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Erler S, Cotter SC, Freitak D, Koch H, Palmer-Young EC, de Roode JC, Smilanich AM, Lattorff HMG. Insects' essential role in understanding and broadening animal medication. Trends Parasitol 2024; 40:338-349. [PMID: 38443305 DOI: 10.1016/j.pt.2024.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 03/07/2024]
Abstract
Like humans, animals use plants and other materials as medication against parasites. Recent decades have shown that the study of insects can greatly advance our understanding of medication behaviors. The ease of rearing insects under laboratory conditions has enabled controlled experiments to test critical hypotheses, while their spectrum of reproductive strategies and living arrangements - ranging from solitary to eusocial communities - has revealed that medication behaviors can evolve to maximize inclusive fitness through both direct and indirect fitness benefits. Studying insects has also demonstrated in some cases that medication can act through modulation of the host's innate immune system and microbiome. We highlight outstanding questions, focusing on costs and benefits in the context of inclusive host fitness.
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Affiliation(s)
- Silvio Erler
- Institute for Bee Protection, Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Braunschweig, Germany; Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.
| | | | - Dalial Freitak
- Institute for Biology, University of Graz, Graz, Austria
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2
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Hoogshagen M, Hastings AP, Chavez J, Duckett M, Pettit R, Pahnke AP, Agrawal AA, de Roode JC. Mixtures of Milkweed Cardenolides Protect Monarch Butterflies against Parasites. J Chem Ecol 2024; 50:52-62. [PMID: 37932621 DOI: 10.1007/s10886-023-01461-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/07/2023] [Accepted: 10/24/2023] [Indexed: 11/08/2023]
Abstract
Plants have evolved a diverse arsenal of defensive secondary metabolites in their evolutionary arms race with insect herbivores. In addition to the bottom-up forces created by plant chemicals, herbivores face top-down pressure from natural enemies, such as predators, parasitoids and parasites. This has led to the evolution of specialist herbivores that do not only tolerate plant secondary metabolites but even use them to fight natural enemies. Monarch butterflies (Danaus plexippus) are known for their use of milkweed chemicals (cardenolides) as protection against vertebrate predators. Recent studies have shown that milkweeds with high cardenolide concentrations can also provide protection against a virulent protozoan parasite. However, whether cardenolides are directly responsible for these effects, and whether individual cardenolides or mixtures of these chemicals are needed to reduce infection, remains unknown. We fed monarch larvae the four most abundant cardenolides found in the anti-parasitic-milkweed Asclepias curassavica at varying concentrations and compositions to determine which provided the highest resistance to parasite infection. Measuring infection rates and infection intensities, we found that resistance is dependent on both concentration and composition of cardenolides, with mixtures of cardenolides performing significantly better than individual compounds, even when mixtures included lower concentrations of individual compounds. These results suggest that cardenolides function synergistically to provide resistance against parasite infection and help explain why only milkweed species that produce diverse cardenolide compounds provide measurable parasite resistance. More broadly, our results suggest that herbivores can benefit from consuming plants with diverse defensive chemical compounds through release from parasitism.
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Affiliation(s)
| | - Amy P Hastings
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | | | | | | | | | - Anurag A Agrawal
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
- Department of Entomology, Cornell University, Ithaca, NY, USA
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3
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Kendzel MJ, Altizer SM, de Roode JC. Interactions between parasitism and migration in monarch butterflies. Curr Opin Insect Sci 2023; 59:101089. [PMID: 37506879 DOI: 10.1016/j.cois.2023.101089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/12/2023] [Accepted: 07/23/2023] [Indexed: 07/30/2023]
Abstract
In many species, migration can increase parasite burdens or diversity as hosts move between diverse habitats with different parasite assemblages. On the other hand, migration can reduce parasite prevalence by letting animals escape infested habitats, or by exacerbating the costs of parasitism, leading to culling or dropout. How the balance between these negative and positive interactions is maintained or how they will change under anthropogenic pressure remains poorly understood. Here, we summarize the relationship between migration and infectious disease in monarch butterflies, finding that migration can reduce parasite prevalence through a combination of migratory culling and dropout. Because parasite prevalence has risen in recent decades, these processes are now resulting in the loss of tens of millions of monarchs. We highlight the remaining questions, asking how migration influences population genetics and virulence, how the establishment of resident populations interferes with migration, and whether infection can interfere with migratory cognition.
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Affiliation(s)
| | - Sonia M Altizer
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
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4
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Mongue AJ, Martin SH, Manweiler REV, Scullion H, Koehn JL, de Roode JC, Walters JR. Genome sequence of Ophryocystis elektroscirrha, an apicomplexan parasite of monarch butterflies: cryptic diversity and response to host-sequestered plant chemicals. BMC Genomics 2023; 24:278. [PMID: 37226080 DOI: 10.1186/s12864-023-09350-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/29/2023] [Indexed: 05/26/2023] Open
Abstract
Apicomplexa are ancient and diverse organisms which have been poorly characterized by modern genomics. To better understand the evolution and diversity of these single-celled eukaryotes, we sequenced the genome of Ophryocystis elektroscirrha, a parasite of monarch butterflies, Danaus plexippus. We contextualize our newly generated resources within apicomplexan genomics before answering longstanding questions specific to this host-parasite system. To start, the genome is miniscule, totaling only 9 million bases and containing fewer than 3,000 genes, half the gene content of two other sequenced invertebrate-infecting apicomplexans, Porospora gigantea and Gregarina niphandrodes. We found that O. elektroscirrha shares different orthologs with each sequenced relative, suggesting the true set of universally conserved apicomplexan genes is very small indeed. Next, we show that sequencing data from other potential host butterflies can be used to diagnose infection status as well as to study diversity of parasite sequences. We recovered a similarly sized parasite genome from another butterfly, Danaus chrysippus, that was highly diverged from the O. elektroscirrha reference, possibly representing a distinct species. Using these two new genomes, we investigated potential evolutionary response by parasites to toxic phytochemicals their hosts ingest and sequester. Monarch butterflies are well-known to tolerate toxic cardenolides thanks to changes in the sequence of their Type II ATPase sodium pumps. We show that Ophryocystis completely lacks Type II or Type 4 sodium pumps, and related proteins PMCA calcium pumps show extreme sequence divergence compared to other Apicomplexa, demonstrating new avenues of research opened by genome sequencing of non-model Apicomplexa.
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Affiliation(s)
- Andrew J Mongue
- Department of Entomology and Nematology, University of Florida, Gainesville, USA.
| | - Simon H Martin
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, UK
| | - Rachel E V Manweiler
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, USA
| | - Helena Scullion
- Department of Entomology and Nematology, University of Florida, Gainesville, USA
| | - Jordyn L Koehn
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, USA
| | | | - James R Walters
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, USA
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5
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Niitepõld K, Parry HA, Harris NR, Appel AG, de Roode JC, Kavazis AN, Hood WR. Flying on empty: Reduced mitochondrial function and flight capacity in food-deprived monarch butterflies. J Exp Biol 2022; 225:275693. [PMID: 35694960 DOI: 10.1242/jeb.244431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/07/2022] [Indexed: 11/20/2022]
Abstract
Mitochondrial function is fundamental to organismal performance, health, and fitness - especially during energetically challenging events, such as migration. With this investigation, we evaluated mitochondrial sensitivity to ecologically relevant stressors. We focused on an iconic migrant, the North American monarch butterfly (Danaus plexippus), and examined the effects of two stressors: seven days of food deprivation, and infection by the protozoan parasite Ophryocystis elektroscirrha (known to reduce survival and flight performance). We measured whole-animal resting (RMR) and peak flight metabolic rate, and mitochondrial respiration of isolated mitochondria from the flight muscles. Food deprivation reduced mass-independent RMR and peak flight metabolic rate, whereas infection did not. Fed monarchs used mainly lipids in flight (respiratory quotient 0.73), but the respiratory quotient dropped in food-deprived individuals, possibly indicating switching to alternative energy sources, such as ketone bodies. Food deprivation decreased mitochondrial maximum oxygen consumption but not basal respiration, resulting in lower respiratory control ratio (RCR). Furthermore, food deprivation decreased mitochondrial complex III activity, but increased complex IV activity. Infection did not result in any changes in these mitochondrial variables. Mitochondrial maximum respiration rate correlated positively with mass-independent RMR and flight metabolic rate, suggesting a link between mitochondria and whole-animal performance. In conclusion, low food availability negatively affects mitochondrial function and flight performance, with potential implications on migration, fitness, and population dynamics. Although previous studies have reported poor flight performance in infected monarchs, we found no differences in physiological performance, suggesting that reduced flight capacity may be due to structural differences or low energy stores.
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Affiliation(s)
- Kristjan Niitepõld
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA.,The Finnish Science Centre Heureka, 01300 Vantaa, Finland
| | - Hailey A Parry
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | - Natalie R Harris
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Arthur G Appel
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | | | | | - Wendy R Hood
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
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6
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Babalola TS, de Roode JC, Villa SM. EXPERIMENTAL INFECTION WITH A NATURALLY OCCURRING PROTOZOAN PARASITE REDUCES MONARCH BUTTERFLY ( DANAUS PLEXIPPUS) MATING SUCCESS. J Parasitol 2022; 108:289-300. [PMID: 35774250 PMCID: PMC9235863 DOI: 10.1645/21-121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Parasitic infection is known to drive sexual selection in persuasive mating systems, where parasites influence the secondary sexual characteristics that underlie mate choice. However, comparatively little is known about their effects on animals that use coercive mating behavior. We use a tractable system consisting of monarch butterflies and their naturally occurring parasite Ophryocystis elektroscirrha to test how parasites influence host mating dynamics when males force females to copulate. Monarchs were placed in mating cages where all, half, or no individuals were experimentally infected with O. elektroscirrha. We found that parasites reduce a male's mating success such that infected males were not only less likely to copulate but obtained fewer lifetime copulations as well. This reduction in mating success was due primarily to the fact that infected males attempt to mate significantly less than uninfected males. However, we found that O. elektroscirrha did not influence male mate choice. Males chose to mate with both infected and uninfected females at similar rates, regardless of their infection status. Overall, our data highlight how mating dynamics in coercive systems are particularly vulnerable to parasites.
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Affiliation(s)
- Tolulope S. Babalola
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, Georgia 30322
| | - Jacobus C. de Roode
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, Georgia 30322
| | - Scott M. Villa
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, Georgia 30322
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7
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Alaidrous W, Villa SM, de Roode JC, Majewska AA. Crowding does not affect monarch butterflies’ resistance to a protozoan parasite. Ecol Evol 2022; 12:e8791. [PMID: 35414899 PMCID: PMC8986514 DOI: 10.1002/ece3.8791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/08/2022] [Accepted: 03/14/2022] [Indexed: 11/12/2022] Open
Abstract
Host density is an important factor when it comes to parasite transmission and host resistance. Increased host density can increase contact rate between individuals and thus parasite transmission. Host density can also cause physiological changes in the host, which can affect host resistance. Yet, the direction in which host density affects host resistance remains unresolved. It is also unclear whether food limitation plays a role in this effect. We investigated the effect of larval density in monarch butterflies, Danaus plexippus, on the resistance to their natural protozoan parasite Ophryocystis elektroscirrha under both unlimited and limited food conditions. We exposed monarchs to various density treatments as larvae to mimic high densities observed in sedentary populations. Data on infection and parasite spore load were collected as well as development time, survival, wing size, and melanization. Disease susceptibility under either food condition or across density treatments was similar. However, we found high larval density impacted development time, adult survival, and wing morphology when food was limited. This study aids our understanding of the dynamics of environmental parasite transmission in monarch populations, which can help explain the increased prevalence of parasites in sedentary monarch populations compared to migratory populations.
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Affiliation(s)
- Wajd Alaidrous
- Department of Biology Emory University Atlanta Georgia USA
- Division of Biological and Environmental Science and Engineering (BESE) King Abdullah University for Science and Technology Thuwal Saudi Arabia
| | - Scott M. Villa
- Department of Biology Emory University Atlanta Georgia USA
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8
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Villa SM, Kelly KP, Hollimon MG, Protil KJ, de Roode JC. Lack of inbreeding avoidance during mate selection in migratory monarch butterflies. Behav Processes 2022; 198:104630. [PMID: 35381312 PMCID: PMC10375862 DOI: 10.1016/j.beproc.2022.104630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/21/2022] [Accepted: 03/28/2022] [Indexed: 11/15/2022]
Abstract
Inbreeding is generally thought to have negative consequences for organismal health. However, despite the potential fitness effects, it remains surprisingly common among wild populations. In many cases, the complex factors that underlie mating dynamics make predicting whether individuals should or do avoid inbreeding quite challenging. One reason inbreeding may persist among species is that the likelihood of encountering relatives can be rare. Thus, even if inbreeding has severe consequences, selection to avoid mating with kin will be weak in species that are highly dispersed. Here we investigated if migratory monarch butterflies (Danaus plexippus), which are famous for their dispersal ability, actively avoid inbreeding. We found that neither female nor male monarchs choose mates based on relatedness. These results support the hypothesis that movement ecology can mask the deleterious effects of inbreeding and relax selection for active inbreeding avoidance behaviors. Overall, our data add to the growing list of studies showing that inbreeding avoidance is not the behavioral "default" for most species. We also highlight the implications that inbreeding may have on the declining populations of this iconic butterfly.
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9
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Majewska AA, Davis AK, Altizer S, de Roode JC. Parasite dynamics in North American monarchs predicted by host density and seasonal migratory culling. J Anim Ecol 2022; 91:780-793. [PMID: 35174493 DOI: 10.1111/1365-2656.13678] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 01/31/2022] [Indexed: 11/30/2022]
Abstract
Insect-pathogen dynamics can show seasonal and inter-annual variation that covaries with fluctuations in insect abundance and climate. Long-term analyses are especially needed to track parasite dynamics in migratory insects, in part because their vast habitat ranges and high mobility might dampen local effects of density and climate on infection prevalence. Monarch butterflies (Danaus plexippus) are commonly infected with the protozoan Ophryocystis elektroscirrha (OE). Because this parasite lowers monarch survival and flight performance, and because migratory monarchs have experienced declines in recent decades, it is important to understand patterns and drivers of infection. 3. Here we compiled data on OE infection spanning 50 years, from wild monarchs sampled in the USA, Canada, and Mexico during summer breeding, fall migrating, and overwintering periods. We examined eastern versus western North American monarchs separately, to ask how abundance estimates, resource availability, climate, and breeding season length impact infection trends. We further assessed the intensity of migratory culling, which occurs when infected individuals are removed from the population during migration. 4. Average infection prevalence was four times higher in western compared to eastern subpopulations. In eastern North America, the proportion of infected monarchs increased three-fold since the mid-2000s. In the western region, the proportion of infected monarchs declined sharply from 2000-2015, and increased thereafter. For both eastern and western subpopulations, years with greater summer adult abundance predicted greater infection prevalence, indicating that transmission increases with host breeding density. Environmental variables (temperature and NDVI) were not associated with changes in infected adults. We found evidence for migratory culling of infected butterflies, based on declines in parasitism during fall migration. We estimated that tens of millions fewer monarchs reach overwintering sites in Mexico as a result of OE, highlighting the need to consider the parasite as a potential threat to the monarch population. 5. Increases in infection among eastern North American monarchs post-2002 suggest that changes to the host's ecology or environment have intensified parasite transmission. Further work is needed to examine the degree to which human practices, such as mass caterpillar rearing and the widespread planting of exotic milkweed, have contributed to this trend.
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Affiliation(s)
| | - Andrew K Davis
- Odum School of Ecology, University of Georgia, Athens, GA, USA
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA, USA
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10
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Tan WH, Talla V, Mongue AJ, de Roode JC, Gerardo NM, Walters JR. Population genomics reveals variable patterns of immune gene evolution in monarch butterflies (Danaus plexippus). Mol Ecol 2021; 30:4381-4391. [PMID: 34245613 DOI: 10.1111/mec.16071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 11/27/2022]
Abstract
Humoral and cellular immune responses provide animals with major defences against harmful pathogens. While it is often assumed that immune genes undergo rapid diversifying selection, this assumption has not been tested in many species. Moreover, it is likely that different classes of immune genes experience different levels of evolutionary constraint, resulting in varying selection patterns. We examined the evolutionary patterns for a set of 91 canonical immune genes of North American monarch butterflies (Danaus plexippus), using as an outgroup the closely related soldier butterfly (Danaus eresimus). As a comparison to these immune genes, we selected a set of control genes that were paired with each immune for approximate size and genomic location. As a whole, these immune genes had a significant but modest reduction in Tajima's D relative to paired-control genes, but otherwise did not show distinct patterns of population genetic variation or evolutionary rates. When further partitioning these immune genes into four functional classes (recognition, signalling, modulation, and effector), we found distinct differences among these groups. Relative to control genes, recognition genes exhibit increased nonsynonymous diversity and divergence, suggesting reduced constraints on evolution, and supporting the notion that coevolution with pathogens results in diversifying selection. In contrast, signalling genes showed an opposite pattern of reduced diversity and divergence, suggesting evolutionary constraints and conservation. Modulator and effector genes showed no statistical differences from controls. These results are consistent with patterns found in immune genes in fruit flies and Pieris butterflies, suggesting that consistent selective pressures on different classes of immune genes broadly govern the evolution of innate immunity among insects.
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Affiliation(s)
- Wen-Hao Tan
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Venkat Talla
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Andrew J Mongue
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA
| | | | | | - James R Walters
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA
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11
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Sánchez CA, Ragonese IG, de Roode JC, Altizer S. Thermal tolerance and environmental persistence of a protozoan parasite in monarch butterflies. J Invertebr Pathol 2021; 183:107544. [PMID: 33582107 DOI: 10.1016/j.jip.2021.107544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 11/29/2022]
Abstract
Many parasites have external transmission stages that persist in the environment prior to infecting a new host. Understanding how long these stages can persist, and how abiotic conditions such as temperature affect parasite persistence, is important for predicting infection dynamics and parasite responses to future environmental change. In this study, we explored environmental persistence and thermal tolerance of a debilitating protozoan parasite that infects monarch butterflies. Parasite transmission occurs when dormant spores, shed by adult butterflies onto host plants and other surfaces, are later consumed by caterpillars. We exposed parasite spores to a gradient of ecologically-relevant temperatures for 2, 35, or 93 weeks. We tested spore viability by feeding controlled spore doses to susceptible monarch larvae, and examined relationships between temperature, time, and resulting infection metrics. We also examined whether distinct parasite genotypes derived from replicate migratory and resident monarch populations differed in their thermal tolerance. Finally, we examined evidence for a trade-off between short-term within-host replication and long-term persistence ability. Parasite viability decreased in response to warmer temperatures over moderate-to-long time scales. Individual parasite genotypes showed high heterogeneity in viability, but differences did not cluster by migratory vs. resident monarch populations. We found no support for a negative relationship between environmental persistence and within-host replication, as might be expected if parasites invest in short-term reproduction at the cost of longer-term survival. Findings here indicate that dormant spores can survive for many months under cooler conditions, and that heat dramatically shortens the window of transmission for this widespread and virulent butterfly parasite.
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Affiliation(s)
- Cecilia A Sánchez
- Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA.
| | - Isabella G Ragonese
- Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA.
| | | | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA.
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12
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Adams KL, Sun EF, Alaidrous W, de Roode JC. Constant Light and Frequent Schedule Changes Do Not Impact Resistance to Parasites in Monarch Butterflies. J Biol Rhythms 2021; 36:286-296. [PMID: 33445989 DOI: 10.1177/0748730420985312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Organisms have evolved internal biological clocks to regulate their activities based on external environmental cues, such as light, temperature, and food. Environmental disruption of these rhythms, such as caused by constant light or frequent light schedule changes, has been shown to impair development, reduce survival, and increase infection susceptibility and disease progression in numerous organisms. However, the precise role of the biological clock in host-parasite interactions is understudied and has focused on unnatural host-parasite combinations in lab-adapted inbred models. Here, we use the natural interaction between monarch butterflies (Danaus plexippus) and their virulent protozoan parasite, Ophryocystis elektroscirrha, to investigate the effects of constant light and frequent light schedule changes on development, survival, and parasite susceptibility. We show that constant light exposure slows the monarchs' rate of development but does not increase susceptibility to parasitic infection. Furthermore, frequent schedule changes decrease parasite growth, but have no effect on egg-to-adult survival of infected monarchs. Interestingly, these conditions are usually disruptive to the biological clock, but do not significantly impact the clock of monarch larvae. These unexpected findings show that constant light and frequent schedule changes can uncouple host and parasite performance and highlight how natural relationships are needed to expand our understanding of clocks in host-parasite interactions.
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Affiliation(s)
- Kandis L Adams
- Department of Biology, Emory University, Atlanta, GA, USA
| | | | - Wajd Alaidrous
- Department of Biology, Emory University, Atlanta, GA, USA
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13
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Bartlett LJ, Boots M, Brosi BJ, de Roode JC, Delaplane KS, Hernandez CA, Wilfert L. Persistent effects of management history on honeybee colony virus abundances. J Invertebr Pathol 2020; 179:107520. [PMID: 33359478 DOI: 10.1016/j.jip.2020.107520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/09/2020] [Accepted: 12/12/2020] [Indexed: 10/22/2022]
Abstract
Infectious diseases are a major threat to both managed and wild pollinators. One key question is how the movement or transplantation of honeybee colonies under different management regimes affects honeybee disease epidemiology. We opportunistically examined any persistent effect of colony management history following relocation by characterising the virus abundances of honeybee colonies from three management histories, representing different management histories: feral, low-intensity management, and high-intensity "industrial" management. The colonies had been maintained for one year under the same approximate 'common garden' condition. Colonies in this observational study differed in their virus abundances according to management history, with the feral population history showing qualitatively different viral abundance patterns compared to colonies from the two managed population management histories; for example, higher abundance of sacbrood virus but lower abundances of various paralysis viruses. Colonies from the high-intensity management history exhibited higher viral abundances for all viruses than colonies from the low-intensity management history. Our results provide evidence that management history has persistent impacts on honeybee disease epidemiology, suggesting that apicultural intensification could be majorly impacting on pollinator health, justifying much more substantial investigation.
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Affiliation(s)
- Lewis J Bartlett
- Centre for Ecology and Conservation, University of Exeter, TR10 9FE, UK; Department of Biology, Emory University, Atlanta, GA 30322, USA; Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Michael Boots
- Centre for Ecology and Conservation, University of Exeter, TR10 9FE, UK; Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA
| | - Berry J Brosi
- Department of Environmental Sciences, Emory University, Atlanta, GA 30322, USA
| | | | - Keith S Delaplane
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Catherine A Hernandez
- Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA
| | - Lena Wilfert
- Centre for Ecology and Conservation, University of Exeter, TR10 9FE, UK; Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Ulm D-89069, Germany
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14
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Decker LE, Jeffrey CS, Ochsenrider KM, Potts AS, de Roode JC, Smilanich AM, Hunter MD. Elevated atmospheric concentrations of CO 2 increase endogenous immune function in a specialist herbivore. J Anim Ecol 2020; 90:628-640. [PMID: 33241571 DOI: 10.1111/1365-2656.13395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/20/2020] [Indexed: 11/30/2022]
Abstract
Animals rely on a balance of endogenous and exogenous sources of immunity to mitigate parasite attack. Understanding how environmental context affects that balance is increasingly urgent under rapid environmental change. In herbivores, immunity is determined, in part, by phytochemistry which is plastic in response to environmental conditions. Monarch butterflies Danaus plexippus, consistently experience infection by a virulent parasite Ophryocystis elektroscirrha, and some medicinal milkweed (Asclepias) species, with high concentrations of toxic steroids (cardenolides), provide a potent source of exogenous immunity. We investigated plant-mediated influences of elevated CO2 (eCO2 ) on endogenous immune responses of monarch larvae to infection by O. elektroscirrha. Recently, transcriptomics have revealed that infection by O. elektroscirrha does not alter monarch immune gene regulation in larvae, corroborating that monarchs rely more on exogenous than endogenous immunity. However, monarchs feeding on medicinal milkweed grown under eCO2 lose tolerance to the parasite, associated with changes in phytochemistry. Whether changes in milkweed phytochemistry induced by eCO2 alter the balance between exogenous and endogenous sources of immunity remains unknown. We fed monarchs two species of milkweed; A. curassavica (medicinal) and A. incarnata (non-medicinal) grown under ambient CO2 (aCO2 ) or eCO2 . We then measured endogenous immune responses (phenoloxidase activity, haemocyte concentration and melanization strength), along with foliar chemistry, to assess mechanisms of monarch immunity under future atmospheric conditions. The melanization response of late-instar larvae was reduced on medicinal milkweed in comparison to non-medicinal milkweed. Moreover, the endogenous immune responses of early-instar larvae to infection by O. elektroscirrha were generally lower in larvae reared on foliage from aCO2 plants and higher in larvae reared on foliage from eCO2 plants. When grown under eCO2 , milkweed plants exhibited lower cardenolide concentrations, lower phytochemical diversity and lower nutritional quality (higher C:N ratios). Together, these results suggest that the loss of exogenous immunity from foliage under eCO2 results in increased endogenous immune function. Animal populations face multiple threats induced by anthropogenic environmental change. Our results suggest that shifts in the balance between exogenous and endogenous sources of immunity to parasite attack may represent an underappreciated consequence of environmental change.
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Affiliation(s)
- Leslie E Decker
- Department of Biology, Stanford University, Stanford, CA, USA.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Abigail S Potts
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
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15
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Abstract
A core hypothesis in coevolutionary theory proposes that parasites adapt to specifically infect common host genotypes. Under this hypothesis, parasites function as agents of negative frequency-dependent selection, favouring rare host genotypes. This parasite-mediated advantage of rarity is key to the idea that parasites maintain genetic variation and select for outcrossing in host populations. Here, we report the results of an experimental test of parasite adaptation to common versus rare host genotypes. We selected the bacterial parasite
Serratia marcescens
to kill
Caenorhabdiis elegans
hosts in uneven mixtures of host genotypes. To examine the effect of commonness itself, independent of host identity, each of four host genotypes was represented as common or rare in experimental host mixtures. After experimental selection, we evaluated a parasite line's change in virulence—the selected fitness trait—on its rare and common host genotypes. Our results were consistent with a slight advantage for rare host genotypes: on average, parasites lost virulence against rare genotypes but not against common genotypes. The response varied substantially, however, with distinct patterns across host genotype mixtures. These findings support the potential for parasites to impose negative frequency-dependent selection, while emphasizing that the cost of being common may vary with host genotype.
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Affiliation(s)
- Amanda K. Gibson
- Department of Biology, Emory University, Atlanta, GA 30322
- Department of Biology, University of Virginia, Virginia 22904, USA
| | - P. Signe White
- Department of Biology, Emory University, Atlanta, GA 30322
- Population Biology, Ecology, and Evolution Graduate Program, Laney Graduate School, Emory University, Atlanta, GA 30322
| | | | | | - Levi T. Morran
- Department of Biology, Emory University, Atlanta, GA 30322
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16
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Talla V, Pierce AA, Adams KL, de Man TJB, Nallu S, Villablanca FX, Kronforst MR, de Roode JC. Genomic evidence for gene flow between monarchs with divergent migratory phenotypes and flight performance. Mol Ecol 2020; 29:2567-2582. [PMID: 32542770 DOI: 10.1111/mec.15508] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 06/05/2020] [Indexed: 12/24/2022]
Abstract
Monarch butterflies are known for their spectacular annual migration in eastern North America, with millions of monarchs flying up to 4,500 km to overwintering sites in central Mexico. Monarchs also live west of the Rocky Mountains, where they travel shorter distances to overwinter along the Pacific Coast. It is often assumed that eastern and western monarchs form distinct evolutionary units, but genomic studies to support this notion are lacking. We used a tethered flight mill to show that migratory eastern monarchs have greater flight performance than western monarchs, consistent with their greater migratory distances. However, analysing more than 20 million SNPs in 43 monarch genomes, we found no evidence for genomic differentiation between eastern and western monarchs. Genomic analysis also showed identical and low levels of genetic diversity, and demographic analyses indicated similar effective population sizes and ongoing gene flow between eastern and western monarchs. Gene expression analysis of a subset of candidate genes during active flight revealed differential gene expression related to nonmuscular motor activity. Our results demonstrate that eastern and western monarchs maintain migratory differences despite ongoing gene flow, and suggest that migratory differences between eastern and western monarchs are not driven by select major-effects alleles. Instead, variation in migratory distance and destination may be driven by environmentally induced differential gene expression or by many alleles of small effect.
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Affiliation(s)
- Venkat Talla
- Department of Biology, Emory University, Atlanta, GA, USA
| | | | - Kandis L Adams
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Tom J B de Man
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Sumitha Nallu
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
| | - Francis X Villablanca
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA, USA
| | - Marcus R Kronforst
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
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17
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Dynes TL, Berry JA, Delaplane KS, de Roode JC, Brosi BJ. Assessing virulence of Varroa destructor mites from different honey bee management regimes. Apidologie 2019; 51:276-289. [PMID: 32355369 PMCID: PMC7175645 DOI: 10.1007/s13592-019-00716-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 09/20/2019] [Accepted: 11/07/2019] [Indexed: 06/11/2023]
Abstract
The mite Varroa destructor is an important honey bee parasite that causes substantial losses of honey bee colonies worldwide. Evolutionary theory suggests that the high densities at which honey bees are managed in large-scale beekeeping settings will likely select for mites with greater growth and virulence, thereby potentially explaining the major damage done by these mites. We tested this hypothesis by collecting mites from feral bee colonies, "lightly" managed colonies (those from small-scale sedentary operations), and "heavily" managed colonies (those from large-scale operations that move thousands of colonies across the US on a yearly basis). We established 8 apiaries, each consisting of 11 colonies from a standardized lightly managed bee background that were cleared of mites, and artificially infested each apiary with controlled numbers of mites from feral, lightly managed, or heavily managed bees or left uninoculated as negative control. We monitored the colonies for more than 2 years for mite levels, colony strength (adult bee population, brood coverage, and honey storage), and survival. As predicted by evolutionary theory, we found that colonies inoculated with mites from managed backgrounds had increased V. destructor mite levels relative to those with mites from feral colonies or negative controls. However, we did not see a difference between heavily and lightly managed colonies, and these higher mite burdens did not translate into greater virulence, as measured by reductions in colony strength and survival. Our results suggest that human management of honey bee colonies may favor the increased population growth rate of V. destructor, but that a range of potential confounders (including viral infections and genotype-by-genotype interactions) likely contribute to the relationship between mite reproduction and virulence.
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Affiliation(s)
- Travis L. Dynes
- Department of Environmental Sciences, Emory University, Atlanta, GA 30322 USA
| | | | | | | | - Berry J. Brosi
- Department of Environmental Sciences, Emory University, Atlanta, GA 30322 USA
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18
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Harris EV, de Roode JC, Gerardo NM. Diet-microbiome-disease: Investigating diet's influence on infectious disease resistance through alteration of the gut microbiome. PLoS Pathog 2019; 15:e1007891. [PMID: 31671152 PMCID: PMC6822718 DOI: 10.1371/journal.ppat.1007891] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Abiotic and biotic factors can affect host resistance to parasites. Host diet and host gut microbiomes are two increasingly recognized factors influencing disease resistance. In particular, recent studies demonstrate that (1) particular diets can reduce parasitism; (2) diets can alter the gut microbiome; and (3) the gut microbiome can decrease parasitism. These three separate relationships suggest the existence of indirect links through which diets reduce parasitism through an alteration of the gut microbiome. However, such links are rarely considered and even more rarely experimentally validated. This is surprising because there is increasing discussion of the therapeutic potential of diets and gut microbiomes to control infectious disease. To elucidate these potential indirect links, we review and examine studies on a wide range of animal systems commonly used in diet, microbiome, and disease research. We also examine the relative benefits and disadvantages of particular systems for the study of these indirect links and conclude that mice and insects are currently the best animal systems to test for the effect of diet-altered protective gut microbiomes on infectious disease. Focusing on these systems, we provide experimental guidelines and highlight challenges that must be overcome. Although previous studies have recommended these systems for microbiome research, here we specifically recommend these systems because of their proven relationships between diet and parasitism, between diet and the microbiome, and between the microbiome and parasite resistance. Thus, they provide a sound foundation to explore the three-way interaction between diet, the microbiome, and infectious disease.
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Affiliation(s)
- Erica V. Harris
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
| | - Jacobus C. de Roode
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, Georgia, United States of America
| | - Nicole M. Gerardo
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, Georgia, United States of America
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19
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Abstract
Every fall, millions of North American monarch butterflies undergo a stunning long-distance migration to reach their overwintering grounds in Mexico. Migration allows the butterflies to escape freezing temperatures and dying host plants, and reduces infections with a virulent parasite. We discuss the multigenerational migration journey and its evolutionary history, and highlight the navigational mechanisms of migratory monarchs. Monarchs use a bidirectional time-compensated sun compass for orientation, which is based on a time-compensating circadian clock that resides in the antennae, and which has a distinctive molecular mechanism. Migrants can also use a light-dependent inclination magnetic compass for orientation under overcast conditions. Additional environmental features, e.g., atmospheric conditions, geologic barriers, and social interactions, likely augment navigation. The publication of the monarch genome and the development of gene-editing strategies have enabled the dissection of the genetic and neurobiological basis of the migration. The monarch butterfly has emerged as an excellent system to study the ecological, neural, and genetic basis of long-distance animal migration.
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Affiliation(s)
- Steven M Reppert
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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20
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Bartlett LJ, Rozins C, Brosi BJ, Delaplane KS, de Roode JC, White A, Wilfert L, Boots M. Industrial bees: The impact of apicultural intensification on local disease prevalence. J Appl Ecol 2019; 56:2195-2205. [PMID: 31588148 PMCID: PMC6771535 DOI: 10.1111/1365-2664.13461] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 06/11/2019] [Indexed: 02/01/2023]
Abstract
It is generally thought that the intensification of farming will result in higher disease prevalences, although there is little specific modelling testing this idea. Focussing on honeybees, we build multi-colony models to inform how "apicultural intensification" is predicted to impact honeybee pathogen epidemiology at the apiary scale.We used both agent-based and analytical models to show that three linked aspects of apicultural intensification (increased population sizes, changes in population network structure and increased between-colony transmission) are unlikely to greatly increase disease prevalence in apiaries. Principally this is because even low-intensity apiculture exhibits high disease prevalence.The greatest impacts of apicultural intensification are found for diseases with relatively low R0 (basic reproduction number), however, such diseases cause little overall disease prevalence and, therefore, the impacts of intensification are minor. Furthermore, the smallest impacts of intensification are for diseases with high R0 values, which we argue are typical of important honeybee diseases. Policy Implications: Our findings contradict the idea that apicultural intensification by crowding honeybee colonies in large, dense apiaries leads to notably higher disease prevalences for established honeybee pathogens. More broadly, our work demonstrates the need for informative models of all agricultural systems and management practices in order to understand the implications of management changes on diseases.
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Affiliation(s)
- Lewis J. Bartlett
- Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- Department of BiologyEmory UniversityAtlantaGeorgia
| | - Carly Rozins
- Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- Department of Integrative BiologyUniversity of CaliforniaBerkeleyCalifornia
| | - Berry J. Brosi
- Department of Environmental SciencesEmory UniversityAtlantaGeorgia
| | | | | | - Andrew White
- Department of MathematicsHeriot‐Watt UniversityEdinburghUK
| | - Lena Wilfert
- Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- Institute of Evolutionary Ecology and Conservation GenomicsUniversity of UlmUlmGermany
| | - Michael Boots
- Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- Department of Integrative BiologyUniversity of CaliforniaBerkeleyCalifornia
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21
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de Roode JC, Hunter MD. Self-medication in insects: when altered behaviors of infected insects are a defense instead of a parasite manipulation. Curr Opin Insect Sci 2019; 33:1-6. [PMID: 31358187 DOI: 10.1016/j.cois.2018.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 06/10/2023]
Abstract
Studies have demonstrated that medication behaviors by insects are much more common than previously thought. Bees, ants, flies, and butterflies can use a wide range of toxic and nutritional compounds to medicate themselves or their genetic kin. Medication occurs either in response to active infection (therapy) or high infection risk (prophylaxis), and can be used to increase resistance or tolerance to infection. While much progress has been made over the last few years, there are also key areas that require in-depth investigation. These include quantifying the costs of medication, especially at the colony level of social insects, and formulating theoretical models that can predict the role of infection risk in driving micro-evolutionary and macro-evolutionary patterns of animal medication behaviors.
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Affiliation(s)
- Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, United States.
| | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, 1105 N University Avenue, Ann Arbor, MI 48109, United States
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22
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Dynes TL, Berry JA, Delaplane KS, Brosi BJ, de Roode JC. Reduced density and visually complex apiaries reduce parasite load and promote honey production and overwintering survival in honey bees. PLoS One 2019; 14:e0216286. [PMID: 31120911 PMCID: PMC6532956 DOI: 10.1371/journal.pone.0216286] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 04/17/2019] [Indexed: 11/18/2022] Open
Abstract
Managed honey bee (Apis mellifera) colonies are kept at much greater densities than naturally occurring feral or wild colonies, which may have detrimental effects on colony health and survival, disease spread, and drifting behavior (bee movement between natal and non-natal colonies). We assessed the effects of a straightforward apiary management intervention (altering the density and visual appearance of colonies) on colony health. Specifically, we established three "high density / high drift" ("HD") and three "low density / low drift" ("LD") apiary configurations, each consisting of eight bee colonies. Hives in the HD apiary configuration were of the same color and placed 1m apart in a single linear array, while hives in the LD apiary configuration were placed 10m apart at different heights, facing outwards in a circle, and made visually distinctive with colors and symbols to reduce accidental drift between colonies. We investigated disease transmission and dynamics between the apiary configurations by clearing all colonies of the parasitic mite Varroa destructor, and subsequently inoculating two randomly-chosen colonies per apiary with controlled mite doses. We monitored the colonies for two years and found that the LD apiary configuration had significantly greater honey production and reduced overwinter mortality. Inoculation and apiary management intervention interacted to affect brood mite levels, with the highest levels in the inoculated colonies in the HD configuration. Finally, foragers were more than three times more likely to drift in the HD apiary configurations. Our results suggest that a relatively straightforward management change-placing colonies in low-density visually complex circles rather than high-density visually similar linear arrays-can provide meaningful benefits to the health and productivity of managed honey bee colonies.
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Affiliation(s)
- Travis L. Dynes
- Department of Environmental Sciences; Emory University, Atlanta, GA, United States of America
| | - Jennifer A. Berry
- Department of Entomology; University of Georgia, Athens, GA, United States of America
| | - Keith S. Delaplane
- Department of Entomology; University of Georgia, Athens, GA, United States of America
| | - Berry J. Brosi
- Department of Environmental Sciences; Emory University, Atlanta, GA, United States of America
| | - Jacobus C. de Roode
- Department of Biology; Emory University, Atlanta, GA, United States of America
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23
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Decker LE, Soule AJ, de Roode JC, Hunter MD. Phytochemical changes in milkweed induced by elevated CO
2
alter wing morphology but not toxin sequestration in monarch butterflies. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13270] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Leslie E. Decker
- Department of Biology Stanford University Stanford California
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan
| | - Abrianna J. Soule
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan
- Department of Biology University of Utah Salt Lake City Utah
| | | | - Mark D. Hunter
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan
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24
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Davis AK, de Roode JC. Effects of the parasite, Ophryocystis elektroscirrha, on wing characteristics important for migration in the monarch butterfly. Animal Migration 2018. [DOI: 10.1515/ami-2018-0008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
There is mounting evidence that the longterm declines of overwintering monarchs in Mexico are exacerbated by losses during the fall migratory journey. Infection with the protozoan, Ophryocystis elektroscirrha (OE), is known to negatively impact migration success. Here we examine how infections affect specific wing traits of monarchs that are important for migratory success. We used a collection of infected and uninfected monarchs reared under identical conditions, and from the (deceased) specimens, measured wing area (larger monarchs are known to have greater migratory success), wing color (the shade of orange pigmentation in monarchs is a known predictor of migration and flight ability), and the physical density of wings (a measure of wing mass per unit area). We also measured the tear-resistance of wings, using an apparatus that measured the force needed to cause a tear in the wing. Results showed no effect of OE on overall wing size, nor on the shade of orange pigmentation, but a clear effect on measures of physical density and tensile strength. Wings of infected monarchs weighed less per unit area (by 6%), and there was a 20% reduction in tear-resistance of wings. All results were qualitatively similar in a follow-up investigation using freshly-killed specimens. Collectively, this indicates infected monarchs are more prone to wing damage, which would be costly during long-distance migration. As such, this would be one more way in which OE infections reduce migratory success. Given the toll of OE to the monarch population, especially during migration, it would be prudent to focus conservation efforts on mitigating human activities that spread this disease.
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25
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Satterfield DA, Maerz JC, Hunter MD, Flockhart DTT, Hobson KA, Norris DR, Streit H, de Roode JC, Altizer S. Migratory monarchs that encounter resident monarchs show life-history differences and higher rates of parasite infection. Ecol Lett 2018; 21:1670-1680. [PMID: 30152196 DOI: 10.1111/ele.13144] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 07/27/2018] [Indexed: 01/24/2023]
Abstract
Environmental change induces some wildlife populations to shift from migratory to resident behaviours. Newly formed resident populations could influence the health and behaviour of remaining migrants. We investigated migrant-resident interactions among monarch butterflies and consequences for life history and parasitism. Eastern North American monarchs migrate annually to Mexico, but some now breed year-round on exotic milkweed in the southern US and experience high infection prevalence of protozoan parasites. Using stable isotopes (δ2 H, δ13 C) and cardenolide profiles to estimate natal origins, we show that migrant and resident monarchs overlap during fall and spring migration. Migrants at sites with residents were 13 times more likely to have infections and three times more likely to be reproductive (outside normal breeding season) compared to other migrants. Exotic milkweed might either attract migrants that are already infected or reproductive, or alternatively, induce these states. Increased migrant-resident interactions could affect monarch parasitism, migratory success and long-term conservation.
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Affiliation(s)
| | - John C Maerz
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - D T Tyler Flockhart
- Departmment of Integrative Biology, University of Guelph, Guelph, ON, N1G2W1, Canada
| | - Keith A Hobson
- Department of Biology, Western University, London, ON, N6A5B7, Canada
| | - D Ryan Norris
- Departmment of Integrative Biology, University of Guelph, Guelph, ON, N1G2W1, Canada
| | - Hillary Streit
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | | | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
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26
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Bushman M, Antia R, Udhayakumar V, de Roode JC. Within-host competition can delay evolution of drug resistance in malaria. PLoS Biol 2018; 16:e2005712. [PMID: 30130363 PMCID: PMC6103507 DOI: 10.1371/journal.pbio.2005712] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 07/16/2018] [Indexed: 12/21/2022] Open
Abstract
In the malaria parasite P. falciparum, drug resistance generally evolves first in low-transmission settings, such as Southeast Asia and South America. Resistance takes noticeably longer to appear in the high-transmission settings of sub-Saharan Africa, although it may spread rapidly thereafter. Here, we test the hypothesis that competitive suppression of drug-resistant parasites by drug-sensitive parasites may inhibit evolution of resistance in high-transmission settings, where mixed-strain infections are common. We employ a cross-scale model, which simulates within-host (infection) dynamics and between-host (transmission) dynamics of sensitive and resistant parasites for a population of humans and mosquitoes. Using this model, we examine the effects of transmission intensity, selection pressure, fitness costs of resistance, and cross-reactivity between strains on the establishment and spread of resistant parasites. We find that resistant parasites, introduced into the population at a low frequency, are more likely to go extinct in high-transmission settings, where drug-sensitive competitors and high levels of acquired immunity reduce the absolute fitness of the resistant parasites. Under strong selection from antimalarial drug use, however, resistance spreads faster in high-transmission settings than low-transmission ones. These contrasting results highlight the distinction between establishment and spread of resistance and suggest that the former but not the latter may be inhibited in high-transmission settings. Our results suggest that within-host competition is a key factor shaping the evolution of drug resistance in P. falciparum. The malaria parasite Plasmodium falciparum has evolved resistance to most antimalarial drugs, greatly complicating treatment and control of the disease. Curiously, although sub-Saharan Africa accounts for the majority of the global burden of malaria, the evolution of drug resistance in Africa has been markedly delayed compared to Asia and the Americas. One reason might be that, in a population in which the prevalence of infection is high, a newly emerged drug-resistant strain faces a high risk of extinction due to competition from drug-sensitive parasites that already “occupy” most of the host population. Using a mathematical model, we confirm that drug-resistant parasites face a much greater risk of extinction in a “high-transmission” setting like sub-Saharan Africa than in a “low-transmission” setting like Southeast Asia. However, we also find that when drug-resistant parasites manage to avoid extinction, their subsequent spread may be more rapid in high-transmission settings than in low-transmission settings, especially when selection is strong. These results offer a novel explanation for global patterns of drug resistance evolution in malaria and suggest a new dimension to consider in resistance prevention and containment efforts: namely, the intrinsic favorability of low- and high-transmission settings for establishment and spread of drug resistance.
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Affiliation(s)
- Mary Bushman
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
| | - Rustom Antia
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jacobus C. de Roode
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
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27
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Tan WH, Tao L, Hoang KM, Hunter MD, de Roode JC. The Effects of Milkweed Induced Defense on Parasite Resistance in Monarch Butterflies, Danaus plexippus. J Chem Ecol 2018; 44:1040-1044. [PMID: 30123937 DOI: 10.1007/s10886-018-1007-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/05/2018] [Accepted: 08/10/2018] [Indexed: 11/24/2022]
Abstract
Many plants express induced defenses against herbivores through increasing the production of toxic secondary chemicals following damage. Phytochemical induction can directly or indirectly affect other organisms within the community. In tri-trophic systems, increased concentrations of plant toxins could be detrimental to plants if herbivores can sequester these toxins as protective chemicals for themselves. Thus, through trophic interactions, induction can lead to either positive or negative effects on plant fitness. We examined the effects of milkweed (Asclepias spp.) induced defenses on the resistance of monarch caterpillars (Danaus plexippus) to a protozoan parasite (Ophryocystis elektroscirrha). Milkweeds contain toxic secondary chemicals called cardenolides, higher concentrations of which are associated with reduced parasite growth. Previous work showed that declines in foliar cardenolides caused by aphid attack render monarch caterpillars more susceptible to infection. Here, we ask whether cardenolide induction by monarchs increases monarch resistance to disease. We subjected the high-cardenolide milkweed A. curassavica and the low-cardenolide A. syriaca to caterpillar grazing, and reared infected and uninfected caterpillars on these plants. As expected, monarchs suffered less parasite growth and disease when reared on A. curassavica than on A. syriaca. We also found that herbivory increased cardenolide concentrations in A. curassavica, but not A. syriaca. However, cardenolide induction in A. curassavica was insufficient to influence monarch resistance to the parasite. Our results suggest that interspecific variation in cardenolide concentration is a more important driver of parasite defense than plasticity via induced defenses in this tri-trophic system.
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Affiliation(s)
- Wen-Hao Tan
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA.
| | - Leiling Tao
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | - Kevin M Hoang
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | - Mark D Hunter
- Department of Ecology & Evolutionary Biology, University of Michigan, 1105 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
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Decker LE, de Roode JC, Hunter MD. Elevated atmospheric concentrations of carbon dioxide reduce monarch tolerance and increase parasite virulence by altering the medicinal properties of milkweeds. Ecol Lett 2018; 21:1353-1363. [PMID: 30134036 DOI: 10.1111/ele.13101] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/28/2018] [Accepted: 05/16/2018] [Indexed: 12/13/2022]
Abstract
Hosts combat their parasites using mechanisms of resistance and tolerance, which together determine parasite virulence. Environmental factors, including diet, mediate the impact of parasites on hosts, with diet providing nutritional and medicinal properties. Here, we present the first evidence that ongoing environmental change decreases host tolerance and increases parasite virulence through a loss of dietary medicinal quality. Monarch butterflies use dietary toxins (cardenolides) to reduce the deleterious impacts of a protozoan parasite. We fed monarch larvae foliage from four milkweed species grown under either elevated or ambient CO2 , and measured changes in resistance, tolerance, and virulence. The most high-cardenolide milkweed species lost its medicinal properties under elevated CO2 ; monarch tolerance to infection decreased, and parasite virulence increased. Declines in medicinal quality were associated with declines in foliar concentrations of lipophilic cardenolides. Our results emphasize that global environmental change may influence parasite-host interactions through changes in the medicinal properties of plants.
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Affiliation(s)
- Leslie E Decker
- Department of Ecology and Evolutionary Biology, University of Michigan, Biological Sciences Building, 1105 North University Avenue, Ann Arbor, MI, 48109-1085, USA
| | - Jacobus C de Roode
- Biology Department, Rollins 1113 O. Wayne Rollins Research Center, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, Biological Sciences Building, 1105 North University Avenue, Ann Arbor, MI, 48109-1085, USA
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29
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Johnson PTJ, Calhoun DM, Stokes AN, Susbilla CB, McDevitt-Galles T, Briggs CJ, Hoverman JT, Tkach VV, de Roode JC. Of poisons and parasites-the defensive role of tetrodotoxin against infections in newts. J Anim Ecol 2018; 87:1192-1204. [PMID: 29476541 DOI: 10.1111/1365-2656.12816] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 01/17/2018] [Indexed: 11/29/2022]
Abstract
Classical research on animal toxicity has focused on the role of toxins in protection against predators, but recent studies suggest these same compounds can offer a powerful defense against parasites and infectious diseases. Newts in the genus Taricha are brightly coloured and contain the potent neurotoxin, tetrodotoxin (TTX), which is hypothesized to have evolved as a defense against vertebrate predators such as garter snakes. However, newt populations often vary dramatically in toxicity, which is only partially explained by predation pressure. The primary aim of this study was to evaluate the relationships between TTX concentration and infection by parasites. By systematically assessing micro- and macroparasite infections among 345 adult newts (sympatric populations of Taricha granulosa and T. torosa), we detected 18 unique taxa of helminths, fungi, viruses and protozoans. For both newt species, per-host concentrations of TTX, which varied from undetectable to >60 μg/cm2 skin, negatively predicted overall parasite richness as well as the likelihood of infection by the chytrid fungus, Batrachochytrium dendrobatidis, and ranavirus. No such effect was found on infection load among infected hosts. Despite commonly occurring at the same wetlands, T. torosa supported higher parasite richness and average infection load than T. granulosa. Host body size and sex (females > males) tended to positively predict infection levels in both species. For hosts in which we quantified leucocyte profiles, total white blood cell count correlated positively with both parasite richness and total infection load. By coupling data on host toxicity and infection by a broad range of micro- and macroparasites, these results suggest that-alongside its effects on predators-tetrodotoxin may help protect newts against parasitic infections, highlighting the importance of integrative research on animal chemistry, immunological defenses and natural enemy ecology.
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Affiliation(s)
- Pieter T J Johnson
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Dana M Calhoun
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Amber N Stokes
- Department of Biology, California State University, Bakersfield, CA, USA
| | - Calvin B Susbilla
- Department of Biology, California State University, Bakersfield, CA, USA
| | - Travis McDevitt-Galles
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Jason T Hoverman
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
| | - Vasyl V Tkach
- Department of Biology, University of North Dakota, Grand Forks, ND, USA
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Niepoth N, Ke G, de Roode JC, Groot AT. Comparing Behavior and Clock Gene Expression between Caterpillars, Butterflies, and Moths. J Biol Rhythms 2017; 33:52-64. [DOI: 10.1177/0748730417746458] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Natalie Niepoth
- *Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, NY, USA
| | - Gao Ke
- *Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Jacobus C. de Roode
- *Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, GA, USA
| | - Astrid T. Groot
- *Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
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Tao L, Hunter MD, de Roode JC. Microbial Root Mutualists Affect the Predators and Pathogens of Herbivores above Ground: Mechanisms, Magnitudes, and Missing Links. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00160] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Lynch ZR, Schlenke TA, Morran LT, de Roode JC. Ethanol confers differential protection against generalist and specialist parasitoids of Drosophila melanogaster. PLoS One 2017; 12:e0180182. [PMID: 28700600 PMCID: PMC5507509 DOI: 10.1371/journal.pone.0180182] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 06/12/2017] [Indexed: 12/20/2022] Open
Abstract
As parasites coevolve with their hosts, they can evolve counter-defenses that render host immune responses ineffective. These counter-defenses are more likely to evolve in specialist parasites than generalist parasites; the latter face variable selection pressures between the different hosts they infect. Natural populations of the fruit fly Drosophila melanogaster are commonly threatened by endoparasitoid wasps in the genus Leptopilina, including the specialist L. boulardi and the generalist L. heterotoma, and both wasp species can incapacitate the cellular immune response of D. melanogaster larvae. Given that ethanol tolerance is high in D. melanogaster and stronger in the specialist wasp than the generalist, we tested whether fly larvae could use ethanol as an anti-parasite defense and whether its effectiveness would differ against the two wasp species. We found that fly larvae benefited from eating ethanol-containing food during exposure to L. heterotoma; we observed a two-fold decrease in parasitization intensity and a 24-fold increase in fly survival to adulthood. Although host ethanol consumption did not affect L. boulardi parasitization rates or intensities, it led to a modest increase in fly survival. Thus, ethanol conferred stronger protection against the generalist wasp than the specialist. We tested whether fly larvae can self-medicate by seeking ethanol-containing food after being attacked by wasps, but found no support for this hypothesis. We also allowed female flies to choose between control and ethanol-containing oviposition sites in the presence vs. absence of wasps and generally found significant preferences for ethanol regardless of wasp presence. Overall, our results suggest that D. melanogaster larvae obtain protection from certain parasitoid wasp species through their mothers’ innate oviposition preferences for ethanol-containing food sources.
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Affiliation(s)
- Zachary R. Lynch
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
| | - Todd A. Schlenke
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Levi T. Morran
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Jacobus C. de Roode
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
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Abstract
Understanding host-parasite interactions is essential for ecological research, wildlife conservation, and health management. While most studies focus on numerical traits of parasite groups, such as changes in parasite load, less focus is placed on the traits of individual parasites such as parasite size and shape (parasite morphology). Parasite morphology has significant effects on parasite fitness such as initial colonization of hosts, avoidance of host immune defenses, and the availability of resources for parasite replication. As such, understanding factors that affect parasite morphology is important in predicting the consequences of host-parasite interactions. Here, we studied how host diet affected the spore morphology of a protozoan parasite ( Ophryocystis elektroscirrha ), a specialist parasite of the monarch butterfly ( Danaus plexippus ). We found that different host plant species (milkweeds; Asclepias spp.) significantly affected parasite spore size. Previous studies have found that cardenolides, secondary chemicals in host plants of monarchs, can reduce parasite loads and increase the lifespan of infected butterflies. Adding to this benefit of high cardenolide milkweeds, we found that infected monarchs reared on milkweeds of higher cardenolide concentrations yielded smaller parasites, a potentially hidden characteristic of cardenolides that may have important implications for monarch-parasite interactions.
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Affiliation(s)
- Kevin Hoang
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia 30322. Correspondence should be sent to Kevin Hoang at:
| | - Leiling Tao
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia 30322. Correspondence should be sent to Kevin Hoang at:
| | - Mark D Hunter
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia 30322. Correspondence should be sent to Kevin Hoang at:
| | - Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia 30322. Correspondence should be sent to Kevin Hoang at:
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Bushman M, Morton L, Duah N, Quashie N, Abuaku B, Koram KA, Dimbu PR, Plucinski M, Gutman J, Lyaruu P, Kachur SP, de Roode JC, Udhayakumar V. Within-host competition and drug resistance in the human malaria parasite Plasmodium falciparum. Proc Biol Sci 2016; 283:20153038. [PMID: 26984625 DOI: 10.1098/rspb.2015.3038] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Infections with the malaria parasite Plasmodium falciparum typically comprise multiple strains, especially in high-transmission areas where infectious mosquito bites occur frequently. However, little is known about the dynamics of mixed-strain infections, particularly whether strains sharing a host compete or grow independently. Competition between drug-sensitive and drug-resistant strains, if it occurs, could be a crucial determinant of the spread of resistance. We analysed 1341 P. falciparum infections in children from Angola, Ghana and Tanzania and found compelling evidence for competition in mixed-strain infections: overall parasite density did not increase with additional strains, and densities of individual chloroquine-sensitive (CQS) and chloroquine-resistant (CQR) strains were reduced in the presence of competitors. We also found that CQR strains exhibited low densities compared with CQS strains (in the absence of chloroquine), which may underlie observed declines of chloroquine resistance in many countries following retirement of chloroquine as a first-line therapy. Our observations support a key role for within-host competition in the evolution of drug-resistant malaria. Malaria control and resistance-management efforts in high-transmission regions may be significantly aided or hindered by the effects of competition in mixed-strain infections. Consideration of within-host dynamics may spur development of novel strategies to minimize resistance while maximizing the benefits of control measures.
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Affiliation(s)
- Mary Bushman
- Department of Biology, Emory University, Atlanta, GA 30322, USA Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Lindsay Morton
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Nancy Duah
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Neils Quashie
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana Centre for Tropical Clinical Pharmacology and Therapeutics, University of Ghana Medical School, Accra, Ghana
| | - Benjamin Abuaku
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Kwadwo A Koram
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | | | - Mateusz Plucinski
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Julie Gutman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Peter Lyaruu
- Ifakara Health Institute, Dar es Salaam, Tanzania
| | - S Patrick Kachur
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | | | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
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Barriga PA, Sternberg ED, Lefèvre T, de Roode JC, Altizer S. Occurrence and host specificity of a neogregarine protozoan in four milkweed butterfly hosts (Danaus spp.). J Invertebr Pathol 2016; 140:75-82. [DOI: 10.1016/j.jip.2016.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 09/08/2016] [Accepted: 09/13/2016] [Indexed: 10/21/2022]
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Pierce AA, de Roode JC, Tao L. Comparative genetics of Na +/K +-ATPase in monarch butterfly populations with varying host plant toxicity. Biol J Linn Soc Lond 2016. [DOI: 10.1111/bij.12797] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Amanda A. Pierce
- Department of Biology; Emory University; 1510 Clifton Road Atlanta GA 30322 USA
| | - Jacobus C. de Roode
- Department of Biology; Emory University; 1510 Clifton Road Atlanta GA 30322 USA
| | - Leiling Tao
- Department of Biology; Emory University; 1510 Clifton Road Atlanta GA 30322 USA
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Tao L, Hoang KM, Hunter MD, de Roode JC. Fitness costs of animal medication: antiparasitic plant chemicals reduce fitness of monarch butterfly hosts. J Anim Ecol 2016; 85:1246-54. [PMID: 27286503 DOI: 10.1111/1365-2656.12558] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 05/25/2016] [Indexed: 12/01/2022]
Abstract
The emerging field of ecological immunology demonstrates that allocation by hosts to immune defence against parasites is constrained by the costs of those defences. However, the costs of non-immunological defences, which are important alternatives to canonical immune systems, are less well characterized. Estimating such costs is essential for our understanding of the ecology and evolution of alternative host defence strategies. Many animals have evolved medication behaviours, whereby they use antiparasitic compounds from their environment to protect themselves or their kin from parasitism. Documenting the costs of medication behaviours is complicated by natural variation in the medicinal components of diets and their covariance with other dietary components, such as macronutrients. In the current study, we explore the costs of the usage of antiparasitic compounds in monarch butterflies (Danaus plexippus), using natural variation in concentrations of antiparasitic compounds among plants. Upon infection by their specialist protozoan parasite Ophryocystis elektroscirrha, monarch butterflies can selectively oviposit on milkweed with high foliar concentrations of cardenolides, secondary chemicals that reduce parasite growth. Here, we show that these antiparasitic cardenolides can also impose significant costs on both uninfected and infected butterflies. Among eight milkweed species that vary substantially in their foliar cardenolide concentration and composition, we observed the opposing effects of cardenolides on monarch fitness traits. While high foliar cardenolide concentrations increased the tolerance of monarch butterflies to infection, they reduced the survival rate of caterpillars to adulthood. Additionally, although non-polar cardenolide compounds decreased the spore load of infected butterflies, they also reduced the life span of uninfected butterflies, resulting in a hump-shaped curve between cardenolide non-polarity and the life span of infected butterflies. Overall, our results suggest that the use of antiparasitic compounds carries substantial costs, which could constrain host investment in medication behaviours.
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Affiliation(s)
- Leiling Tao
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | - Kevin M Hoang
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, 830 N University Avenue, Ann Arbor, MI, 48109, USA
| | - Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
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Abstract
AbstractLong-distance migration can be seen throughout
the animal kingdom and can have large impacts on
population dynamics and species distributions. The act
of migration itself also affects the evolution of a species,
as evolutionary forces select for certain characteristics in
animals conducting long-distance migration. Monarch
butterflies are best known for their annual migration from
Canada and the northern United States to central Mexico,
but some populations of monarchs have lost the ability to
migrate. Previous research found that migratory monarchs
had larger, more elongated wings than their non-migratory
counterparts and it was hypothesized that these traits were
beneficial for migration. However, Bergmann’s rule - which
predicts larger body sizes with increasing latitude - could
also explain this pattern as migratory populations are
found at higher latitudes. To understand the role of wing
dimensions in migration, we examined forewing size and
shape of migratory and non-migratory monarchs from
seven worldwide populations varying in latitude. Results
showed that larger forewing size was indeed correlated
with migratory status rather than latitude. However,
migratory monarchs did not have more elongated forewing
shape than non-migratory monarchs across the globe. Our
study indicates that size may play a larger role than shape
in long-distance migratory capability.
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Affiliation(s)
| | - Amanda A Pierce
- 2Emory University, Department of Biology
- 3University of North Carolina at Chapel Hill, Department of Biology
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Tao L, Gowler CD, Ahmad A, Hunter MD, de Roode JC. Disease ecology across soil boundaries: effects of below-ground fungi on above-ground host-parasite interactions. Proc Biol Sci 2015; 282:20151993. [PMID: 26468247 PMCID: PMC4633881 DOI: 10.1098/rspb.2015.1993] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 09/17/2015] [Indexed: 11/12/2022] Open
Abstract
Host-parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host-parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host-parasite systems.
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Affiliation(s)
- Leiling Tao
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
| | - Camden D Gowler
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA Department of Ecology and Evolutionary Biology, University of Michigan, 830 N University, Ann Arbor, MI 48109, USA
| | - Aamina Ahmad
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
| | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, 830 N University, Ann Arbor, MI 48109, USA
| | - Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
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Abstract
Infectious diseases often emerge from interactions among multiple species and across nested levels of biological organization. Threats as diverse as Ebola virus, human malaria, and bat white-nose syndrome illustrate the need for a mechanistic understanding of the ecological interactions underlying emerging infections. We describe how recent advances in community ecology can be adopted to address contemporary challenges in disease research. These analytical tools can identify the factors governing complex assemblages of multiple hosts, parasites, and vectors, and reveal how processes link across scales from individual hosts to regions. They can also determine the drivers of heterogeneities among individuals, species, and regions to aid targeting of control strategies. We provide examples where these principles have enhanced disease management and illustrate how they can be further extended.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
| | | | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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41
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Pierce AA, Zalucki MP, Bangura M, Udawatta M, Kronforst MR, Altizer S, Haeger JF, de Roode JC. Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies. Proc Biol Sci 2015; 281:rspb.2014.2230. [PMID: 25377462 DOI: 10.1098/rspb.2014.2230] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Range expansions can result in founder effects, increasing genetic differentiation between expanding populations and reducing genetic diversity along the expansion front. However, few studies have addressed these effects in long-distance migratory species, for which high dispersal ability might counter the effects of genetic drift. Monarchs (Danaus plexippus) are best known for undertaking a long-distance annual migration in North America, but have also dispersed around the world to form populations that do not migrate or travel only short distances. Here, we used microsatellite markers to assess genetic differentiation among 18 monarch populations and to determine worldwide colonization routes. Our results indicate that North American monarch populations connected by land show limited differentiation, probably because of the monarch's ability to migrate long distances. Conversely, we found high genetic differentiation between populations separated by large bodies of water. Moreover, we show evidence for serial founder effects across the Pacific, suggesting stepwise dispersal from a North American origin. These findings demonstrate that genetic drift played a major role in shaping allele frequencies and created genetic differentiation among newly formed populations. Thus, range expansion can give rise to genetic differentiation and declines in genetic diversity, even in highly mobile species.
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Affiliation(s)
- Amanda A Pierce
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Myron P Zalucki
- School of Biological Sciences, The University of Queensland, Brisbane 4072, Australia
| | - Marie Bangura
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Milan Udawatta
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Marcus R Kronforst
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
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Sternberg ED, de Roode JC, Hunter MD. Trans-generational parasite protection associated with paternal diet. J Anim Ecol 2014; 84:310-21. [PMID: 25251734 DOI: 10.1111/1365-2656.12289] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 09/19/2014] [Indexed: 11/29/2022]
Abstract
Multiple generations of hosts are often exposed to the same pathogens, favouring the evolution of trans-generational defences. Because females have more opportunities to transfer protective molecules to offspring, many studies have focused on maternally derived protection. However, males of many species can transfer compounds along with sperm, including chemicals that could provide protection. Here, we assess maternally and paternally derived protection in a monarch butterfly-protozoan parasite system where parasite resistance is heavily influenced by secondary plant chemicals, known as cardenolides, present in the larval diet of milkweed plants. We reared monarch butterflies on medicinal and non-medicinal milkweed species and then measured resistance of their offspring to infection. We also measured cardenolide content in adult monarchs reared on the two species, and in the eggs that they produced. We found that offspring were more resistant to infection when their fathers were reared on medicinal milkweed, while maternal diet had less of an effect. We also found that eggs contained the highest levels of cardenolides when both parents were reared on the medicinal species. Moreover, females reared on non-medicinal milkweed produced eggs with significantly higher levels of cardenolides if they mated with males reared on the medicinal milkweed species. However, we found an equivocal relationship between the cardenolides present in eggs and parasite resistance in the offspring. Our results demonstrate that males reared on medicinal plants can transfer protection to their offspring, but the exact mechanism remains unresolved. This suggests that paternal protection from parasitism might be important, particularly when there are environmental sources of parasite resistance and when males transfer spermatophores during mating.
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Affiliation(s)
- Eleanore D Sternberg
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA.,Center for Infectious Disease Dynamics, Pennsylvania State University, 111 Merkle Building, University Park, PA, 16802, USA
| | - Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | - Mark D Hunter
- Department of Ecology and Evolutionary Biology, University of Michigan, 2053 Natural Sciences Building, 830 North University, Ann Arbor, MI, 48109-1048, USA
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43
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Choisy M, de Roode JC. The ecology and evolution of animal medication: genetically fixed response versus phenotypic plasticity. Am Nat 2014; 184 Suppl 1:S31-46. [PMID: 25061676 DOI: 10.1086/676928] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Animal medication against parasites can occur either as a genetically fixed (constitutive) or phenotypically plastic (induced) behavior. Taking the tritrophic interaction between the monarch butterfly Danaus plexippus, its protozoan parasite Ophryocystis elektroscirrha, and its food plant Asclepias spp. as a test case, we develop a game-theory model to identify the epidemiological (parasite prevalence and virulence) and environmental (plant toxicity and abundance) conditions that predict the evolution of genetically fixed versus phenotypically plastic forms of medication. Our model shows that the relative benefits (the antiparasitic properties of medicinal food) and costs (side effects of medicine, the costs of searching for medicine, and the costs of plasticity itself) crucially determine whether medication is genetically fixed or phenotypically plastic. Our model suggests that animals evolve phenotypic plasticity when parasite risk (a combination of virulence and prevalence and thus a measure of the strength of parasite-mediated selection) is relatively low to moderately high and genetically fixed medication when parasite risk becomes very high. The latter occurs because at high parasite risk, the costs of plasticity are outweighed by the benefits of medication. Our model provides a simple and general framework to study the conditions that drive the evolution of alternative forms of animal medication.
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Affiliation(s)
- Marc Choisy
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC; CNRS 5290, Institut de Recherche pour le Développement 224, Universities of Montpellier 1 and 2), Montpellier, France
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44
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Affiliation(s)
- Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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45
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Pierce AA, de Roode JC, Altizer S, Bartel RA. Extreme heterogeneity in parasitism despite low population genetic structure among monarch butterflies inhabiting the Hawaiian Islands. PLoS One 2014; 9:e100061. [PMID: 24926796 PMCID: PMC4057267 DOI: 10.1371/journal.pone.0100061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 05/22/2014] [Indexed: 11/18/2022] Open
Abstract
Host movement and spatial structure can strongly influence the ecology and evolution of infectious diseases, with limited host movement potentially leading to high spatial heterogeneity in infection. Monarch butterflies (Danaus plexippus) are best known for undertaking a spectacular long-distance migration in eastern North America; however, they also form non-migratory populations that breed year-round in milder climates such as Hawaii and other tropical locations. Prior work showed an inverse relationship between monarch migratory propensity and the prevalence of the protozoan parasite, Ophryocystis elektroscirrha. Here, we sampled monarchs from replicate sites within each of four Hawaiian Islands to ask whether these populations show consistently high prevalence of the protozoan parasite as seen for monarchs from several other non-migratory populations. Counter to our predictions, we observed striking spatial heterogeneity in parasite prevalence, with infection rates per site ranging from 4-85%. We next used microsatellite markers to ask whether the observed variation in infection might be explained by limited host movement and spatial sub-structuring among sites. Our results showed that monarchs across the Hawaiian Islands form one admixed population, supporting high gene flow among sites. Moreover, measures of individual-level genetic diversity did not predict host infection status, as might be expected if more inbred hosts harbored higher parasite loads. These results suggest that other factors such as landscape-level environmental variation or colonization-extinction processes might instead cause the extreme heterogeneity in monarch butterfly infection observed here.
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Affiliation(s)
- Amanda A. Pierce
- Biology Department, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
| | - Jacobus C. de Roode
- Biology Department, Emory University, Atlanta, Georgia, United States of America
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
| | - Rebecca A. Bartel
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- Red Wolf Recovery Program, United States Fish and Wildlife Service, Manteo, North Carolina, United States of America
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Sternberg ED, Li H, Wang R, Gowler C, de Roode JC. Patterns of Host-Parasite Adaptation in Three Populations of Monarch Butterflies Infected with a Naturally Occurring Protozoan Disease: Virulence, Resistance, and Tolerance. Am Nat 2013; 182:E235-48. [DOI: 10.1086/673442] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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47
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Sander SE, Altizer S, de Roode JC, Davis AK. Genetic Factors and Host Traits Predict Spore Morphology for a Butterfly Pathogen. Insects 2013; 4:447-62. [PMID: 26462429 PMCID: PMC4553475 DOI: 10.3390/insects4030447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 08/14/2013] [Accepted: 08/15/2013] [Indexed: 12/04/2022]
Abstract
Monarch butterflies (Danaus plexippus) throughout the world are commonly infected by the specialist pathogen Ophryocystis elektroscirrha (OE). This protozoan is transmitted when larvae ingest infectious stages (spores) scattered onto host plant leaves by infected adults. Parasites replicate internally during larval and pupal stages, and adult monarchs emerge covered with millions of dormant spores on the outsides of their bodies. Across multiple monarch populations, OE varies in prevalence and virulence. Here, we examined geographic and genetic variation in OE spore morphology using clonal parasite lineages derived from each of four host populations (eastern and western North America, South Florida and Hawaii). Spores were harvested from experimentally inoculated, captive-reared adult monarchs. Using light microscopy and digital image analysis, we measured the size, shape and color of 30 replicate spores per host. Analyses examined predictors of spore morphology, including parasite source population and clone, parasite load, and the following host traits: family line, sex, wing area, and wing color (orange and black pigmentation). Results showed significant differences in spore size and shape among parasite clones, suggesting genetic determinants of morphological variation. Spore size also increased with monarch wing size, and monarchs with larger and darker orange wings tended to have darker colored spores, consistent with the idea that parasite development depends on variation in host quality and resources. We found no evidence for effects of source population on variation in spore morphology. Collectively, these results provide support for heritable variation in spore morphology and a role for host traits in affecting parasite development.
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Affiliation(s)
- Sarah E Sander
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.
| | | | - Andrew K Davis
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.
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48
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Alizon S, de Roode JC, Michalakis Y. Multiple infections and the evolution of virulence. Ecol Lett 2013; 16:556-67. [PMID: 23347009 DOI: 10.1111/ele.12076] [Citation(s) in RCA: 304] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 10/30/2012] [Accepted: 12/17/2012] [Indexed: 12/13/2022]
Abstract
Infections that consist of multiple parasite strains or species are common in the wild and are a major public health concern. Theory suggests that these infections have a key influence on the evolution of infectious diseases and, more specifically, on virulence evolution. However, we still lack an overall vision of the empirical support for these predictions. We argue that within-host interactions between parasites largely determine how virulence evolves and that experimental data support model predictions. Then, we explore the main limitation of the experimental study of such 'mixed infections', which is that it draws conclusions on evolutionary outcomes from studies conducted at the individual level. We also discuss differences between coinfections caused by different strains of the same species or by different species. Overall, we argue that it is possible to make sense out of the complexity inherent to multiple infections and that experimental evolution settings may provide the best opportunity to further our understanding of virulence evolution.
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Affiliation(s)
- Samuel Alizon
- Laboratoire MIVEGEC (UMR CNRS 5290, UR IRD 224, UM1, UM2), Montpellier, France.
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Abstract
Parasites can dramatically reduce the fitness of their hosts, and natural selection should favor defense mechanisms that can protect hosts against disease. Much work has focused on understanding genetic and physiological immunity against parasites, but hosts can also use behaviors to avoid infection, reduce parasite growth or alleviate disease symptoms. It is increasingly recognized that such behaviors are common in insects, providing strong protection against parasites and parasitoids. We review the current evidence for behavioral immunity in insects, present a framework for investigating such behavior, and emphasize that behavioral immunity may act through indirect rather than direct fitness benefits. We also discuss the implications for host-parasite co-evolution, local adaptation, and the evolution of non-behavioral physiological immune systems. Finally, we argue that the study of behavioral immunity in insects has much to offer for investigations in vertebrates, in which this topic has traditionally been studied.
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Affiliation(s)
- Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA.
| | - Thierry Lefèvre
- MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), Centre IRD, 911 Av. Agropolis-BP 64501, Montpellier 34394, France.
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Sternberg ED, Lefèvre T, Li J, de Castillejo CLF, Li H, Hunter MD, de Roode JC. Food plant derived disease tolerance and resistance in a natural butterfly-plant-parasite interactions. Evolution 2012; 66:3367-76. [PMID: 23106703 DOI: 10.1111/j.1558-5646.2012.01693.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Organisms can protect themselves against parasite-induced fitness costs through resistance or tolerance. Resistance includes mechanisms that prevent infection or limit parasite growth while tolerance alleviates the fitness costs from parasitism without limiting infection. Although tolerance and resistance affect host-parasite coevolution in fundamentally different ways, tolerance has often been ignored in animal-parasite systems. Where it has been studied, tolerance has been assumed to be a genetic mechanism, unaffected by the host environment. Here we studied the effects of host ecology on tolerance and resistance to infection by rearing monarch butterflies on 12 different species of milkweed food plants and infecting them with a naturally occurring protozoan parasite. Our results show that monarch butterflies experience different levels of tolerance to parasitism depending on the species of milkweed that they feed on, with some species providing over twofold greater tolerance than other milkweed species. Resistance was also affected by milkweed species, but there was no relationship between milkweed-conferred resistance and tolerance. Chemical analysis suggests that infected monarchs obtain highest fitness when reared on milkweeds with an intermediate concentration, diversity, and polarity of toxic secondary plant chemicals known as cardenolides. Our results demonstrate that environmental factors-such as interacting species in ecological food webs-are important drivers of disease tolerance.
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Affiliation(s)
- Eleanore D Sternberg
- Department of Biology, Emory University, 1510 Clifton Rd, Atlanta, Georgia 30322, USA.
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