can be used as a link between soil, plant, animal, human and ecosystem health. Finally, we highlight four key areas for future research on resilience in agriculture, namely spatial and temporal scaling of resilience; effects of diversity; the role of networks for resilience; and stakeholder involvement.
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Affiliation(s)
- Thomas F Döring
- Organic Research Centre, Elm Farm, Hamstead Marshall, Newbury, RG20 0HR, UK; Faculty of Agriculture and Horticulture, Humboldt University Berlin, Albrecht Thaer-Weg 5, 14195, Berlin, Germany
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8
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Pautasso M, Jeger MJ. Network epidemiology and plant trade networks. AOB PLANTS 2014; 6:plu007. [PMID: 24790128 PMCID: PMC4038442 DOI: 10.1093/aobpla/plu007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 02/11/2014] [Indexed: 05/29/2023]
Abstract
Models of epidemics in complex networks are improving our predictive understanding of infectious disease outbreaks. Nonetheless, applying network theory to plant pathology is still a challenge. This overview summarizes some key developments in network epidemiology that are likely to facilitate its application in the study and management of plant diseases. Recent surveys have provided much-needed datasets on contact patterns and human mobility in social networks, but plant trade networks are still understudied. Human (and plant) mobility levels across the planet are unprecedented-there is thus much potential in the use of network theory by plant health authorities and researchers. Given the directed and hierarchical nature of plant trade networks, there is a need for plant epidemiologists to further develop models based on undirected and homogeneous networks. More realistic plant health scenarios would also be obtained by developing epidemic models in dynamic, rather than static, networks. For plant diseases spread by the horticultural and ornamental trade, there is the challenge of developing spatio-temporal epidemic simulations integrating network data. The use of network theory in plant epidemiology is a promising avenue and could contribute to anticipating and preventing plant health emergencies such as European ash dieback.
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Affiliation(s)
- Marco Pautasso
- Forest Pathology and Dendrology, Institute of Integrative Biology, ETHZ, Zurich, Switzerland
| | - Mike J. Jeger
- Division of Ecology and Evolution & Centre for Environmental Policy, Imperial College London, London, UK
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9
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Lacroix C, Jolles A, Seabloom EW, Power AG, Mitchell CE, Borer ET. Non-random biodiversity loss underlies predictable increases in viral disease prevalence. J R Soc Interface 2014; 11:20130947. [PMID: 24352672 PMCID: PMC3899862 DOI: 10.1098/rsif.2013.0947] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 11/28/2013] [Indexed: 11/12/2022] Open
Abstract
Disease dilution (reduced disease prevalence with increasing biodiversity) has been described for many different pathogens. Although the mechanisms causing this phenomenon remain unclear, the disassembly of communities to predictable subsets of species, which can be caused by changing climate, land use or invasive species, underlies one important hypothesis. In this case, infection prevalence could reflect the competence of the remaining hosts. To test this hypothesis, we measured local host species abundance and prevalence of four generalist aphid-vectored pathogens (barley and cereal yellow dwarf viruses) in a ubiquitous annual grass host at 10 sites spanning 2000 km along the North American West Coast. In laboratory and field trials, we measured viral infection as well as aphid fecundity and feeding preference on several host species. Virus prevalence increased as local host richness declined. Community disassembly was non-random: ubiquitous hosts dominating species-poor assemblages were among the most competent for vector production and virus transmission. This suggests that non-random biodiversity loss led to increased virus prevalence. Because diversity loss is occurring globally in response to anthropogenic changes, such work can inform medical, agricultural and veterinary disease research by providing insights into the dynamics of pathogens nested within a complex web of environmental forces.
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Affiliation(s)
- Christelle Lacroix
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA
| | - Anna Jolles
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR 97331, USA
- Department of Zoology, Oregon State University, Corvallis, OR 97331, USA
| | - Eric W. Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA
| | - Alison G. Power
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Charles E. Mitchell
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Elizabeth T. Borer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA
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10
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Abstract
Co-infection of individual hosts by multiple parasite species is a pattern that is very commonly observed in natural populations. Understanding the processes that generate these patterns poses a challenge. For example, it is difficult to discern the relative roles of exposure and susceptibility in generating the mixture and density of parasites within hosts. Yet discern them we must, if we are to design and deliver successful medical interventions for co-infected populations. Here, we synthesise an emergent understanding of how processes operate and interact to generate patterns of co-infection. We consider within-host communities (or infracommunities) generally, that is including not only classical parasites but also the microbiota that are so abundant on mucosal surfaces and which are increasingly understood to be so influential on host biology. We focus on communities that include a helminth, but we expect similar inferences to pertain to other taxa. We suggest that, thanks to recent research at both the within-host (e.g. immunological) and between-host (e.g. epidemiological) scales, researchers are poised to reveal the processes that generate the observed distribution of parasite communities among hosts. Progress will be facilitated by using new technologies as well as statistical and experimental tools to test competing hypotheses about processes that might generate patterns in co-infection data. By understanding the multiple interactions that underlie patterns of co-infection, we will be able to understand and intelligently predict how a suite of co-infections (and thus the host that bears them) will together respond to medical interventions as well as other environmental changes. The challenge for us all is to become scholars of co-infections.
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Affiliation(s)
- Mark E Viney
- School of Biological Sciences, University of Bristol, Woodland Road, UK.
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11
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Farrell MJ, Berrang-Ford L, Davies TJ. The study of parasite sharing for surveillance of zoonotic diseases. ENVIRONMENTAL RESEARCH LETTERS : ERL [WEB SITE] 2013; 8:015036. [PMID: 32288780 PMCID: PMC7106949 DOI: 10.1088/1748-9326/8/1/015036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/04/2013] [Indexed: 06/11/2023]
Abstract
Determining the factors that influence the transmission of parasites among hosts is important for directing surveillance of animal parasites before they successfully emerge in humans, and increasing the efficacy of programs for the control and management of zoonotic diseases. Here we present a review of recent advances in the study of parasite sharing, wildlife ecology, and epidemiology that could be extended and incorporated into proactive surveillance frameworks for multi-host infectious diseases. These methods reflect emerging interdisciplinary techniques with significant promise for the identification of future zoonotic parasites and unknown reservoirs of current zoonoses, strategies for the reduction of parasite prevalence and transmission among hosts, and decreasing the burden of infectious diseases.
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Affiliation(s)
- Maxwell J Farrell
- Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, QC, H3A 1B1,
- Department of Geography, McGill University, 805 Sherbrooke Street, West Montreal, QC, H3A 0B9, Canada
| | - Lea Berrang-Ford
- Department of Geography, McGill University, 805 Sherbrooke Street, West Montreal, QC, H3A 0B9, Canada
| | - T Jonathan Davies
- Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, QC, H3A 1B1,
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Seabloom EW, Borer ET, Lacroix C, Mitchell CE, Power AG. Richness and composition of niche-assembled viral pathogen communities. PLoS One 2013; 8:e55675. [PMID: 23468848 PMCID: PMC3582609 DOI: 10.1371/journal.pone.0055675] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/02/2013] [Indexed: 01/20/2023] Open
Abstract
The pathogen and parasite community that inhabits every free-living organism can control host vital rates including lifespan and reproductive output. To date, however, there have been few experiments examining pathogen community assembly replicated at large-enough spatial scales to inform our understanding of pathogen dynamics in natural systems. Pathogen community assembly may be driven by neutral stochastic colonization and extinction events or by niche differentiation that constrains pathogen distributions to particular environmental conditions, hosts, or vectors. Here, we present results from a regionally-replicated experiment investigating the community of barley and cereal yellow dwarf viruses (B/CYDV's) in over 5000 experimentally planted individuals of six grass species along a 700 km latitudinal gradient along the Pacific coast of North America (USA) in response to experimentally manipulated nitrogen and phosphorus supplies. The composition of the virus community varied predictably among hosts and across nutrient-addition treatments, indicating niche differentiation among virus species. There were some concordant responses among the viral species. For example, the prevalence of most viral species increased consistently with perennial grass cover, leading to a 60% increase in the richness of the viral community within individual hosts (i.e., coinfection) in perennial-dominated plots. Furthermore, infection rates of the six host species in the field were highly correlated with vector preferences assessed in laboratory trials. Our results reveal the importance of niche differentiation in structuring virus assemblages. Virus species distributions reflected a combination of local host community composition, host species-specific vector preferences, and virus responses to host nutrition. In addition, our results suggest that heterogeneity among host species in their capacity to attract vectors or support pathogens between growing seasons can lead to positive covariation among virus species.
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Affiliation(s)
- Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, USA.
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Mundt CC, Sackett KE. Spatial scaling relationships for spread of disease caused by a wind-dispersed plant pathogen. Ecosphere 2012; 3:art24. [PMID: 24077925 PMCID: PMC3785091 DOI: 10.1890/es11-00281.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spatial scale is of great importance to understanding the spread of organisms exhibiting long-distance dispersal (LDD). We tested whether epidemics spread in direct proportion to the size of the host population and size of the initial disease focus. This was done through analysis of a previous study of the effects of landscape heterogeneity variables on the spread of accelerating epidemics of wheat (Triticum aestivum) stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici. End-of-season disease gradients were constructed by estimating disease prevalence at regular distances from artificially inoculated foci of different sizes, in field plots of different dimensions. In one set of comparisons, all linear dimensions (plot width and length, focus width and length, and distance between observation points) differed by a factor of four. Disease spread was substantially greater in large plot/large focus treatments than in small plot/small focus treatments. However, when disease gradients were plotted using focus width as the unit distance, they were found to be highly similar, suggesting a proportional relationship between focus or plot size and disease spread. A similar relationship held when comparing same-size plots inoculated with different-sized foci, an indication that focus size is the driver of this proportionality. Our results suggest that power law dispersal of LDD organisms results in scale-invariant relationships, which are useful for better understanding spatial spread of biological invasions, extrapolating results from small-scale experiments to invasions spreading over larger scales, and predicting speed and pattern of spread as an invasion expands.
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Affiliation(s)
- Christopher C. Mundt
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331-2902 USA
| | - Kathryn E. Sackett
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331-2902 USA
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