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Phylogeny and Density Dynamics of Wolbachia Infection of the Health Pest Paederus fuscipes Curtis (Coleoptera: Staphylinidae). INSECTS 2020; 11:insects11090625. [PMID: 32932887 PMCID: PMC7564247 DOI: 10.3390/insects11090625] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/08/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022]
Abstract
The maternally inherited obligate intracellular bacteria Wolbachia infects the reproductive tissues of a wide range of arthropods and affects host reproduction. Wolbachia is a credible biocontrol agent for reducing the impact of diseases associated with arthropod vectors. Paederus fuscipes is a small staphylinid beetle that causes dermatitis linearis and conjunctivitis in humans when they come into contact with skin. Wolbachia occur in this beetle, but their relatedness to other Wolbachia, their infection dynamics, and their potential host effects remain unknown. In this study, we report the phylogenetic position and density dynamics of Wolbachia in P. fuscipes. The phylogeny of Wolbachia based on an analysis of MLST genotyping showed that the bacteria from P. fuscipes belong to supergroup B. Quantitative PCR indicated that the infection density in adults was higher than in any other life stage (egg, larva or pupa), and that reproductive tissue in adults had the highest infection densities, with similar densities in the sexes. These findings provide a starting point for understanding the Wolbachia infection dynamics in P. fuscipes, and interactions with other components of the microbiota.
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52
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Raza MF, Yao Z, Bai S, Cai Z, Zhang H. Tephritidae fruit fly gut microbiome diversity, function and potential for applications. BULLETIN OF ENTOMOLOGICAL RESEARCH 2020; 110:423-437. [PMID: 32041675 DOI: 10.1017/s0007485319000853] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The family Tephritidae (order: Diptera), commonly known as fruit flies, comprises a widely distributed group of agricultural pests. The tephritid pests infest multiple species of fruits and vegetables, resulting in huge crop losses. Here, we summarize the composition and diversity of tephritid gut-associated bacteria communities and host intrinsic and environmental factors that influence the microbiome structures. Diverse members of Enterobacteriaceae, most commonly Klebsiella and Enterobacter bacteria, are prevalent in fruit flies guts. Roles played by gut bacteria in host nutrition, development, physiology and resistance to insecticides and pathogens are also addressed. This review provides an overview of fruit fly microbiome structure and points to diverse roles that it can play in fly physiology and survival. It also considers potential use of this knowledge for the control of economically important fruit flies, including the sterile insect technique and cue-lure baiting.
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Affiliation(s)
- Muhammad Fahim Raza
- State Key Laboratory of Agricultural Microbiology, Key Laboratory of Horticultural Plant Biology (MOE), China-Australia Joint Research Centre for Horticultural and Urban Pests, Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Zhichao Yao
- State Key Laboratory of Agricultural Microbiology, Key Laboratory of Horticultural Plant Biology (MOE), China-Australia Joint Research Centre for Horticultural and Urban Pests, Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Shuai Bai
- State Key Laboratory of Agricultural Microbiology, Key Laboratory of Horticultural Plant Biology (MOE), China-Australia Joint Research Centre for Horticultural and Urban Pests, Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Zhaohui Cai
- State Key Laboratory of Agricultural Microbiology, Key Laboratory of Horticultural Plant Biology (MOE), China-Australia Joint Research Centre for Horticultural and Urban Pests, Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Hongyu Zhang
- State Key Laboratory of Agricultural Microbiology, Key Laboratory of Horticultural Plant Biology (MOE), China-Australia Joint Research Centre for Horticultural and Urban Pests, Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
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53
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Hague MTJ, Mavengere H, Matute DR, Cooper BS. Environmental and Genetic Contributions to Imperfect wMel-Like Wolbachia Transmission and Frequency Variation. Genetics 2020; 215:1117-1132. [PMID: 32546497 PMCID: PMC7404227 DOI: 10.1534/genetics.120.303330] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/13/2020] [Indexed: 12/11/2022] Open
Abstract
Maternally transmitted Wolbachia bacteria infect about half of all insect species. They usually show imperfect maternal transmission and often produce cytoplasmic incompatibility (CI). Irrespective of CI, Wolbachia frequencies tend to increase when rare only if they benefit host fitness. Several Wolbachia, including wMel that infects Drosophila melanogaster, cause weak or no CI and persist at intermediate frequencies. On the island of São Tomé off West Africa, the frequencies of wMel-like Wolbachia infecting Drosophila yakuba (wYak) and Drosophila santomea (wSan) fluctuate, and the contributions of imperfect maternal transmission, fitness effects, and CI to these fluctuations are unknown. We demonstrate spatial variation in wYak frequency and transmission on São Tomé. Concurrent field estimates of imperfect maternal transmission do not predict spatial variation in wYak frequencies, which are highest at high altitudes where maternal transmission is the most imperfect. Genomic and genetic analyses provide little support for D. yakuba effects on wYak transmission. Instead, rearing at cool temperatures reduces wYak titer and increases imperfect transmission to levels observed on São Tomé. Using mathematical models of Wolbachia frequency dynamics and equilibria, we infer that temporally variable imperfect transmission or spatially variable effects on host fitness and reproduction are required to explain wYak frequencies. In contrast, spatially stable wSan frequencies are plausibly explained by imperfect transmission, modest fitness effects, and weak CI. Our results provide insight into causes of wMel-like frequency variation in divergent hosts. Understanding this variation is crucial to explain Wolbachia spread and to improve wMel biocontrol of human disease in transinfected mosquito systems.
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Affiliation(s)
- Michael T J Hague
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812
| | - Heidi Mavengere
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Daniel R Matute
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Brandon S Cooper
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812
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54
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Phenotypic Response of Wolbachia pipientis in a Cell-Free Medium. Microorganisms 2020; 8:microorganisms8071060. [PMID: 32708688 PMCID: PMC7409048 DOI: 10.3390/microorganisms8071060] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/30/2020] [Accepted: 07/14/2020] [Indexed: 12/22/2022] Open
Abstract
Wolbachia, an obligate intracellular bacterium estimated to infect millions of arthropod species worldwide, is currently being utilized in novel control strategies to limit the transmission of Dengue and Zika viruses. A limitation for Wolbachia-based control approaches is the difficulty of transferring Wolbachia to novel hosts and the lack of tools for the genetic transformation of Wolbachia due to the inability to culture Wolbachia outside the insect host cell in an axenic media. Here, we applied extracellular Wolbachia to phenotypic microarrays to measure the metabolic response of Wolbachia in media formulations with different pH levels and supplementation with Casamino acids. Results suggested a pH of 6.5–6.8 and showed that the supplementation of 1 mg/mL casamino acids increased the survival and longevity of Wolbachia in an axenic medium. In addition, phenotypic microarrays are a useful tool to measure the phenotypic response of Wolbachia under different media conditions, as well as determine specific components that may be required for an axenic medium. This study is an initial step toward the development of a potential Wolbachia axenic culture system.
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55
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The role of increased gonotrophic cycles in the establishment of Wolbachia in Anopheles populations. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00457-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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56
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Singh R, Linksvayer TA. Wolbachia-infected ant colonies have increased reproductive investment and an accelerated life cycle. J Exp Biol 2020; 223:jeb220079. [PMID: 32253286 DOI: 10.1242/jeb.220079] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 03/26/2020] [Indexed: 12/31/2022]
Abstract
Wolbachia is a widespread genus of maternally transmitted endosymbiotic bacteria that often manipulates the reproductive strategy and life history of its hosts to favor its own transmission. Wolbachia-mediated phenotypic effects are well characterized in solitary hosts, but effects in social hosts are unclear. The invasive pharaoh ant, Monomorium pharaonis, shows natural variation in Wolbachia infection between colonies and can be readily bred under laboratory conditions. We previously showed that Wolbachia-infected pharaoh ant colonies had more queen-biased sex ratios than uninfected colonies, which is expected to favor the spread of maternally transmitted Wolbachia Here, we further characterize the effects of Wolbachia on the short- and longer-term reproductive and life history traits of pharaoh ant colonies. First, we characterized the reproductive differences between naturally infected and uninfected colonies at three discrete time points and found that infected colonies had higher reproductive investment (i.e. infected colonies produced more new queens), particularly when existing colony queens were 3 months old. Next, we compared the long-term growth and reproduction dynamics of infected and uninfected colonies across their whole life cycle. Infected colonies had increased colony-level growth and early colony reproduction, resulting in a shorter colony life cycle, when compared with uninfected colonies.
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Affiliation(s)
- Rohini Singh
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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57
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Zélé F, Santos I, Matos M, Weill M, Vavre F, Magalhães S. Endosymbiont diversity in natural populations of Tetranychus mites is rapidly lost under laboratory conditions. Heredity (Edinb) 2020; 124:603-617. [PMID: 32047292 PMCID: PMC7080723 DOI: 10.1038/s41437-020-0297-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 01/24/2020] [Accepted: 01/24/2020] [Indexed: 01/30/2023] Open
Abstract
Although the diversity of bacterial endosymbionts in arthropods is well documented, whether and how such diversity is maintained remains an open question. We investigated the temporal changes occurring in the prevalence and composition of endosymbionts after transferring natural populations of Tetranychus spider mites from the field to the laboratory. These populations, belonging to three different Tetranychus species (T. urticae, T. ludeni and T. evansi) carried variable infection frequencies of Wolbachia, Cardinium, and Rickettsia. We report a rapid change of the infection status of these populations after only 6 months of laboratory rearing, with an apparent loss of Rickettsia and Cardinium, while Wolbachia apparently either reached fixation or was lost. We show that Wolbachia had variable effects on host longevity and fecundity, and induced variable levels of cytoplasmic incompatibility (CI) in each fully infected population, despite no sequence divergence in the markers used and full CI rescue between all populations. This suggests that such effects are largely dependent upon the host genotype. Subsequently, we used these data to parameterize a theoretical model for the invasion of CI-inducing symbionts in haplodiploids, which shows that symbiont effects are sufficient to explain their dynamics in the laboratory. This further suggests that symbiont diversity and prevalence in the field are likely maintained by environmental heterogeneity, which is reduced in the laboratory. Overall, this study highlights the lability of endosymbiont infections and draws attention to the limitations of laboratory studies to understand host-symbiont interactions in natural populations.
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Affiliation(s)
- Flore Zélé
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Edificio C2, Piso-3 Campo Grande, 1749016, Lisbon, Portugal.
| | - Inês Santos
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Edificio C2, Piso-3 Campo Grande, 1749016, Lisbon, Portugal
| | - Margarida Matos
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Edificio C2, Piso-3 Campo Grande, 1749016, Lisbon, Portugal
| | - Mylène Weill
- Institut des Sciences de l'Evolution (CNRS-Université de Montpellier-IRD-EPHE), 34095, CEDEX 5, Montpellier, France
| | - Fabrice Vavre
- CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, Université Lyon 1, Université de Lyon, F-69622, Villeurbanne, France
| | - Sara Magalhães
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Edificio C2, Piso-3 Campo Grande, 1749016, Lisbon, Portugal
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58
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Mancini MV, Herd CS, Ant TH, Murdochy SM, Sinkins SP. Wolbachia strain wAu efficiently blocks arbovirus transmission in Aedes albopictus. PLoS Negl Trop Dis 2020; 14:e0007926. [PMID: 32155143 PMCID: PMC7083328 DOI: 10.1371/journal.pntd.0007926] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/20/2020] [Accepted: 01/17/2020] [Indexed: 12/22/2022] Open
Abstract
The global incidence of arboviral diseases transmitted by Aedes mosquitoes, including dengue, chikungunya, yellow fever, and Zika, has increased dramatically in recent decades. The release of Aedes aegypti carrying the maternally inherited symbiont Wolbachia as an intervention to control arboviruses is being trialled in several countries. However, these efforts are compromised in many endemic regions due to the co-localization of the secondary vector Aedes albopictus, the Asian tiger mosquito. Ae. albopictus has an expanding global distribution following incursions into a number of new territories. To date, only the wMel and wPip strains of Wolbachia have been reported to be transferred into and characterized in this vector. A Wolbachia strain naturally infecting Drosophila simulans, wAu, was selected for transfer into a Malaysian Ae. albopictus line to create a novel triple-strain infection. The newly generated line showed self-compatibility, moderate fitness cost and complete resistance to Zika and dengue infections.
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Affiliation(s)
| | - Christie S. Herd
- MRC- University of Glasgow- Centre for Virus Research, Glasgow, United Kingdom
| | - Thomas H. Ant
- MRC- University of Glasgow- Centre for Virus Research, Glasgow, United Kingdom
| | - Shivan M. Murdochy
- MRC- University of Glasgow- Centre for Virus Research, Glasgow, United Kingdom
| | - Steven P. Sinkins
- MRC- University of Glasgow- Centre for Virus Research, Glasgow, United Kingdom
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59
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Ross PA, Callahan AG, Yang Q, Jasper M, Arif MAK, Afizah AN, Nazni WA, Hoffmann AA. An elusive endosymbiont: Does Wolbachia occur naturally in Aedes aegypti? Ecol Evol 2020; 10:1581-1591. [PMID: 32076535 PMCID: PMC7029055 DOI: 10.1002/ece3.6012] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 02/06/2023] Open
Abstract
Wolbachia are maternally inherited endosymbiotic bacteria found within many insect species. Aedes mosquitoes experimentally infected with Wolbachia are being released into the field for Aedes-borne disease control. These Wolbachia infections induce cytoplasmic incompatibility which is used to suppress populations through incompatible matings or replace populations through the reproductive advantage provided by this mechanism. However, the presence of naturally occurring Wolbachia in target populations could interfere with both population replacement and suppression programs depending on the compatibility patterns between strains. Aedes aegypti were thought to not harbor Wolbachia naturally but several recent studies have detected Wolbachia in natural populations of this mosquito. We therefore review the evidence for natural Wolbachia infections in A. aegypti to date and discuss limitations of these studies. We draw on research from other mosquito species to outline the potential implications of natural Wolbachia infections in A. aegypti for disease control. To validate previous reports, we obtained a laboratory population of A. aegypti from New Mexico, USA, that harbors a natural Wolbachia infection, and we conducted field surveys in Kuala Lumpur, Malaysia, where a natural Wolbachia infection has also been reported. However, we were unable to detect Wolbachia in both the laboratory and field populations. Because the presence of naturally occurring Wolbachia in A. aegypti could have profound implications for Wolbachia-based disease control programs, it is important to continue to accurately assess the Wolbachia status of target Aedes populations.
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Affiliation(s)
- Perran A Ross
- Pest and Environmental Adaptation Research Group School of BioSciences Bio21 Institute The University of Melbourne Parkville Victoria Australia
| | - Ashley G Callahan
- Pest and Environmental Adaptation Research Group School of BioSciences Bio21 Institute The University of Melbourne Parkville Victoria Australia
| | - Qiong Yang
- Pest and Environmental Adaptation Research Group School of BioSciences Bio21 Institute The University of Melbourne Parkville Victoria Australia
| | - Moshe Jasper
- Pest and Environmental Adaptation Research Group School of BioSciences Bio21 Institute The University of Melbourne Parkville Victoria Australia
| | - Mohd A K Arif
- Institute for Medical Research Kuala Lumpur Malaysia
| | | | - Wasi A Nazni
- Institute for Medical Research Kuala Lumpur Malaysia
| | - Ary A Hoffmann
- Pest and Environmental Adaptation Research Group School of BioSciences Bio21 Institute The University of Melbourne Parkville Victoria Australia
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60
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Bockoven AA, Bondy EC, Flores MJ, Kelly SE, Ravenscraft AM, Hunter MS. What Goes Up Might Come Down: the Spectacular Spread of an Endosymbiont Is Followed by Its Decline a Decade Later. MICROBIAL ECOLOGY 2020; 79:482-494. [PMID: 31407021 DOI: 10.1007/s00248-019-01417-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
Facultative, intracellular bacterial symbionts of arthropods may dramatically affect host biology and reproduction. The length of these symbiont-host associations may be thousands to millions of years, and while symbiont loss is predicted, there have been very few observations of a decline of symbiont infection rates. In a population of the sweet potato whitefly species (Bemisia tabaci MEAM1) in Arizona, USA, we documented the frequency decline of a strain of Rickettsia in the Rickettsia bellii clade from near-fixation in 2011 to 36% of whiteflies infected in 2017. In previous studies, Rickettsia had been shown to increase from 1 to 97% from 2000 to 2006 and remained at high frequency for at least five years. At that time, Rickettsia infection was associated with both fitness benefits and female bias. In the current study, we established matrilines of whiteflies from the field (2016, Rickettsia infection frequency = 58%) and studied (a) Rickettsia vertical transmission, (b) fitness and sex ratios associated with Rickettsia infection, (c) symbiont titer, and (d) bacterial communities within whiteflies. The vertical transmission rate was high, approximately 98%. Rickettsia infection in the matrilines was not associated with fitness benefits or sex ratio bias and appeared to be slightly costly, as more Rickettsia-infected individuals produced non-hatching eggs. Overall, the titer of Rickettsia in the matrilines was lower in 2016 than in the whiteflies collected in 2011, but the titer distribution appeared bimodal, with high- and low-titer lines, and constancy of the average titer within lines over three generations. We found neither association between Rickettsia titer and fitness benefits or sex ratio bias nor evidence that Rickettsia was replaced by another secondary symbiont. The change in the interaction between symbiont and host in 2016 whiteflies may explain the drop in symbiont frequency we observed.
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Affiliation(s)
- Alison A Bockoven
- Center for Insect Science, The University of Arizona, P.O. Box 210106, Tucson, AZ, 85721, USA
| | - Elizabeth C Bondy
- Graduate Interdisciplinary Program in Entomology and Insect Science, The University of Arizona, P.O. Box 210036, Tucson, AZ, 85721, USA
| | - Matthew J Flores
- Department of Biological Sciences, Virginia Tech University, Derring Hall Room 2125, 926 West Campus Drive, Mail Code 0406, Blacksburg, VA, 24061, USA
| | - Suzanne E Kelly
- Department of Entomology, The University of Arizona, 410 Forbes Building, Tucson, AZ, 85721, USA
| | - Alison M Ravenscraft
- Center for Insect Science, The University of Arizona, P.O. Box 210106, Tucson, AZ, 85721, USA
- Department of Biology, University of Texas at Arlington, 501 S Nedderman Dr, Arlington, TX, 76019, USA
| | - Martha S Hunter
- Department of Entomology, The University of Arizona, 410 Forbes Building, Tucson, AZ, 85721, USA.
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61
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Martinez J, Bruner-Montero G, Arunkumar R, Smith SCL, Day JP, Longdon B, Jiggins FM. Virus evolution in Wolbachia-infected Drosophila. Proc Biol Sci 2019; 286:20192117. [PMID: 31662085 PMCID: PMC6823055 DOI: 10.1098/rspb.2019.2117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 10/08/2019] [Indexed: 12/30/2022] Open
Abstract
Wolbachia, a common vertically transmitted symbiont, can protect insects against viral infection and prevent mosquitoes from transmitting viral pathogens. For this reason, Wolbachia-infected mosquitoes are being released to prevent the transmission of dengue and other arboviruses. An important question for the long-term success of these programmes is whether viruses can evolve to escape the antiviral effects of Wolbachia. We have found that Wolbachia altered the outcome of competition between strains of the DCV virus in Drosophila. However, Wolbachia still effectively blocked the virus genotypes that were favoured in the presence of the symbiont. We conclude that Wolbachia did cause an evolutionary response in viruses, but this has little or no impact on the effectiveness of virus blocking.
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Affiliation(s)
- Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, UK
| | | | | | | | - Jonathan P. Day
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge, UK
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
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62
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Abstract
Wolbachia is an endosymbiotic Alphaproteobacteria that can suppress insect-borne diseases through decreasing host virus transmission (population replacement) or through decreasing host population density (population suppression). We contrast natural Wolbachia infections in insect populations with Wolbachia transinfections in mosquitoes to gain insights into factors potentially affecting the long-term success of Wolbachia releases. Natural Wolbachia infections can spread rapidly, whereas the slow spread of transinfections is governed by deleterious effects on host fitness and demographic factors. Cytoplasmic incompatibility (CI) generated by Wolbachia is central to both population replacement and suppression programs, but CI in nature can be variable and evolve, as can Wolbachia fitness effects and virus blocking. Wolbachia spread is also influenced by environmental factors that decrease Wolbachia titer and reduce maternal Wolbachia transmission frequency. More information is needed on the interactions between Wolbachia and host nuclear/mitochondrial genomes, the interaction between invasion success and local ecological factors, and the long-term stability of Wolbachia-mediated virus blocking.
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Affiliation(s)
- Perran A Ross
- Pest and Environmental Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Victoria 3052, Australia
| | - Michael Turelli
- Department of Evolution and Ecology, University of California, Davis, California 95616, USA;
| | - Ary A Hoffmann
- Pest and Environmental Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Victoria 3052, Australia
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63
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Treanor D, Hughes WOH. Limited female dispersal predicts the incidence of Wolbachia across ants (Hymenoptera: Formicidae). J Evol Biol 2019; 32:1163-1170. [PMID: 31334893 DOI: 10.1111/jeb.13510] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 06/14/2019] [Accepted: 07/01/2019] [Indexed: 01/13/2023]
Abstract
The endosymbiotic bacterium Wolbachia is perhaps the greatest panzootic in the history of life on Earth, yet remarkably little is known regarding the factors that determine its incidence across species. One possibility is that Wolbachia more easily invades species with structured populations, due to the increased strength of genetic drift and higher initial frequency of infection. This should enable strains that induce mating incompatibilities to more easily cross the threshold prevalence above which they spread to either fixation or a stable equilibrium infection prevalence. Here, we provide empirical support for this hypothesis by analysing the relationship between female dispersal (as a proxy for population structure) and the incidence of Wolbachia across 250 species of ants. We show that species in which the dispersal of reproductive females is limited are significantly more likely to be infected with Wolbachia than species whose reproductive ecology is consistent with significant dispersal of females, and that this relationship remains after controlling for host phylogeny. We suggest that structured host populations, in this case resulting from limited female dispersal, may be an important feature determining how easily Wolbachia becomes successfully established in a novel host, and thus its occurrence across a wide diversity of invertebrate hosts.
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Affiliation(s)
- David Treanor
- School of Life Sciences, University of Sussex, Brighton, UK
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64
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Cooper BS, Vanderpool D, Conner WR, Matute DR, Turelli M. Wolbachia Acquisition by Drosophila yakuba-Clade Hosts and Transfer of Incompatibility Loci Between Distantly Related Wolbachia. Genetics 2019; 212:1399-1419. [PMID: 31227544 PMCID: PMC6707468 DOI: 10.1534/genetics.119.302349] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 06/04/2019] [Indexed: 12/14/2022] Open
Abstract
Maternally transmitted Wolbachia infect about half of insect species, yet the predominant mode(s) of Wolbachia acquisition remains uncertain. Species-specific associations could be old, with Wolbachia and hosts codiversifying (i.e., cladogenic acquisition), or relatively young and acquired by horizontal transfer or introgression. The three Drosophila yakuba-clade hosts [(D. santomea, D. yakuba) D. teissieri] diverged ∼3 MYA and currently hybridize on the West African islands Bioko and São Tomé. Each species is polymorphic for nearly identical Wolbachia that cause weak cytoplasmic incompatibility (CI)-reduced egg hatch when uninfected females mate with infected males. D. yakuba-clade Wolbachia are closely related to wMel, globally polymorphic in D. melanogaster We use draft Wolbachia and mitochondrial genomes to demonstrate that D. yakuba-clade phylogenies for Wolbachia and mitochondria tend to follow host nuclear phylogenies. However, roughly half of D. santomea individuals, sampled both inside and outside of the São Tomé hybrid zone, have introgressed D. yakuba mitochondria. Both mitochondria and Wolbachia possess far more recent common ancestors than the bulk of the host nuclear genomes, precluding cladogenic Wolbachia acquisition. General concordance of Wolbachia and mitochondrial phylogenies suggests that horizontal transmission is rare, but varying relative rates of molecular divergence complicate chronogram-based statistical tests. Loci that cause CI in wMel are disrupted in D. yakuba-clade Wolbachia; but a second set of loci predicted to cause CI are located in the same WO prophage region. These alternative CI loci seem to have been acquired horizontally from distantly related Wolbachia, with transfer mediated by flanking Wolbachia-specific ISWpi1 transposons.
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Affiliation(s)
- Brandon S Cooper
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812
| | - Dan Vanderpool
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - William R Conner
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812
| | - Daniel R Matute
- Biology Department, University of North Carolina at Chapel Hill, North Carolina 27510
| | - Michael Turelli
- Department of Evolution and Ecology, University of California, Davis, California 95616
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65
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Siozios S, Gerth M, Griffin JS, Hurst GDD. Symbiosis: Wolbachia Host Shifts in the Fast Lane. Curr Biol 2019; 28:R269-R271. [PMID: 29558644 DOI: 10.1016/j.cub.2018.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The inherited bacterium Wolbachia is an important component of the biology of many arthropods. What makes it so common? An analysis of drosophilids revealed one strain host shifts at a surprisingly high rate, infecting eight species in under 30,000 years.
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Affiliation(s)
- Stefanos Siozios
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Michael Gerth
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Joanne S Griffin
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Gregory D D Hurst
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK.
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66
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Schebeck M, Feldkirchner L, Stauffer C, Schuler H. Dynamics of an Ongoing Wolbachia Spread in the European Cherry Fruit Fly, Rhagoletis cerasi (Diptera: Tephritidae). INSECTS 2019; 10:insects10060172. [PMID: 31208002 PMCID: PMC6627601 DOI: 10.3390/insects10060172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/06/2019] [Accepted: 06/11/2019] [Indexed: 11/20/2022]
Abstract
Numerous terrestrial arthropods are infected with the alphaproteobacterium Wolbachia. This endosymbiont is usually transmitted vertically from infected females to their offspring and can alter the reproduction of hosts through various manipulations, like cytoplasmic incompatibility (CI), enhancing its spread in new host populations. Studies on the spatial and temporal dynamics of Wolbachia under natural conditions are scarce. Here, we analyzed Wolbachia infection frequencies in populations of the European cherry fruit fly, Rhagoletis cerasi (L.), in central Germany—an area of an ongoing spread of the CI-inducing strain wCer2. In total, 295 individuals from 19 populations were PCR-screened for the presence of wCer2 and their mitochondrial haplotype. Results were compared with historic data to understand the infection dynamics of the ongoing wCer2 invasion. An overall wCer2 infection frequency of about 30% was found, ranging from 0% to 100% per population. In contrast to an expected smooth transition from wCer2-infected to completely wCer2-uninfected populations, a relatively scattered infection pattern across geography was observed. Moreover, a strong Wolbachia-haplotype association was detected, with only a few rare misassociations. Our results show a complex dynamic of an ongoing Wolbachia spread in natural field populations of R. cerasi.
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Affiliation(s)
- Martin Schebeck
- Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, BOKU, Peter-Jordan-Straße 82/I, A-1190 Vienna, Austria.
| | - Lukas Feldkirchner
- Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, BOKU, Peter-Jordan-Straße 82/I, A-1190 Vienna, Austria.
| | - Christian Stauffer
- Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, BOKU, Peter-Jordan-Straße 82/I, A-1190 Vienna, Austria.
| | - Hannes Schuler
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Universitätsplatz 5, I-39100 Bozen-Bolzano, Italy.
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67
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Bakovic V, Schebeck M, Telschow A, Stauffer C, Schuler H. Spatial spread of Wolbachia in Rhagoletis cerasi populations. Biol Lett 2019; 14:rsbl.2018.0161. [PMID: 29794009 PMCID: PMC6012700 DOI: 10.1098/rsbl.2018.0161] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/02/2018] [Indexed: 12/18/2022] Open
Abstract
The bacterial endosymbiont Wolbachia has been used to control insect pests owing to its ability to manipulate their life history and suppress infectious diseases. Therefore, knowledge on Wolbachia dynamics in natural populations is fundamental. The European cherry fruit fly, Rhagoletis cerasi, is infected with the Wolbachia strain wCer2, mainly present in southern and central European populations, and is currently spreading into wCer2-uninfected populations driven by high unidirectional cytoplasmic incompatibility. Here, we describe the distribution of wCer2 along two transition zones where the infection is spreading into wCer2-uninfected R. cerasi populations. Fine-scale sampling of 19 populations in the Czech Republic showed a smooth decrease of wCer2 frequency from south to north within a distance of less than 20 km. Sampling of 12 Hungarian populations, however, showed a sharp decline of wCer2 infection frequency within a few kilometres. We fitted a standard wave equation to our empirical data and estimated a Wolbachia wave speed of 1.9 km yr−1 in the Czech Republic and 1.0 km yr−1 in Hungary. Considering the univoltine life cycle and limited dispersal ability of R. cerasi, our study highlights a rapid Wolbachia spread in natural host populations.
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Affiliation(s)
- Vid Bakovic
- Department of Forest and Soil Sciences, Boku, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Martin Schebeck
- Department of Forest and Soil Sciences, Boku, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Arndt Telschow
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Christian Stauffer
- Department of Forest and Soil Sciences, Boku, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Hannes Schuler
- Department of Forest and Soil Sciences, Boku, University of Natural Resources and Life Sciences, Vienna, Austria.,Laimburg Research Centre, Pfatten, Italy
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68
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Meany MK, Conner WR, Richter SV, Bailey JA, Turelli M, Cooper BS. Loss of cytoplasmic incompatibility and minimal fecundity effects explain relatively low Wolbachia frequencies in Drosophila mauritiana. Evolution 2019; 73:1278-1295. [PMID: 31001816 PMCID: PMC6554066 DOI: 10.1111/evo.13745] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 03/29/2019] [Indexed: 12/16/2022]
Abstract
Maternally transmitted Wolbachia bacteria infect about half of all insect species. Many Wolbachia cause cytoplasmic incompatibility (CI) and reduced egg hatch when uninfected females mate with infected males. Although CI produces a frequency-dependent fitness advantage that leads to high equilibrium Wolbachia frequencies, it does not aid Wolbachia spread from low frequencies. Indeed, the fitness advantages that produce initial Wolbachia spread and maintain non-CI Wolbachia remain elusive. wMau Wolbachia infecting Drosophila mauritiana do not cause CI, despite being very similar to CI-causing wNo from Drosophila simulans (0.068% sequence divergence over 682,494 bp), suggesting recent CI loss. Using draft wMau genomes, we identify a deletion in a CI-associated gene, consistent with theory predicting that selection within host lineages does not act to increase or maintain CI. In the laboratory, wMau shows near-perfect maternal transmission; but we find no significant effect on host fecundity, in contrast to published data. Intermediate wMau frequencies on the island of Mauritius are consistent with a balance between unidentified small, positive fitness effects and imperfect maternal transmission. Our phylogenomic analyses suggest that group-B Wolbachia, including wMau and wPip, diverged from group-A Wolbachia, such as wMel and wRi, 6-46 million years ago, more recently than previously estimated.
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Affiliation(s)
- Megan K. Meany
- Division of Biological Sciences, University of Montana,
Missoula, MT USA
| | - William R. Conner
- Division of Biological Sciences, University of Montana,
Missoula, MT USA
| | - Sophia V. Richter
- Division of Biological Sciences, University of Montana,
Missoula, MT USA
| | - Jessica A. Bailey
- Division of Biological Sciences, University of Montana,
Missoula, MT USA
| | - Michael Turelli
- Department of Evolution and Ecology, University of
California, Davis, CA USA
| | - Brandon S. Cooper
- Division of Biological Sciences, University of Montana,
Missoula, MT USA
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69
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Abstract
Microbial symbioses exhibit astounding adaptations, yet all symbionts face the problem of how to reliably associate with host offspring every generation. A common strategy is vertical transmission, in which symbionts are directly transmitted from the female to her offspring. The diversity of symbionts and vertical transmission mechanisms is as expansive as the diversity of eukaryotic host taxa that house them. However, there are several common themes among these mechanisms based on the degree to which symbionts associate with the host germline during transmission. In this review, we detail three distinct vertical transmission strategies, starting with associations that are transmitted from host somatic cells to offspring somatic cells, either due to lacking a germline or avoiding it. A second strategy involves somatically-localized symbionts that migrate into the germline during host development. The third strategy we discuss is one in which the symbiont maintains continuous association with the germline throughout development. Unexpectedly, the vast majority of documented vertically inherited symbionts rely on the second strategy: soma-to-germline migration. Given that not all eukaryotes contain a sequestered germline and instead produce offspring from somatic stem cell lineages, this soma-to-germline migration is discussed in the context of multicellular evolution. Lastly, as recent genomics data have revealed an abundance of horizontal gene transfer events from symbiotic and non-symbiotic bacteria to host genomes, we discuss their impact on eukaryotic host evolution.
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Affiliation(s)
- Shelbi L Russell
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, United States.
| | - Laura Chappell
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, United States
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, United States
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70
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Miraldo A, Duplouy A. High Wolbachia Strain Diversity in a Clade of Dung Beetles Endemic to Madagascar. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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71
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Cao LJ, Jiang W, Hoffmann AA. Life History Effects Linked to an Advantage for wAu Wolbachia in Drosophila. INSECTS 2019; 10:E126. [PMID: 31052498 PMCID: PMC6571653 DOI: 10.3390/insects10050126] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 04/24/2019] [Accepted: 04/30/2019] [Indexed: 12/22/2022]
Abstract
Wolbachia endosymbiont infections can persist and spread in insect populations without causing apparent effects on reproduction of their insect hosts, but the mechanisms involved are largely unknown. Here, we test for fitness effects of the wAu infection of Drosophila simulans by comparing multiple infected and uninfected polymorphic isofemale lines derived from nature. We show a fitness advantage (higher offspring number) for lines with the wAu Wolbachia infection when breeding on grapes, but only where there was Talaromyces and Penicillium fungal mycelial growth. When breeding on laboratory medium, the wAu infection extended the development time and resulted in larger females with higher fecundity, life history traits, which may increase fitness. A chemical associated with the fungi (ochratoxin A) did not specifically alter the fitness of wAu-infected larvae, which developed slower and emerged with a greater weight regardless of toxin levels. These findings suggest that the fitness benefits of Wolbachia in natural populations may reflect life history changes that are advantageous under particular circumstances, such as when breeding occurs in rotting fruit covered by abundant mycelial growth.
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Affiliation(s)
- Li-Jun Cao
- Pest and Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
- Institute of Plant and Environmental Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
| | - Weibin Jiang
- Pest and Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
- College of Life & Environmental Science, Shanghai Normal University, Shanghai 200234, China.
| | - Ary A Hoffmann
- Pest and Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
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72
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Richardson KM, Griffin PC, Lee SF, Ross PA, Endersby-Harshman NM, Schiffer M, Hoffmann AA. A Wolbachia infection from Drosophila that causes cytoplasmic incompatibility despite low prevalence and densities in males. Heredity (Edinb) 2019; 122:428-440. [PMID: 30139962 PMCID: PMC6460763 DOI: 10.1038/s41437-018-0133-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 07/23/2018] [Accepted: 07/26/2018] [Indexed: 02/06/2023] Open
Abstract
Wolbachia bacteria are common insect endosymbionts transmitted maternally and capable of spreading through insect populations by cytoplasmic incompatibility (CI) when infected males cause embryo death after mating with uninfected females. Selection in the Wolbachia endosymbiont occurs on female hosts and is expected to favour strong maternal transmission to female offspring, even at the cost of reduced CI. With maternal leakage, nuclear genes are expected to be selected to suppress cytoplasmic incompatibility caused by males while also reducing any deleterious effects associated with the infection. Here we describe a new type of Wolbachia strain from Drosophila pseudotakahashii likely to have arisen from evolutionary processes on host and/or Wolbachia genomes. This strain is often absent from adult male offspring, but always transmitted to females. It leads to males with low or non-detectable Wolbachia that nevertheless show CI. When detected in adult males, the infection has a low density relative to that in females, a phenomenon not previously seen in Wolbachia infections of Drosophila. This Wolbachia strain is common in natural populations, and shows reduced CI when older (infected) males are crossed. These patterns highlight that endosymbionts can have strong sex-specific effects and that high frequency Wolbachia strains persist through effects on female reproduction. Female-limited Wolbachia infections may be of applied interest if the low level of Wolbachia in males reduces deleterious fitness effects on the host.
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Affiliation(s)
- Kelly M Richardson
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Philippa C Griffin
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Siu F Lee
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
- CSIRO Land and Water, Black Mountain, ACT 2601, Canberra, Australia
| | - Perran A Ross
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Nancy M Endersby-Harshman
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Michele Schiffer
- Daintree Rainforest Observatory, James Cook University, Cape Tribulation, Douglas, QLD, 4873, Australia
| | - Ary A Hoffmann
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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73
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Newton ILG, Slatko BE. Symbiosis Comes of age at the 10 th Biennial Meeting of Wolbachia Researchers. Appl Environ Microbiol 2019; 85:AEM.03071-18. [PMID: 30796064 PMCID: PMC6450017 DOI: 10.1128/aem.03071-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Wolbachia pipientis is an alpha-proteobacterial, obligate intracellular microbe and arguably the most successful infection on our planet, colonizing 40-60% of insect species. Wolbachia are also present in most, but not all, filarial nematodes where they are obligate mutualists and are the targets for anti-filarial drug discovery. Although Wolbachia are related to important human pathogens they do not infect mammals, but instead are well known for their reproductive manipulations of insect populations, inducing the following phenotypes: male-killing, feminization, parthenogenesis induction, or cytoplasmic incompatibility (CI). The most common of these, CI, results in a sperm-egg incompatibility and increases the relative fecundity of infected females in a population. In the last decade, Wolbachia have also been shown to provide a benefit to insects, where the infection can inhibit RNA virus replication within the host. Wolbachia cannot be cultivated outside of host cells and no genetic tools are available in the symbiont, limiting approaches available to its study. This means that many questions fundamental to our understanding of Wolbachia basic biology remained unknown for decades. The tenth biennial international Wolbachia conference, "Wolbachia Evolution, Ecology, Genomics and Cell Biology: A Chronicle of the Most Ubiquitous Symbiont", was held on June 17-22, 2018, Salem, MA USA. In the review below we highlight the new science presented at the meeting, link it to prior efforts to answer these questions across the Wolbachia genus, and the importance to the field of symbiosis. The topics covered in this review are based on the presentations at the conference.
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Affiliation(s)
| | - Barton E. Slatko
- Molecular Parasitology Group, New England BioLabs, Ipswich, Massachusetts, USA
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74
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Zheng B, Yu J. Characterization of Wolbachia enhancing domain in mosquitoes with imperfect maternal transmission. JOURNAL OF BIOLOGICAL DYNAMICS 2018; 12:596-610. [PMID: 30025503 DOI: 10.1080/17513758.2018.1499969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
A novel method to reduce the burden of dengue is to seed wild mosquitoes with Wolbachia-infected mosquitoes in dengue-endemic areas. Concerns in current mathematical models are to locate the Wolbachia introduction threshold. Our recent findings manifest that the threshold is highly dependent on the initial population size once Wolbachia infection alters the logistic control death rate of infected females. However, counting mosquitoes is beyond the realms of possibility. A plausible method is to monitor the infection frequency. We propose the concept of Wolbachia enhancing domain in which the infection frequency keeps increasing. A detailed description of the domain is presented. Our results suggest that both the initial population size and the infection frequency should be taken into account for optimal release strategies. Both Wolbachia fixation and extinction permit the oscillation of the infection frequency.
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Affiliation(s)
- Bo Zheng
- a College of Mathematics and Information Sciences , Guangzhou University , Guangzhou , People's Republic of China
- b Center for Applied Mathematics , Guangzhou University , Guangzhou , People's Republic of China
| | - Jianshe Yu
- a College of Mathematics and Information Sciences , Guangzhou University , Guangzhou , People's Republic of China
- b Center for Applied Mathematics , Guangzhou University , Guangzhou , People's Republic of China
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75
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Faria VG, Martins NE, Schlötterer C, Sucena É. Readapting to DCV Infection without Wolbachia: Frequency Changes of Drosophila Antiviral Alleles Can Replace Endosymbiont Protection. Genome Biol Evol 2018; 10:1783-1791. [PMID: 29947761 PMCID: PMC6054199 DOI: 10.1093/gbe/evy137] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2018] [Indexed: 12/19/2022] Open
Abstract
There is now ample evidence that endosymbionts can contribute to host adaptation to environmental challenges. However, how endosymbiont presence affects the adaptive trajectory and outcome of the host is yet largely unexplored. In Drosophila, Wolbachia confers protection to RNA virus infection, an effect that differs between Wolbachia strains and can be targeted by selection. Adaptation to RNA virus infections is mediated by both Wolbachia and the host, raising the question of whether adaptive genetic changes in the host vary with the presence/absence of the endosymbiont. Here, we address this question using a polymorphic D. melanogaster population previously adapted to DCV infection for 35 generations in the presence of Wolbachia, from which we removed the endosymbiont and followed survival over the subsequent 20 generations of infection. After an initial severe drop, survival frequencies upon DCV selection increased significantly, as seen before in the presence of Wolbachia. Whole-genome sequencing, revealed that the major genes involved in the first selection experiment, pastrel and Ubc-E2H, continued to be selected in Wolbachia-free D. melanogaster, with the frequencies of protective alleles being closer to fixation in the absence of Wolbachia. Our results suggest that heterogeneity in Wolbachia infection status may be sufficient to maintain polymorphisms even in the absence of costs.
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Affiliation(s)
- Vitor G Faria
- Instituto Gulbenkian de Ciência, Rua da quinta grande 6, 2780-156 Oeiras, Portugal.,Zoological Institute, Basel University, Basel, Switzerland
| | - Nelson E Martins
- Instituto Gulbenkian de Ciência, Rua da quinta grande 6, 2780-156 Oeiras, Portugal.,CNRS UPR9022, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Christian Schlötterer
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Élio Sucena
- Instituto Gulbenkian de Ciência, Rua da quinta grande 6, 2780-156 Oeiras, Portugal.,Departamento de Biologia Animal, edifício C2, Faculdade de Ciências, Universidade de Lisboa, Portugal
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76
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Yeap HL, Endersby-Harshman NM, Hoffmann AA. The Effect of Nonrandom Mating on Wolbachia Dynamics: Implications for Population Replacement and Sterile Releases in Aedes Mosquitoes. Am J Trop Med Hyg 2018; 99:608-617. [PMID: 29968550 PMCID: PMC6169187 DOI: 10.4269/ajtmh.18-0178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/22/2018] [Indexed: 01/11/2023] Open
Abstract
Wolbachia bacteria are known to cause deviations from random mating and affect sperm competition (SC) in some of their arthropod hosts. Because these effects could influence the effectiveness of Wolbachia in mosquito population replacement and suppression programs, we developed a theoretical framework to investigate them and we collected relevant data for the wMel infection in Aedes aegypti. Using incompatibility patterns as a measure of mating success of infected versus uninfected mosquitoes, we found some evidence that uninfected males sire more offspring than infected males. However, our theoretical framework suggests that this effect is unlikely to hamper Wolbachia invasion and has only minor effects on population suppression programs. Nevertheless, we suggest that mating effects and SC need to be monitored in an ongoing manner in release programs, given the possibility of ongoing selection for altered mating patterns.
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Affiliation(s)
- Heng Lin Yeap
- Pest, and Environmental Adaptation Research Group (PEARG), School of Bioscience, Bio21 Institute University of Melbourne, Melbourne, Australia
- Commonwealth Scientific, and Industrial Research Organisation (CSIRO), Black Mountain Laboratories, Black Mountain, Canberra, Australia
| | - Nancy Margaret Endersby-Harshman
- Pest, and Environmental Adaptation Research Group (PEARG), School of Bioscience, Bio21 Institute University of Melbourne, Melbourne, Australia
| | - Ary Anthony Hoffmann
- Pest, and Environmental Adaptation Research Group (PEARG), School of Bioscience, Bio21 Institute University of Melbourne, Melbourne, Australia
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77
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Abstract
Aedes mosquito-transmitted diseases, such as dengue, Zika and chikungunya, are becoming major global health emergencies while old threats, such as yellow fever, are re-emerging. Traditional control methods, which have focused on reducing mosquito populations through the application of insecticides or preventing breeding through removal of larval habitat, are largely ineffective, as evidenced by the increasing global disease burden. Here, we review novel mosquito population reduction and population modification approaches with a focus on control methods based on the release of mosquitoes, including the release of Wolbachia-infected mosquitoes and strategies to genetically modify the vector, that are currently under development and have the potential to contribute to a reversal of the current alarming disease trends.
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Affiliation(s)
- Heather A Flores
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | - Scott L O'Neill
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia.
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78
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Kriesner P, Hoffmann AA. Rapid spread of a Wolbachia infection that does not affect host reproduction in Drosophila simulans cage populations. Evolution 2018; 72:1475-1487. [PMID: 29766491 DOI: 10.1111/evo.13506] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 04/12/2018] [Accepted: 04/23/2018] [Indexed: 12/24/2022]
Abstract
Wolbachia endosymbionts that are maternally inherited can spread rapidly in host populations through inducing sterility in uninfected females, but some Wolbachia infections do not influence host reproduction yet still persist. These infections are particularly interesting because they likely represent mutualistic endosymbionts, spreading by increasing host fitness. Here, we document such a spread in the wAu infection of Drosophila simulans. By establishing multiple replicate cage populations, we show that wAu consistently increased from an intermediate frequency to near fixation, representing an estimated fitness advantage of around 20% for infected females. The effective population size in the cages was estimated from SNP markers to be around a few thousand individuals, precluding large effects of genetic drift in the populations. The exact reasons for the fitness advantage are unclear but viral protection and nutritional benefits are two possibilities.
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Affiliation(s)
- Peter Kriesner
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, 3010, Australia
| | - Ary A Hoffmann
- School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, 3010, Australia
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79
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Zheng B, Guo W, Hu L, Huang M, Yu J. Complex wolbachia infection dynamics in mosquitoes with imperfect maternal transmission. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2018; 15:523-541. [PMID: 29161848 DOI: 10.3934/mbe.2018024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dengue, malaria, and Zika are dangerous diseases primarily transmitted by Aedes aegypti, Aedes albopictus, and Anopheles stephensi. In the last few years, a new disease control method, besides pesticide spraying to kill mosquitoes, has been developed by releasing mosquitoes carrying bacterium Wolbachia into the natural areas to infect the wild population of mosquitoes and block disease transmission. The bacterium is transmitted by infected mothers and the maternal transmission was assumed to be perfect in virtually all previous models. However, recent experiments on Aedes aegypti and Anopheles stephensi showed that the transmission can be imperfect. In this work, we develop a model to describe how the imperfect maternal transmission affects the dynamics of Wolbachia spread. We establish two useful identities and employ them to find sufficient and necessary conditions under which the system exhibits monomorphic, bistable, and polymorphic dynamics. These analytical results may help find a plausible explanation for the recent observation that the Wolbachia strain ωMelPop failed to establish in the natural populations in Australia and Vietnam.
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Affiliation(s)
- Bo Zheng
- College of Mathematics and Information Sciences, Guangzhou University, Guangzhou, Guangdong 510006, China
| | - Wenliang Guo
- College of Mathematics and Information Sciences, Guangzhou University, Guangzhou, Guangdong 510006, China
| | - Linchao Hu
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Mugen Huang
- College of Mathematics and Information Sciences, Guangzhou University, Guangzhou, Guangdong 510006, China
| | - Jianshe Yu
- School of Mathematics and Information Science, Guangzhou University, Guangzhou 510006, China
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80
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Schuler H, Egan SP, Hood GR, Busbee RW, Driscoe AL, Ott JR. Diversity and distribution of Wolbachia in relation to geography, host plant affiliation and life cycle of a heterogonic gall wasp. BMC Evol Biol 2018; 18:37. [PMID: 29587626 PMCID: PMC5870337 DOI: 10.1186/s12862-018-1151-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 03/09/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The maternally inherited endosymbiont Wolbachia is widespread in arthropods and nematodes and can play an important role in the ecology and evolution of its host through reproductive manipulation. Here, we survey Wolbachia in Belonocnema treatae, a widely distributed North American cynipid gall forming wasp that exhibits regional host specialization on three species of oaks and alternation of sexually and asexually reproducing generations. We investigated whether patterns of Wolbachia infection and diversity in B. treatae are associated with the insect's geographic distribution, host plant association, life cycle, and mitochondrial evolutionary history. RESULTS Screening of 463 individuals from 23 populations including sexual and asexual generations from all three host plants across the southern U.S. showed an average infection rate of 56% with three common Wolbachia strains: wTre1-3 and an additional rare variant wTre4. Phylogenetic analysis based on wsp showed that these strains are unrelated and likely independently inherited. We found no difference in Wolbachia infection frequency among host plant associated populations or between the asexual and sexual generations, or between males and females of the sexual generation. Partially incomplete Wolbachia transmission rates might explain the occurrence of uninfected individuals. A parallel analysis of the mitochondrial cytochrome oxidase I gene in B. treatae showed high mtDNA haplotype diversity in both infected and uninfected populations suggesting an ancestral infection by Wolbachia as well as a clear split between eastern and western B. treatae mtDNA clades with a sequence divergence of > 6%. The strain wTre1 was present almost exclusively in the western clade while wTre2 and wTre3 occur almost exclusively in eastern populations. In contrast, the same strains co-occur as double-infections in Georgia and triple-infections in two populations in central Florida. CONCLUSIONS The diversity of Wolbachia across geographically and genetically distinct populations of B. treatae and the co-occurrence of the same strains within three populations highlights the complex infection dynamics in this system. Moreover, the association of distinct Wolbachia strains with mitochondrial haplotypes of its host in populations infected by different Wolbachia strains suggests a potential role of the endosymbiont in reproductive isolation in B. treatae.
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Affiliation(s)
- Hannes Schuler
- Institute of Forest Entomology, Forest Pathology and Forest Protection, Boku, University of Natural Resources & Life Sciences, Peter-Jordan-Straße 82/I, 1190, Vienna, Austria. .,Present Address: Laimburg Research Centre, Laimburg 6, 39040, Pfatten, Italy.
| | - Scott P Egan
- Department of BioSciences, Rice University, Houston, TX, 77005, USA
| | - Glen R Hood
- Department of BioSciences, Rice University, Houston, TX, 77005, USA
| | - Robert W Busbee
- Population and Conservation Biology Program, Department of Biology, Texas State University, San Marcos, TX, 78666, USA
| | - Amanda L Driscoe
- Population and Conservation Biology Program, Department of Biology, Texas State University, San Marcos, TX, 78666, USA
| | - James R Ott
- Population and Conservation Biology Program, Department of Biology, Texas State University, San Marcos, TX, 78666, USA
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81
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Turelli M, Cooper BS, Richardson KM, Ginsberg PS, Peckenpaugh B, Antelope CX, Kim KJ, May MR, Abrieux A, Wilson DA, Bronski MJ, Moore BR, Gao JJ, Eisen MB, Chiu JC, Conner WR, Hoffmann AA. Rapid Global Spread of wRi-like Wolbachia across Multiple Drosophila. Curr Biol 2018; 28:963-971.e8. [PMID: 29526588 PMCID: PMC5882237 DOI: 10.1016/j.cub.2018.02.015] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/16/2018] [Accepted: 02/07/2018] [Indexed: 01/08/2023]
Abstract
Maternally transmitted Wolbachia, Spiroplasma, and Cardinium bacteria are common in insects [1], but their interspecific spread is poorly understood. Endosymbionts can spread rapidly within host species by manipulating host reproduction, as typified by the global spread of wRi Wolbachia observed in Drosophila simulans [2, 3]. However, because Wolbachia cannot survive outside host cells, spread between distantly related host species requires horizontal transfers that are presumably rare [4-7]. Here, we document spread of wRi-like Wolbachia among eight highly diverged Drosophila hosts (10-50 million years) over only about 14,000 years (5,000-27,000). Comparing 110 wRi-like genomes, we find ≤0.02% divergence from the wRi variant that spread rapidly through California populations of D. simulans. The hosts include both globally invasive species (D. simulans, D. suzukii, and D. ananassae) and narrowly distributed Australian endemics (D. anomalata and D. pandora) [8]. Phylogenetic analyses that include mtDNA genomes indicate introgressive transfer of wRi-like Wolbachia between closely related species D. ananassae, D. anomalata, and D. pandora but no horizontal transmission within species. Our analyses suggest D. ananassae as the Wolbachia source for the recent wRi invasion of D. simulans and D. suzukii as the source of Wolbachia in its sister species D. subpulchrella. Although six of these wRi-like variants cause strong cytoplasmic incompatibility, two cause no detectable reproductive effects, indicating that pervasive mutualistic effects [9, 10] complement the reproductive manipulations for which Wolbachia are best known. "Super spreader" variants like wRi may be particularly useful for controlling insect pests and vector-borne diseases with Wolbachia transinfections [11].
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Affiliation(s)
- Michael Turelli
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA.
| | - Brandon S Cooper
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Kelly M Richardson
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Paul S Ginsberg
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA; Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Brooke Peckenpaugh
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA; Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA
| | - Chenling X Antelope
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA; Department of Computer Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kevin J Kim
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - Michael R May
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - Antoine Abrieux
- Department of Entomology and Nematology, University of California, Davis, Davis, CA 95616, USA
| | - Derek A Wilson
- Department of Entomology and Nematology, University of California, Davis, Davis, CA 95616, USA
| | - Michael J Bronski
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Brian R Moore
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - Jian-Jun Gao
- Laboratory of Ecology and Evolutionary Biology, Yunnan University, Kunming, Yunnan 650091, China
| | - Michael B Eisen
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Joanna C Chiu
- Department of Entomology and Nematology, University of California, Davis, Davis, CA 95616, USA
| | - William R Conner
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - Ary A Hoffmann
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, 3010, Australia.
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82
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Abstract
The power and ease of Drosophila genetics and the medical relevance of mosquito-transmitted viruses have made dipterans important model organisms in antiviral immunology. Studies of virus-host interactions at the molecular and population levels have illuminated determinants of resistance to virus infection. Here, we review the sources and nature of variation in antiviral immunity and virus susceptibility in model dipteran insects, specifically the fruit fly Drosophila melanogaster and vector mosquitoes of the genera Aedes and Culex. We first discuss antiviral immune mechanisms and describe the virus-specificity of these responses. In the following sections, we review genetic and microbiota-dependent variation in antiviral immunity. In the final sections, we explore less well-studied sources of variation, including abiotic factors, sexual dimorphism, infection history, and endogenous viral elements. We borrow from work on other pathogen types and non-dipteran species when it parallels or complements studies in dipterans. Understanding natural variation in virus-host interactions may lead to the identification of novel restriction factors and immune mechanisms and shed light on the molecular determinants of vector competence.
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Affiliation(s)
- William H Palmer
- Institute of Evolutionary Biology and Centre for Infection, Evolution and Immunity, University of Edinburgh, Edinburgh EH9 3FL UK.
| | - Finny S Varghese
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, P.O. Box 9101, Nijmegen 6500 HB, The Netherlands.
- Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen 6525 GA, The Netherlands.
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, P.O. Box 9101, Nijmegen 6500 HB, The Netherlands.
- Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen 6525 GA, The Netherlands.
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83
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Zug R, Hammerstein P. Evolution of reproductive parasites with direct fitness benefits. Heredity (Edinb) 2018; 120:266-281. [PMID: 29234159 PMCID: PMC5836592 DOI: 10.1038/s41437-017-0022-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 10/18/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022] Open
Abstract
Maternally inherited symbionts such as Wolbachia have long been seen mainly as reproductive parasites, with deleterious effects on host fitness. It is becoming clear, however, that, frequently, these symbionts also have beneficial effects on host fitness, either along with reproductive parasitism or not. Using the examples of cytoplasmic incompatibility (CI) and male-killing (MK), we here analyze the effect of direct fitness benefits on the evolution of reproductive parasites. By means of a simple theoretical framework, we synthesize and extend earlier modeling approaches for CI and MK, which usually ignore fitness benefits. Moreover, our framework is not restricted to a particular mechanism underlying the fitness benefit (e.g., protection against pathogens). We derive invasion conditions and equilibrium frequencies for the different infection scenarios. Our results demonstrate the importance of a symbiont's "effective fecundity" (i.e., the product of the relative fecundity of an infected female and her transmission efficiency) for a symbiont's invasion success. In particular, we adopt the concept of effective fecundity to scenarios where CI and MK co-occur in one host population. We confirm that direct fitness benefits substantially facilitate the invasion and spread of infections (for example, by lowering or removing the invasion threshold) or even make invasion possible in the first place (for example, if reproductive parasitism is weak or absent). Finally, we discuss the role of direct fitness benefits in long-term evolutionary dynamics of reproductive phenotypes and highlight their potential to resolve genetic conflicts between maternally inherited symbionts and their hosts.
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Affiliation(s)
- Roman Zug
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 4, 10115, Berlin, Germany.
| | - Peter Hammerstein
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 4, 10115, Berlin, Germany
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84
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Marshall JM, Akbari OS. Can CRISPR-Based Gene Drive Be Confined in the Wild? A Question for Molecular and Population Biology. ACS Chem Biol 2018; 13:424-430. [PMID: 29370514 DOI: 10.1021/acschembio.7b00923] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The recent discovery of CRISPR and its application as a gene editing tool has enabled a range of gene drive systems to be engineered with greater ease. In order for the benefits of this technology to be realized, in some circumstances drive systems should be developed that are capable of both spreading into populations to achieve their desired impact and being recalled in the event of unwanted consequences or public disfavor. We review the performance of three broad categories of drive systems at achieving these goals: threshold-dependent drives, homing-based drive and remediation systems, and temporally self-limiting systems such as daisy-chain drives.
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Affiliation(s)
- John M Marshall
- Divisions of Biostatistics and Epidemiology, School of Public Health, University of California , Berkeley, California 94720, United States
| | - Omar S Akbari
- Section of Cell and Developmental Biology, University of California, San Diego , La Jolla, California 92093, United States of America
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85
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The Wolbachia strain wAu provides highly efficient virus transmission blocking in Aedes aegypti. PLoS Pathog 2018. [PMID: 29370307 DOI: 10.1371/journal.ppat.1006815.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Introduced transinfections of the inherited bacteria Wolbachia can inhibit transmission of viruses by Aedes mosquitoes, and in Ae. aegypti are now being deployed for dengue control in a number of countries. Only three Wolbachia strains from the large number that exist in nature have to date been introduced and characterized in this species. Here novel Ae. aegypti transinfections were generated using the wAlbA and wAu strains. In its native Ae. albopictus, wAlbA is maintained at lower density than the co-infecting wAlbB, but following transfer to Ae. aegypti the relative strain density was reversed, illustrating the strain-specific nature of Wolbachia-host co-adaptation in determining density. The wAu strain also reached high densities in Ae. aegypti, and provided highly efficient transmission blocking of dengue and Zika viruses. Both wAu and wAlbA were less susceptible than wMel to density reduction/incomplete maternal transmission resulting from elevated larval rearing temperatures. Although wAu does not induce cytoplasmic incompatibility (CI), it was stably combined with a CI-inducing strain as a superinfection, and this would facilitate its spread into wild populations. Wolbachia wAu provides a very promising new option for arbovirus control, particularly for deployment in hot tropical climates.
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86
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Ant TH, Herd CS, Geoghegan V, Hoffmann AA, Sinkins SP. The Wolbachia strain wAu provides highly efficient virus transmission blocking in Aedes aegypti. PLoS Pathog 2018; 14:e1006815. [PMID: 29370307 PMCID: PMC5784998 DOI: 10.1371/journal.ppat.1006815] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 12/14/2017] [Indexed: 11/18/2022] Open
Abstract
Introduced transinfections of the inherited bacteria Wolbachia can inhibit transmission of viruses by Aedes mosquitoes, and in Ae. aegypti are now being deployed for dengue control in a number of countries. Only three Wolbachia strains from the large number that exist in nature have to date been introduced and characterized in this species. Here novel Ae. aegypti transinfections were generated using the wAlbA and wAu strains. In its native Ae. albopictus, wAlbA is maintained at lower density than the co-infecting wAlbB, but following transfer to Ae. aegypti the relative strain density was reversed, illustrating the strain-specific nature of Wolbachia-host co-adaptation in determining density. The wAu strain also reached high densities in Ae. aegypti, and provided highly efficient transmission blocking of dengue and Zika viruses. Both wAu and wAlbA were less susceptible than wMel to density reduction/incomplete maternal transmission resulting from elevated larval rearing temperatures. Although wAu does not induce cytoplasmic incompatibility (CI), it was stably combined with a CI-inducing strain as a superinfection, and this would facilitate its spread into wild populations. Wolbachia wAu provides a very promising new option for arbovirus control, particularly for deployment in hot tropical climates.
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Affiliation(s)
- Thomas H. Ant
- Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
- Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Christie S. Herd
- Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
- Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Vincent Geoghegan
- Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
- Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Ary A. Hoffmann
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Steven P. Sinkins
- Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
- Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
- * E-mail:
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87
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Betelman K, Caspi-Fluger A, Shamir M, Chiel E. Identification and characterization of bacterial symbionts in three species of filth fly parasitoids. FEMS Microbiol Ecol 2018; 93:4097188. [PMID: 28957585 DOI: 10.1093/femsec/fix107] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/28/2017] [Indexed: 01/08/2023] Open
Abstract
Facultative bacterial symbionts are widespread among insects and have diverse effects on their biology. Here, we focused on bacterial symbionts of three ecologically and economically important filth flies parasitoid species-Spalangia cameroni, Spalangia endius and Muscidifurax raptor.
Both Spalangia species harbored a Sodalis bacterium that is closely related to Sodalis praecaptivus (a free-living bacterium) and to Sodalis symbionts of weevils. This is the only case of Sodalis infection in the important order Hymenoptera. We also found, for the first time in this parasitoid guild, a Rickettsia infecting the two Spalangia spp., albeit in much higher prevalence in S. cameroni. Molecular and phylogenetic analyses revealed that it is closely related to Rickettsia felis and other Rickettsia species from the 'transitional' group. All three parasitoid species harbored Wolbachia. Using multi-locus sequence typing, we found that M. raptor harbors a single Wolbachia strain whereas the Spalangia spp. have multiple strains. By controlled crossings, we found that Wolbachia infection in S. endius causes incomplete cytoplasmic incompatibility and increased longevity, thereby promoting Wolbachia's spread. In contrast, no effects of Wolbachia on the reproduction and longevity of M. raptor were found. This study underscores the diversity and nature of symbiotic interactions between microbes and insects.
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Affiliation(s)
- Kfir Betelman
- Department of Biology and Environment, University of Haifa-Oranim, Oranim College, Qiryat Amal Rd., Tivon 3600600, Israel.,Department of Evolutionary and Environmental Biology, University of Haifa, 199 Aba Khoushy Ave., Mount Carmel, Haifa 3498838, Israel
| | - Ayelet Caspi-Fluger
- Department of Biology and Environment, University of Haifa-Oranim, Oranim College, Qiryat Amal Rd., Tivon 3600600, Israel
| | - Maayan Shamir
- Department of Biology and Environment, University of Haifa-Oranim, Oranim College, Qiryat Amal Rd., Tivon 3600600, Israel
| | - Elad Chiel
- Department of Biology and Environment, University of Haifa-Oranim, Oranim College, Qiryat Amal Rd., Tivon 3600600, Israel
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88
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Bleidorn C, Gerth M. A critical re-evaluation of multilocus sequence typing (MLST) efforts in Wolbachia. FEMS Microbiol Ecol 2017; 94:4654844. [DOI: 10.1093/femsec/fix163] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 11/22/2017] [Indexed: 01/10/2023] Open
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89
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Conner WR, Blaxter ML, Anfora G, Ometto L, Rota‐Stabelli O, Turelli M. Genome comparisons indicate recent transfer of wRi-like Wolbachia between sister species Drosophila suzukii and D. subpulchrella. Ecol Evol 2017; 7:9391-9404. [PMID: 29187976 PMCID: PMC5696437 DOI: 10.1002/ece3.3449] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/26/2017] [Accepted: 09/01/2017] [Indexed: 12/22/2022] Open
Abstract
Wolbachia endosymbionts may be acquired by horizontal transfer, by introgression through hybridization between closely related species, or by cladogenic retention during speciation. All three modes of acquisition have been demonstrated, but their relative frequency is largely unknown. Drosophila suzukii and its sister species D. subpulchrella harbor Wolbachia, denoted wSuz and wSpc, very closely related to wRi, identified in California populations of D. simulans. However, these variants differ in their induced phenotypes: wRi causes significant cytoplasmic incompatibility (CI) in D. simulans, but CI has not been detected in D. suzukii or D. subpulchrella. Our draft genomes of wSuz and wSpc contain full-length copies of 703 of the 734 single-copy genes found in wRi. Over these coding sequences, wSuz and wSpc differ by only 0.004% (i.e., 28 of 704,883 bp); they are sisters relative to wRi, from which each differs by 0.014%-0.015%. Using published data from D. melanogaster, Nasonia wasps and Nomada bees to calibrate relative rates of Wolbachia versus host nuclear divergence, we conclude that wSuz and wSpc are too similar-by at least a factor of 100-to be plausible candidates for cladogenic transmission. These three wRi-like Wolbachia, which differ in CI phenotype in their native hosts, have different numbers of orthologs of genes postulated to contribute to CI; and the CI loci differ at several nucleotides that may account for the CI difference. We discuss the general problem of distinguishing alternative modes of Wolbachia acquisition, focusing on the difficulties posed by limited knowledge of variation in absolute and relative rates of molecular evolution for host nuclear genomes, mitochondria, and Wolbachia.
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Affiliation(s)
- William R. Conner
- Department of Evolution and EcologyUniversity of CaliforniaDavisCAUSA
| | - Mark L. Blaxter
- Institute of Evolutionary Biology and Edinburgh Genomics FacilityUniversity of EdinburghEdinburghUK
| | - Gianfranco Anfora
- Chemical Ecology LaboratoryDepartment of Sustainable Agro‐Ecosystems and Bio‐ResourcesFondazione Edmund MachSan Michele all'AdigeTNItaly
- Centre Agriculture Food EnvironmentUniversity of TrentoSan Michele all'AdigeTNItaly
| | - Lino Ometto
- Chemical Ecology LaboratoryDepartment of Sustainable Agro‐Ecosystems and Bio‐ResourcesFondazione Edmund MachSan Michele all'AdigeTNItaly
- Present address:
MezzocoronaTNItaly
| | - Omar Rota‐Stabelli
- Chemical Ecology LaboratoryDepartment of Sustainable Agro‐Ecosystems and Bio‐ResourcesFondazione Edmund MachSan Michele all'AdigeTNItaly
| | - Michael Turelli
- Department of Evolution and EcologyUniversity of CaliforniaDavisCAUSA
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90
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Macias VM, Ohm JR, Rasgon JL. Gene Drive for Mosquito Control: Where Did It Come from and Where Are We Headed? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:E1006. [PMID: 28869513 PMCID: PMC5615543 DOI: 10.3390/ijerph14091006] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 02/08/2023]
Abstract
Mosquito-borne pathogens place an enormous burden on human health. The existing toolkit is insufficient to support ongoing vector-control efforts towards meeting disease elimination and eradication goals. The perspective that genetic approaches can potentially add a significant set of tools toward mosquito control is not new, but the recent improvements in site-specific gene editing with CRISPR/Cas9 systems have enhanced our ability to both study mosquito biology using reverse genetics and produce genetics-based tools. Cas9-mediated gene-editing is an efficient and adaptable platform for gene drive strategies, which have advantages over innundative release strategies for introgressing desirable suppression and pathogen-blocking genotypes into wild mosquito populations; until recently, an effective gene drive has been largely out of reach. Many considerations will inform the effective use of new genetic tools, including gene drives. Here we review the lengthy history of genetic advances in mosquito biology and discuss both the impact of efficient site-specific gene editing on vector biology and the resulting potential to deploy new genetic tools for the abatement of mosquito-borne disease.
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Affiliation(s)
- Vanessa M Macias
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Johanna R Ohm
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
| | - Jason L Rasgon
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
- The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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91
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Faria VG, Sucena É. From Nature to the Lab: Establishing Drosophila Resources for Evolutionary Genetics. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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92
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Wolbachia spreading dynamics in mosquitoes with imperfect maternal transmission. J Math Biol 2017; 76:235-263. [PMID: 28573466 DOI: 10.1007/s00285-017-1142-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 05/17/2017] [Indexed: 10/19/2022]
Abstract
Mosquitoes are primary vectors of life-threatening diseases such as dengue, malaria, and Zika. A new control method involves releasing mosquitoes carrying bacterium Wolbachia into the natural areas to infect wild mosquitoes and block disease transmission. In this work, we use differential equations to describe Wolbachia spreading dynamics, focusing on the poorly understood effect of imperfect maternal transmission. We establish two useful identities and employ them to prove that the system exhibits monomorphic, bistable, and polymorphic dynamics, and give sufficient and necessary conditions for each case. The results suggest that the largest maternal transmission leakage rate supporting Wolbachia spreading does not necessarily increase with the fitness of infected mosquitoes. The bistable dynamics is defined by the existence of two stable equilibria, whose basins of attraction are divided by the separatrix of a saddle point. By exploring the analytical property of the separatrix with some sharp estimates, we find that Wolbachia in a completely infected population could be wiped out ultimately if the initial population size is small. Surprisingly, when the infection shortens the lifespan of infected females that would impede Wolbachia spreading, such a reversion phenomenon does not occur.
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93
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Abstract
In many regions of the world, mosquito-borne viruses pose a growing threat to human health. As an alternative to traditional control measures, the bacterial symbiont Wolbachia has been transferred from Drosophila into the mosquito Aedes aegypti, where it can block the transmission of dengue and Zika viruses. A recent paper has reported large-scale releases of Wolbachia-infected Ae. aegypti in the city of Cairns, Australia. Wolbachia, which is maternally transmitted, invaded and spread through the populations due to a sperm–egg incompatibility called cytoplasmic incompatibility. Over a period of 2 years, a wave of Wolbachia infection slowly spread out from 2 release sites, demonstrating that it will be possible to deploy this strategy in large urban areas. In line with theoretical predictions, Wolbachia infection at a third, smaller release site collapsed due to the immigration of Wolbachia-free mosquitoes from surrounding areas. This remarkable field experiment has both validated theoretical models of Wolbachia population dynamics and demonstrated that this is a viable strategy to modify mosquito populations.
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94
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Schmidt TL, Barton NH, Rašić G, Turley AP, Montgomery BL, Iturbe-Ormaetxe I, Cook PE, Ryan PA, Ritchie SA, Hoffmann AA, O’Neill SL, Turelli M. Local introduction and heterogeneous spatial spread of dengue-suppressing Wolbachia through an urban population of Aedes aegypti. PLoS Biol 2017; 15:e2001894. [PMID: 28557993 PMCID: PMC5448718 DOI: 10.1371/journal.pbio.2001894] [Citation(s) in RCA: 144] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 04/17/2017] [Indexed: 11/30/2022] Open
Abstract
Dengue-suppressing Wolbachia strains are promising tools for arbovirus control, particularly as they have the potential to self-spread following local introductions. To test this, we followed the frequency of the transinfected Wolbachia strain wMel through Ae. aegypti in Cairns, Australia, following releases at 3 nonisolated locations within the city in early 2013. Spatial spread was analysed graphically using interpolation and by fitting a statistical model describing the position and width of the wave. For the larger 2 of the 3 releases (covering 0.97 km2 and 0.52 km2), we observed slow but steady spatial spread, at about 100–200 m per year, roughly consistent with theoretical predictions. In contrast, the smallest release (0.11 km2) produced erratic temporal and spatial dynamics, with little evidence of spread after 2 years. This is consistent with the prediction concerning fitness-decreasing Wolbachia transinfections that a minimum release area is needed to achieve stable local establishment and spread in continuous habitats. Our graphical and likelihood analyses produced broadly consistent estimates of wave speed and wave width. Spread at all sites was spatially heterogeneous, suggesting that environmental heterogeneity will affect large-scale Wolbachia transformations of urban mosquito populations. The persistence and spread of Wolbachia in release areas meeting minimum area requirements indicates the promise of successful large-scale population transformation. Wolbachia are bacteria that live inside insect cells. In insects that act as viral vectors, Wolbachia can suppress virus transmission to new hosts. Wolbachia have been experimentally introduced into Aedes aegypti mosquito populations to reduce the transmission of dengue, Zika, and other arboviruses that cause human disease. Wolbachia invade populations by causing cytoplasmic incompatibility, a phenomenon whereby embryos from crosses between infected males and uninfected females fail to hatch. While Wolbachia have been shown to successfully invade and remain established in isolated Ae. aegypti populations, outward spread from urban release zones has not been previously documented. This is an important step in demonstrating that Wolbachia can be used to combat mosquito-borne infectious disease in cities. Here we describe Wolbachia spread from 2 introduction areas within Cairns in northeastern Australia at a rate of about 100–200 meters per year. Spread occurs only when introduction areas are sufficiently large. The slow rates of observed spread are broadly consistent with mathematical predictions based on estimated Ae. aegypti dispersal distances, Wolbachia dynamics, and effects seen in isolated populations. Spread is uneven and likely depends on local characteristics (e.g., barriers) that affect mosquito density and dispersal. Our data indicate that Wolbachia can be introduced locally in large cities, remain established where released, and slowly spread from release areas. These dynamics indicate that high Wolbachia infection frequencies can be established gradually across large urban areas through local releases.
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Affiliation(s)
- Tom L. Schmidt
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | | | - Gordana Rašić
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Andrew P. Turley
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | - Brian L. Montgomery
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | | | - Peter E. Cook
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | - Peter A. Ryan
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | - Scott A. Ritchie
- School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Cairns, Queensland, Australia
| | - Ary A. Hoffmann
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Scott L. O’Neill
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | - Michael Turelli
- Department of Evolution and Ecology, University of California, Davis, Davis, California, United States of America
- * E-mail:
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95
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Grau T, Brandt A, DeLeon S, Meixner MD, Strauß JF, Joop G, Telschow A. A Comparison of Wolbachia Infection Frequencies in Varroa With Prevalence of Deformed Wing Virus. JOURNAL OF INSECT SCIENCE (ONLINE) 2017; 17:3836770. [PMID: 28973572 PMCID: PMC5538322 DOI: 10.1093/jisesa/iex039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Indexed: 06/07/2023]
Abstract
Wolbachia are widely distributed bacterial endosymbionts of arthropods and filarial nematodes. These bacteria can affect host fitness in a variety of ways, such as protecting hosts against viruses and other pathogens. Here, we investigate the possible role of Wolbachia in the prevalence of the deformed wing virus (DWV), a highly virulent pathogen of honey bees (Apis mellifera) that is transmitted by parasitic Varroa mites (Varroa destructor). About 180 Varroa mites from 18 beehives were tested for infection with Wolbachia and DWV. We first screened for Wolbachia using two standard primers (wsp and 16S rDNA), and found 26% of the mites to be positive for Wolbachia using the wsp primer and 64% of the mites to be positive using the 16S rDNA primer. Using these intermediate Wolbachia frequencies, we then tested for statistical correlations with virus infection frequencies. The analysis revealed a significant positive correlation between DWV and Wolbachia using the wsp primer, but no significant association between DWV and Wolbachia using the 16S rDNA primer. In conclusion, there is no evidence for an anti-pathogenic effect of Wolbachia in V. destructor, but weak evidence for a pro-pathogenic effect. These results encourage further examination of Wolbachia-virus interactions in Varroa mites since an increased vector competence of the mites may significantly impact disease outbreaks in honey bees.
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Affiliation(s)
- Thorben Grau
- Institute of Insect Biotechnology, Justus-Liebig University Giessen, Giessen, Germany (; ; )
| | | | - Sara DeLeon
- Institute of Insect Biotechnology, Justus-Liebig University Giessen, Giessen, Germany (; ; )
| | | | - Jakob Friedrich Strauß
- Institute for Evolution and Biodiversity, Westfaelische Wilhelms University Muenster, Muenster, Germany (; )
| | - Gerrit Joop
- Institute of Insect Biotechnology, Justus-Liebig University Giessen, Giessen, Germany (; ; )
| | - Arndt Telschow
- Institute for Evolution and Biodiversity, Westfaelische Wilhelms University Muenster, Muenster, Germany (; )
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96
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Turelli M, Barton NH. Deploying dengue-suppressing Wolbachia : Robust models predict slow but effective spatial spread in Aedes aegypti. Theor Popul Biol 2017; 115:45-60. [PMID: 28411063 PMCID: PMC5476474 DOI: 10.1016/j.tpb.2017.03.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 03/12/2017] [Accepted: 03/15/2017] [Indexed: 01/27/2023]
Abstract
A novel strategy for controlling the spread of arboviral diseases such as dengue, Zika and chikungunya is to transform mosquito populations with virus-suppressing Wolbachia. In general, Wolbachia transinfected into mosquitoes induce fitness costs through lower viability or fecundity. These maternally inherited bacteria also produce a frequency-dependent advantage for infected females by inducing cytoplasmic incompatibility (CI), which kills the embryos produced by uninfected females mated to infected males. These competing effects, a frequency-dependent advantage and frequency-independent costs, produce bistable Wolbachia frequency dynamics. Above a threshold frequency, denoted p̂, CI drives fitness-decreasing Wolbachia transinfections through local populations; but below p̂, infection frequencies tend to decline to zero. If p̂ is not too high, CI also drives spatial spread once infections become established over sufficiently large areas. We illustrate how simple models provide testable predictions concerning the spatial and temporal dynamics of Wolbachia introductions, focusing on rate of spatial spread, the shape of spreading waves, and the conditions for initiating spread from local introductions. First, we consider the robustness of diffusion-based predictions to incorporating two important features of wMel-Aedes aegypti biology that may be inconsistent with the diffusion approximations, namely fast local dynamics induced by complete CI (i.e., all embryos produced from incompatible crosses die) and long-tailed, non-Gaussian dispersal. With complete CI, our numerical analyses show that long-tailed dispersal changes wave-width predictions only slightly; but it can significantly reduce wave speed relative to the diffusion prediction; it also allows smaller local introductions to initiate spatial spread. Second, we use approximations for p̂ and dispersal distances to predict the outcome of 2013 releases of wMel-infected Aedes aegypti in Cairns, Australia, Third, we describe new data from Aedes aegypti populations near Cairns, Australia that demonstrate long-distance dispersal and provide an approximate lower bound on p̂ for wMel in northeastern Australia. Finally, we apply our analyses to produce operational guidelines for efficient transformation of vector populations over large areas. We demonstrate that even very slow spatial spread, on the order of 10-20 m/month (as predicted), can produce area-wide population transformation within a few years following initial releases covering about 20-30% of the target area.
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Affiliation(s)
- Michael Turelli
- Department of Evolution and Ecology, University of California, Davis, CA, USA.
| | - Nicholas H Barton
- Institute of Science and Technology, Am Campus 1, A-3400 Klosterneuburg, Austria.
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97
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Johannesen J. Tracing the history and ecological context of Wolbachia double infection in a specialist host ( Urophora cardui)-parasitoid ( Eurytoma serratulae) system. Ecol Evol 2017; 7:986-996. [PMID: 28168034 PMCID: PMC5288247 DOI: 10.1002/ece3.2713] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 11/24/2016] [Accepted: 12/17/2016] [Indexed: 12/03/2022] Open
Abstract
The endosymbiotic bacterium Wolbachia is the most widespread bacteria in insects, yet the ecology of novel acquisitions in natural host populations is poorly understood. Using temporal data separated by 12 years, I tested the hypothesis that immigration of a parasitoid wasp led to transmission of its Wolbachia strain to its dipteran host, resulting in double‐strain infection, and I used geographic and community surveys to explore the history of transmission in fly and parasitoid. Double infection in the fly host was present before immigration of the parasitoid. Equal prevalence of double infection in males and females, constant prevalence before and after immigration in two regions, and increase in one region of immigration indicate little if no competition between strains. Double infection was present throughout the fly's distribution range, but proportions varied highly (0–0.71, mean = 0.26). Two fly‐specific MLST strains, observed in Eastern and Western Europe, respectively, differed at hcpA only. Flies with either fly‐strain could be double infected with the parasitoid's strain. The geographic distribution of double infection implies that it is older than the fly host's extent distribution range and that different proportions of double infection are caused by demographic fluctuations in the fly. The geographic data in combination with community surveys of infections and strains further suggest that the parasitoid strain was the fly's ancestral strain that was transmitted to the parasitoid, that is, the reverse transmission route as first hypothesized. Based on these findings together with a comparison of oviposition strategies of other hosts harboring related Wolbachia strains, I hypothesize that trans‐infection during an insect host's puparial metamorphosis might be important in promoting horizontal transmission among diverse holometabolic taxa.
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Affiliation(s)
- Jes Johannesen
- Department of Evolutionary Ecology Zoological Institute University of Mainz Mainz Germany
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98
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Cooper BS, Ginsberg PS, Turelli M, Matute DR. Wolbachia in the Drosophila yakuba Complex: Pervasive Frequency Variation and Weak Cytoplasmic Incompatibility, but No Apparent Effect on Reproductive Isolation. Genetics 2017; 205:333-351. [PMID: 27821433 PMCID: PMC5223512 DOI: 10.1534/genetics.116.196238] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/24/2016] [Indexed: 11/18/2022] Open
Abstract
Three hybridizing species-the clade [(Drosophila yakuba, D. santomea), D. teissieri]-comprise the yakuba complex in the D. melanogaster subgroup. Their ranges overlap on Bioko and São Tomé, islands off west Africa. All three species are infected with Wolbachia-maternally inherited, endosymbiotic bacteria, best known for manipulating host reproduction to favor infected females. Previous analyses reported no cytoplasmic incompatibility (CI) in these species. However, we discovered that Wolbachia from each species cause intraspecific and interspecific CI. In D teissieri, analyses of F1 and backcross genotypes show that both host genotype and Wolbachia variation modulate CI intensity. Wolbachia-infected females seem largely protected from intraspecific and interspecific CI, irrespective of Wolbachia and host genotypes. Wolbachia do not affect host mating behavior or female fecundity, within or between species. The latter suggests little apparent effect of Wolbachia on premating or gametic reproductive isolation (RI) between host species. In nature, Wolbachia frequencies varied spatially for D. yakuba in 2009, with 76% (N = 155) infected on São Tomé, and only 3% (N = 36) infected on Bioko; frequencies also varied temporally in D. yakuba and D. santomea on São Tomé between 2009 and 2015. These temporal frequency fluctuations could generate asymmetries in interspecific mating success, and contribute to postzygotic RI. However, the fluctuations in Wolbachia frequencies that we observe also suggest that asymmetries are unlikely to persist. Finally, we address theoretical questions that our empirical findings raise about Wolbachia persistence when conditions fluctuate, and about the stable coexistence of Wolbachia and host variants that modulate Wolbachia effects.
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Affiliation(s)
- Brandon S Cooper
- Department of Evolution and Ecology, Center for Population Biology, University of California, Davis, California 95616
| | - Paul S Ginsberg
- Department of Evolution and Ecology, Center for Population Biology, University of California, Davis, California 95616
| | - Michael Turelli
- Department of Evolution and Ecology, Center for Population Biology, University of California, Davis, California 95616
| | - Daniel R Matute
- Biology Department, University of North Carolina, Chapel Hill, North Carolina 27510
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99
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Faria VG, Martins NE, Magalhães S, Paulo TF, Nolte V, Schlötterer C, Sucena É, Teixeira L. Drosophila Adaptation to Viral Infection through Defensive Symbiont Evolution. PLoS Genet 2016; 12:e1006297. [PMID: 27684942 PMCID: PMC5042464 DOI: 10.1371/journal.pgen.1006297] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 08/12/2016] [Indexed: 11/18/2022] Open
Abstract
Microbial symbionts can modulate host interactions with biotic and abiotic factors. Such interactions may affect the evolutionary trajectories of both host and symbiont. Wolbachia protects Drosophila melanogaster against several viral infections and the strength of the protection varies between variants of this endosymbiont. Since Wolbachia is maternally transmitted, its fitness depends on the fitness of its host. Therefore, Wolbachia populations may be under selection when Drosophila is subjected to viral infection. Here we show that in D. melanogaster populations selected for increased survival upon infection with Drosophila C virus there is a strong selection coefficient for specific Wolbachia variants, leading to their fixation. Flies carrying these selected Wolbachia variants have higher survival and fertility upon viral infection when compared to flies with the other variants. These findings demonstrate how the interaction of a host with pathogens shapes the genetic composition of symbiont populations. Furthermore, host adaptation can result from the evolution of its symbionts, with host and symbiont functioning as a single evolutionary unit. Animals live in close association with microbial partners that can shape many aspects of their lives. For instance, several insects carry bacteria that defend them against parasites and infectious diseases. The intracellular bacterium Wolbachia protects the fruit fly Drosophila melanogaster against viral infection. Natural populations of Drosophila carry different variants of Wolbachia, which differ from one another in the strength of this protection. Here we show that a population of Drosophila infected with viruses during several generations adapts to this challenge through turnover in Wolbachia composition. The Wolbachia variants that give higher protection to viruses, by increasing fly survival and fecundity upon infection, are strongly selected. This work demonstrates that the interaction of an animal with a pathogen can shape its associated microbial populations. We show that adaptation to pathogens can be achieved not only through selection of resistance on the host proper but also through the evolutionary shaping of its microbial community.
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Affiliation(s)
| | | | - Sara Magalhães
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | | | - Viola Nolte
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
| | | | - Élio Sucena
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (ES); (LT)
| | - Luis Teixeira
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- * E-mail: (ES); (LT)
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100
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Wolbachia Endosymbionts Modify Drosophila Ovary Protein Levels in a Context-Dependent Manner. Appl Environ Microbiol 2016; 82:5354-63. [PMID: 27342560 PMCID: PMC4988175 DOI: 10.1128/aem.01255-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/18/2016] [Indexed: 11/20/2022] Open
Abstract
Endosymbiosis is a unique form of interaction between organisms, with one organism dwelling inside the other. One of the most widespread endosymbionts is Wolbachia pipientis, a maternally transmitted bacterium carried by insects, crustaceans, mites, and filarial nematodes. Although candidate proteins that contribute to maternal transmission have been identified, the molecular basis for maternal Wolbachia transmission remains largely unknown. To investigate transmission-related processes in response to Wolbachia infection, ovarian proteomes were analyzed from Wolbachia-infected Drosophila melanogaster and D. simulans. Endogenous and variant host-strain combinations were investigated. Significant and differentially abundant ovarian proteins were detected, indicating substantial regulatory changes in response to Wolbachia. Variant Wolbachia strains were associated with a broader impact on the ovary proteome than endogenous Wolbachia strains. The D. melanogaster ovarian environment also exhibited a higher level of diversity of proteomic responses to Wolbachia than D. simulans. Overall, many Wolbachia-responsive ovarian proteins detected in this study were consistent with expectations from the experimental literature. This suggests that context-specific changes in protein abundance contribute to Wolbachia manipulation of transmission-related mechanisms in oogenesis. IMPORTANCE Millions of insect species naturally carry bacterial endosymbionts called Wolbachia. Wolbachia bacteria are transmitted by females to their offspring through a robust egg-loading mechanism. The molecular basis for Wolbachia transmission remains poorly understood at this time, however. This proteomic study identified specific fruit fly ovarian proteins as being upregulated or downregulated in response to Wolbachia infection. The majority of these protein responses correlated specifically with the type of host and Wolbachia strain involved. This work corroborates previously identified factors and mechanisms while also framing the broader context of ovarian manipulation by Wolbachia.
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