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Slowik AR, Hesketh H, Sait SM, De Fine Licht HH. Thermal ecology shapes disease outcomes of entomopathogenic fungi infecting warm-adapted insects. J Invertebr Pathol 2024; 204:108106. [PMID: 38621520 DOI: 10.1016/j.jip.2024.108106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 03/13/2024] [Accepted: 04/10/2024] [Indexed: 04/17/2024]
Abstract
The thermal environment is a critical determinant of outcomes in host-pathogen interactions, yet the complexities of this relationship remain underexplored in many ecological systems. We examined the Thermal Mismatch Hypothesis (TMH) by measuring phenotypic variation in individual thermal performance profiles using a model system of two species of entomopathogenic fungi (EPF) that differ in their ecological niche, Metarhizium brunneum and M. flavoviride, and a warm-adapted model host, the mealworm Tenebrio molitor. We conducted experiments across ecologically relevant temperatures to determine the thermal performance curves for growth and virulence, measured as % survival, identify critical thresholds for these measures, and elucidate interactive host-pathogen effects. Both EPF species and the host exhibited a shared growth optima at 28 °C, while the host's growth response was moderated in sublethal pathogen infections that depended on fungus identity and temperature. However, variances in virulence patterns were different between pathogens. The fungus M. brunneum exhibited a broader optimal temperature range (23-28 °C) for virulence than M. flavoviride, which displayed a multiphasic virulence-temperature relationship with distinct peaks at 18 and 28 °C. Contrary to predictions of the TMH, both EPF displayed peak virulence at the host's optimal temperature (28 °C). The thermal profile for M. brunneum aligned more closely with that of T. molitor than that for M. flavoviride. Moreover, the individual thermal profile of M. flavoviride closely paralleled its virulence thermal profile, whereas the virulence thermal profile of M. brunneum did not track with its individual thermal performance. This suggests an indirect, midrange (23 °C) effect, where M. brunneum virulence exceeded growth. These findings suggest that the evolutionary histories and ecological adaptations of these EPF species have produced distinct thermal niches during the host interaction. This study contributes to our understanding of thermal ecology in host-pathogen interactions, underpinning the ecological and evolutionary factors that shape infection outcomes in entomopathogenic fungi. The study has ecological implications for insect population dynamics in the face of a changing climate, as well as practically for the use of these organisms in biological control.
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Affiliation(s)
- Anna R Slowik
- University of Copenhagen, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871 Frederiksberg C., Denmark; UK Centre for Ecology & Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford OX10 8BB, United Kingdom; School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - Helen Hesketh
- UK Centre for Ecology & Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford OX10 8BB, United Kingdom.
| | - Steven M Sait
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - Henrik H De Fine Licht
- University of Copenhagen, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871 Frederiksberg C., Denmark.
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Hector TE, Shocket MS, Sgrò CM, Hall MD. Acclimation to warmer temperatures can protect host populations from both further heat stress and the potential invasion of pathogens. GLOBAL CHANGE BIOLOGY 2024; 30:e17341. [PMID: 38837568 DOI: 10.1111/gcb.17341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 04/15/2024] [Accepted: 04/20/2024] [Indexed: 06/07/2024]
Abstract
Thermal acclimation can provide an essential buffer against heat stress for host populations, while acting simultaneously on various life-history traits that determine population growth. In turn, the ability of a pathogen to invade a host population is intimately linked to these changes via the supply of new susceptible hosts, as well as the impact of warming on its immediate infection dynamics. Acclimation therefore has consequences for hosts and pathogens that extend beyond simply coping with heat stress-governing both population growth trajectories and, as a result, an inherent propensity for a disease outbreak to occur. The impact of thermal acclimation on heat tolerances, however, is rarely considered simultaneously with metrics of both host and pathogen population growth, and ultimately fitness. Using the host Daphnia magna and its bacterial pathogen, we investigated how thermal acclimation impacts host and pathogen performance at both the individual and population scales. We first tested the effect of maternal and direct thermal acclimation on the life-history traits of infected and uninfected individuals, such as heat tolerance, fecundity, and lifespan, as well as pathogen infection success and spore production. We then predicted the effects of each acclimation treatment on rates of host and pathogen population increase by deriving a host's intrinsic growth rate (rm) and a pathogen's basic reproductive number (R0). We found that direct acclimation to warming enhanced a host's heat tolerance and rate of population growth, despite a decline in life-history traits such as lifetime fecundity and lifespan. In contrast, pathogen performance was consistently worse under warming, with within-host pathogen success, and ultimately the potential for disease spread, severely hampered at higher temperatures. Our results suggest that hosts could benefit more from warming than their pathogens, but only by linking multiple individual traits to population processes can the full impact of higher temperatures on host and pathogen population dynamics be realised.
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Affiliation(s)
| | - Marta S Shocket
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Carla M Sgrò
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Matthew D Hall
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
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Greenrod STE, Cazares D, Johnson S, Hector TE, Stevens EJ, MacLean RC, King KC. Warming alters life-history traits and competition in a phage community. Appl Environ Microbiol 2024; 90:e0028624. [PMID: 38624196 PMCID: PMC11107170 DOI: 10.1128/aem.00286-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 03/26/2024] [Indexed: 04/17/2024] Open
Abstract
Host-parasite interactions are highly susceptible to changes in temperature due to mismatches in species thermal responses. In nature, parasites often exist in communities, and responses to temperature are expected to vary between host-parasite pairs. Temperature change thus has consequences for both host-parasite dynamics and parasite-parasite interactions. Here, we investigate the impact of warming (37°C, 40°C, and 42°C) on parasite life-history traits and competition using the opportunistic bacterial pathogen Pseudomonas aeruginosa (host) and a panel of three genetically diverse lytic bacteriophages (parasites). We show that phages vary in their responses to temperature. While 37°C and 40°C did not have a major effect on phage infectivity, infection by two phages was restricted at 42°C. This outcome was attributed to disruption of different phage life-history traits including host attachment and replication inside hosts. Furthermore, we show that temperature mediates competition between phages by altering their competitiveness. These results highlight phage trait variation across thermal regimes with the potential to drive community dynamics. Our results have important implications for eukaryotic viromes and the design of phage cocktail therapies.IMPORTANCEMammalian hosts often elevate their body temperatures through fevers to restrict the growth of bacterial infections. However, the extent to which fever temperatures affect the communities of phages with the ability to parasitize those bacteria remains unclear. In this study, we investigate the impact of warming across a fever temperature range (37°C, 40°C, and 42°C) on phage life-history traits and competition using a bacterium (host) and bacteriophage (parasite) system. We show that phages vary in their responses to temperature due to disruption of different phage life-history traits. Furthermore, we show that temperature can alter phage competitiveness and shape phage-phage competition outcomes. These results suggest that fever temperatures have the potential to restrict phage infectivity and drive phage community dynamics. We discuss implications for the role of temperature in shaping host-parasite interactions more widely.
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Affiliation(s)
| | - Daniel Cazares
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Serena Johnson
- Department of Biology, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Tobias E. Hector
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Emily J. Stevens
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - R. Craig MacLean
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Kayla C. King
- Department of Biology, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of British Columbia, Vancouver, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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Li JD, Gao YY, Stevens EJ, King KC. Dual stressors of infection and warming can destabilize host microbiomes. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230069. [PMID: 38497264 PMCID: PMC10945407 DOI: 10.1098/rstb.2023.0069] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 01/02/2024] [Indexed: 03/19/2024] Open
Abstract
Climate change is causing extreme heating events and intensifying infectious disease outbreaks. Animals harbour microbial communities, which are vital for their survival and fitness under stressful conditions. Understanding how microbiome structures change in response to infection and warming may be important for forecasting host performance under global change. Here, we evaluated alterations in the microbiomes of several wild Caenorhabditis elegans isolates spanning a range of latitudes, upon warming temperatures and infection by the parasite Leucobacter musarum. Using 16S rRNA sequencing, we found that microbiome diversity decreased, and dispersion increased over time, with the former being more prominent in uninfected adults and the latter aggravated by infection. Infection reduced dominance of specific microbial taxa, and increased microbiome dispersion, indicating destabilizing effects on host microbial communities. Exposing infected hosts to warming did not have an additive destabilizing effect on their microbiomes. Moreover, warming during pre-adult development alleviated the destabilizing effects of infection on host microbiomes. These results revealed an opposing interaction between biotic and abiotic factors on microbiome structure. Lastly, we showed that increased microbiome dispersion might be associated with decreased variability in microbial species interaction strength. Overall, these findings improve our understanding of animal microbiome dynamics amidst concurrent climate change and epidemics. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.
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Affiliation(s)
- J. D. Li
- Department of Biology, University of Oxford, Oxford OX1 2JD, UK
| | - Y. Y. Gao
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, People's Republic of China
- School of Ecology and Nature Conservation, Beijing Forestry University, 35 Tsinghua East Road, Beijing 100083, People's Republic of China
| | - E. J. Stevens
- Department of Biology, University of Oxford, Oxford OX1 2JD, UK
| | - K. C. King
- Department of Biology, University of Oxford, Oxford OX1 2JD, UK
- Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, V6T 1Z3, Canada
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Johnson PTJ, Merrill TS, Calhoun DM, McDevitt-Galles T, Hobart B. Into the danger zone: How the within-host distribution of parasites controls virulence. Ecol Lett 2024; 27:e14352. [PMID: 38115188 PMCID: PMC10872350 DOI: 10.1111/ele.14352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 12/21/2023]
Abstract
Despite the importance of virulence in epidemiological theory, the relative contributions of host and parasite to virulence outcomes remain poorly understood. Here, we use reciprocal cross experiments to disentangle the influence of host and parasite on core virulence components-infection and pathology-and understand dramatic differences in parasite-induced malformations in California amphibians. Surveys across 319 populations revealed that amphibians' malformation risk was 2.7× greater in low-elevation ponds, even while controlling for trematode infection load. Factorial experiments revealed that parasites from low-elevation sites induced higher per-parasite pathology (reduced host survival and growth), whereas there were no effects of host source on resistance or tolerance. Parasite populations also exhibited marked differences in within-host distribution: ~90% of low-elevation cysts aggregated around the hind limbs, relative to <60% from high-elevation. This offers a novel, mechanistic basis for regional variation in parasite-induced malformations while promoting a framework for partitioning host and parasite contributions to virulence.
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Affiliation(s)
| | - Tara Stewart Merrill
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
- Coastal and Marine Laboratory, Florida State University, St. Teresa, FL, 32358, USA
| | - Dana M. Calhoun
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Travis McDevitt-Galles
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
- Current address: USGS National Wildlife Health Center, Madison, WI, USA
| | - Brendan Hobart
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
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Juarez-Estrada MA, Graham D, Hernandez-Velasco X, Tellez-Isaias G. Editorial: Parasitism: the good, the bad and the ugly. Front Vet Sci 2023; 10:1304206. [PMID: 37915945 PMCID: PMC10616899 DOI: 10.3389/fvets.2023.1304206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 10/06/2023] [Indexed: 11/03/2023] Open
Affiliation(s)
- Marco A. Juarez-Estrada
- Department of Medicine and Zootechnics of Birds, College of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Mexico City, Mexico
| | - Danielle Graham
- Division of Agriculture, Department of Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Xochitl Hernandez-Velasco
- Department of Medicine and Zootechnics of Birds, College of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Mexico City, Mexico
| | - Guillermo Tellez-Isaias
- Division of Agriculture, Department of Poultry Science, University of Arkansas, Fayetteville, AR, United States
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Dallas JW, Warne RW. Ranavirus infection does not reduce heat tolerance in a larval amphibian. J Therm Biol 2023; 114:103584. [PMID: 37209633 DOI: 10.1016/j.jtherbio.2023.103584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 04/24/2023] [Accepted: 04/27/2023] [Indexed: 05/22/2023]
Abstract
Extreme heat events and emerging infectious diseases negatively impact wildlife populations, but the interacting effects of infection and host heat tolerance remain understudied. The few studies covering this subject have demonstrated that pathogens lower the heat tolerance of their hosts, which places infected hosts at a greater risk experiencing lethal heat stress. Here, we studied how ranavirus infection influenced heat tolerance in larval wood frogs (Lithobates sylvaticus). In line with similar studies, we predicted the elevated costs of ranavirus infection would lower heat tolerance, measured as critical thermal maximum (CTmax), compared to uninfected controls. Ranavirus infection did not reduce CTmax and there was a positive relationship between CTmax and viral loads. Our results demonstrate that ranavirus-infected wood frog larvae had no loss in heat tolerance compared to uninfected larvae, even at viral loads associated with high mortality rates, which contradicts the common pattern for other pathogenic infections in ectotherms. Larval anurans may prioritize maintenance of their CTmax when infected with ranavirus to promote selection of warmer temperatures during behavioral fever that can improve pathogen clearance. Our study represents the first to examine the effect of ranavirus infection on host heat tolerance, and because no decline in CTmax was observed, this suggests that infected hosts would not be under greater risk of heat stress.
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Affiliation(s)
- Jason W Dallas
- School of Biological Sciences, Southern Illinois University Carbondale, 1125 Lincoln Street, Carbondale, IL, 62901, USA.
| | - Robin W Warne
- School of Biological Sciences, Southern Illinois University Carbondale, 1125 Lincoln Street, Carbondale, IL, 62901, USA
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