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Carson BD, Orians CM, Crone EE. Caterpillar movement mediates spatially local interactions and determines the relationship between population density and contact. MOVEMENT ECOLOGY 2024; 12:34. [PMID: 38689374 PMCID: PMC11061915 DOI: 10.1186/s40462-024-00473-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 04/10/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND While interactions in nature are inherently local, ecological models often assume homogeneity across space, allowing for generalization across systems and greater mathematical tractability. Density-dependent disease models are a prominent example of models that assume homogeneous interactions, leading to the prediction that disease transmission will scale linearly with population density. In this study, we examined how the scale of larval butterfly movement interacts with the resource landscape to influence the relationship between larval contact and population density in the Baltimore checkerspot (Euphydryas phaeton). Our study was inspired by the recent discovery of a viral pathogen that is transmitted horizontally among Baltimore checkerspot larvae. METHODS We used multi-year larvae location data across six Baltimore checkerspot populations in the eastern U.S. to test whether larval nests are spatially clustered. We then integrated these spatial data with larval movement data in different resource contexts to investigate whether heterogeneity in spatially local interactions alters the assumed linear relationship between larval nest density and contact. We used Correlated Random Walk (CRW) models and field observations of larval movement behavior to construct Probability Distribution Functions (PDFs) of larval dispersal, and calculated the overlap in these PDFs to estimate conspecific contact within each population. RESULTS We found that all populations exhibited significant spatial clustering in their habitat use. Subsequent larval movement rates were influenced by encounters with host plants and larval age, and under many movement scenarios, the scale of predicted larval movement was not sufficient to allow for the "homogeneous mixing" assumed in density dependent disease models. Therefore, relationships between population density and larval contact were typically non-linear. We also found that observed use of available habitat patches led to significantly greater contact than would occur if habitat use were spatially random. CONCLUSIONS These findings strongly suggest that incorporating larval movement and spatial variation in larval interactions is critical to modeling disease outcomes in E. phaeton. Epidemiological models that assume a linear relationship between population density and larval contact have the potential to underestimate transmission rates, especially in small populations that are already vulnerable to extinction.
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Affiliation(s)
- Brendan D Carson
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
| | - Colin M Orians
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Elizabeth E Crone
- Department of Biology, Tufts University, Medford, MA, 02155, USA
- Department of Evolution and Ecology, University of California, Davis, CA, 95616, USA
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Parras-Jurado A, Muñoz D, Beperet I, Williams T, Caballero P. Insecticidal Traits of Variants in a Genotypically Diverse Natural Isolate of Anticarsia Gemmatalis Multiple Nucleopolyhedrovirus (AgMNPV). Viruses 2023; 15:1526. [PMID: 37515212 PMCID: PMC10386246 DOI: 10.3390/v15071526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/04/2023] [Accepted: 07/08/2023] [Indexed: 07/30/2023] Open
Abstract
Outbreaks of Anticarsia gemmatalis (Hübner, 1818) (Lepidoptera: Erebidae), a major pest of soybean, can be controlled below economic thresholds with methods that do not involve the application of synthetic insecticides. Formulations based on natural isolates of the Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) (Baculoviridae: Alphabaculovirus) played a significant role in integrated pest management programs in the early 2000s, but a new generation of chemical insecticides and transgenic soybean have displaced AgMNPV-based products over the past decade. However, the marked genotypic variability present among and within alphabaculovirus isolates suggests that highly insecticidal genotypic variants can be isolated and used to reduce virus production costs or overcome isolate-dependent host resistance. This study aimed to select novel variants of AgMNPV with suitable insecticidal traits that could complement the existing AgMNPV active ingredients. Three distinct AgMNPV isolates were compared using their restriction endonuclease profile and in terms of their occlusion body (OB) pathogenicity. One isolate was selected (AgABB51) from which eighteen genotypic variants were plaque purified and characterized in terms of their insecticidal properties. The five most pathogenic variants varied in OB pathogenicity, although none of them was faster-killing or had higher OB production characteristics than the wild-type isolate. We conclude that the AgABB51 wild-type isolates appear to be genotypically structured for fast speed of kill and high OB production, both of which would favor horizontal transmission. Interactions among the component variants are likely to influence this insecticidal phenotype.
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Affiliation(s)
- Ana Parras-Jurado
- Institute for Multidisciplinary Research in Applied Biology, Universidad Pública de Navarra, 31006 Pamplona, Spain
- Departamento de Investigación y Desarrollo, Bioinsectis SL, Polígono Industrial Mocholi Plaza Cein 5, Nave A14, 31110 Noáin, Spain
| | - Delia Muñoz
- Institute for Multidisciplinary Research in Applied Biology, Universidad Pública de Navarra, 31006 Pamplona, Spain
| | - Inés Beperet
- Departamento de Investigación y Desarrollo, Bioinsectis SL, Polígono Industrial Mocholi Plaza Cein 5, Nave A14, 31110 Noáin, Spain
| | - Trevor Williams
- Instituto de Ecología AC (INECOL), Xalapa 91073, Veracruz, Mexico
| | - Primitivo Caballero
- Institute for Multidisciplinary Research in Applied Biology, Universidad Pública de Navarra, 31006 Pamplona, Spain
- Departamento de Investigación y Desarrollo, Bioinsectis SL, Polígono Industrial Mocholi Plaza Cein 5, Nave A14, 31110 Noáin, Spain
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Hancock JT, Russell G. Downstream Signalling from Molecular Hydrogen. PLANTS (BASEL, SWITZERLAND) 2021; 10:367. [PMID: 33672953 PMCID: PMC7918658 DOI: 10.3390/plants10020367] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/09/2021] [Accepted: 02/09/2021] [Indexed: 12/23/2022]
Abstract
Molecular hydrogen (H2) is now considered part of the suite of small molecules that can control cellular activity. As such, H2 has been suggested to be used in the therapy of diseases in humans and in plant science to enhance the growth and productivity of plants. Treatments of plants may involve the creation of hydrogen-rich water (HRW), which can then be applied to the foliage or roots systems of the plants. However, the molecular action of H2 remains elusive. It has been suggested that the presence of H2 may act as an antioxidant or on the antioxidant capacity of cells, perhaps through the scavenging of hydroxyl radicals. H2 may act through influencing heme oxygenase activity or through the interaction with reactive nitrogen species. However, controversy exists around all the mechanisms suggested. Here, the downstream mechanisms in which H2 may be involved are critically reviewed, with a particular emphasis on the H2 mitigation of stress responses. Hopefully, this review will provide insight that may inform future research in this area.
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Affiliation(s)
- John T Hancock
- Department of Applied Sciences, University of the West of England, Bristol BS16 1QY, UK
| | - Grace Russell
- Department of Applied Sciences, University of the West of England, Bristol BS16 1QY, UK
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Resnik JL, Smilanich AM. The Effect of Phenoloxidase Activity on Survival Is Host Plant Dependent in Virus-Infected Caterpillars. JOURNAL OF INSECT SCIENCE (ONLINE) 2020; 20:5934963. [PMID: 33089871 PMCID: PMC7583276 DOI: 10.1093/jisesa/ieaa116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Indexed: 06/11/2023]
Abstract
An important goal of disease ecology is to understand trophic interactions influencing the host-pathogen relationship. This study focused on the effects of diet and immunity on the outcome of viral infection for the polyphagous butterfly, Vanessa cardui Linnaeus (Lepidoptera: Nymphalidae) (painted lady). Specifically, we aimed to understand the role that larval host plants play when fighting a viral pathogen. Larvae were orally inoculated with the entomopathogenic virus, Junonia coenia densovirus (JcDV) (Parvovirididae: Densovirinae, Lepidopteran Potoambidensovirus 1) and reared on two different host plants (Lupinus albifrons Bentham (Fabales: Fabaceae) or Plantago lanceolata Linnaeus (Lamiales: Plantaginaceae)). Following viral infection, the immune response (i.e., phenoloxidase [PO] activity), survival to adulthood, and viral load were measured for individuals on each host plant. We found that the interaction between the immune response and survival of the viral infection was host plant dependent. The likelihood of survival was lowest for infected larvae exhibiting suppressed PO activity and feeding on P. lanceolata, providing some evidence that PO activity may be an important defense against viral infection. However, for individuals reared on L. albifrons, the viral infection had a negligible effect on the immune response, and these individuals also had higher survival and lower viral load when infected with the pathogen compared to the controls. Therefore, we suggest that host plant modifies the effects of JcDV infection and influences caterpillars' response when infected with the virus. Overall, we conclude that the outcome of viral infection is highly dependent upon diet, and that certain host plants can provide protection from pathogens regardless of immunity.
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Wang JY, Zhang H, Siemann E, Ji XY, Chen YJ, Wang Y, Jiang JX, Wan NF. Immunity of an insect herbivore to an entomovirus is affected by different host plants. PEST MANAGEMENT SCIENCE 2020; 76:1004-1010. [PMID: 31489764 DOI: 10.1002/ps.5609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/02/2019] [Accepted: 09/02/2019] [Indexed: 05/28/2023]
Abstract
BACKGROUND Interactions between herbivorous insects and entomoviruses may depend on host plant, perhaps mediated through changes in herbivore innate immunity. RESULTS Caterpillars (Spodoptera exigua) fed Glycine max had high viral loads and low melanization rates together with low melanization enzyme [PO, DDC, TH] activities and gene expressions. Caterpillars fed Ipomoea aquatica had low viral loads and high melanization, gene activities and gene expressions while those fed Brassica oleracea or artificial diet had intermediate levels of each. Melanization rates were negatively correlated with viral loads and positively correlated with activity and expression of each of the three enzymes. Some diet effects on enzymes were constitutive because the same diets led to low (G. max) or high (I. aquatica) melanization related gene activities and expressions without infection. CONCLUSION Diet influences the interactions between insect herbivores and viruses by shaping the innate immune response both at the onset of infection and afterwards as viral loads accumulate over a period of days. In addition, diets that lead to low viral loads are associated with high activities and gene expressions of a variety of melanization related enzymes suggesting a common causative mechanism. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Jin-Yan Wang
- Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai, China
| | - Hao Zhang
- Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai, China
| | - Evan Siemann
- Department of Biosciences, Rice University, Houston, TX, USA
| | - Xiang-Yun Ji
- Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai, China
| | - Yi-Juan Chen
- Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai, China
| | - Yi Wang
- Laboratory of Ecology and Evolutionary Biology, Yunnan University, Kunming, China
| | - Jie-Xian Jiang
- Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai, China
| | - Nian-Feng Wan
- Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai, China
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Understanding the Evolutionary Ecology of host--pathogen Interactions Provides Insights into the Outcomes of Insect Pest Biocontrol. Viruses 2020; 12:v12020141. [PMID: 31991772 PMCID: PMC7077243 DOI: 10.3390/v12020141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/15/2020] [Accepted: 01/17/2020] [Indexed: 01/07/2023] Open
Abstract
The use of viral pathogens to control thepopulation size of pest insects has produced both successful and unsuccessful outcomes. Here, we investigate whether those biocontrol successes and failures can be explained by key ecological and evolutionary processes between hosts and pathogens. Specifically, we examine how heterogeneity inpathogen transmission, ecological and evolutionary tradeoffs, andpathogen diversity affect insect population density and thus successful control. Wefirst review theexisting literature and then use numerical simulations of mathematical models to further explore these processes. Our results show that thecontrol of insect densities using viruses depends strongly on theheterogeneity of virus transmission among insects. Overall, increased heterogeneity of transmission reduces theeffect of viruses on insect densities and increases thelong-term stability of insect populations. Lower equilibrium insect densities occur when transmission is heritable and when there is atradeoff between mean transmission and insect fecundity compared to when theheterogeneity of transmission arises from non-genetic sources. Thus, theheterogeneity of transmission is akey parameter that regulates thelong-term population dynamics of insects and their pathogens. Wealso show that both heterogeneity of transmission and life-history tradeoffs modulate characteristics of population dynamics such as thefrequency and intensity of ``boom--bust" population cycles. Furthermore, we show that because of life-history tradeoffs affecting thetransmission rate, theuse of multiple pathogen strains is more effective than theuse of asingle strain to control insect densities only when thepathogen strains differ considerably intheir transmission characteristics. By quantifying theeffects of ecology and evolution on population densities, we are able to offer recommendations to assess thelong-term effects of classical biocontrol.
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Thézé J, Lopez-Vaamonde C, Cory JS, Herniou EA. Biodiversity, Evolution and Ecological Specialization of Baculoviruses: A Treasure Trove for Future Applied Research. Viruses 2018; 10:E366. [PMID: 29997344 PMCID: PMC6071083 DOI: 10.3390/v10070366] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/02/2018] [Accepted: 07/05/2018] [Indexed: 11/16/2022] Open
Abstract
The Baculoviridae, a family of insect-specific large DNA viruses, is widely used in both biotechnology and biological control. Its applied value stems from millions of years of evolution influenced by interactions with their hosts and the environment. To understand how ecological interactions have shaped baculovirus diversification, we reconstructed a robust molecular phylogeny using 217 complete genomes and ~580 isolates for which at least one of four lepidopteran core genes was available. We then used a phylogenetic-concept-based approach (mPTP) to delimit 165 baculovirus species, including 38 species derived from new genetic data. Phylogenetic optimization of ecological characters revealed a general pattern of host conservatism punctuated by occasional shifts between closely related hosts and major shifts between lepidopteran superfamilies. Moreover, we found significant phylogenetic conservatism between baculoviruses and the type of plant growth (woody or herbaceous) associated with their insect hosts. In addition, we found that colonization of new ecological niches sometimes led to viral radiation. These macroevolutionary patterns show that besides selection during the infection process, baculovirus diversification was influenced by tritrophic interactions, explained by their persistence on plants and interactions in the midgut during horizontal transmission. This complete eco-evolutionary framework highlights the potential innovations that could still be harnessed from the diversity of baculoviruses.
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Affiliation(s)
- Julien Thézé
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261, CNRS-Université de Tours, 37200 Tours, France.
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3SY, UK.
| | - Carlos Lopez-Vaamonde
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261, CNRS-Université de Tours, 37200 Tours, France.
- INRA, UR633 Zoologie Forestière, 45075 Orléans, France.
| | - Jenny S Cory
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
| | - Elisabeth A Herniou
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261, CNRS-Université de Tours, 37200 Tours, France.
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Bernal A, Simón O, Williams T, Muñoz D, Caballero P. Remarkably efficient production of a highly insecticidal Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV) isolate in its homologous host. PEST MANAGEMENT SCIENCE 2018; 74:1586-1592. [PMID: 29297971 DOI: 10.1002/ps.4846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/21/2017] [Accepted: 12/22/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND A Chrysodeixis chalcites nucleopolyhedrovirus from the Canary Islands (ChchNPV-TF1) has proved to be effective for control of Chrysodeixis chalcites on banana crops. Commercialization of this virus as a bioinsecticide requires an efficient production system. RESULTS The sixth instar (L6 ) was the most suitable for virus production, producing 1.80 × 1011 occlusion bodies (OB)/larva and showed a lower prevalence of cannibalism (5.4%) than fourth (L4 ) or fifth (L5 ) instars. Inoculation of L6 at 24 h post molting produced six times more OB (5.72 × 1011 OB/larva) than recently molted L6 larvae (1.00 × 1011 OB/larva). No significant differences were recorded in mean time to death (165-175 h) or OB production per larva (3.75 × 1011 to 5.97 × 1011 ) or per mg larval weight (1.30 × 1011 to 2.11 × 109 ), in larvae inoculated with a range of inoculum concentrations (LC50 -LC90 ). Groups of infected L6 larvae reared at a density of 150 larvae/container produced a greater total number of OBs (8.07 × 1013 OB/container) than lower densities (25, 50 and 100 OB/container), and a similar number to containers with 200 inoculated larvae (8.43 × 1013 OB/container). CONCLUSION The processes described here allow efficient production of sufficient OBs to treat ∼ 40 ha of banana crops using the insects from a single container. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Alexandra Bernal
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Spain
| | - Oihane Simón
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Spain
| | | | - Delia Muñoz
- Dpto. Producción Agraria, Universidad Pública de Navarra, Pamplona, Spain
| | - Primitivo Caballero
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Spain
- Dpto. Producción Agraria, Universidad Pública de Navarra, Pamplona, Spain
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9
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Time-lagged intraspecific competition in temporally separated cohorts of a generalist insect. Oecologia 2018; 186:711-718. [PMID: 29383507 DOI: 10.1007/s00442-018-4067-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 01/11/2018] [Indexed: 10/18/2022]
Abstract
Competition can have far-reaching consequences for insect fitness and dispersion. Time-lagged interspecific competition is known to negatively affect fitness, yet time-lagged intraspecific competition is rarely studied outside of outbreak conditions. We tested the impact of competition between larval cohorts of the western tent caterpillar (Malacosoma californicum) feeding on chokecherry (Prunus virginiana). We reared larvae on host plants that either had or did not have feeding damage from tent caterpillars the previous season to test the bottom-up fitness effects of intraspecific competition. We measured host-plant quality to test potential mechanisms for bottom-up effects and conducted field oviposition surveys to determine if female adult tent caterpillars avoided host plants with evidence of prior tent caterpillar presence. We found that time-lagged intraspecific competition impacted tent caterpillar fitness by reducing female pupal mass, which is a predictor of lifetime fitness. We found that plants that had been fed upon by tent caterpillars the previous season had leaves that were significantly tougher than plants that had not been fed upon by tent caterpillars, which may explain why female tent caterpillars suffered reduced fitness on these plants. Finally, we found that there were fewer tent caterpillar egg masses on plants that had tent caterpillars earlier in the season than plants without tent caterpillars, which suggests that adult females avoid these plants for oviposition. Our results confirm that intraspecific competition occurs among tent caterpillars and suggests that time-lagged intraspecific competition has been overlooked as an important component of insect fitness.
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Shikano I, McCarthy EM, Elderd BD, Hoover K. Plant genotype and induced defenses affect the productivity of an insect-killing obligate viral pathogen. J Invertebr Pathol 2017; 148:34-42. [PMID: 28483639 DOI: 10.1016/j.jip.2017.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/22/2017] [Accepted: 05/04/2017] [Indexed: 11/18/2022]
Abstract
Plant-mediated variations in the outcomes of host-pathogen interactions can strongly affect epizootics and the population dynamics of numerous species, including devastating agricultural pests such as the fall armyworm. Most studies of plant-mediated effects on insect pathogens focus on host mortality, but few have measured pathogen yield, which can affect whether or not an epizootic outbreak occurs. Insects challenged with baculoviruses on different plant species and parts can vary in levels of mortality and yield of infectious stages (occlusion bodies; OBs). We previously demonstrated that soybean genotypes and induced anti-herbivore defenses influence baculovirus infectivity. Here, we used a soybean genotype that strongly reduced baculovirus infectivity when virus was ingested on induced plants (Braxton) and another that did not reduce infectivity (Gasoy), to determine how soybean genotype and induced defenses influence OB yield and speed of kill. These are key fitness measures because baculoviruses are obligate-killing pathogens. We challenged fall armyworm, Spodoptera frugiperda, with the baculovirus S. frugiperda multi-nucleocapsid nucleopolyhedrovirus (SfMNPV) during short or long-term exposure to plant treatments (i.e., induced or non-induced genotypes). Caterpillars were either fed plant treatments only during virus ingestion (short-term exposure to foliage) or from the point of virus ingestion until death (long-term exposure). We found trade-offs of increasing OB yield with slower speed of kill and decreasing virus dose. OB yield increased more with longer time to death and decreased more with increasing virus dose after short-term feeding on Braxton compared with Gasoy. OB yield increased significantly more with time to death in larvae that fed until death on non-induced foliage than induced foliage. Moreover, fewer OBs per unit of host tissue were produced when larvae were fed induced foliage than non-induced foliage. These findings highlight the potential importance of plant effects, even at the individual plant level, on entomopathogen fitness, which may impact epizootic transmission events and host population dynamics.
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Affiliation(s)
- Ikkei Shikano
- Department of Entomology and Center for Chemical Ecology, Pennsylvania State University, University Park, PA 16802, USA.
| | | | - Bret D Elderd
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Kelli Hoover
- Department of Entomology and Center for Chemical Ecology, Pennsylvania State University, University Park, PA 16802, USA
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11
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Shikano I. Evolutionary Ecology of Multitrophic Interactions between Plants, Insect Herbivores and Entomopathogens. J Chem Ecol 2017; 43:586-598. [DOI: 10.1007/s10886-017-0850-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 05/06/2017] [Accepted: 05/15/2017] [Indexed: 02/07/2023]
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12
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Martemyanov VV, Podgwaite JD, Belousova IA, Pavlushin SV, Slavicek JM, Baturina OA, Kabilov MR, Ilyinykh AV. A comparison of the adaptations of strains of Lymantria dispar multiple nucleopolyhedrovirus to hosts from spatially isolated populations. J Invertebr Pathol 2017; 146:41-46. [PMID: 28392286 DOI: 10.1016/j.jip.2017.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/17/2017] [Accepted: 04/05/2017] [Indexed: 11/18/2022]
Abstract
The adaptation of pathogens to either their hosts or to environmental conditions is the focus of many current ecological studies. In this work we compared the ability of six spatially-distant Lymantria dispar (gypsy moth) multiple nucleopolyhedrovirus (LdMNPV) strains (three from eastern North America and three from central Asia) to induce acute infection in gypsy moth larvae. We also sequenced the complete genome of one Asian (LdMNPV-27/0) and one North American (LdMNPV-45/0) strain which were used for bioassay. We found that all of the North American virus strains, with the exception of one, demonstrated higher potency than the Asian virus strains, either in North American (Lymantria dispar) larvae or, in Asian (Lymantria dispar asiatica) larvae. Complete genome sequencing revealed two gene deletions in the LdMNPV-27/0 strain: the virus enhancin factor gene (vef-1) and the baculovirus repeated orf gene (bro-p). These deletions were not seen in the LdMNPV-45/0 strain nor in other American strains available in archiving systems. We also found deletions of the bro-e and bro-o genes in LdMNPV-45/0 strain but not in the LdMNPV-27/0 strain. The phylogenetic inference with an alignment of the 37 core gene nucleotide sequences revealed the close relationship of the LdMNPV-45/0 strain with other American strains accessed in GenBank (Ab-a624 and 5-6) while the LdMNPV-27/0 strain was clustered together with the LdMNPV-3054 strain (isolated in Spain) instead of predicted clustering with LdMNPV- 3029 (isolated in Asia). Our study demonstrated that first, different LdMNPV isolates from the same metapopulations of L. dispar exhibit little or no difference in the degree of virulence towards host larvae and second, that locality of host population is not an important driver of LdMNPV virulence. Virulence of LdMNPV is determined only by viral genetics. The genetic differences between North American and Central Asian virus strains are discussed.
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Affiliation(s)
- V V Martemyanov
- Laboratory of Ecological Parasitology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, 630091 Novosibirsk, Russia; Biological Institute, National Research Tomsk State University, Lenin av. 36, 634050 Tomsk, Russia.
| | - J D Podgwaite
- USDA Forest Service, Northern Research Station, 51 Mill Pond Rd., Hamden, CT 06514, United States.
| | - I A Belousova
- Laboratory of Ecological Parasitology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, 630091 Novosibirsk, Russia; Institute of Biology, Irkutsk State University, Karl Marx str. 1, Irkutsk 664003, Russia.
| | - S V Pavlushin
- Laboratory of Ecological Parasitology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, 630091 Novosibirsk, Russia.
| | - J M Slavicek
- USDA Forest Service, Northern Research Station, 359 Main Rd., Delaware, OH 43015, United States.
| | - O A Baturina
- Genomics Core Facility, Institute of Chemical Biology and Fundamental Medicine SB RAS, Lavrentyev av. 8, 630090 Novosibirsk, Russia.
| | - M R Kabilov
- Genomics Core Facility, Institute of Chemical Biology and Fundamental Medicine SB RAS, Lavrentyev av. 8, 630090 Novosibirsk, Russia.
| | - A V Ilyinykh
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animal SB RAS, Frunze str. 11, 630091 Novosibirsk, Russia.
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Mursinoff S, Tack AJM. Spatial variation in soil biota mediates plant adaptation to a foliar pathogen. THE NEW PHYTOLOGIST 2017; 214:644-654. [PMID: 28042886 DOI: 10.1111/nph.14402] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/24/2016] [Indexed: 06/06/2023]
Abstract
Theory suggests that below-ground spatial heterogeneity may mediate host-parasite evolutionary dynamics and patterns of local adaptation, but this has rarely been tested in natural systems. Here, we test experimentally for the impact of spatial variation in the abiotic and biotic soil environment on the evolutionary outcome of the interaction between the host plant Plantago lanceolata and its specialist foliar pathogen Podosphaera plantaginis. Plants showed no adaptation to the local soil environment in the absence of natural enemies. However, quantitative, but not qualitative, plant resistance against local pathogens was higher when plants were grown in their local field soil than when they were grown in nonlocal field soil. This pattern was robust when extending the spatial scale beyond a single region, but disappeared with soil sterilization, indicating that soil biota mediated plant adaptation. We conclude that below-ground biotic heterogeneity mediates above-ground patterns of plant adaptation, resulting in increased plant resistance when plants are grown in their local soil environment. From an applied perspective, our findings emphasize the importance of using locally selected seeds in restoration ecology and low-input agriculture.
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Affiliation(s)
- Sini Mursinoff
- Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
| | - Ayco J M Tack
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
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Plant-mediated effects on an insect-pathogen interaction vary with intraspecific genetic variation in plant defences. Oecologia 2017; 183:1121-1134. [PMID: 28144733 DOI: 10.1007/s00442-017-3826-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 01/20/2017] [Indexed: 01/21/2023]
Abstract
Baculoviruses are food-borne microbial pathogens that are ingested by insects on contaminated foliage. Oxidation of plant-derived phenolics, activated by insect feeding, can directly interfere with infections in the gut. Since phenolic oxidation is an important component of plant resistance against insects, baculoviruses are suggested to be incompatible with plant defences. However, plants among and within species invest differently in a myriad of chemical and physical defences. Therefore, we hypothesized that among eight soybean genotypes, some genotypes would be able to maintain both high resistance against an insect pest and high efficacy of a baculovirus. Soybean constitutive (non-induced) and jasmonic acid (JA)-induced (anti-herbivore response) resistance was measured against the fall armyworm Spodoptera frugiperda (weight gain, leaf consumption and utilization). Indicators of phenolic oxidation were measured as foliar phenolic content and peroxidase activity. Levels of armyworm mortality inflicted by baculovirus (SfMNPV) did not vary among soybean genotypes when the virus was ingested with non-induced foliage. Ingestion of the virus on JA-induced foliage reduced armyworm mortality, relative to non-induced foliage, on some soybean genotypes. Baculovirus efficacy was lower when ingested with foliage that contained higher phenolic content and defensive properties that reduced armyworm weight gain and leaf utilization. However, soybean genotypes that defended the plant by reducing consumption rate and strongly deterred feeding upon JA-induction did not reduce baculovirus efficacy, indicating that these defences may be more compatible with baculoviruses to maximize plant protection. Differential compatibility of defence traits with the third trophic level highlights an important cost/trade-off associated with plant defence strategies.
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Genetic and phenotypic comparisons of viral genotypes from two nucleopolyhedroviruses interacting with a common host species, Spodoptera litura (Lepidoptera: Noctuidae). J Invertebr Pathol 2016; 139:42-49. [DOI: 10.1016/j.jip.2016.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 07/15/2016] [Accepted: 07/19/2016] [Indexed: 11/20/2022]
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16
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Redman EM, Wilson K, Cory JS. Trade-offs and mixed infections in an obligate-killing insect pathogen. J Anim Ecol 2016; 85:1200-9. [PMID: 27155461 PMCID: PMC4988505 DOI: 10.1111/1365-2656.12547] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/24/2016] [Indexed: 02/01/2023]
Abstract
Natural populations of pathogens are frequently composed of numerous interacting strains. Understanding what maintains this diversity remains a key focus of research in disease ecology. In addition, within-host pathogen dynamics can have a strong impact on both infection outcome and the evolution of pathogen virulence, and thus, understanding the impact of pathogen diversity is important for disease management. We compared eight genetically distinguishable variants from Spodoptera exempta nucleopolyhedrovirus (SpexNPV) isolated from the African armyworm, Spodoptera exempta. NPVs are obligate killers, and the vast majority of transmission stages are not released until after the host has died. The NPV variants differed significantly in their virulence and could be clustered into two groups based on their dose-response curves. They also differed in their speed of kill and productivity (transmission potential) for S. exempta. The mixed-genotype wild-type (WT) SpexNPV, from which each variant was isolated, was significantly more virulent than any individual variant and its mean mortality rate was within the fastest group of individual variants. However, the WT virus produced fewer new infectious stages than any single variant, which might reflect competition among the variants. A survival analysis, combining the mortality and speed of kill data, confirmed the superiority of the genetically mixed WT virus over any single variant. Spodoptera exempta larvae infected with WT SpexNPV were predicted to die 2·7 and 1·9 times faster than insects infected with isolates from either of the two clusters of genotypes. Theory suggests that there are likely to be trade-offs between pathogen fitness traits. Across all larvae, there was a negative linear relationship between virus yield and speed of kill, such that more rapid host death carried the cost of producing fewer transmission stages. We also found a near-significant relationship for the same trend at the intervariant level. However, there was no evidence for a significant relationship between the induced level of mortality and transmission potential (virus yield) or speed of kill.
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Affiliation(s)
- Elizabeth M Redman
- Molecular Ecology and Biocontrol Group, NERC Centre for Ecology and Hydrology, Mansfield Road, Oxford, OX1 3SR, UK
| | - Kenneth Wilson
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Jenny S Cory
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, BC, Canada
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17
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Lymantria mathura nucleopolyhedrovirus: Identification, occurrence and genetic diversity in Iwate Prefecture, Japan. J Invertebr Pathol 2016; 138:1-9. [PMID: 27234422 DOI: 10.1016/j.jip.2016.05.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 05/01/2016] [Accepted: 05/24/2016] [Indexed: 11/23/2022]
Abstract
A high prevalence of nuclear polyhedrosis has been observed in larval outbreaks of Lymantria mathura in Iwate Prefecture, Japan. However, the virus responsible has not been identified. Here the virus was designated Lymantria mathura nucleopolyhedrovirus (LymaNPV), based on partial sequence results of the lef-8, lef-9, and polh genes and transmission electron microscopic observations. Diagnosis by polymerase chain reaction targeting of the partial polh gene and a subsequent restriction fragment length polymorphism (RFLP) analysis indicated that LymaNPV was an exclusive causative agent for the nuclear polyhedrosis of the L. mathura larvae. LymaNPV was also detected from a very small fraction of L. dispar larvae that co-occurred with L. mathura larvae where the prevalence of LymaNPV-caused disease was high. A bioassay using LymaNPV against L. dispar larvae produced infection with the inoculated virus. This finding was consistent with the results of the field sample analysis. LymaNPV contained six genome types in the L. mathura populations sampled, as determined by RFLP of LymaNPV genomic DNA and southern blot hybridization analyses. None of the genome types was unique to any sampling site, indicating that some flow had occurred among sites. However, genome-type composition seemed to differ among sites. This study provides basic information about the interaction between L. mathura and LymaNPV.
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18
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Myers JH, Cory JS. Ecology and evolution of pathogens in natural populations of Lepidoptera. Evol Appl 2016; 9:231-47. [PMID: 27087850 PMCID: PMC4780379 DOI: 10.1111/eva.12328] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/19/2015] [Indexed: 01/25/2023] Open
Abstract
Pathogens are ubiquitous in insect populations and yet few studies examine their dynamics and impacts on host populations. We discuss four lepidopteran systems and explore their contributions to disease ecology and evolution. More specifically, we elucidate the role of pathogens in insect population dynamics. For three species, western tent caterpillars, African armyworm and introduced populations of gypsy moth, infection by nucleopolyhedrovirus (NPV) clearly regulates host populations or reduces their outbreaks. Transmission of NPV is largely horizontal although low levels of vertical transmission occur, and high levels of covert infection in some cases suggest that the virus can persist in a nonsymptomatic form. The prevalence of a mostly vertically transmitted protozoan parasite, Ophryocystis elektroscirrha, in monarch butterflies is intimately related to their migratory behaviour that culls highly infected individuals. Virulence and transmission are positively related among genotypes of this parasite. These systems clearly demonstrate that the interactions between insects and pathogens are highly context dependent. Not only is the outcome a consequence of changes in density and genetic diversity: environmental factors, particularly diet, can have strong impacts on virulence, transmission and host resistance or tolerance. What maintains the high level of host and pathogen diversity in these systems, however, remains a question.
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Affiliation(s)
- Judith H. Myers
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
| | - Jenny S. Cory
- Department of Biological SciencesSimon Fraser UniversityBurnabyBCCanada
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Tseng M, Myers JH. The relationship between parasite fitness and host condition in an insect--virus system. PLoS One 2014; 9:e106401. [PMID: 25208329 PMCID: PMC4160166 DOI: 10.1371/journal.pone.0106401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 07/30/2014] [Indexed: 11/19/2022] Open
Abstract
Research in host-parasite evolutionary ecology has demonstrated that environmental variation plays a large role in mediating the outcome of parasite infection. For example, crowding or low food availability can reduce host condition and make them more vulnerable to parasite infection. This observation that poor-condition hosts often suffer more from parasite infection compared to healthy hosts has led to the assumption that parasite productivity is higher in poor-condition hosts. However, the ubiquity of this negative relationship between host condition and parasite fitness is unknown. Moreover, examining the effect of environmental variation on parasite fitness has been largely overlooked in the host-parasite literature. Here we investigate the relationship between parasite fitness and host condition by using a laboratory experiment with the cabbage looper Trichoplusia ni and its viral pathogen, AcMNPV, and by surveying published host-parasite literature. Our experiments demonstrated that virus productivity was positively correlated with host food availability and the literature survey revealed both positive and negative relationships between host condition and parasite fitness. Together these data demonstrate that contrary to previous assumptions, parasite fitness can be positively or negatively correlated with host fitness. We discuss the significance of these findings for host-parasite population biology.
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Affiliation(s)
- Michelle Tseng
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
| | - Judith H. Myers
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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20
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Lively CM, de Roode JC, Duffy MA, Graham AL, Koskella B. Interesting open questions in disease ecology and evolution. Am Nat 2014; 184 Suppl 1:S1-8. [PMID: 25061674 DOI: 10.1086/677032] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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Bernal A, Simón O, Williams T, Caballero P. Stage-specific insecticidal characteristics of a nucleopolyhedrovirus isolate from Chrysodeixis chalcites enhanced by optical brighteners. PEST MANAGEMENT SCIENCE 2014; 70:798-804. [PMID: 23893929 DOI: 10.1002/ps.3617] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/17/2013] [Accepted: 07/26/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Chrysodeixis chalcites is a major noctuid pest of banana crops in the Canary Islands. The stage-specific susceptibility of this pest to C. chalcites single nucleopolyhedrovirus (ChchSNPV-TF1) was determined, as well as the effect of selected optical brighteners as enhancers of primary infection. RESULTS Susceptibility to ChchSNPV-TF1 occlusion bodies (OBs) decreased as larval stage increased; second instars (L2) were 10,000-fold more susceptible than sixth instars (L6). Virus speed of kill was 42 h faster in L2 than in L6 . OB production increased in late instars; L6 larvae produced 23-fold more OBs than L4 . Addition of 10 mg mL(-1) Tinopal enhanced OB pathogenicity by 4.43- to 397-fold depending on instar, whereas 10 µL mL(-1) Leucophor resulted in potentiation of OB pathogenicity from 1.46- to 143-fold. Mean time to death decreased by 14 to 26 h when larvae consumed OBs in mixtures with 10 mg mL(-1) Tinopal, or 10 µL mL(-1) Leucophor, although in these treatments OB yields were reduced by up to 8.5-fold (Tinopal) or up to 3.8-fold (Leucophor). CONCLUSION These results have clear applications for the use of ChchSNPV-TF1 as a biological insecticide in control programs against C. chalcites in the Canary Islands.
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Affiliation(s)
- Alexandra Bernal
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Spain
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Affiliation(s)
- Arjen Biere
- Department of Terrestrial Ecology Netherlands Institute of Ecology NIOO‐KNAW Droevendaalsesteeg 10 6708 PB Wageningen The Netherlands
| | - Alison E. Bennett
- Ecological Sciences The James Hutton Institute Errol Road Invergowrie Dundee DD2 5DA UK
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23
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Biere A, Tack AJM. Evolutionary adaptation in three‐way interactions between plants, microbes and arthropods. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12096] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Arjen Biere
- Department of Terrestrial Ecology Netherlands Institute of Ecology, NIOO‐KNAW Droevendaalsesteeg 10 6708 PB Wageningen The Netherlands
| | - Ayco J. M. Tack
- Metapopulation Research Group, Department of Biosciences University of Helsinki P. O. Box 65 (Viikinkaari 1) FI‐00014 Helsinki Finland
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24
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Cory JS, Franklin MT. Evolution and the microbial control of insects. Evol Appl 2012; 5:455-69. [PMID: 22949921 PMCID: PMC3407864 DOI: 10.1111/j.1752-4571.2012.00269.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 04/24/2012] [Indexed: 11/26/2022] Open
Abstract
Insect pathogens can be utilized in a variety of pest management approaches, from inundative release to augmentation and classical biological control, and microevolution and the consideration of evolutionary principles can potentially influence the success of all these strategies. Considerable diversity exists in natural entomopathogen populations and this diversity can be either beneficial or detrimental for pest suppression, depending on the pathogen and its mode of competition, and this should be considered in the selection of isolates for biological control. Target hosts can exhibit considerable variation in their susceptibility to entomopathogens, and cases of field-evolved resistance have been documented for Bacillus thuringiensis and baculoviruses. Strong selection, limited pathogen diversity, reduced gene flow, and host plant chemistry are linked to cases of resistance and should be considered when developing resistance management strategies. Pre- and post-release monitoring of microbial control programs have received little attention; however, to date there have been no reports of host-range evolution or long-term negative effects on nontarget hosts. Comparative analyses of pathogen population structure, virulence, and host resistance over time are required to elucidate the evolutionary dynamics of microbial control systems.
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Affiliation(s)
- Jenny S Cory
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, BC, Canada
- * Correspondence Jenny S. Cory, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. Tel.: 17787825714; fax: 17787823496; e-mail:
| | - Michelle T Franklin
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, BC, Canada
- Department of Zoology, University of British ColumbiaVancouver, BC, Canada
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25
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Koskella B, Thompson JN, Preston GM, Buckling A. Local biotic environment shapes the spatial scale of bacteriophage adaptation to bacteria. Am Nat 2011; 177:440-51. [PMID: 21460566 DOI: 10.1086/658991] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The ecological, epidemiological, and evolutionary consequences of host-parasite interactions are critically shaped by the spatial scale at which parasites adapt to hosts. The scale of interaction between hyperparasites and their parasites is likely to be influenced by the host of the parasite and potentially likely to differ among within-host environments. Here we examine the scale at which bacteriophages adapt to their host bacteria by studying natural isolates from the surface or interior of horse chestnut leaves. We find that phages are more infective to bacteria from the same tree relative to those from other trees but do not differ in infectivity to bacteria from different leaves within the same tree. The results suggest that phages target common bacterial species, including an important plant pathogen, within plant host tissues; this result has important implications for therapeutic phage epidemiology. Furthermore, we show that phages from the leaf interior are more infective to their local hosts than phages from the leaf surface are to theirs, suggesting either increased resistance of bacteria on the leaf surface or increased phage adaptation within the leaf. These results highlight that biotic environment can play a key role in shaping the spatial scale of parasite adaptation and influencing the outcome of coevolutionary interactions.
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Affiliation(s)
- Britt Koskella
- Department of Zoology, University of Oxford, South Parks Road, Oxford, United Kingdom.
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26
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Indirect plant-mediated effects on insect immunity and disease resistance in a tritrophic system. Basic Appl Ecol 2010. [DOI: 10.1016/j.baae.2009.06.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
Estimating parasite fitness is central to studies aiming to understand parasite evolution. Theoretical models generally use the basic reproductive rate R(0) to express fitness, yet it is very difficult to quantify R(0) empirically and experimental studies often use fitness components such as infection intensity or infectivity as substitutes. These surrogate measures may be biased in several ways. We assessed local adaptation of the microsporidium Ordospora colligata to its host, the crustacean Daphnia magna using two different parasite fitness components: infection persistence over several host generations in experimental populations and infection intensity in individual hosts. We argue that infection persistence is a close estimator of R(0), whereas infection intensity measures only a component of it. Both measures show a pattern that is consistent with parasite local adaptation and they correlate positively. However, several inconsistencies between them suggest that infection intensity may at times provide an inadequate estimate of parasite fitness.
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Affiliation(s)
- D Refardt
- Unitè Ecologie et Evolution, Département de Biologie, Chemin du Musée 10, Fribourg, Switzerland.
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28
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Abstract
Much evolutionary theory assumes that parasite virulence (i.e. parasite-induced host mortality) is determined by within-host parasite reproduction and by the specific parasite genotypes causing infection. However, many other factors could influence the level of virulence experienced by hosts. We studied the protozoan parasite Ophryocystis elektroscirrha in its host, the monarch butterfly, Danaus plexippus. We exposed monarch larvae to wild-isolated parasites and assessed the effects of within-host replication and parasite genotype on host fitness measures, including pre-adult development time and adult weight and longevity. Per capita replication rates of parasites were high, and infection resulted in high parasite loads. Of all host fitness traits, adult longevity showed the clearest relationship with infection status, and decreased continuously with increasing parasite loads. Parasite genotypes differed in their virulence, and these differences were maintained across ecologically relevant variables, including inoculation dose, host sex and host age at infection. Thus, virulence appears to be a robust genetic parasite trait in this system. Although parasite loads and genotypes had strong effects on virulence, inoculation dose, host sex and age at infection were also important. These results have implications for virulence evolution and emphasize the need for a detailed understanding of specific host-parasite systems for addressing theory.
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Affiliation(s)
- J C de Roode
- Department of Environmental Studies, Emory University, Atlanta, GA 30322, USA.
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Inceoglu AB, Kamita SG, Hammock BD. Genetically modified baculoviruses: a historical overview and future outlook. Adv Virus Res 2006; 68:323-60. [PMID: 16997016 DOI: 10.1016/s0065-3527(06)68009-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The concept of using genetic engineering to improve the natural insecticidal activity of baculoviruses emerged during the 1980s. Both academic and industrial laboratories have since invested a great deal of effort to generate genetically modified (GM) or recombinant baculoviruses with dramatically improved speeds of kill. Optimal production methodologies and formulations have also been developed, and the safety and ecology of the recombinant baculoviruses have been thoroughly investigated. Unfortunately, the initial excitement that was generated by these technologies was tempered when industry made a critical decision to not complete the registration process of GM baculoviruses for pest insect control. In this chapter, we summarize the developments in the field from a historical perspective and provide our opinions as to the current status and future potential of the technology. We will argue that GM baculoviruses are valuable and viable tools for pest insect control both alone and in combination with wild-type viruses. We believe that these highly effective biopesticides still have a bright future in modern agriculture as public awareness and acceptance of GM organisms, including GM baculoviruses, increases.
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Affiliation(s)
- A Bora Inceoglu
- Department of Entomology and Cancer Research Center University of California, Davis, California 95616, USA
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30
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Liu X, Zhang Q, Xu B, Li J. Effects of Cry1Ac toxin of Bacillus thuringiensis and nuclear polyhedrosis virus of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on larval mortality and pupation. PEST MANAGEMENT SCIENCE 2006; 62:729-37. [PMID: 16770833 DOI: 10.1002/ps.1229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In the laboratory, the percentage mortality and pupation of Helicoverpa armigera (Hübner) were investigated when larvae were exposed to Cry1Ac of Bacillus thuringiensis Berliner, nuclear polyhedrosis virus of H. armigera (HaNPV) or Cry1Ac and HaNPV together. The results revealed that interactions between Cry1Ac and HaNPV varied with bioassay method and concentration of the suspension. When larvae were infected using a suspension containing both HaNPV and Cry1Ac, most combinations of Cry1Ac (62.5, 125 and 250 microg mL(-1)) and HaNPV (1.2 x 10(6), 6.0 x 10(6) and 3.0 x 10(7) PIB mL(-1)) showed an antagonistic effect. In the bioassay procedure where larvae were force fed diet containing Cry1Ac 48 h after being infected by HaNPV, interaction between Cry1Ac (0.5, 1, 2, 4 and 8 microg mL(-1)) and HaNPV (6.0 x 10(6) and 3.0 x 10(7) PIB mL(-1)) showed an additive effect, while combinations of Cry1Ac (0.5, 1, 2 and 4 microg mL(-1)) and HaNPV (1.2 x 10(6) PIB mL(-1)) showed an antagonistic effect. In the bioassay procedure where larvae being infected by HaNPV were fed on Cry1Ac diet from neonate to death or pupation, the results suggested that Cry1Ac and HaNPV showed an additive interaction. The percentage mortality was lower in the treatment of larvae infected by transgenic Bt cotton leaf discs containing HaNPV suspension than in the treatment of larvae by conventional cotton leaf discs containing HaNPV, while the pupation rate was higher. The combination of Bt cotton and HaNPV showed antagonism. The present results showed that a combination of Cry1Ac and HaNPV usually resulted in mortality levels greater than in the case of Cry1Ac but not greater than with the virus alone.
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Affiliation(s)
- Xiaoxia Liu
- Department of Entomology, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100094, PR China
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31
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Brown G, Shilton C, Shine R. Do parasites matter? Assessing the fitness consequences of haemogregarine infection in snakes. CAN J ZOOL 2006. [DOI: 10.1139/z06-044] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although much research in evolutionary ecology is based upon the premise that high levels of parasitism impair the host's functioning, the assumed link between parasitism and fitness has been assessed for relatively few kinds of animals. At our study site in tropical Australia, keelback snakes ( Tropidonophis mairii (Gray, 1841), Colubridae) are heavily infected with haemogregarine blood parasites: 90% of snakes that we tested carried the parasite, with the proportion of erythrocytes containing haemogregarines averaging 15% and ranging up to a remarkable 64%. Prevalence increased with snake body size, but intensity decreased with age. Unlike lizards studied previously, the snakes did not respond to haemogregarine infection by releasing immature erythrocytes into the circulation. In striking contrast to results from a recent study on a sympatric snake species, we did not find any empirical links between parasite numbers and several measures of host fitness (body condition, growth rate, feeding rate, antipredator behaviour, locomotor performance, reproductive status, reproductive output, and recapture rate). The association between this parasite and its host thus appears to be surprisingly benign, suggesting that host–parasite interactions sometimes may have only trivial consequences for host fitness in natural populations. Plausibly, host–parasite coevolution weakens or eliminates fitness costs of parasitism.
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Affiliation(s)
- G.P. Brown
- School of Biological Sciences, University of Sydney, NSW 2006, Australia
- Berrimah Veterinary Laboratories, Department of Business, Industry and Resource Development, Darwin, NT 0801, Australia
| | - C.M. Shilton
- School of Biological Sciences, University of Sydney, NSW 2006, Australia
- Berrimah Veterinary Laboratories, Department of Business, Industry and Resource Development, Darwin, NT 0801, Australia
| | - R. Shine
- School of Biological Sciences, University of Sydney, NSW 2006, Australia
- Berrimah Veterinary Laboratories, Department of Business, Industry and Resource Development, Darwin, NT 0801, Australia
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Cory JS, Hoover K. Plant-mediated effects in insect-pathogen interactions. Trends Ecol Evol 2006; 21:278-86. [PMID: 16697914 DOI: 10.1016/j.tree.2006.02.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Revised: 01/27/2006] [Accepted: 02/08/2006] [Indexed: 11/16/2022]
Abstract
Interactions between insect herbivores and their pathogens can be modulated by host plants. Inter- and intraspecific differences in plant chemistry and structure can alter the susceptibility of insects to infection and the production and environmental persistence of pathogens. Whether plants can manipulate insect pathogens to act as "bodyguards" and increase their own fitness remains to be shown. Reduced insect performance owing to poor plant quality can enhance the susceptibility of an insect to disease while these same phytochemicals can also reduce the effectiveness of entomopathogens in killing the host. As we discuss here, plants have an important role in the evolution of insect-pathogen relationships and a tritrophic perspective should thus be incorporated into the study of insects and their pathogens.
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Affiliation(s)
- Jenny S Cory
- Great Lakes Forestry Centre, 1219 Queen Street East, Sault Ste. Marie, Ontario, Canada P6A 2E5.
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Cory JS, Green BM, Paul RK, Hunter-Fujita F. Genotypic and phenotypic diversity of a baculovirus population within an individual insect host. J Invertebr Pathol 2005; 89:101-11. [PMID: 15876438 DOI: 10.1016/j.jip.2005.03.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Revised: 03/07/2005] [Accepted: 03/25/2005] [Indexed: 10/25/2022]
Abstract
It is becoming increasingly apparent that many pathogen populations, including those of insects, show high levels of genotypic variation. Baculoviruses are known to be highly variable, with isolates collected from the same species in different geographical locations frequently showing genetic variation and differences in their biology. More recent studies at smaller scales have also shown that virus DNA profiles from individual larvae can show polymorphisms within and between populations of the same species. Here, we investigate the genotypic and phenotypic variation of an insect baculovirus infection within a single insect host. Twenty four genotypically distinct nucleopolyhedrovirus (NPV) variants were isolated from an individual pine beauty moth, Panolis flammea, caterpillar by in vivo cloning techniques. No variant appeared to be dominant in the population. The PaflNPV variants have been mapped using three restriction endonucleases and shown to contain three hypervariable regions containing insertions of 70-750 bp. Comparison of seven of these variants in an alternative host, Mamestra brassicae, demonstrated that the variants differed significantly in both pathogenicity and speed of kill. The generation and maintenance of pathogen heterogeneity are discussed.
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Affiliation(s)
- Jenny S Cory
- Molecular Ecology and Biocontrol Group, NERC Centre for Ecology and Hydrology, Mansfield Road, Oxford OX1 3SR, UK.
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