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Zhou SO, Arunkumar R, Irfan A, Ding SD, Leitão AB, Jiggins FM. The evolution of constitutively active humoral immune defenses in Drosophila populations under high parasite pressure. PLoS Pathog 2024; 20:e1011729. [PMID: 38206983 PMCID: PMC10807768 DOI: 10.1371/journal.ppat.1011729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/24/2024] [Accepted: 01/04/2024] [Indexed: 01/13/2024] Open
Abstract
Both constitutive and inducible immune mechanisms are employed by hosts for defense against infection. Constitutive immunity allows for a faster response, but it comes with an associated cost that is always present. This trade-off between speed and fitness costs leads to the theoretical prediction that constitutive immunity will be favored where parasite exposure is frequent. We selected populations of Drosophila melanogaster under high parasite pressure from the parasitoid wasp Leptopilina boulardi. With RNA sequencing, we found the evolution of resistance in these populations was associated with them developing constitutively active humoral immunity, mediated by the larval fat body. Furthermore, these evolved populations were also able to induce gene expression in response to infection to a greater level, which indicates an overall more activated humoral immune response to parasitization. The anti-parasitoid immune response also relies on the JAK/STAT signaling pathway being activated in muscles following infection, and this induced response was only seen in populations that had evolved under high parasite pressure. We found that the cytokine Upd3, which induces this JAK/STAT response, is being expressed by immature lamellocytes. Furthermore, these immune cells became constitutively present when populations evolved resistance, potentially explaining why they gained the ability to activate JAK/STAT signaling. Thus, under intense parasitism, populations evolved resistance by increasing both constitutive and induced immune defenses, and there is likely an interplay between these two forms of immunity.
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Affiliation(s)
- Shuyu Olivia Zhou
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ramesh Arunkumar
- Section of population genetics, School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Amina Irfan
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | | | - Alexandre B. Leitão
- Champalimaud Foundation, Champalimaud Centre of the Unknown, Lisbon, Portugal
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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2
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Inwood SN, Skelly J, Guhlin JG, Harrop TWR, Goldson SL, Dearden PK. Chromosome-level genome assemblies of two parasitoid biocontrol wasps reveal the parthenogenesis mechanism and an associated novel virus. BMC Genomics 2023; 24:440. [PMID: 37543591 PMCID: PMC10403939 DOI: 10.1186/s12864-023-09538-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 07/27/2023] [Indexed: 08/07/2023] Open
Abstract
BACKGROUND Biocontrol is a key technology for the control of pest species. Microctonus parasitoid wasps (Hymenoptera: Braconidae) have been released in Aotearoa New Zealand as biocontrol agents, targeting three different pest weevil species. Despite their value as biocontrol agents, no genome assemblies are currently available for these Microctonus wasps, limiting investigations into key biological differences between the different species and strains. METHODS AND FINDINGS Here we present high-quality genomes for Microctonus hyperodae and Microctonus aethiopoides, assembled with short read sequencing and Hi-C scaffolding. These assemblies have total lengths of 106.7 Mb for M. hyperodae and 129.2 Mb for M. aethiopoides, with scaffold N50 values of 9 Mb and 23 Mb respectively. With these assemblies we investigated differences in reproductive mechanisms, and association with viruses between Microctonus wasps. Meiosis-specific genes are conserved in asexual Microctonus, with in-situ hybridisation validating expression of one of these genes in the ovaries of asexual Microctonus aethiopoides. This implies asexual reproduction in these Microctonus wasps involves meiosis, with the potential for sexual reproduction maintained. Investigation of viral gene content revealed candidate genes that may be involved in virus-like particle production in M. aethiopoides, as well as a novel virus infecting M. hyperodae, for which a complete genome was assembled. CONCLUSION AND SIGNIFICANCE These are the first published genomes for Microctonus wasps which have been deployed as biocontrol agents, in Aotearoa New Zealand. These assemblies will be valuable resources for continued investigation and monitoring of these biocontrol systems. Understanding the biology underpinning Microctonus biocontrol is crucial if we are to maintain its efficacy, or in the case of M. hyperodae to understand what may have influenced the significant decline of biocontrol efficacy. The potential for sexual reproduction in asexual Microctonus is significant given that empirical modelling suggests this asexual reproduction is likely to have contributed to biocontrol decline. Furthermore the identification of a novel virus in M. hyperodae highlights a previously unknown aspect of this biocontrol system, which may contribute to premature mortality of the host pest. These findings have potential to be exploited in future in attempt to increase the effectiveness of M. hyperodae biocontrol.
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Affiliation(s)
- Sarah N Inwood
- Bioprotection Aotearoa and Biochemistry Department, University of Otago, Dunedin, Aotearoa, New Zealand
| | - John Skelly
- Bioprotection Aotearoa and Biochemistry Department, University of Otago, Dunedin, Aotearoa, New Zealand
- Humble Bee Bio, Wellington, Aotearoa, New Zealand
| | - Joseph G Guhlin
- Genomics Aotearoa, University of Otago, Dunedin, Aotearoa, New Zealand
| | - Thomas W R Harrop
- Melbourne Bioinformatics, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Stephen L Goldson
- Biocontrol and Biosecurity Group, AgResearch Limited, Lincoln, Aotearoa, New Zealand
| | - Peter K Dearden
- Bioprotection Aotearoa and Biochemistry Department, University of Otago, Dunedin, Aotearoa, New Zealand.
- Genomics Aotearoa, University of Otago, Dunedin, Aotearoa, New Zealand.
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3
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Demir E. Mechanisms and biological impacts of graphene and multi-walled carbon nanotubes on Drosophila melanogaster: Oxidative stress, genotoxic damage, phenotypic variations, locomotor behavior, parasitoid resistance, and cellular immune response. J Appl Toxicol 2021; 42:450-474. [PMID: 34486762 DOI: 10.1002/jat.4232] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/18/2021] [Accepted: 08/18/2021] [Indexed: 12/12/2022]
Abstract
The use of graphene and multi-walled carbon nanotubes (MWCNTs) has now become rather common in medical applications as well as several other areas thanks to their useful physicochemical properties. While in vitro testing offers some potential, in vivo research into toxic effects of graphene and MWCNTs could yield much more reliable data. Drosophila melanogaster has recently gained significant popularity as a dynamic eukaryotic model in examining toxicity, genotoxicity, and biological effects of exposure to nanomaterials, including oxidative stress, cellular immune response against two strains (NSRef and G486) of parasitoid wasp (Leptopilina boulardi), phenotypic variations, and locomotor behavior risks. D. melanogaster was used as a model organism in our study to identify the potential risks of exposure to graphene (thickness: 2-18 nm) and MWCNTs in different properties (as pure [OD: 10-20 nm short], modified by amide [NH2 ] [OD: 7-13 nm length: 55 μm], and modified by carboxyl [COOH] [OD: 30-50 nm and length: 0.5-2 μm]) at concentrations ranging from 0.1 to 250 μg/ml. Significant effects were observed at two high doses (100 and 250 μg/ml) of graphene or MWCNTs. This is the first study to report findings of cellular immune response against hematopoiesis and parasitoids, nanogenotoxicity, phenotypic variations, and locomotor behavior in D. melanogaster.
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Affiliation(s)
- Eşref Demir
- Vocational School of Health Services, Department of Medical Services and Techniques, Medical Laboratory Techniques Programme, Antalya Bilim University, Antalya, Turkey
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4
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Trainor JE, KR P, Mortimer NT. Immune Cell Production Is Targeted by Parasitoid Wasp Virulence in a Drosophila-Parasitoid Wasp Interaction. Pathogens 2021; 10:49. [PMID: 33429864 PMCID: PMC7826891 DOI: 10.3390/pathogens10010049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 12/29/2020] [Accepted: 01/05/2021] [Indexed: 11/26/2022] Open
Abstract
The interactions between Drosophila melanogaster and the parasitoid wasps that infect Drosophila species provide an important model for understanding host-parasite relationships. Following parasitoid infection, D. melanogaster larvae mount a response in which immune cells (hemocytes) form a capsule around the wasp egg, which then melanizes, leading to death of the parasitoid. Previous studies have found that host hemocyte load; the number of hemocytes available for the encapsulation response; and the production of lamellocytes, an infection induced hemocyte type, are major determinants of host resistance. Parasitoids have evolved various virulence mechanisms to overcome the immune response of the D. melanogaster host, including both active immune suppression by venom proteins and passive immune evasive mechanisms. We identified a previously undescribed parasitoid species, Asobara sp. AsDen, which utilizes an active virulence mechanism to infect D. melanogaster hosts. Asobara sp. AsDen infection inhibits host hemocyte expression of msn, a member of the JNK signaling pathway, which plays a role in lamellocyte production. Asobara sp. AsDen infection restricts the production of lamellocytes as assayed by hemocyte cell morphology and altered msn expression. Our findings suggest that Asobara sp. AsDen infection alters host signaling to suppress immunity.
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Affiliation(s)
| | | | - Nathan T. Mortimer
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA; (J.E.T.); (P.K.)
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5
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Leitão AB, Arunkumar R, Day JP, Geldman EM, Morin-Poulard I, Crozatier M, Jiggins FM. Constitutive activation of cellular immunity underlies the evolution of resistance to infection in Drosophila. eLife 2020; 9:59095. [PMID: 33357377 PMCID: PMC7785293 DOI: 10.7554/elife.59095] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 12/23/2020] [Indexed: 12/21/2022] Open
Abstract
Organisms rely on inducible and constitutive immune defences to combat infection. Constitutive immunity enables a rapid response to infection but may carry a cost for uninfected individuals, leading to the prediction that it will be favoured when infection rates are high. When we exposed populations of Drosophila melanogaster to intense parasitism by the parasitoid wasp Leptopilina boulardi, they evolved resistance by developing a more reactive cellular immune response. Using single-cell RNA sequencing, we found that immune-inducible genes had become constitutively upregulated. This was the result of resistant larvae differentiating precursors of specialized immune cells called lamellocytes that were previously only produced after infection. Therefore, populations evolved resistance by genetically hard-wiring the first steps of an induced immune response to become constitutive.
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Affiliation(s)
- Alexandre B Leitão
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ramesh Arunkumar
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Emma M Geldman
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ismaël Morin-Poulard
- Centre de Biologie du Développement, Centre de Biologie Intégrative, University Paul Sabatier, Toulouse, France
| | - Michèle Crozatier
- Centre de Biologie du Développement, Centre de Biologie Intégrative, University Paul Sabatier, Toulouse, France
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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6
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Wey B, Heavner ME, Wittmeyer KT, Briese T, Hopper KR, Govind S. Immune Suppressive Extracellular Vesicle Proteins of Leptopilina heterotoma Are Encoded in the Wasp Genome. G3 (BETHESDA, MD.) 2020; 10:1-12. [PMID: 31676506 PMCID: PMC6945029 DOI: 10.1534/g3.119.400349] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 10/22/2019] [Indexed: 12/29/2022]
Abstract
Leptopilina heterotoma are obligate parasitoid wasps that develop in the body of their Drosophila hosts. During oviposition, female wasps introduce venom into the larval hosts' body cavity. The venom contains discrete, 300 nm-wide, mixed-strategy extracellular vesicles (MSEVs), until recently referred to as virus-like particles. While the crucial immune suppressive functions of L. heterotoma MSEVs have remained undisputed, their biotic nature and origin still remain controversial. In recent proteomics analyses of L. heterotoma MSEVs, we identified 161 proteins in three classes: conserved eukaryotic proteins, infection and immunity related proteins, and proteins without clear annotation. Here we report 246 additional proteins from the L. heterotoma MSEV proteome. An enrichment analysis of the entire proteome supports vesicular nature of these structures. Sequences for more than 90% of these proteins are present in the whole-body transcriptome. Sequencing and de novo assembly of the 460 Mb-sized L. heterotoma genome revealed 90% of MSEV proteins have coding regions within the genomic scaffolds. Altogether, these results explain the stable association of MSEVs with their wasps, and like other wasp structures, their vertical inheritance. While our results do not rule out a viral origin of MSEVs, they suggest that a similar strategy for co-opting cellular machinery for immune suppression may be shared by other wasps to gain advantage over their hosts. These results are relevant to our understanding of the evolution of figitid and related wasp species.
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Affiliation(s)
- Brian Wey
- Biology Department, The City College of New York, 160 Convent Avenue, New York, 10031
- PhD Program in Biology, The Graduate Center of the City University of New York
| | - Mary Ellen Heavner
- Biology Department, The City College of New York, 160 Convent Avenue, New York, 10031
- PhD Program in Biochemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, 10016
- Laboratory of Host-Pathogen Biology, Rockefeller University, 1230 York Ave, New York, 10065
| | - Kameron T Wittmeyer
- USDA-ARS, Beneficial Insect Introductions Research Unit, Newark, DE 19713, and
| | - Thomas Briese
- Center of Infection and Immunity, and Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, 10032
| | - Keith R Hopper
- USDA-ARS, Beneficial Insect Introductions Research Unit, Newark, DE 19713, and
| | - Shubha Govind
- Biology Department, The City College of New York, 160 Convent Avenue, New York, 10031,
- PhD Program in Biology, The Graduate Center of the City University of New York
- PhD Program in Biochemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, 10016
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7
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French RK, Holmes EC. An Ecosystems Perspective on Virus Evolution and Emergence. Trends Microbiol 2019; 28:165-175. [PMID: 31744665 DOI: 10.1016/j.tim.2019.10.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/19/2019] [Accepted: 10/21/2019] [Indexed: 12/18/2022]
Abstract
Understanding the emergence of pathogenic viruses has dominated studies of virus evolution. However, new metagenomic studies imply that relatively few of an immense number of viruses may lead to overt disease. This suggests a change in emphasis, from viruses as habitual pathogens to integral components of ecosystems. Here we show how viruses alter interactions between host individuals, populations, and ecosystems, impacting ecosystem health, resilience, and function, and how host ecology in turn impacts viral abundance and diversity. Moving to an ecosystems perspective will put virus evolution and disease emergence in its true context, and enhance our understanding of ecological processes.
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Affiliation(s)
- Rebecca K French
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia.
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8
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Leitão AB, Bian X, Day JP, Pitton S, Demir E, Jiggins FM. Independent effects on cellular and humoral immune responses underlie genotype-by-genotype interactions between Drosophila and parasitoids. PLoS Pathog 2019; 15:e1008084. [PMID: 31589659 PMCID: PMC6797232 DOI: 10.1371/journal.ppat.1008084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 10/17/2019] [Accepted: 09/16/2019] [Indexed: 11/18/2022] Open
Abstract
It is common to find abundant genetic variation in host resistance and parasite infectivity within populations, with the outcome of infection frequently depending on genotype-specific interactions. Underlying these effects are complex immune defenses that are under the control of both host and parasite genes. We have found extensive variation in Drosophila melanogaster's immune response against the parasitoid wasp Leptopilina boulardi. Some aspects of the immune response, such as phenoloxidase activity, are predominantly affected by the host genotype. Some, such as upregulation of the complement-like protein Tep1, are controlled by the parasite genotype. Others, like the differentiation of immune cells called lamellocytes, depend on the specific combination of host and parasite genotypes. These observations illustrate how the outcome of infection depends on independent genetic effects on different aspects of host immunity. As parasite-killing results from the concerted action of different components of the immune response, these observations provide a physiological mechanism to generate phenomena like epistasis and genotype-interactions that underlie models of coevolution.
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Affiliation(s)
| | - Xueni Bian
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan P. Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Simone Pitton
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Eşref Demir
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Antalya Bilim University, Faculty of Engineering, Department of Material Science and Nanotechnology Engineering, Dosemealti, Antalya, Turkey
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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9
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Delpuech JM. Sublethal effects from endosulfan on parasitization by the parasitoid wasp Leptopilina boulardi and specificity of nervous pathways involved. PEST MANAGEMENT SCIENCE 2019; 75:1411-1415. [PMID: 30417536 DOI: 10.1002/ps.5261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/25/2018] [Accepted: 11/04/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Endosulfan is a semi-permanent pollutant that can be transported long distances through the atmosphere. Although phased out in many countries, it is still used in some highly populated areas and thus greatly contributes to environmental pollution. It can impact non-target species such as Leptopilina boulardi, a hymenopteran parasitoid that is beneficial because it controls the populations of its host. Only one L. boulardi egg can successfully develop in its host, a Drosophila larva. Consequently, parasitoid females generally lay only one egg per host, except when they are infected by a virus (LbFV) that triggers superparasitization behavior (laying more than one egg per host). The effects of an LC20 of endosulfan on the parasitization behavior of two L. boulardi strains, one infected by LbFV and the other not, were evaluated. RESULTS Endosulfan decreased the number of host larvae parasitized by both strains (decreased rate of parasitization) but had no impact on the number of eggs laid per host (i.e., the rate of superparasitization) irrespective of whether the strain was infected by LbFV or not. CONCLUSIONS Recent research has shown that the organophosphorus insecticide chlorpyrifos induced superparasitization in parasitoid females. Both endosulfan and chlorpyrifos are neurotoxic and induce nervous system hyperstimulation. The fact that endosulfan does not trigger superparasitization, whereas chlorpyrifos does suggests that this effect is due to the specific pathway impacted by chlorpyrifos, the cholinergic nervous pathway. The consequences of these results in the context of awareness of environmental pollution by pesticides are discussed. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Jean-Marie Delpuech
- Université de Lyon, CNRS, Université Claude Bernard Lyon 1, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne, France
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10
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Delpuech JM. Elicitation of superparasitization behavior from the parasitoid wasp Leptopilina boulardi by the organophosphorus insecticide chlorpyrifos. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 580:907-911. [PMID: 28040222 DOI: 10.1016/j.scitotenv.2016.12.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 12/02/2016] [Accepted: 12/04/2016] [Indexed: 06/06/2023]
Abstract
Chlorpyrifos is an organophosphorus insecticide that largely contributes to environmental pollution. Parasitoids, as any other non-target species, can be exposed to insecticides through environmental pollution. Parasitoids are key species because they regulate natural populations of other insects. The hymenopterous parasitoid Leptopilina boulardi, whose larvae develop inside Drosophila larvae, is a solitary parasitoid; thus, only one larva can successfully develop per host. Therefore, females generally lay only one egg per host because any increase in the number of eggs laid will decrease its fitness. The effects of an LC20 of chlorpyrifos on the parasitization behavior of two strains (NS and S) of L. boulardi were evaluated. The NS and S strains were genetically identical but differed in that the S strain was infected by a virus, LbFV, which modifies the parasitization behavior of the parasitoid. In control conditions, parasitoid females from the NS strain rarely superparasitized (laid more than one egg per host) their host whereas females from the S strain frequently superparasitized their host. When parasitoids were exposed to an LC20 of chlorpyrifos, the rates of host larvae superparasitized by females and the mean numbers of eggs laid per host larva increased for both NS and S strains. Therefore, both the insecticide and the virus induced an increase in the superparasitization of the host. The effect of the insecticide on the superparasitization behavior of the parasitoid is discussed according to its mode of action.
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Affiliation(s)
- Jean-Marie Delpuech
- Université de Lyon, CNRS, Université Claude Bernard Lyon 1, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France.
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11
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Oliveira DS, Gomes TMFF, Loreto ELS. The rearranged mitochondrial genome of Leptopilina boulardi (Hymenoptera: Figitidae), a parasitoid wasp of Drosophila. Genet Mol Biol 2016; 39:611-615. [PMID: 27648767 PMCID: PMC5127158 DOI: 10.1590/1678-4685-gmb-2016-0062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 08/02/2016] [Indexed: 11/22/2022] Open
Abstract
The partial mitochondrial genome sequence of Leptopilina boulardi (Hymenoptera: Figitidae) was characterized. Illumina sequencing was used yielding 35,999,679 reads, from which 102,482 were utilized in the assembly. The length of the sequenced region of this partial mitochondrial genome is 15,417 bp, consisting of 13 protein-coding, two rRNA, and 21tRNA genes (the trnaM failed to be sequenced) and a partial A+T-rich region. All protein-coding genes start with ATN codons. Eleven protein-coding genes presented TAA stop codons, whereas ND6 and COII that presented TA, and T nucleotides, respectively. The gene pattern revealed extensive rearrangements compared to the typical pattern generally observed in insects. These rearrangements involve two protein-coding and two ribosomal genes, along with the 16 tRNA genes. This gene order is different from the pattern described for Ibalia leucospoides (Ibaliidae, Cynipoidea), suggesting that this particular gene order can be variable among Cynipoidea superfamily members. A maximum likelihood phylogenetic analysis of the main groups of Apocrita was performed using amino acid sequence of 13 protein-coding genes, showing monophyly for the Cynipoidea superfamily within the Hymenoptera phylogeny.
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Affiliation(s)
- Daniel S Oliveira
- Curso Ciências Biológicas, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Tiago M F F Gomes
- Curso Ciências Biológicas, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Elgion L S Loreto
- Departamento de Bioquímica e Biologia Molecular (CCNE), Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
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12
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Parratt SR, Frost CL, Schenkel MA, Rice A, Hurst GDD, King KC. Superparasitism Drives Heritable Symbiont Epidemiology and Host Sex Ratio in a Wasp. PLoS Pathog 2016; 12:e1005629. [PMID: 27322651 PMCID: PMC4920596 DOI: 10.1371/journal.ppat.1005629] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/22/2016] [Indexed: 02/06/2023] Open
Abstract
Heritable microbial symbionts have profound impacts upon the biology of their arthropod hosts. Whilst our current understanding of the dynamics of these symbionts is typically cast within a framework of vertical transmission only, horizontal transmission has been observed in a number of cases. For instance, several symbionts can transmit horizontally when their parasitoid hosts share oviposition patches with uninfected conspecifics, a phenomenon called superparasitism. Despite this, horizontal transmission, and the host contact structures that facilitates it, have not been considered in heritable symbiont epidemiology. Here, we tested for the importance of host contact, and resulting horizontal transmission, for the epidemiology of a male-killing heritable symbiont (Arsenophonus nasoniae) in parasitoid wasp hosts. We observed that host contact through superparasitism is necessary for this symbiont's spread in populations of its primary host Nasonia vitripennis, such that when superparasitism rates are high, A. nasoniae almost reaches fixation, causes highly female biased population sex ratios and consequently causes local host extinction. We further tested if natural interspecific variation in superparasitism behaviours predicted symbiont dynamics among parasitoid species. We found that A. nasoniae was maintained in laboratory populations of a closely related set of Nasonia species, but declined in other, more distantly related pteromalid hosts. The natural proclivity of a species to superparasitise was the primary factor determining symbiont persistence. Our results thus indicate that host contact behaviour is a key factor for heritable microbe dynamics when horizontal transmission is possible, and that 'reproductive parasite' phenotypes, such as male-killing, may be of secondary importance in the dynamics of such symbiont infections.
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Affiliation(s)
- Steven R. Parratt
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | - Crystal L. Frost
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Martijn A. Schenkel
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Annabel Rice
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Gregory D. D. Hurst
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Kayla C. King
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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13
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Martinez J, Lepetit D, Ravallec M, Fleury F, Varaldi J. Additional heritable virus in the parasitic wasp Leptopilina boulardi: prevalence, transmission and phenotypic effects. J Gen Virol 2016; 97:523-535. [DOI: 10.1099/jgv.0.000360] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Julien Martinez
- Université Lyon 1, CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Lyon, France
| | - David Lepetit
- Université Lyon 1, CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Lyon, France
| | - Marc Ravallec
- Unité BiVi (Biologie Intégrative et Virologie des Insectes), Université Montpellier II-INRA 1231, France
| | - Frédéric Fleury
- Université Lyon 1, CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Lyon, France
| | - Julien Varaldi
- Université Lyon 1, CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Lyon, France
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Martinez J, Fleury F, Varaldi J. Competitive outcome of multiple infections in a behavior-manipulating virus/wasp interaction. Ecol Evol 2015; 5:5934-45. [PMID: 26811766 PMCID: PMC4717342 DOI: 10.1002/ece3.1749] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 11/17/2022] Open
Abstract
Infections by multiple parasites are common in nature and may impact the evolution of host–parasite interactions. We investigated the existence of multiple infections involving the DNA virus LbFV and the Drosophila parasitoid Leptopilina boulardi. This vertically transmitted virus forces infected females to lay their eggs in already parasitized Drosophila larvae (a behavior called superparasitism), thus favoring its spread through horizontal transmission. Previous theoretical work indicated that the evolution of the level of the manipulation strongly depends on whether infected parasitoids can be re‐infected or not. Here, we describe a strain of LbFV that differs from the reference strain by showing a deletion within the locus used for PCR detection. We used this polymorphism to test for the existence of multiple infections in this system. Viral strains did not differ on their vertical or horizontal transmission rates nor on the way they affect the parasitoid's phenotype, including their ability to manipulate behavior. Although already infected parasitoids were much less susceptible to new infection than uninfected ones, frequent coinfection was detected. However, following coinfection, competition between viral strains led to the rapid elimination of one strain or the other after a few generations of vertical transmission. We discuss the implications of these results for the evolution of the behavioral manipulation.
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Affiliation(s)
- Julien Martinez
- Department of Genetics University of Cambridge Cambridge CB2 3EH UK
| | - Frédéric Fleury
- Laboratoire de Biométrie et Biologie Evolutive Université de Lyon69000 Lyon France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 5558 Université Lyon 169622 Villeurbanne France
| | - Julien Varaldi
- Laboratoire de Biométrie et Biologie Evolutive Université de Lyon69000 Lyon France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 5558 Université Lyon 169622 Villeurbanne France
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15
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Han Y, van Oers MM, van Houte S, Ros VID. Virus-Induced Behavioural Changes in Insects. HOST MANIPULATIONS BY PARASITES AND VIRUSES 2015. [DOI: 10.1007/978-3-319-22936-2_10] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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16
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van Houte S, Ros VID, van Oers MM. Walking with insects: molecular mechanisms behind parasitic manipulation of host behaviour. Mol Ecol 2013; 22:3458-75. [DOI: 10.1111/mec.12307] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 02/27/2013] [Accepted: 03/05/2013] [Indexed: 12/26/2022]
Affiliation(s)
- Stineke van Houte
- Laboratory of Virology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
| | - Vera I. D. Ros
- Laboratory of Virology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
| | - Monique M. van Oers
- Laboratory of Virology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
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17
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Patot S, Allemand R, Fleury F, Varaldi J. An inherited virus influences the coexistence of parasitoid species through behaviour manipulation. Ecol Lett 2012; 15:603-10. [PMID: 22487404 DOI: 10.1111/j.1461-0248.2012.01774.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The potential role of pathogens or parasites in maintaining species coexistence is well documented. However, the impact of vertically transmitted symbionts, that can markedly modify their host's biology, is largely unknown. Some females of the Drosophila parasitoid Leptopilina boulardi are infected with an inherited virus (LbFV). The virus forces females to lay supernumerary eggs in already parasitised hosts, thus allowing its horizontal transmission. Using two independent experimental procedures, we found that LbFV impacts inter-specific competition between L. boulardi and the related L. heterotoma. While L. boulardi rapidly outcompetes L. heterotoma in the absence of the virus, L. heterotoma was able to maintain or even to eliminate L. boulardi in the presence of LbFV. By forcing females to superparasitise, LbFV induced egg wastage in L. boulardi thus explaining its impact on the competition outcome. We conclude that this symbiont whose transmission is L. boulardi-density-dependant may affect the coexistence of Leptopilina species.
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Affiliation(s)
- Sabine Patot
- Laboratoire de Bactériologie, Faculté de Médecine Lyon Est, site Laennec, INSERM U851, Rue Guillaume Paradin, Université de Lyon, Lyon, France
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18
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MARTINEZ J, FLEURY F, VARALDI J. Heritable variation in an extended phenotype: the case of a parasitoid manipulated by a virus. J Evol Biol 2011; 25:54-65. [DOI: 10.1111/j.1420-9101.2011.02405.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Patot S, Martinez J, Allemand R, Gandon S, Varaldi J, Fleury F. Prevalence of a virus inducing behavioural manipulation near species range border. Mol Ecol 2010; 19:2995-3007. [PMID: 20565576 DOI: 10.1111/j.1365-294x.2010.04686.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The densities of conspecific individuals may vary through space, especially at the edge of species range. This variation in density is predicted to influence the diffusion of species-specific horizontally transmitted symbionts. However, to date there is very little data on how parasite prevalence varies around the border of a host species. Using a molecular epidemiology approach, we studied the prevalence of a vertically and horizontally transmitted virus at the edge of the geographic range of its insect host, the Drosophila parasitoid wasp Leptopilina boulardi. L. boulardi is a Mediterranean parasitoid species showing a recent range expansion to the north (in France). The LbFV virus manipulates the behaviour of females, increasing their tendency to lay additional eggs in already parasitized Drosophila larvae (superparasitism). This is beneficial for the virus because it allows the virus to be horizontally transferred during superparasitism. We show that LbFV prevalence is very high in central populations, intermediate in marginal populations and almost absent from newly established peripheral populations of L. boulardi. We failed to detect any influence of temperature and diapause on viral transmission efficiency but we observed a clear relationship between prevalence and parasitoid density, and between parasitoid density and the occurrence of superparasitism, as predicted by our epidemiological model. Viral strains were all efficient at inducing the behavioural manipulation and viral gene sequencing revealed very low sequence variation. We conclude that the prevalence reached by the virus critically depends on density-dependent factors, i.e. superparasitism, underlying the selective pressures acting on the virus to manipulate the behaviour of the parasitoid.
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Affiliation(s)
- S Patot
- Université de Lyon; F-69000, Lyon, France.
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20
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Varaldi J, Patot S, Nardin M, Gandon S. A virus-shaping reproductive strategy in a Drosophila parasitoid. ADVANCES IN PARASITOLOGY 2009; 70:333-63. [PMID: 19773077 DOI: 10.1016/s0065-308x(09)70013-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Insect parasitoids are often infected with heritable viruses. Some of them, such as polydnaviruses, have evolved toward an obligatory relationship with the parasitoid because they are necessary to protect the parasitoid egg from the host immune reaction. However, recent and past discoveries have revealed the presence of facultative inherited viruses in parasitoids for which no clear phenotypic effect was observed. In this chapter, we present how such an inherited virus was recently discovered in the Drosophila parasitoid, Leptopilina boulardi. We show that this virus is responsible for an increase in the superparasitism tendency of the infected females. This alteration is beneficial for the virus, since superparasitism conditions permit the horizontal transmission of the virus. We review theoretical developments suggesting that this leads to a conflict of interest between the parasitoid and the virus. The direct and indirect influence of the virus on several other fitness traits has also been studied both empirically and theoretically, in particular the egg load. Finally, because the frequency of horizontal transmission is a crucial parameter for the evolution of the superparasitism manipulation, we present an attempt to select the virus for high or low manipulation intensity.
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Affiliation(s)
- Julien Varaldi
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR 5558, F-69622 Villeurbanne, France
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21
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Thiel A, Hoffmeister TS. Decision-making dynamics in parasitoids of Drosophila. ADVANCES IN PARASITOLOGY 2009; 70:45-66. [PMID: 19773066 DOI: 10.1016/s0065-308x(09)70002-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Drosophilids and their associated parasitoids live in environments that vary in resource availability and quality within and between generations. The use of information to adapt behavior to the current environment is a key feature under such circumstances and Drosophila parasitic wasps are excellent model systems to study learning and information use. They are among the few parasitoid model species that have been tested in a wide array of situations. Moreover, several related species have been tested under similar conditions, allowing the analysis of within and between species variability, the effect of natural selection in a typical environment, the current physiological status, and previous experience of the individual. This holds for host habitat and host location as well as for host choice and search time allocation. Here, we review patterns of learning and memory, of information use and updating mechanisms, and we point out that information use itself is under strong selective pressure and thus, optimized by parasitic wasps.
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Affiliation(s)
- Andra Thiel
- Institute of Ecology, University of Bremen, FB 02, D-28359 Bremen, Germany
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22
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Fleury F, Gibert P, Ris N, Allemand R. Ecology and life history evolution of frugivorous Drosophila parasitoids. ADVANCES IN PARASITOLOGY 2009; 70:3-44. [PMID: 19773065 DOI: 10.1016/s0065-308x(09)70001-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Parasitoids and their hosts are linked by intimate and harmful interactions that make them well suited to analyze fundamental ecological and evolutionary processes with regard to life histories evolution of parasitic association. Drosophila aspects of what parasitoid Hymenoptera have become model organisms to study aspects that cannot be investigated with other associations. These include the genetic bases of fitness traits variations, physiology and genetics of resistance/virulence, and coevolutionary dynamics leading to local adaptation. Recent research on evolutionary ecology of Drosophila parasitoids were performed mainly on species that thrive in fermenting fruits (genera Leptopilina and Asobara). Here, we review information and add original data regarding community ecology of these parasitoids, including species distribution, pattern of abundance and diversity, host range and the nature and intensity of species interactions. Biology and the evolution of life histories in response to habitat heterogeneity and possible local adaptations leading to specialization of these wasps are reported with special emphasis on species living in southern Europe. We expose the diversity and intensity of selective constraints acting on parasitoid life history traits, which vary geographically and highlight the importance of considering both biotic and abiotic factors with their interactions to understand ecological and evolutionary dynamics of host-parasitoid associations.
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Affiliation(s)
- Frédéric Fleury
- Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France
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23
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Lee MJ, Kalamarz ME, Paddibhatla I, Small C, Rajwani R, Govind S. Virulence factors and strategies of Leptopilina spp.: selective responses in Drosophila hosts. ADVANCES IN PARASITOLOGY 2009; 70:123-45. [PMID: 19773069 DOI: 10.1016/s0065-308x(09)70005-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
To ensure survival, parasitic wasps of Drosophila have evolved strategies to optimize host development to their advantage. They also produce virulence factors that allow them to overcome or evade host defense. Wasp infection provokes cellular and humoral defense reactions, resulting in alteration in gene expression of the host. The activation of these reactions is controlled by conserved mechanisms shared by other invertebrate and vertebrate animals. Application of genomics and bioinformatics approaches is beginning to reveal comparative host gene expression changes after infection by different parasitic wasps. We analyze this comparison in the context of host physiology and immune cells, as well as the biology of the venom factors that wasps introduce into their hosts during oviposition. We compare virulence strategies of Leptopilina boulardi and L. heterotoma, in relation to genome-wide changes in gene expression in the fly hosts after infection. This analysis highlights fundamental differences in the changes that the host undergoes in its immune and general physiology in response to the two parasitic wasps. Such a comparative approach has the potential of revealing mechanisms governing the evolution of pathogenicity and how it impacts host range.
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Affiliation(s)
- Mark J Lee
- Department of Biology, City College of New York, New York, NY 10031, USA
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24
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Gandon S, Varaldi J, Fleury F, Rivero A. EVOLUTION AND MANIPULATION OF PARASITOID EGG LOAD. Evolution 2009; 63:2974-84. [DOI: 10.1111/j.1558-5646.2009.00776.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Ferrarese R, Morales J, Fimiarz D, Webb BA, Govind S. A supracellular system of actin-lined canals controls biogenesis and release of virulence factors in parasitoid venom glands. ACTA ACUST UNITED AC 2009; 212:2261-8. [PMID: 19561216 DOI: 10.1242/jeb.025718] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Parasitoid wasps produce virulence factors that bear significant resemblance to viruses and have the ability to block host defense responses. The function of these virulence factors, produced predominantly in wasp venom glands, and the ways in which they interfere with host development and physiology remain mysterious. Here, we report the discovery of a specialized system of canals in venom glands of five parasitoid wasps that differ in their infection strategies. This supracellular canal system is made up of individual secretory units, one per secretory cell. Individual units merge into the canal lumen. The membrane surface of the proximal end of each canal within the secretory cell assumes brush border morphology, lined with bundles of F-actin. Systemic administration of cytochalasin D compromises the integrity of the secretory unit. We show a dynamic and continuous association of p40, a protein of virus-like particles from a Drosophila parasitoid, L. heterotoma, with the canal and venom gland lumen. Similar structures in three Leptopilina species and Ganaspis xanthopoda, parasitoids of Drosophila spp., and Campoletis sonorenesis, a parasitoid of Heliothis virescens, suggest that this novel supracellular canal system is likely to be a common trait of parasitoid venom glands that is essential for efficient biogenesis and delivery of virulence factors.
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Affiliation(s)
- Roberto Ferrarese
- Biology Department MR526, City College of the City University of New York, 138th street and Convent Avenue, New York, NY 10031, USA
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26
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Differential use of conspecific-derived information by sexual and asexual parasitic wasps exploiting partially depleted host patches. Behav Ecol Sociobiol 2008. [DOI: 10.1007/s00265-008-0691-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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27
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Molecular detection, penetrance, and transmission of an inherited virus responsible for behavioral manipulation of an insect parasitoid. Appl Environ Microbiol 2008; 75:703-10. [PMID: 19060167 DOI: 10.1128/aem.01778-08] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For insects, the prevalence of numerous vertically transmitted viruses can be high in their host populations. These viruses often have few, if any, pathological effects on their hosts, and consequently, many of them can remain unnoticed for long periods, despite their potential role in the evolution of the host phenotype. Some females of Leptopilina boulardi, a solitary parasitoid of Drosophila larvae, are infected by an inherited virus (LbFV) that manipulates the behavior of the wasp by increasing its tendency to lay eggs in a host that is already parasitized (superparasitism). This behavioral alteration allows horizontal transmission of the virus within superparasitized Drosophila larvae. Using suppressive subtractive hybridization with infected and uninfected lines, we identified one putative viral sequence. Based on this sequence, we developed a simple PCR test. We tested the correlation between the superparasitism phenotype and PCR amplification of the putative viral marker using several experimental conditions (including horizontal transfers) and several parasitoid genotypes. All of the results revealed that there was a perfect match between the superparasitism phenotype and the amplification profile, which validated use of the molecular marker as a tool to track the presence of the virus and provided the first genomic data for this fascinating virus. The results also show that there was very efficient horizontal and vertical transmission of LbFV, which probably explains its high prevalence in the French populations that we sampled (67 and 70% of infected females). This manipulative virus is likely to play a major role in the ecology and evolution of its parasitoid host.
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28
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Lagrue C, Kaldonski N, Perrot-Minnot MJ, Motreuil S, Bollache L. MODIFICATION OF HOSTS' BEHAVIOR BY A PARASITE: FIELD EVIDENCE FOR ADAPTIVE MANIPULATION. Ecology 2007; 88:2839-47. [DOI: 10.1890/06-2105.1] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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29
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Varaldi J, Ravallec M, Labrosse C, Lopez-Ferber M, Boulétreau M, Fleury F. Artifical transfer and morphological description of virus particles associated with superparasitism behaviour in a parasitoid wasp. JOURNAL OF INSECT PHYSIOLOGY 2006; 52:1202-12. [PMID: 17070831 DOI: 10.1016/j.jinsphys.2006.09.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 09/05/2006] [Accepted: 09/05/2006] [Indexed: 05/12/2023]
Abstract
In parasitoids, the adaptive significance of superparasitism (laying of egg(s) in already parasitized hosts) has been the subject of strong controversy. The current view is to interpret this behaviour as an adaptation to increased competition for hosts, because the supernumerary egg still has a chance to win possession for the host. However, we recently discovered that in the solitary parasitoid Leptopilina boulardi, superparasitism is rather caused by an unknown infectious element: stable non superparasitizing lineages (NS) are transformed into stable superparasitizing lineages (S) after eggs from both lineages have competed inside the same host (superparasitism). In this report, we investigate the nature and location of the causative agent. Involvement of bacteria is unlikely because antibiotic treatments do not affect wasp phenotype and because bacterial 16S ribosomal DNA was not detected using PCR. We report successful injection experiments showing that the causative agents are located in wasp poison gland and ovaries and are stably inherited. Electron microscopic studies demonstrate that long filamentous virus particles located in wasp oviducts are strongly associated with superparasitism behaviour, leading to reconsider the adaptive significance of this behaviour in parasitoids. Interestingly, parasitoids are often infected with similar viruses for which no phenotypic effect has been documented. This raises the possibility that they could induce the same behavioural manipulation.
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Affiliation(s)
- Julien Varaldi
- Laboratoire de Biométrie et Biologie Evolutive (UMR 5558);CNRS; Université Lyon 1, 43 bd 11 nov, 69622, Villeurbanne Cedex, France.
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