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Christensen T, Dyer LA, Forister ML, Bowers MD, Carper A, Teglas MB, Hurtado P, Smilanich AM. Host plant-mediation of viral transmission and its consequences for a native butterfly. Ecology 2024; 105:e4282. [PMID: 38483138 DOI: 10.1002/ecy.4282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 11/11/2023] [Accepted: 01/18/2024] [Indexed: 04/04/2024]
Abstract
Pathogens play a key role in insect population dynamics, contributing to short-term fluctuations in abundance as well as long-term demographic trends. Two key factors that influence the effects of entomopathogens on herbivorous insect populations are modes of pathogen transmission and larval host plants. In this study, we examined tritrophic interactions between a sequestering specialist lepidopteran, Euphydryas phaeton, and a viral pathogen, Junonia coenia densovirus, on its native host plant, Chelone glabra, and a novel host plant, Plantago lanceolata, to explore whether host plant mediates viral transmission, survival, and viral loads. A two-factor factorial experiment was conducted in the laboratory with natal larval clusters randomly assigned to either the native or novel host plant and crossed with either uninoculated controls or viral inoculation (20% of individuals in the cluster inoculated). Diapausing clusters were overwintered in the laboratory and checked weekly for mortality. At the end of diapause, all surviving individuals were reared to adulthood to estimate survivorship. All individuals were screened to quantify viral loads, and estimate horizontal transmission postmortem. To test for vertical transmission, adults were mated, and the progeny were screened for viral presence. Within virus-treated groups, we found evidence for both horizontal and vertical transmission. Larval clusters reared on the native host plant had slightly higher horizontal transmission. Survival probability was lower in clusters feeding on the native host plant, with inoculated groups reared on the native host plant experiencing complete mortality. Viral loads did not differ by the host plant, although viral loads decreased with increased sequestration of secondary compounds on both host plants. Our results indicate that the use of a novel host plant may confer fitness benefits in terms of survival and reduced viral transmission when larvae feeding on it are infected with this pathogen, supporting hypotheses of potential evolutionary advantages of a host range expansion in the context of tritrophic interactions.
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Affiliation(s)
- Tara Christensen
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - Lee A Dyer
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - Matthew L Forister
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - M Deane Bowers
- Department of Ecology and Evolutionary Biology and Museum of Natural History, University of Colorado, Boulder, Boulder, Colorado, USA
| | - Adrian Carper
- Department of Ecology and Evolutionary Biology and Museum of Natural History, University of Colorado, Boulder, Boulder, Colorado, USA
| | - Mike B Teglas
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Agriculture, Veterinary and Rangeland Sciences, University of Nevada, Reno, Nevada, USA
| | - Paul Hurtado
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Mathematics and Statistics, University of Nevada, Reno, Nevada, USA
| | - Angela M Smilanich
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
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Gallon ME, Muchoney ND, Smilanich AM. Viral Infection Induces Changes to the Metabolome, Immune Response and Development of a Generalist Insect Herbivore. J Chem Ecol 2024; 50:152-167. [PMID: 38353894 DOI: 10.1007/s10886-024-01472-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 01/15/2024] [Accepted: 01/20/2024] [Indexed: 04/25/2024]
Abstract
Host plant consumption and pathogen infection commonly influence insect traits related to development and immunity, which are ultimately reflected in the behavior and physiology of the insect. Herein, we explored changes in the metabolome of a generalist insect herbivore, Vanessa cardui (Lepidoptera: Nymphalidae), in response to both dietary variation and pathogen infection in order to gain insight into tritrophic interactions for insect metabolism and immunity. Caterpillars were reared on two different host plants, Plantago lanceolata (Plantaginaceae) and Taraxacum officinale (Asteraceae) and subjected to a viral infection by Junonia coenia densovirus (JcDV), along with assays to determine the insect immune response and development. Richness and diversity of plant and caterpillar metabolites were evaluated using a liquid chromatography-mass spectrometry approach and showed that viral infection induced changes to the chemical content of V. cardui hemolymph and frass dependent upon host plant consumption. Overall, the immune response as measured by phenoloxidase (PO) enzymatic activity was higher in individuals feeding on P. lanceolata compared with those feeding on T. officinale. Additionally, infection with JcDV caused suppression of PO activity, which was not host plant dependent. We conclude that viral infection combined with host plant consumption creates a unique chemical environment, particularly within the insect hemolymph. Whether and how these metabolites contribute to defense against viral infection is an open question in chemical ecology.
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Affiliation(s)
- Marilia Elias Gallon
- Department of Biology, University of Nevada, 1664 N. Virginia St., Reno, NV, 89557, USA.
- Núcleo de Pesquisa em Produtos Naturais e Sintéticos, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Av. do Café s/n°, Ribeirão Preto, SP, 14040-903, Brazil.
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Muchoney ND, Bowers MD, Carper AL, Teglas MB, Smilanich AM. Use of an exotic host plant reduces viral burden in a native insect herbivore. Ecol Lett 2023; 26:425-436. [PMID: 36688250 DOI: 10.1111/ele.14162] [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: 07/06/2022] [Accepted: 12/16/2022] [Indexed: 01/24/2023]
Abstract
Incorporation of exotic plants into the diets of native herbivores is a common phenomenon, influencing interactions with natural enemies and providing insight into the tritrophic costs and benefits of dietary expansion. We evaluated how use of an exotic plant, Plantago lanceolata, impacted immune performance, development and susceptibility to pathogen infection in the neotropical herbivore Anartia jatrophae (Lepidoptera: Nymphalidae). Caterpillars were reared on P. lanceolata or a native plant, Bacopa monnieri, and experimentally infected with a pathogenic virus, Junonia coenia densovirus. We found that virus-challenged herbivores exhibited higher survival rates and lower viral burdens when reared on P. lanceolata compared to B. monnieri, though immune performance and development time were largely similar on the two plants. These findings reveal that use of an exotic plant can impact the vulnerability of a native herbivore to pathogen infection, suggesting diet-mediated protection against disease as a potential mechanism facilitating the incorporation of novel resources.
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Affiliation(s)
- Nadya D Muchoney
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA.,Department of Biology, University of Nevada, Reno, Nevada, USA
| | - M Deane Bowers
- Department of Ecology and Evolutionary Biology & Museum of Natural History, University of Colorado, Boulder, Colorado, USA
| | - Adrian L Carper
- Department of Ecology and Evolutionary Biology & Museum of Natural History, University of Colorado, Boulder, Colorado, USA
| | - Mike B Teglas
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA.,Department of Agriculture, Veterinary and Rangeland Sciences, University of Nevada, Nevada, Reno, USA
| | - Angela M Smilanich
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA.,Department of Biology, University of Nevada, Reno, Nevada, USA
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Gallon ME, Smilanich AM. Effects of Host Plants on Development and Immunity of a Generalist Insect Herbivore. J Chem Ecol 2023; 49:142-154. [PMID: 36763248 DOI: 10.1007/s10886-023-01410-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023]
Abstract
Secondary plant chemistry mediates a variety of communication signals among species, playing a fundamental role in the evolutionary diversification of communities and ecosystems. Herein, we explored diet-mediated host plant effects on development and immune response of a generalist insect herbivore. Vanessa cardui (Nymphalidae) caterpillars were reared on leaves of three host plants that vary in secondary metabolites, Plantago lanceolata (Plantaginaceae), Taraxacum officinale (Asteraceae) and Tithonia diversifolia (Asteraceae). Insect development was evaluated by larval and pupal viabilities, survivorship, and development rate. Immune response was measured as phenoloxidase (PO) activity. Additionally, chemical profiles of the host plants were obtained by liquid chromatograph-mass spectrometry (LC-MS) and the discriminant metabolites were determined using a metabolomic approach. Caterpillars reared on P. lanceolata exhibited the highest larval and pupal viabilities, as well as PO activity, and P. lanceolata leaves were chemically characterized by the presence of iridoid glycosides, phenylpropanoids and flavonoids. Taraxacum officinale leaves were characterized mainly by the presence of phenylpropanoids, flavones O-glycoside and germacranolide-type sesquiterpene lactones; caterpillars reared on this host plant fully developed to the adult stage, however they exhibited lower larval and pupal viabilities compared to individuals reared on P. lanceolata. Conversely, caterpillars reared on T. diversifolia leaves, which contain phenylpropanoids, flavones and diverse furanoheliangolide-type sesquiterpene lactones, were not able to complete larval development and exhibited the lowest PO activity. These findings suggested that V. cardui have adapted to tolerate potentially toxic metabolites occurring in P. lanceolata (iridoid glycosides), however caterpillars were not able to cope with potentially detrimental metabolites occurring in T. diversifolia (furanoheliangolides). Therefore, we suggest that furanoheliangolide-type sesquiterpene lactones were responsible for the poor development and immune response observed for caterpillars reared on T. diversifolia.
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Affiliation(s)
- Marilia Elias Gallon
- Department of Biology, University of Nevada, 1664 N. Virginia St., Reno, NV, 89557, USA. .,Núcleo de Pesquisa em Produtos Naturais e Sintéticos, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Av. do Café s/n°, Ribeirão Preto, SP, 14040-903, Brazil.
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Mo C, Smilanich AM. Feeding on an exotic host plant enhances plasma levels of phenoloxidase by modulating feeding efficiency in a specialist insect herbivore. Front Physiol 2023; 14:1127670. [PMID: 36909228 PMCID: PMC9998540 DOI: 10.3389/fphys.2023.1127670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 02/14/2023] [Indexed: 03/14/2023] Open
Abstract
Background: Exotic plant species represent a novel resource for invertebrates and many herbivorous insects have incorporated exotic plants into their diet. Using a new host plant can have physiological repercussions for these herbivores that may be beneficial or detrimental. In this study, we compared how using an exotic versus native host plant affected the immune system response and feeding efficiency of a specialist lepidopteran, the common buckeye (Junonia coenia: Nymphalidae, Hübner 1822). Materials and Methods: In a lab experiment, larvae were reared on either the exotic host plant, Plantago lanceolata (Plantaginaceae), or the native host plant, Mimulus guttatus (Phrymaceae). Beginning at second instar feeding efficiency data were collected every 2 days until fifth instar when immune assays were performed. Immune assays consisted of standing phenoloxidase activity, total phenoloxidase activity, and melanization. Results: Interestingly, we found that all three immune system parameters were higher on the exotic host plant compared to the native host plant. The exotic host plant also supported higher pupal weights, faster development time, greater consumption, and more efficient approximate digestibility. In contrast, the native host plant supported higher efficiency of conversion of ingested and digested food. The relationship between immunity and feeding efficiency was more complex but showed a large positive effect of greater host plant consumption on all immune parameters, particularly for the exotic host plant. While not as strong, the efficiency of conversion of digested food tended to show a negative effect on the three immune parameters. Conclusion: Overall, the exotic host plant proved to be beneficial for this specialist insect with regard to immunity and many of the feeding efficiency parameters and continued use of this host plant is predicted for populations already using it.
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Affiliation(s)
- Carmen Mo
- Department of Biology, University of Nevada, Reno, NV, United States
| | - Angela M Smilanich
- Department of Biology, University of Nevada, Reno, NV, United States.,Ecology, Evolution, and Conservation Biology Graduate Program, University of Nevada, Reno, NV, United States
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Yoon SA, Harrison JG, Smilanich AM, Forister ML. Experimental removal of extracellular egg‐associated microbes has long‐lasting effects for larval performance. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Su’ad A. Yoon
- Okinawa Institute of Science and Technology Okinawa Japan
| | | | - Angela M. Smilanich
- University of Nevada Reno, Department of Biology, Program of Ecology, Evolution, and Conservation Biology Reno NV
| | - Matthew L. Forister
- University of Nevada Reno, Department of Biology, Program of Ecology, Evolution, and Conservation Biology Reno NV
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Muchoney ND, Bowers MD, Carper AL, Mason PA, Teglas MB, Smilanich AM. Use of an exotic host plant shifts immunity, chemical defense, and viral burden in wild populations of a specialist insect herbivore. Ecol Evol 2022; 12:e8723. [PMID: 35342612 PMCID: PMC8928866 DOI: 10.1002/ece3.8723] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 02/08/2022] [Accepted: 02/11/2022] [Indexed: 12/31/2022] Open
Affiliation(s)
- Nadya D. Muchoney
- Program in Ecology, Evolution, and Conservation Biology University of Nevada Reno Nevada USA
- Department of Biology University of Nevada Reno Nevada USA
| | - M. Deane Bowers
- Department of Ecology and Evolutionary Biology & Museum of Natural History University of Colorado Boulder Colorado USA
| | - Adrian L. Carper
- Department of Ecology and Evolutionary Biology & Museum of Natural History University of Colorado Boulder Colorado USA
| | - Peri A. Mason
- Department of Ecology and Evolutionary Biology & Museum of Natural History University of Colorado Boulder Colorado USA
| | - Mike B. Teglas
- Program in Ecology, Evolution, and Conservation Biology University of Nevada Reno Nevada USA
- Department of Agriculture, Veterinary and Rangeland Sciences University of Nevada Reno Nevada USA
| | - Angela M. Smilanich
- Program in Ecology, Evolution, and Conservation Biology University of Nevada Reno Nevada USA
- Department of Biology University of Nevada Reno Nevada USA
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