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Rubiano-Buitrago P, Pradhan S, Aceves AA, Mohammadi S, Paetz C, Rowland HM. Cardenolides in the defensive fluid of adult large milkweed bugs have differential potency on vertebrate and invertebrate predator Na +/K +-ATPases. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231735. [PMID: 39100152 PMCID: PMC11296140 DOI: 10.1098/rsos.231735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/19/2024] [Accepted: 04/23/2024] [Indexed: 08/06/2024]
Abstract
Aposematic animals rely on diverse secondary metabolites for defence. Various hypotheses, such as competition, life history and multifunctionality, have been posited to explain defence variability and diversity. We investigate the compound selectivity hypothesis using large milkweed bugs, Oncopeltus fasciatus, to determine if distinct cardenolides vary in toxicity to different predators. We quantify cardenolides in the bug's defensive secretions and body tissues and test the individual compounds against predator target sites, the Na+/K+-ATPases, that are predicted to differ in sensitivity. Frugoside, gofruside, glucopyranosyl frugoside and glucopyranosyl gofruside were the dominant cardenolides in the body tissues of the insects, whereas the two monoglycosidic cardenolides-frugoside and gofruside-were the most abundant in the defensive fluid. These monoglycosidic cardenolides were highly toxic (IC50 < 1 μM) to an invertebrate and a sensitive vertebrate enzyme, in comparison to the glucosylated compounds. Gofruside was the weakest inhibitor for a putatively resistant vertebrate predator. Glucopyranosyl calotropin, found in only 60% of bugs, was also an effective inhibitor of sensitive vertebrate enzymes. Our results suggest that the compounds sequestered by O. fasciatus probably provide consistency in protection against a range of predators and underscore the need to consider predator communities in prey defence evolution.
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Affiliation(s)
- P. Rubiano-Buitrago
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Jena, Germany
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - S. Pradhan
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - A. A. Aceves
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - S. Mohammadi
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - C. Paetz
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - H. M. Rowland
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Jena, Germany
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Heyworth HC, Pokharel P, Blount JD, Mitchell C, Petschenka G, Rowland HM. Antioxidant availability trades off with warning signals and toxin sequestration in the large milkweed bug ( Oncopeltus fasciatus). Ecol Evol 2023; 13:e9971. [PMID: 37038513 PMCID: PMC10082154 DOI: 10.1002/ece3.9971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 04/12/2023] Open
Abstract
In some aposematic species the conspicuousness of an individual's warning signal and the concentration of its chemical defense are positively correlated. Several mechanisms have been proposed to explain this phenomenon, including resource allocation trade-offs where the same limiting resource is needed to produce both the warning signal and chemical defense. Here, the large milkweed bug (Oncopeltus fasciatus: Heteroptera, Lygaeinae) was used to test whether allocation of antioxidants, that can impart color, trade against their availability to prevent self-damage caused by toxin sequestration. We investigated if (i) the sequestration of cardenolides is associated with costs in the form of changes in oxidative state; and (ii) oxidative state can affect the capacity of individuals to produce warning signals. We reared milkweed bugs on artificial diets with increasing quantities of cardenolides and examined how this affected signal quality (brightness and chroma) across different instars. We then related the expression of warning colors to the quantity of sequestered cardenolides and indicators of oxidative state-oxidative lipid damage (malondialdehyde), and two antioxidants: total superoxide dismutase and total glutathione. Bugs that sequestered more cardenolides had significantly lower levels of the antioxidant glutathione, and bugs with less total glutathione had less luminant orange warning signals and reduced chroma of their black patches compared to bugs with more glutathione. Bugs that sequestered more cardenolides also had reduced red-green chroma of their black patches that was unrelated to oxidative state. Our results give tentative support for a physiological cost of sequestration in milkweed bugs and a mechanistic link between antioxidant availability, sequestration, and warning signals.
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Affiliation(s)
- H. Cecilia Heyworth
- Predators and Toxic Prey Research GroupMax Planck Institute for Chemical EcologyJenaGermany
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Prayan Pokharel
- Department of Applied Entomology, Institute of PhytomedicineUniversity of HohenheimStuttgartGermany
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Christopher Mitchell
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Georg Petschenka
- Department of Applied Entomology, Institute of PhytomedicineUniversity of HohenheimStuttgartGermany
| | - Hannah M. Rowland
- Predators and Toxic Prey Research GroupMax Planck Institute for Chemical EcologyJenaGermany
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Blount JD, Rowland HM, Mitchell C, Speed MP, Ruxton GD, Endler JA, Brower LP. The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly. Proc Biol Sci 2023; 290:20222068. [PMID: 36651049 PMCID: PMC9845971 DOI: 10.1098/rspb.2022.2068] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In a variety of aposematic species, the conspicuousness of an individual's warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments and in protecting against oxidative damage. To test for such trade-offs, we raised monarch butterflies (Danaus plexippus) on different species of their milkweed host plants (Apocynaceae) that vary in quantities of cardenolides to test whether (i) the sequestration of cardenolides as a secondary defence is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (ii) lower oxidative state is associated with a reduced capacity to produce aposematic displays. In male monarchs conspicuousness was explained by an interaction between oxidative damage and sequestration: males with high levels of oxidative damage became less conspicuous with increased sequestration of cardenolides, whereas those with low oxidative damage became more conspicuous with increased levels of cardenolides. There was no significant effect of oxidative damage or concentration of sequestered cardenolides on female conspicuousness. Our results demonstrate a physiological linkage between the production of coloration and oxidative state, and differential costs of sequestration and signalling in monarch butterflies.
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Affiliation(s)
- Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Hannah M. Rowland
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, Jena, 07745, Germany
| | - Christopher Mitchell
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Michael P. Speed
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7BE, UK
| | - Graeme D. Ruxton
- School of Biology, Sir Harold Mitchell Building, Greenside Place, St Andrews, UK
| | - John A. Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Lincoln P. Brower
- Department of Biology, Sweet Briar College, Sweet Briar, VA 24595, USA
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Mc Auley MT. Dietary restriction and ageing: Recent evolutionary perspectives. Mech Ageing Dev 2022; 208:111741. [PMID: 36167215 DOI: 10.1016/j.mad.2022.111741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/07/2022] [Accepted: 09/22/2022] [Indexed: 12/30/2022]
Abstract
Dietary restriction (DR) represents one of the most robust interventions for extending lifespan. It is not known how DR increases lifespan. The prevailing evolutionary hypothesis suggests the DR response redirects metabolic resources towards somatic maintenance at the expense of investment in reproduction. Consequently, DR acts as a proximate mechanism which promotes a pro-longevity phenotype. This idea is known as resource reallocation. However, growing findings suggest this paradigm could be incomplete. It has been argued that during DR it is not always possible to identify a trade-off between reproduction and lifespan. It is also suggested the relationship between reproduction and somatic maintenance can be uncoupled by the removal or inclusion of specific nutrients. These findings have created an imperative to re-explore the nexus between DR and evolutionary theory. In this review I will address this evolutionary conundrum. My overarching objectives are fourfold: (1) to outline some of the evidence for and against resource reallocation; (2) to examine recent findings which have necessitated a theoretical re-evaluation of the link between life history theory and DR; (3) to present alternatives to the resource reallocation model; (4) to present emerging variables which potentially influence how DR effects evolutionary trade-offs.
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Affiliation(s)
- Mark T Mc Auley
- Faculty of Science and Engineering, Thornton Science Park, University of Chester, Parkgate Road, Chester CH1 4BJ, UK.
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Jeckel AM, Beran F, Züst T, Younkin G, Petschenka G, Pokharel P, Dreisbach D, Ganal-Vonarburg SC, Robert CAM. Metabolization and sequestration of plant specialized metabolites in insect herbivores: Current and emerging approaches. Front Physiol 2022; 13:1001032. [PMID: 36237530 PMCID: PMC9552321 DOI: 10.3389/fphys.2022.1001032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Herbivorous insects encounter diverse plant specialized metabolites (PSMs) in their diet, that have deterrent, anti-nutritional, or toxic properties. Understanding how they cope with PSMs is crucial to understand their biology, population dynamics, and evolution. This review summarizes current and emerging cutting-edge methods that can be used to characterize the metabolic fate of PSMs, from ingestion to excretion or sequestration. It further emphasizes a workflow that enables not only to study PSM metabolism at different scales, but also to tackle and validate the genetic and biochemical mechanisms involved in PSM resistance by herbivores. This review thus aims at facilitating research on PSM-mediated plant-herbivore interactions.
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Affiliation(s)
- Adriana Moriguchi Jeckel
- Laboratory of Chemical Ecology, Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Franziska Beran
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Tobias Züst
- Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, Switzerland
| | - Gordon Younkin
- Boyce Thompson Institute, Ithaca, NY, United States
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
| | - Georg Petschenka
- Department of Applied Entomology, Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
| | - Prayan Pokharel
- Department of Applied Entomology, Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
| | - Domenic Dreisbach
- Institute for Inorganic and Analytical Chemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Stephanie Christine Ganal-Vonarburg
- Department of Visceral Surgery and Medicine, Bern University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, Visceral Surgery and Medicine, University of Bern, Bern, Switzerland
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Mattila ALK, Jiggins CD, Saastamoinen M. Condition dependence in biosynthesized chemical defenses of an aposematic and mimetic Heliconius butterfly. Ecol Evol 2022; 12:e9041. [PMID: 35784031 PMCID: PMC9227709 DOI: 10.1002/ece3.9041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/20/2022] [Accepted: 05/27/2022] [Indexed: 11/08/2022] Open
Abstract
Aposematic animals advertise their toxicity or unpalatability with bright warning coloration. However, acquiring and maintaining chemical defenses can be energetically costly, and consequent associations with other important traits could shape chemical defense evolution. Here, we have tested whether chemical defenses are involved in energetic trade-offs with other traits, or whether the levels of chemical defenses are condition dependent, by studying associations between biosynthesized cyanogenic toxicity and a suite of key life-history and fitness traits in a Heliconius butterfly under a controlled laboratory setting. Heliconius butterflies are well known for the diversity of their warning color patterns and widespread mimicry and can both sequester the cyanogenic glucosides of their Passiflora host plants and biosynthesize these toxins de novo. We find energetically costly life-history traits to be either unassociated or to show a general positive association with biosynthesized cyanogenic toxicity. More toxic individuals developed faster and had higher mass as adults and a tendency for increased lifespan and fecundity. These results thus indicate that toxicity level of adult butterflies may be dependent on individual condition, influenced by genetic background or earlier conditions, with maternal effects as one strong candidate mechanism. Additionally, toxicity was higher in older individuals, consistent with previous studies indicating accumulation of toxins with age. As toxicity level at death was independent of lifespan, cyanogenic glucoside compounds may have been recycled to release resources relevant for longevity in these long-living butterflies. Understanding the origins and maintenance of variation in defenses is necessary in building a more complete picture of factors shaping the evolution of aposematic and mimetic systems.
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Affiliation(s)
- Anniina L. K. Mattila
- Research Centre for Ecological Change, Organismal and Evolutionary Biology Research ProgrammeUniversity of HelsinkiHelsinkiFinland
- HiLIFE – Helsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
- Finnish Museum of Natural History (LUOMUS)University of HelsinkiHelsinkiFinland
| | | | - Marjo Saastamoinen
- Research Centre for Ecological Change, Organismal and Evolutionary Biology Research ProgrammeUniversity of HelsinkiHelsinkiFinland
- HiLIFE – Helsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
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Functional evidence supports adaptive plant chemical defense along a geographical cline. Proc Natl Acad Sci U S A 2022; 119:e2205073119. [PMID: 35696564 PMCID: PMC9231628 DOI: 10.1073/pnas.2205073119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Environmental clines in organismal defensive traits are usually attributed to stronger selection by enemies at lower latitudes or near the host's range center. Nonetheless, little functional evidence has supported this hypothesis, especially for coevolving plants and herbivores. We quantified cardenolide toxins in seeds of 24 populations of common milkweed (Asclepias syriaca) across 13 degrees of latitude, revealing a pattern of increasing cardenolide concentrations toward the host's range center. The unusual nitrogen-containing cardenolide labriformin was an exception and peaked at higher latitudes. Milkweed seeds are eaten by specialist lygaeid bugs that are even more tolerant of cardenolides than the monarch butterfly, concentrating most cardenolides (but not labriformin) from seeds into their bodies. Accordingly, whether cardenolides defend seeds against these specialist bugs is unclear. We demonstrate that Oncopeltus fasciatus (Lygaeidae) metabolized two major compounds (glycosylated aspecioside and labriformin) into distinct products that were sequestered without impairing growth. We next tested several isolated cardenolides in vitro on the physiological target of cardenolides (Na+/K+-ATPase); there was little variation among compounds in inhibition of an unadapted Na+/K+-ATPase, but tremendous variation in impacts on that of monarchs and Oncopeltus. Labriformin was the most inhibitive compound tested for both insects, but Oncopeltus had the greater advantage over monarchs in tolerating labriformin compared to other compounds. Three metabolized (and stored) cardenolides were less toxic than their parent compounds found in seeds. Our results suggest that a potent plant defense is evolving by natural selection along a geographical cline and targets specialist herbivores, but is met by insect tolerance, detoxification, and sequestration.
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