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Łukasik P, Kolasa MR. With a little help from my friends: the roles of microbial symbionts in insect populations and communities. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230122. [PMID: 38705185 PMCID: PMC11070262 DOI: 10.1098/rstb.2023.0122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 12/14/2023] [Indexed: 05/07/2024] Open
Abstract
To understand insect abundance, distribution and dynamics, we need to understand the relevant drivers of their populations and communities. While microbial symbionts are known to strongly affect many aspects of insect biology, we lack data on their effects on populations or community processes, or on insects' evolutionary responses at different timescales. How these effects change as the anthropogenic effects on ecosystems intensify is an area of intense research. Recent developments in sequencing and bioinformatics permit cost-effective microbial diversity surveys, tracking symbiont transmission, and identification of functions across insect populations and multi-species communities. In this review, we explore how different functional categories of symbionts can influence insect life-history traits, how these effects could affect insect populations and their interactions with other species, and how they may affect processes and patterns at the level of entire communities. We argue that insect-associated microbes should be considered important drivers of insect response and adaptation to environmental challenges and opportunities. We also outline the emerging approaches for surveying and characterizing insect-associated microbiota at population and community scales. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.
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Affiliation(s)
- Piotr Łukasik
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Michał R. Kolasa
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
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Peng L, Hoban J, Joffe J, Smith AH, Carpenter M, Marcelis T, Patel V, Lynn-Bell N, Oliver KM, Russell JA. Cryptic community structure and metabolic interactions among the heritable facultative symbionts of the pea aphid. J Evol Biol 2023; 36:1712-1730. [PMID: 37702036 DOI: 10.1111/jeb.14216] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 06/07/2023] [Accepted: 07/18/2023] [Indexed: 09/14/2023]
Abstract
Most insects harbour influential, yet non-essential heritable microbes in their hemocoel. Communities of these symbionts exhibit low diversity. But their frequent multi-species nature raises intriguing questions on roles for symbiont-symbiont synergies in host adaptation, and on the stability of the symbiont communities, themselves. In this study, we build on knowledge of species-defined symbiont community structure across US populations of the pea aphid, Acyrthosiphon pisum. Through extensive symbiont genotyping, we show that pea aphids' microbiomes can be more precisely defined at the symbiont strain level, with strain variability shaping five out of nine previously reported co-infection trends. Field data provide a mixture of evidence for synergistic fitness effects and symbiont hitchhiking, revealing causes and consequences of these co-infection trends. To test whether within-host metabolic interactions predict common versus rare strain-defined communities, we leveraged the high relatedness of our dominant, community-defined symbiont strains vs. 12 pea aphid-derived Gammaproteobacteria with sequenced genomes. Genomic inference, using metabolic complementarity indices, revealed high potential for cooperation among one pair of symbionts-Serratia symbiotica and Rickettsiella viridis. Applying the expansion network algorithm, through additional use of pea aphid and obligate Buchnera symbiont genomes, Serratia and Rickettsiella emerged as the only symbiont community requiring both parties to expand holobiont metabolism. Through their joint expansion of the biotin biosynthesis pathway, these symbionts may span missing gaps, creating a multi-party mutualism within their nutrient-limited, phloem-feeding hosts. Recent, complementary gene inactivation, within the biotin pathways of Serratia and Rickettsiella, raises further questions on the origins of mutualisms and host-symbiont interdependencies.
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Affiliation(s)
- Linyao Peng
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Jessica Hoban
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Jonah Joffe
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Andrew H Smith
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Melissa Carpenter
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, Philadelphia, Pennsylvania, USA
| | - Tracy Marcelis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Vilas Patel
- Department of Entomology, University of Georgia, Athens, Georgia, USA
| | - Nicole Lynn-Bell
- Department of Entomology, University of Georgia, Athens, Georgia, USA
| | - Kerry M Oliver
- Department of Entomology, University of Georgia, Athens, Georgia, USA
| | - Jacob A Russell
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
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Complexities of Inferring Symbiont Function: Paraburkholderia Symbiont Dynamics in Social Amoeba Populations and Their Impacts on the Amoeba Microbiota. Appl Environ Microbiol 2022; 88:e0128522. [PMID: 36043858 PMCID: PMC9499018 DOI: 10.1128/aem.01285-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The relationship between the social amoeba Dictyostelium discoideum and its endosymbiotic bacteria Paraburkholderia provides a model system for studying the development of symbiotic relationships. Laboratory experiments have shown that any of three species of the Paraburkholderia symbiont allow D. discoideum food bacteria to persist through the amoeba life cycle and survive in amoeba spores rather than being fully digested. This phenomenon is termed "farming," as it potentially allows spores dispersed to food-poor locations to grow their own. The occurrence and impact of farming in natural populations, however, have been a challenge to measure. Here, we surveyed natural D. discoideum populations and found that only one of the three symbiont species, Paraburkholderia agricolaris, remained prevalent. We then explored the effect of Paraburkholderia on the amoeba microbiota, expecting that by facilitating bacterial food carriage, it would diversify the microbiota. Contrary to our expectations, Paraburkholderia tended to infectiously dominate the D. discoideum microbiota, in some cases decreasing diversity. Similarly, we found little evidence for Paraburkholderia facilitating the carriage of particular food bacteria. These findings highlight the complexities of inferring symbiont function in nature and suggest the possibility that Paraburkholderia could be playing multiple roles for its host. IMPORTANCE The functions of symbionts in natural populations can be difficult to completely discern. The three Paraburkholderia bacterial farming symbionts of the social amoeba Dictyostelium discoideum have been shown in the laboratory environment to allow the amoebas to carry, rather than fully digest, food bacteria. This potentially provides a fitness benefit to the amoebas upon dispersal to food-poor environments, as they could grow their food. We expected that meaningful food carriage would manifest as a more diverse microbiota. Surprisingly, we found that Paraburkholderia tended to infectiously dominate the D. discoideum microbiota rather than diversifying it. We determined that only one of the three Paraburkholderia symbionts has increased in prevalence in natural populations in the past 20 years, suggesting that this symbiont may be beneficial, however. These findings suggest that Paraburkholderia may have an alternative function for its host, which drives its prevalence in natural populations.
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Carpenter M, Peng L, Smith AH, Joffe J, O’Connor M, Oliver KM, Russell JA. Frequent Drivers, Occasional Passengers: Signals of Symbiont-Driven Seasonal Adaptation and Hitchhiking in the Pea Aphid, Acyrthosiphon pisum. INSECTS 2021; 12:805. [PMID: 34564245 PMCID: PMC8466206 DOI: 10.3390/insects12090805] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 12/25/2022]
Abstract
Insects harbor a variety of maternally inherited bacterial symbionts. As such, variation in symbiont presence/absence, in the combinations of harbored symbionts, and in the genotypes of harbored symbiont species provide heritable genetic variation of potential use in the insects' adaptive repertoires. Understanding the natural importance of symbionts is challenging but studying their dynamics over time can help to elucidate the potential for such symbiont-driven insect adaptation. Toward this end, we studied the seasonal dynamics of six maternally transferred bacterial symbiont species in the multivoltine pea aphid (Acyrthosiphon pisum). Our sampling focused on six alfalfa fields in southeastern Pennsylvania, and spanned 14 timepoints within the 2012 growing season, in addition to two overwintering periods. To test and generate hypotheses on the natural relevance of these non-essential symbionts, we examined whether symbiont dynamics correlated with any of ten measured environmental variables from the 2012 growing season, including some of known importance in the lab. We found that five symbionts changed prevalence across one or both overwintering periods, and that the same five species underwent such frequency shifts across the 2012 growing season. Intriguingly, the frequencies of these dynamic symbionts showed robust correlations with a subset of our measured environmental variables. Several of these trends supported the natural relevance of lab-discovered symbiont roles, including anti-pathogen defense. For a seventh symbiont-Hamiltonella defensa-studied previously across the same study periods, we tested whether a reported correlation between prevalence and temperature stemmed not from thermally varying host-level fitness effects, but from selection on co-infecting symbionts or on aphid-encoded alleles associated with this bacterium. In general, such "hitchhiking" effects were not evident during times with strongly correlated Hamiltonella and temperature shifts. However, we did identify at least one time period in which Hamiltonella spread was likely driven by selection on a co-infecting symbiont-Rickettsiella viridis. Recognizing the broader potential for such hitchhiking, we explored selection on co-infecting symbionts as a possible driver behind the dynamics of the remaining six species. Out of twelve examined instances of symbiont dynamics unfolding across 2-week periods or overwintering spans, we found eight in which the focal symbiont underwent parallel frequency shifts under single infection and one or more co-infection contexts. This supported the idea that phenotypic variation created by the presence/absence of individual symbionts is a direct target for selection, and that symbiont effects can be robust under co-habitation with other symbionts. Contrastingly, in two cases, we found that selection may target phenotypes emerging from symbiont co-infections, with specific species combinations driving overall trends for the focal dynamic symbionts, without correlated change under single infection. Finally, in three cases-including the one described above for Hamiltonella-our data suggested that incidental co-infection with a (dis)favored symbiont could lead to large frequency shifts for "passenger" symbionts, conferring no apparent cost or benefit. Such hitchhiking has rarely been studied in heritable symbiont systems. We propose that it is more common than appreciated, given the widespread nature of maternally inherited bacteria, and the frequency of multi-species symbiotic communities across insects.
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Affiliation(s)
- Melissa Carpenter
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
| | - Linyao Peng
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
| | - Andrew H. Smith
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
| | - Jonah Joffe
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
| | - Michael O’Connor
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
| | - Kerry M. Oliver
- Department of Entomology, University of Georgia, 120 Cedar St., Athens, GA 30602, USA;
| | - Jacob A. Russell
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
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Smith AH, O'Connor MP, Deal B, Kotzer C, Lee A, Wagner B, Joffe J, Woloszynek S, Oliver KM, Russell JA. Does getting defensive get you anywhere?-Seasonal balancing selection, temperature, and parasitoids shape real-world, protective endosymbiont dynamics in the pea aphid. Mol Ecol 2021; 30:2449-2472. [PMID: 33876478 DOI: 10.1111/mec.15906] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/16/2021] [Accepted: 03/25/2021] [Indexed: 12/11/2022]
Abstract
Facultative, heritable endosymbionts are found at intermediate prevalence within most insect species, playing frequent roles in their hosts' defence against environmental pressures. Focusing on Hamiltonella defensa, a common bacterial endosymbiont of aphids, we tested the hypothesis that such pressures impose seasonal balancing selection, shaping a widespread infection polymorphism. In our studied pea aphid (Acyrthosiphon pisum) population, Hamiltonella frequencies ranged from 23.2% to 68.1% across a six-month longitudinal survey. Rapid spikes and declines were often consistent across fields, and we estimated that selection coefficients for Hamiltonella-infected aphids changed sign within this field season. Prior laboratory research suggested antiparasitoid defence as the major Hamiltonella benefit, and costs under parasitoid absence. While a prior field study suggested these forces can sometimes act as counter-weights in a regime of seasonal balancing selection, our present survey showed no significant relationship between parasitoid wasps and Hamiltonella prevalence. Field cage experiments provided some explanation: parasitoids drove modest ~10% boosts to Hamiltonella frequencies that would be hard to detect under less controlled conditions. They also showed that Hamiltonella was not always costly under parasitoid exclusion, contradicting another prediction. Instead, our longitudinal survey - and two overwintering studies - showed temperature to be the strongest predictor of Hamiltonella prevalence. Matching some prior lab discoveries, this suggested that thermally sensitive costs and benefits, unrelated to parasitism, can shape Hamiltonella dynamics. These results add to a growing body of evidence for rapid, seasonal adaptation in multivoltine organisms, suggesting that such adaptation can be mediated through the diverse impacts of heritable bacterial endosymbionts.
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Affiliation(s)
- Andrew H Smith
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Michael P O'Connor
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, Philadelphia, PA, USA
| | - Brooke Deal
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Coleman Kotzer
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Amanda Lee
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Barrett Wagner
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Jonah Joffe
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | | | - Kerry M Oliver
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Jacob A Russell
- Department of Biology, Drexel University, Philadelphia, PA, USA
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Ginete DR, Goodrich-Blair H. From Binary Model Systems to the Human Microbiome: Factors That Drive Strain Specificity in Host-Symbiont Associations. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.614197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Microbial symbionts are ubiquitous and can have significant impact on hosts. These impacts can vary in the sign (positive or negative) and degree depending on the identity of the interacting partners. Studies on host-symbiont associations indicate that subspecies (strain) genetic variation can influence interaction outcomes, making it necessary to go beyond species-level distinction to understand host-symbiont dynamics. In this review, we discuss examples of strain specificity found in host-symbiont associations, from binary model systems to the human microbiome. Although host and bacterial factors identified as mediators for specificity could be distinct at the molecular level, they generally fall into two broad functional categories: (1) those that contribute a required activity in support of the association and (2) those involved in antagonistic interactions with organisms outside of the association. We argue here based on current literature that factors from these two categories can work in concert to drive strain specificity and that this strain specificity must be considered to fully understand the molecular and ecological dynamics of host-symbiont associations, including the human microbiome.
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Spiroplasma Infection among Ixodid Ticks Exhibits Species Dependence and Suggests a Vertical Pattern of Transmission. Microorganisms 2021; 9:microorganisms9020333. [PMID: 33567677 PMCID: PMC7915285 DOI: 10.3390/microorganisms9020333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/26/2021] [Accepted: 02/05/2021] [Indexed: 11/24/2022] Open
Abstract
Members of the genus Spiroplasma are Gram-positive bacteria without cell walls. Some Spiroplasma species can cause disease in arthropods such as bees, whereas others provide their host with resistance to pathogens. Ticks also harbour Spiroplasma, but their role has not been elucidated yet. Here, the infection status and genetic diversity of Spiroplasma in ticks were investigated using samples collected from different geographic regions in Japan. A total of 712 ticks were tested for Spiroplasma infection by PCR targeting 16S rDNA, and Spiroplasma species were genetically characterized based on 16S rDNA, ITS, dnaA, and rpoB gene sequences. A total of 109 samples originating from eight tick species were positive for Spiroplasma infection, with infection rates ranging from 0% to 84% depending on the species. A linear mixed model indicated that tick species was the primary factor associated with Spiroplasma infection. Moreover, certain Spiroplasma alleles that are highly adapted to specific tick species may explain the high infection rates in Ixodes ovatus and Haemaphysalis kitaokai. A comparison of the alleles obtained suggests that horizontal transmission between tick species may not be a frequent event. These findings provide clues to understand the transmission cycle of Spiroplasma species in wild tick populations and their roles in host ticks.
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Gerth M, Martinez-Montoya H, Ramirez P, Masson F, Griffin JS, Aramayo R, Siozios S, Lemaitre B, Mateos M, Hurst GDD. Rapid molecular evolution of Spiroplasma symbionts of Drosophila. Microb Genom 2021; 7:000503. [PMID: 33591248 PMCID: PMC8208695 DOI: 10.1099/mgen.0.000503] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 01/22/2021] [Indexed: 12/21/2022] Open
Abstract
Spiroplasma is a genus of Mollicutes whose members include plant pathogens, insect pathogens and endosymbionts of animals. Spiroplasma phenotypes have been repeatedly observed to be spontaneously lost in Drosophila cultures, and several studies have documented a high genomic turnover in Spiroplasma symbionts and plant pathogens. These observations suggest that Spiroplasma evolves quickly in comparison to other insect symbionts. Here, we systematically assess evolutionary rates and patterns of Spiroplasma poulsonii, a natural symbiont of Drosophila. We analysed genomic evolution of sHy within flies, and sMel within in vitro culture over several years. We observed that S. poulsonii substitution rates are among the highest reported for any bacteria, and around two orders of magnitude higher compared with other inherited arthropod endosymbionts. The absence of mismatch repair loci mutS and mutL is conserved across Spiroplasma, and likely contributes to elevated substitution rates. Further, the closely related strains sMel and sHy (>99.5 % sequence identity in shared loci) show extensive structural genomic differences, which potentially indicates a higher degree of host adaptation in sHy, a protective symbiont of Drosophila hydei. Finally, comparison across diverse Spiroplasma lineages confirms previous reports of dynamic evolution of toxins, and identifies loci similar to the male-killing toxin Spaid in several Spiroplasma lineages and other endosymbionts. Overall, our results highlight the peculiar nature of Spiroplasma genome evolution, which may explain unusual features of its evolutionary ecology.
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Affiliation(s)
- Michael Gerth
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Present address: Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Humberto Martinez-Montoya
- Laboratorio de Genética y Genómica Comparativa, Unidad Académica Multidisciplinaria Reynosa Aztlán, Universidad Autónoma de Tamaulipas, Reynosa, Mexico
| | - Paulino Ramirez
- Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Florent Masson
- Global Health Institute, School of Life Sciences, Swiss Federal Institute of Technology Lausanne (École Polytechnique Fédérale de Lausanne), Lausanne, Switzerland
| | - Joanne S. Griffin
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Rodolfo Aramayo
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Stefanos Siozios
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Bruno Lemaitre
- Global Health Institute, School of Life Sciences, Swiss Federal Institute of Technology Lausanne (École Polytechnique Fédérale de Lausanne), Lausanne, Switzerland
| | - Mariana Mateos
- Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, USA
| | - Gregory D. D. Hurst
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
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Multiple origins of obligate nematode and insect symbionts by a clade of bacteria closely related to plant pathogens. Proc Natl Acad Sci U S A 2020; 117:31979-31986. [PMID: 33257562 DOI: 10.1073/pnas.2000860117] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Obligate symbioses involving intracellular bacteria have transformed eukaryotic life, from providing aerobic respiration and photosynthesis to enabling colonization of previously inaccessible niches, such as feeding on xylem and phloem, and surviving in deep-sea hydrothermal vents. A major challenge in the study of obligate symbioses is to understand how they arise. Because the best studied obligate symbioses are ancient, it is especially challenging to identify early or intermediate stages. Here we report the discovery of a nascent obligate symbiosis in Howardula aoronymphium, a well-studied nematode parasite of Drosophila flies. We have found that H aoronymphium and its sister species harbor a maternally inherited intracellular bacterial symbiont. We never find the symbiont in nematode-free flies, and virtually all nematodes in the field and the laboratory are infected. Treating nematodes with antibiotics causes a severe reduction in fly infection success. The association is recent, as more distantly related insect-parasitic tylenchid nematodes do not host these endosymbionts. We also report that the Howardula nematode symbiont is a member of a widespread monophyletic group of invertebrate host-associated microbes that has independently given rise to at least four obligate symbioses, one in nematodes and three in insects, and that is sister to Pectobacterium, a lineage of plant pathogenic bacteria. Comparative genomic analysis of this group, which we name Candidatus Symbiopectobacterium, shows signatures of genome erosion characteristic of early stages of symbiosis, with the Howardula symbiont's genome containing over a thousand predicted pseudogenes, comprising a third of its genome.
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Comparison Between the Microbial Diversity in Carpenter Ant (Camponotus) Gut and Weaver Ant (Oecophylla) Gut. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2019. [DOI: 10.22207/jpam.13.4.58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Zaada DSY, Ben-Yosef M, Yuval B, Jurkevitch E. The host fruit amplifies mutualistic interaction between Ceratitis capitata larvae and associated bacteria. BMC Biotechnol 2019; 19:92. [PMID: 31847844 PMCID: PMC6918632 DOI: 10.1186/s12896-019-0581-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background The Mediterranean fruit fly Ceratitis capitata is a major pest in horticulture. The development of fly larvae is mediated by bacterial decay in the fruit tissue. Despite the importance of bacteria on larval development, very little is known about the interaction between bacteria and larvae in their true ecological context. Understanding their relationship and inter-dependence in the host fruit is important for the development of new pest control interfaces to deal with this pest. Results We find no negative effects on egg hatch or larval development brought about by the bacterial isolates tested. The various symbionts inhabiting the fly’s digestive system differ in their degree of contribution to the development of fly larvae depending on the given host and their sensitivity to induced inhibition caused by female produced antimicrobial peptides. These differences were observed not only at the genus or species level but also between isolates of the same species. We demonstrate how the microbiota from the mother’s gut supports the development of larvae in the fruit host and show that larvae play a major role in spreading the bacterial contagion in the infected fruit itself. In addition, we present (for the first time) evidence for horizontal transfer of bacteria between larvae of different maternal origin that develop together in the same fruit. Conclusions Larvae play a major role in the spread and shaping of the microbial population in the fruit. The transfer of bacteria between different individuals developing in the same fruit suggests that the infested fruit serves as a microbial hub for the amplification and spread of bacterial strains between individuals.
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Affiliation(s)
- Doron Shalom Yishai Zaada
- Departments of Entomology, Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, POB 12, 76100, Rehovot, Israel.
| | - Michael Ben-Yosef
- Departments of Entomology, Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, POB 12, 76100, Rehovot, Israel
| | - Boaz Yuval
- Departments of Entomology, Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, POB 12, 76100, Rehovot, Israel
| | - Edouard Jurkevitch
- Departments of Plant Pathology & Microbiology, Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, POB 12, 76100, Rehovot, Israel
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12
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Mathé‐Hubert H, Kaech H, Hertaeg C, Jaenike J, Vorburger C. Nonrandom associations of maternally transmitted symbionts in insects: The roles of drift versus biased cotransmission and selection. Mol Ecol 2019; 28:5330-5346. [DOI: 10.1111/mec.15206] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 07/29/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Hugo Mathé‐Hubert
- Eawag Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
| | - Heidi Kaech
- Eawag Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
- Institute of Integrative Biology Department of Environmental Systems Science ETH Zürich Zürich Switzerland
| | - Corinne Hertaeg
- Eawag Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
- Institute of Agricultural Sciences Department of Environmental Systems Science ETH Zürich Zürich Switzerland
| | - John Jaenike
- Department of Biology University of Rochester Rochester NY USA
| | - Christoph Vorburger
- Eawag Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
- Institute of Integrative Biology Department of Environmental Systems Science ETH Zürich Zürich Switzerland
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13
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Oliver KM. Editorial overview: Microbial manipulation of insect-parasite interactions. CURRENT OPINION IN INSECT SCIENCE 2019; 32:vi-ix. [PMID: 31113641 DOI: 10.1016/j.cois.2019.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Kerry M Oliver
- Department of Entomology, University of Georgia, Athens, GA 30602, USA.
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Monticelli LS, Outreman Y, Frago E, Desneux N. Impact of host endosymbionts on parasitoid host range - from mechanisms to communities. CURRENT OPINION IN INSECT SCIENCE 2019; 32:77-82. [PMID: 31113635 DOI: 10.1016/j.cois.2018.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 11/16/2018] [Accepted: 11/16/2018] [Indexed: 06/09/2023]
Abstract
In insects, bacterial endosymbionts are known to influence the ecology of their hosts by modifying interactions with natural enemies such as parasitoids. Symbionts can modulate both parasitoid behavioral and/or physiological traits as well as host behaviors and life-history traits. Together these suggest that endosymbionts may impact the host range of parasitoids. For example, endosymbionts may narrow parasitoid host range through first, reducing parasitoid ability to locate hosts and/or larval survival, second, affecting fitness traits of the emerging adult parasitoid and/or third, modulating the outcome of interference and exploitative competition between parasitoid species. From both a fundamental and applied point of view, these symbiotic effects would influence the ecology and evolution of parasitoids and associated population-level processes and ecosystem services (e.g. biocontrol).
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Affiliation(s)
- Lucie S Monticelli
- INRA (French National Institute for Agricultural Research), Université Côte d'Azur, CNRS UMR1355-7254, Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France
| | - Yannick Outreman
- Agrocampus Ouest, INRA, Université de Rennes 1, Université Bretagne-Loire, UMR IGEPP, 35000, Rennes, France
| | - Enric Frago
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, Saint-Pierre, Reunion, France
| | - Nicolas Desneux
- INRA (French National Institute for Agricultural Research), Université Côte d'Azur, CNRS UMR1355-7254, Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France.
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15
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Ballinger MJ, Perlman SJ. The defensive Spiroplasma. CURRENT OPINION IN INSECT SCIENCE 2019; 32:36-41. [PMID: 31113629 DOI: 10.1016/j.cois.2018.10.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 10/11/2018] [Accepted: 10/15/2018] [Indexed: 05/06/2023]
Abstract
Defensive microbes are of great interest for their roles in arthropod health, disease transmission, and biocontrol efforts. Obligate bacterial passengers of arthropods, such as Spiroplasma, confer protection against the natural enemies of their hosts to improve their own fitness. Although known for less than a decade, Spiroplasma's defensive reach extends to diverse parasites, both microbial and multicellular. We provide an overview of known defensive phenotypes against nematodes, parasitoid wasps, and fungi, and highlight recent studies supporting the role of Spiroplasma-encoded ribosome-inactivating proteins in protection. With cellular features well-suited for life in the hemolymph, broad distribution among invertebrate hosts, and the capacity to repeatedly evolve vertical transmission, Spiroplasma may be uniquely equipped to form intimate, defensive associations to combat extracellular parasites. Along with insights into defensive mechanisms, recent significant advances have been made in male-killing - a phenotype with interesting evolutionary ties to defense. Finally, we look forward to an exciting decade using the genetic tools of Drosophila, and the rapidly-advancing tractability of Spiroplasma itself, to better understand mechanisms and evolution in defensive symbiosis.
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Affiliation(s)
- Matthew J Ballinger
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, 39762, USA.
| | - Steve J Perlman
- Department of Biology, University of Victoria, Victoria, BC, V8W 2Y2, Canada
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16
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Ballinger MJ, Gawryluk RMR, Perlman SJ. Toxin and Genome Evolution in a Drosophila Defensive Symbiosis. Genome Biol Evol 2019; 11:253-262. [PMID: 30576446 PMCID: PMC6349354 DOI: 10.1093/gbe/evy272] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2018] [Indexed: 12/25/2022] Open
Abstract
Defenses conferred by microbial symbionts play a vital role in the health and fitness of their animal hosts. An important outstanding question in the study of defensive symbiosis is what determines long term stability and effectiveness against diverse natural enemies. In this study, we combine genome and transcriptome sequencing, symbiont transfection and parasite protection experiments, and toxin activity assays to examine the evolution of the defensive symbiosis between Drosophila flies and their vertically transmitted Spiroplasma bacterial symbionts, focusing in particular on ribosome-inactivating proteins (RIPs), symbiont-encoded toxins that have been implicated in protection against both parasitic wasps and nematodes. Although many strains of Spiroplasma, including the male-killing symbiont (sMel) of Drosophila melanogaster, protect against parasitic wasps, only the strain (sNeo) that infects the mycophagous fly Drosophila neotestacea appears to protect against parasitic nematodes. We find that RIP repertoire is a major differentiating factor between strains that do and do not offer nematode protection, and that sMel RIPs do not show activity against nematode ribosomes in vivo. We also discovered a strain of Spiroplasma infecting a mycophagous phorid fly, Megaselia nigra. Although both the host and its Spiroplasma are distantly related to D. neotestacea and its symbiont, genome sequencing revealed that the M. nigra symbiont encodes abundant and diverse RIPs, including plasmid-encoded toxins that are closely related to the RIPs in sNeo. Our results suggest that distantly related Spiroplasma RIP toxins may perform specialized functions with regard to parasite specificity and suggest an important role for horizontal gene transfer in the emergence of novel defensive phenotypes.
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Affiliation(s)
- Matthew J Ballinger
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS
| | - Ryan M R Gawryluk
- Department of Biology, University of Victoria, British Columbia, Canada
| | - Steve J Perlman
- Department of Biology, University of Victoria, British Columbia, Canada
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17
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Vorburger C, Perlman SJ. The role of defensive symbionts in host-parasite coevolution. Biol Rev Camb Philos Soc 2018; 93:1747-1764. [PMID: 29663622 DOI: 10.1111/brv.12417] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 03/20/2018] [Accepted: 03/23/2018] [Indexed: 02/06/2023]
Abstract
Understanding the coevolution of hosts and parasites is a long-standing goal of evolutionary biology. There is a well-developed theoretical framework to describe the evolution of host-parasite interactions under the assumption of direct, two-species interactions, which can result in arms race dynamics or sustained genotype fluctuations driven by negative frequency dependence (Red Queen dynamics). However, many hosts rely on symbionts for defence against parasites. Whilst the ubiquity of defensive symbionts and their potential importance for disease control are increasingly recognized, there is still a gap in our understanding of how symbionts mediate or possibly take part in host-parasite coevolution. Herein we address this question by synthesizing information already available from theoretical and empirical studies. First, we briefly introduce current hypotheses on how defensive mutualisms evolved from more parasitic relationships and highlight exciting new experimental evidence showing that this can occur very rapidly. We go on to show that defensive symbionts influence virtually all important determinants of coevolutionary dynamics, namely the variation in host resistance available to selection by parasites, the specificity of host resistance, and the trade-off structure between host resistance and other components of fitness. In light of these findings, we turn to the limited theory and experiments available for such three-species interactions to assess the role of defensive symbionts in host-parasite coevolution. Specifically, we discuss under which conditions the defensive symbiont may take over from the host the reciprocal adaptation with parasites and undergo its own selection dynamics, thereby altering or relaxing selection on the hosts' own immune defences. Finally, we address potential effects of defensive symbionts on the evolution of parasite virulence. This is an important problem for which there is no single, clear-cut prediction. The selection on parasite virulence resulting from the presence of defensive symbionts in their hosts will depend on the underlying mechanism of defence. We identify the evolutionary predictions for different functional categories of symbiont-conferred resistance and we evaluate the empirical literature for supporting evidence. We end this review with outstanding questions and promising avenues for future research to improve our understanding of symbiont-mediated coevolution between hosts and parasites.
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Affiliation(s)
- Christoph Vorburger
- Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland.,Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Universitätsstrasse 16, 8092, Zürich, Switzerland
| | - Steve J Perlman
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2, Canada
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18
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Abstract
Male-killing is one strategy used by maternally transmitted bacterial symbionts to boost transmission and spread in populations. In Drosophila melanogaster, Spiroplasma target males by hijacking an essential, male-limited epigenetic process. A new study reveals clues to the mode of killing.
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Desirò A, Hao Z, Liber JA, Benucci GMN, Lowry D, Roberson R, Bonito G. Mycoplasma-related endobacteria within Mortierellomycotina fungi: diversity, distribution and functional insights into their lifestyle. ISME JOURNAL 2018; 12:1743-1757. [PMID: 29476142 DOI: 10.1038/s41396-018-0053-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 12/22/2017] [Accepted: 01/10/2018] [Indexed: 11/09/2022]
Abstract
Bacterial interactions with animals and plants have been examined for over a century; by contrast, the study of bacterial-fungal interactions has received less attention. Bacteria interact with fungi in diverse ways, and endobacteria that reside inside fungal cells represent the most intimate interaction. The most significant bacterial endosymbionts that have been studied are associated with Mucoromycota and include two main groups: Burkholderia-related and Mycoplasma-related endobacteria (MRE). Examples of Burkholderia-related endobacteria have been reported in the three Mucoromycota subphyla. By contrast, MRE have only been identified in Glomeromycotina and Mucoromycotina. This study aims to understand whether MRE dwell in Mortierellomycotina and, if so, to determine their impact on the fungal host. We carried out a large-scale screening of 394 Mortierellomycotina strains and employed a combination of microscopy, molecular phylogeny, next-generation sequencing and qPCR. We detected MRE in 12 strains. These endosymbionts represent novel bacterial phylotypes and show evidence of recombination. Their presence in Mortierellomycotina demonstrates that MRE occur within fungi across Mucoromycota and they may have lived in their common ancestor. We cured the fungus of its endosymbionts with antibiotics and observed improved biomass production in isogenic lines lacking MRE, demonstrating that these endobacteria impose some fitness costs to their fungal host. Here we provided the first functional insights into the lifestyle of MRE. Our findings indicate that MRE may be antagonistic to their fungal hosts, and adapted to a non-lethal parasitic lifestyle in the mycelium of Mucoromycota. However, context-dependent adaptive benefits to their host at minimal cost cannot not be excluded. Finally, we conclude that Mortierellomycotina represent attractive model organisms for exploring interactions between MRE and fungi.
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Affiliation(s)
- Alessandro Desirò
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA.
| | - Zhen Hao
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA
| | - Julian A Liber
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA
| | | | - David Lowry
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Robert Roberson
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Gregory Bonito
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA
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20
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Guidolin AS, Cataldi TR, Labate CA, Francis F, Cônsoli FL. Spiroplasma affects host aphid proteomics feeding on two nutritional resources. Sci Rep 2018; 8:2466. [PMID: 29410456 PMCID: PMC5802742 DOI: 10.1038/s41598-018-20497-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 01/21/2018] [Indexed: 12/25/2022] Open
Abstract
Bacterial symbionts are broadly distributed among insects, influencing their bioecology to different degrees. Aphids carry a number of secondary symbionts that can influence aphid physiology and fitness attributes. Spiroplasma is seldom reported as an aphid symbiont, but a high level of infection has been observed in one population of the tropical aphid Aphis citricidus. We used sister isolines of Spiroplasma-infected (Ac-BS) and Spiroplasma-free (Ac-B) aphids reared on sweet orange (optimum host) and orange jasmine (suboptimum host) to demonstrate the effects of Spiroplasma infection in the aphid proteome profile. A higher number of proteins were differently abundant in aphids feeding on orange jasmine, indicating an impact of host plant quality. In both host plants, the majority of proteins affected by Spiroplasma infection were heat shock proteins, proteins linked to cell function and structure, and energy metabolism. Spiroplasma also induced changes in proteins involved in antimicrobial activity, carbohydrate processing and metabolism, amino acid synthesis and metabolism in aphids feeding on orange jasmine. We discuss on how the aphid host proteome is differentially affected by Spiroplasma infection when the host is exploiting host plants with different nutritional values.
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Affiliation(s)
- Aline Sartori Guidolin
- Insect Interactions Laboratory, Department of Entomology and Acarology, ESALQ, University of São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brazil
| | - Thaís Regiani Cataldi
- Max Feffer Laboratory of Plant Genetics, Department of Genetics, ESALQ, University of São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brazil
| | - Carlos Alberto Labate
- Max Feffer Laboratory of Plant Genetics, Department of Genetics, ESALQ, University of São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brazil
| | - Frederic Francis
- Entomologie Fonctionnelle et Evolutive, Gembloux Agro-Bio Tech, Université de Liège, 2 Passage des Déportés, 5030, Gembloux, Belgium
| | - Fernando Luis Cônsoli
- Insect Interactions Laboratory, Department of Entomology and Acarology, ESALQ, University of São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brazil.
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21
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Evolution and Diversity of Inherited Spiroplasma Symbionts in Myrmica Ants. Appl Environ Microbiol 2018; 84:AEM.02299-17. [PMID: 29196290 DOI: 10.1128/aem.02299-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 11/27/2017] [Indexed: 12/20/2022] Open
Abstract
Microbial partners play important roles in the biology and ecology of animals. In insects, maternally transmitted symbionts are especially common and can have host effects ranging from reproductive manipulation to nutrient provisioning and defense against natural enemies. In this study, we report a genus-wide association of Myrmica ants with the inherited bacterial symbiont Spiroplasma We screen Myrmica ants collected from the wild, including the invasive European fire ant, Myrmica rubra, and find an extraordinarily high prevalence of this symbiont-8 of 9 species, 42 of 43 colonies, and 250 of 276 individual workers harbored Spiroplasma-only one host species was uninfected. In our screens, each host species carried a distinct Spiroplasma strain, and none were infected with more than one strain. All symbionts belong to the citri clade, allied most closely with pathogenic strains of Spiroplasma infecting corn crops and honeybees, and there is strong evidence of host-symbiont persistence across evolutionary time scales. Genome sequencing of two Spiroplasma symbionts revealed candidate genes that may play a part in the symbiosis, a nutrient transporter absent from other Spiroplasma strains, and a ribosome-inactivating protein previously implicated in parasite defense. These results together suggest long-term, likely mutualistic, relationships atypical of Spiroplasma-insect associations with potential significance for broad ecological interactions with MyrmicaIMPORTANCE Animal-associated microbial symbionts can dramatically affect the biology of their hosts. The identification and characterization of these intimate partnerships remain an essential component of describing and predicting species interactions, especially for invasive host species. Ants perform crucial ecological functions as ecosystem engineers, scavengers, and predators, and ants in the genus Myrmica can be aggressive resource competitors and reach high densities in their native and invaded habitats. In this study, a novel symbiosis is identified between Myrmica ants and the facultative bacterial symbiont Spiroplasma Broad host distribution, high frequencies of infection, and host-symbiont codivergence over evolutionary time scales, an uncommon feature of Spiroplasma associations, suggest an important likely mutualistic interaction. Genome sequencing identified highly divergent gene candidates that may contribute to Spiroplasma's role as a possible defensive or nutritional partner in Myrmica.
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22
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Eleftherianos I, Yadav S, Kenney E, Cooper D, Ozakman Y, Patrnogic J. Role of Endosymbionts in Insect-Parasitic Nematode Interactions. Trends Parasitol 2017; 34:430-444. [PMID: 29150386 DOI: 10.1016/j.pt.2017.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/12/2017] [Accepted: 10/19/2017] [Indexed: 12/12/2022]
Abstract
Endosymbiotic bacteria exist in many animals where they develop relationships that affect certain physiological processes in the host. Insects and their nematode parasites form great models for understanding the genetic and molecular basis of immune and parasitic processes. Both organisms contain endosymbionts that possess the ability to interfere with certain mechanisms of immune function and pathogenicity. This review summarizes recent information on the involvement of insect endosymbionts in the response to parasitic nematode infections, and the influence of nematode endosymbionts on specific aspects of the insect immune system. Analyzing this information will be particularly useful for devising endosymbiont-based strategies to intervene in insect immunity or nematode parasitism for the efficient management of noxious insects in the field.
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Affiliation(s)
- Ioannis Eleftherianos
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA.
| | - Shruti Yadav
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Eric Kenney
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Dustin Cooper
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Yaprak Ozakman
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Jelena Patrnogic
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
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23
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Ballinger MJ, Perlman SJ. Generality of toxins in defensive symbiosis: Ribosome-inactivating proteins and defense against parasitic wasps in Drosophila. PLoS Pathog 2017; 13:e1006431. [PMID: 28683136 PMCID: PMC5500355 DOI: 10.1371/journal.ppat.1006431] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 05/23/2017] [Indexed: 01/11/2023] Open
Abstract
While it has become increasingly clear that multicellular organisms often harbor microbial symbionts that protect their hosts against natural enemies, the mechanistic underpinnings underlying most defensive symbioses are largely unknown. Spiroplasma bacteria are widespread associates of terrestrial arthropods, and include strains that protect diverse Drosophila flies against parasitic wasps and nematodes. Recent work implicated a ribosome-inactivating protein (RIP) encoded by Spiroplasma, and related to Shiga-like toxins in enterohemorrhagic Escherichia coli, in defense against a virulent parasitic nematode in the woodland fly, Drosophila neotestacea. Here we test the generality of RIP-mediated protection by examining whether Spiroplasma RIPs also play a role in wasp protection, in D. melanogaster and D. neotestacea. We find strong evidence for a major role of RIPs, with ribosomal RNA (rRNA) from the larval endoparasitic wasps, Leptopilina heterotoma and Leptopilina boulardi, exhibiting the hallmarks of RIP activity. In Spiroplasma-containing hosts, parasitic wasp ribosomes show abundant site-specific depurination in the α-sarcin/ricin loop of the 28S rRNA, with depurination occurring soon after wasp eggs hatch inside fly larvae. Interestingly, we found that the pupal ectoparasitic wasp, Pachycrepoideus vindemmiae, escapes protection by Spiroplasma, and its ribosomes do not show high levels of depurination. We also show that fly ribosomes show little evidence of targeting by RIPs. Finally, we find that the genome of D. neotestacea's defensive Spiroplasma encodes a diverse repertoire of RIP genes, which are differ in abundance. This work suggests that specificity of defensive symbionts against different natural enemies may be driven by the evolution of toxin repertoires, and that toxin diversity may play a role in shaping host-symbiont-enemy interactions.
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Affiliation(s)
| | - Steve J. Perlman
- Department of Biology, University of Victoria, Victoria, BC, Canada
- Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Toronto, ON, Canada
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24
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Sanders D, Kehoe R, van Veen FF, McLean A, Godfray HCJ, Dicke M, Gols R, Frago E. Defensive insect symbiont leads to cascading extinctions and community collapse. Ecol Lett 2017; 19:789-99. [PMID: 27282315 PMCID: PMC4949664 DOI: 10.1111/ele.12616] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/25/2015] [Accepted: 04/10/2016] [Indexed: 12/19/2022]
Abstract
Animals often engage in mutualistic associations with microorganisms that protect them from predation, parasitism or pathogen infection. Studies of these interactions in insects have mostly focussed on the direct effects of symbiont infection on natural enemies without studying community‐wide effects. Here, we explore the effect of a defensive symbiont on population dynamics and species extinctions in an experimental community composed of three aphid species and their associated specialist parasitoids. We found that introducing a bacterial symbiont with a protective (but not a non‐protective) phenotype into one aphid species led to it being able to escape from its natural enemy and increase in density. This changed the relative density of the three aphid species which resulted in the extinction of the two other parasitoid species. Our results show that defensive symbionts can cause extinction cascades in experimental communities and so may play a significant role in the stability of consumer‐herbivore communities in the field.
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Affiliation(s)
- Dirk Sanders
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Rachel Kehoe
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Fj Frank van Veen
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Ailsa McLean
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - H Charles J Godfray
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Marcel Dicke
- Laboratory of Entomology, Wageningen University, P.O. Box 16, Wageningen, 6700AA, The Netherlands
| | - Rieta Gols
- Laboratory of Entomology, Wageningen University, P.O. Box 16, Wageningen, 6700AA, The Netherlands
| | - Enric Frago
- Laboratory of Entomology, Wageningen University, P.O. Box 16, Wageningen, 6700AA, The Netherlands
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25
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Abstract
Vertically transmitted symbionts that protect their hosts against parasites and pathogens are well known from insects, yet the underlying mechanisms of symbiont-mediated defense are largely unclear. A striking example of an ecologically important defensive symbiosis involves the woodland fly Drosophila neotestacea, which is protected by the bacterial endosymbiont Spiroplasma when parasitized by the nematode Howardula aoronymphium. The benefit of this defense strategy has led to the rapid spread of Spiroplasma throughout the range of D. neotestacea, although the molecular basis for this protection has been unresolved. Here, we show that Spiroplasma encodes a ribosome-inactivating protein (RIP) related to Shiga-like toxins from enterohemorrhagic Escherichia coli and that Howardula ribosomal RNA (rRNA) is depurinated during Spiroplasma-mediated protection of D. neotestacea. First, we show that recombinant Spiroplasma RIP catalyzes depurination of 28S rRNAs in a cell-free assay, as well as Howardula rRNA in vitro at the canonical RIP target site within the α-sarcin/ricin loop (SRL) of 28S rRNA. We then show that Howardula parasites in Spiroplasma-infected flies show a strong signal of rRNA depurination consistent with RIP-dependent modification and large decreases in the proportion of 28S rRNA intact at the α-sarcin/ricin loop. Notably, host 28S rRNA is largely unaffected, suggesting targeted specificity. Collectively, our study identifies a novel RIP in an insect defensive symbiont and suggests an underlying RIP-dependent mechanism in Spiroplasma-mediated defense.
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26
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Łukasik P, Guo H, van Asch M, Henry LM, Godfray HCJ, Ferrari J. Horizontal transfer of facultative endosymbionts is limited by host relatedness. Evolution 2015; 69:2757-66. [DOI: 10.1111/evo.12767] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 07/31/2015] [Accepted: 08/14/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Piotr Łukasik
- Department of Zoology; University of Oxford; South Parks Road Oxford OX1 3PS United Kingdom
| | - Huifang Guo
- Department of Zoology; University of Oxford; South Parks Road Oxford OX1 3PS United Kingdom
- Institute of Plant Protection; Jiangsu Academy of Agricultural Sciences; Zhongling Street Nanjing 210014 China
| | - Margriet van Asch
- Department of Zoology; University of Oxford; South Parks Road Oxford OX1 3PS United Kingdom
| | - Lee M. Henry
- Department of Zoology; University of Oxford; South Parks Road Oxford OX1 3PS United Kingdom
| | - H. Charles J. Godfray
- Department of Zoology; University of Oxford; South Parks Road Oxford OX1 3PS United Kingdom
| | - Julia Ferrari
- Department of Zoology; University of Oxford; South Parks Road Oxford OX1 3PS United Kingdom
- Department of Biology; University of York; York YO10 5DD United Kingdom
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27
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Christian N, Whitaker BK, Clay K. Microbiomes: unifying animal and plant systems through the lens of community ecology theory. Front Microbiol 2015; 6:869. [PMID: 26441846 PMCID: PMC4561359 DOI: 10.3389/fmicb.2015.00869] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 08/10/2015] [Indexed: 12/20/2022] Open
Abstract
The field of microbiome research is arguably one of the fastest growing in biology. Bacteria feature prominently in studies on animal health, but fungi appear to be the more prominent functional symbionts for plants. Despite the similarities in the ecological organization and evolutionary importance of animal-bacterial and plant-fungal microbiomes, there is a general failure across disciplines to integrate the advances made in each system. Researchers studying bacterial symbionts in animals benefit from greater access to efficient sequencing pipelines and taxonomic reference databases, perhaps due to high medical and veterinary interest. However, researchers studying plant-fungal symbionts benefit from the relative tractability of fungi under laboratory conditions and ease of cultivation. Thus each system has strengths to offer, but both suffer from the lack of a common conceptual framework. We argue that community ecology best illuminates complex species interactions across space and time. In this synthesis we compare and contrast the animal-bacterial and plant-fungal microbiomes using six core theories in community ecology (i.e., succession, community assembly, metacommunities, multi-trophic interactions, disturbance, restoration). The examples and questions raised are meant to spark discussion amongst biologists and lead to the integration of these two systems, as well as more informative, manipulatory experiments on microbiomes research.
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Affiliation(s)
- Natalie Christian
- *Correspondence: Natalie Christian and Briana K. Whitaker, Evolution, Ecology and Behavior Program, Department of Biology, Indiana University, Jordan Hall, 1001 East 3rd Street, Bloomington, IN 47405, USA, ;
| | - Briana K. Whitaker
- *Correspondence: Natalie Christian and Briana K. Whitaker, Evolution, Ecology and Behavior Program, Department of Biology, Indiana University, Jordan Hall, 1001 East 3rd Street, Bloomington, IN 47405, USA, ;
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Abstract
Ecologically important traits of insects are often affected by facultative bacterial endosymbionts. This is best studied in the pea aphid Acyrthosiphon pisum, which is frequently infected by one or more of eight facultative symbiont species. Many of these symbiont species have been shown to provide one ecological benefit, but we have little understanding of the range of effects that a single strain can have. Here, we describe the phenotypes conferred by three strains of the recently discovered bacterium known as X-type (Enterobacteriaceae), each in their original aphid genotype which also carries a Spiroplasma symbiont. All comparisons are made between aphids that are coinfected with Spiroplasma and X-type and aphids of the same genotype that harbour only Spiroplasma. We show that in all cases, infection with X-type protects aphids from the lethal fungal pathogen Pandora neoaphidis, and in two cases, resistance to the parasitoid Aphidius ervi also increases. X-type can additionally affect aphid stress responses--the presence of X-type increased reproduction after the aphids were heat-stressed. Two of the three strains of X-type are able to provide all of these benefits. Under benign conditions, the aphids tended to suffer from reduced fecundity when harbouring X-type, a mechanism that might maintain intermediate frequencies in field populations. These findings highlight that a single strain of a facultative endosymbiont has the potential to provide diverse benefits to its aphid host.
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Affiliation(s)
- E R Heyworth
- Department of Biology, University of York, York, UK
| | - J Ferrari
- Department of Biology, University of York, York, UK
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29
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Haselkorn TS, Jaenike J. Macroevolutionary persistence of heritable endosymbionts: acquisition, retention and expression of adaptive phenotypes inSpiroplasma. Mol Ecol 2015; 24:3752-65. [DOI: 10.1111/mec.13261] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 06/01/2015] [Accepted: 06/02/2015] [Indexed: 11/26/2022]
Affiliation(s)
| | - John Jaenike
- Department of Biology; University of Rochester; Rochester NY 14627 USA
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30
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Xie J, Winter C, Winter L, Mateos M. Rapid spread of the defensive endosymbiont Spiroplasma in Drosophila hydei under high parasitoid wasp pressure. FEMS Microbiol Ecol 2014; 91:1-11. [DOI: 10.1093/femsec/fiu017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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31
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Bolaños LM, Servín-Garcidueñas LE, Martínez-Romero E. Arthropod-Spiroplasma relationship in the genomic era. FEMS Microbiol Ecol 2014; 91:1-8. [PMID: 25764543 DOI: 10.1093/femsec/fiu008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The genus Spiroplasma comprises wall-less, low-GC bacteria that establish pathogenic, mutualistic and commensal symbiotic associations with arthropods and plants. This review focuses on the symbiotic relationships between Spiroplasma bacteria and arthropod hosts in the context of the available genomic sequences. Spiroplasma genomes are reduced and some contain highly repetitive plectrovirus-related sequences. Spiroplasma's diversity in viral invasion susceptibility, virulence factors, substrate utilization, genome dynamics and symbiotic associations with arthropods make this bacterial genus a biological model that provides insights about the evolutionary traits that shape bacterial symbiotic relationships with eukaryotes.
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Affiliation(s)
- Luis M Bolaños
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Luis E Servín-Garcidueñas
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Esperanza Martínez-Romero
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
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32
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Linneman J, Paulus D, Lim-Fong G, Lopanik NB. Latitudinal variation of a defensive symbiosis in the Bugula neritina (Bryozoa) sibling species complex. PLoS One 2014; 9:e108783. [PMID: 25275632 PMCID: PMC4183541 DOI: 10.1371/journal.pone.0108783] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 09/04/2014] [Indexed: 11/27/2022] Open
Abstract
Mutualistic relationships are beneficial for both partners and are often studied within a single environment. However, when the range of the partners is large, geographical differences in selective pressure may shift the relationship outcome from positive to negative. The marine bryozoan Bugula neritina is a colonial invertebrate common in temperate waters worldwide. It is the source of bioactive polyketide metabolites, the bryostatins. Evidence suggests that an uncultured vertically transmitted symbiont, "Candidatus Endobugula sertula", hosted by B. neritina produces the bryostatins, which protect the vulnerable larvae from predation. Studies of B. neritina along the North American Atlantic coast revealed a complex of two morphologically similar sibling species separated by an apparent biogeographic barrier: the Type S sibling species was found below Cape Hatteras, North Carolina, while Type N was found above. Interestingly, the Type N colonies lack "Ca. Endobugula sertula" and, subsequently, defensive bryostatins; their documented northern distribution was consistent with traditional biogeographical paradigms of latitudinal variation in predation pressure. Upon further sampling of B. neritina populations, we found that both host types occur in wider distribution, with Type N colonies living south of Cape Hatteras, and Type S to the north. Distribution of the symbiont, however, was not restricted to Type S hosts. Genetic and microscopic evidence demonstrates the presence of the symbiont in some Type N colonies, and larvae from these colonies are endowed with defensive bryostatins and contain "Ca. Endobugula sertula". Molecular analysis of the symbiont from Type N colonies suggests an evolutionarily recent acquisition, which is remarkable for a symbiont thought to be transmitted only vertically. Furthermore, most Type S colonies found at higher latitudes lack the symbiont, suggesting that this host-symbiont relationship is more flexible than previously thought. Our data suggest that the symbiont, but not the host, is restricted by biogeographical boundaries.
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Affiliation(s)
- Jonathan Linneman
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Darcy Paulus
- Department of Biology, Randolph-Macon College, Ashland, Virginia, United States of America
| | - Grace Lim-Fong
- Department of Biology, Randolph-Macon College, Ashland, Virginia, United States of America
| | - Nicole B. Lopanik
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
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Oliver KM, Martinez AJ. How resident microbes modulate ecologically-important traits of insects. CURRENT OPINION IN INSECT SCIENCE 2014; 4:1-7. [PMID: 28043402 DOI: 10.1016/j.cois.2014.08.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 07/30/2014] [Accepted: 08/05/2014] [Indexed: 05/20/2023]
Abstract
The microbiota inhabiting insects influence a wide range of ecologically-important traits. In addition to their better-known roles in nutrient provisioning and degrading plant polymers, there is emerging evidence that microorganisms also aid herbivores in countering plant defenses. The latter can be mediated by enzymes that degrade plant allelochemicals or via the modulation of plant signaling pathways. Symbionts are also increasingly recognized to protect insects from attack by a wide range of natural enemies. Underlying mechanisms are poorly understood, but some microbes produce antimicrobials or toxins, while others modulate insect immune responses. Ecologically-relevant symbioses can exhibit dynamic variation in strength and specificity of conferred phenotypes, transfer key traits among unrelated insects, and have effects that extend to interacting players and beyond.
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Affiliation(s)
- Kerry M Oliver
- Department of Entomology, University of Georgia, Athens, GA 30602, USA.
| | - Adam J Martinez
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
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34
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Hamilton PT, Leong JS, Koop BF, Perlman SJ. Transcriptional responses in a Drosophila defensive symbiosis. Mol Ecol 2013; 23:1558-1570. [PMID: 24274471 DOI: 10.1111/mec.12603] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 11/29/2022]
Abstract
Inherited symbionts are ubiquitous in insects and can have important consequences for the fitness of their hosts. Many inherited symbionts defend their hosts against parasites or other natural enemies; however, the means by which most symbionts confer protection is virtually unknown. We examine the mechanisms of defence in a recently discovered case of symbiont-mediated protection, where the bacterial symbiont Spiroplasma defends the fly Drosophila neotestacea from a virulent nematode parasite, Howardula aoronymphium. Using quantitative PCR of Spiroplasma infection intensities and whole transcriptome sequencing, we attempt to distinguish between the following modes of defence: symbiont-parasite competition, host immune priming and the production of toxic factors by Spiroplasma. Our findings do not support a model of exploitative competition between Howardula and Spiroplasma to mediate defence, nor do we find strong support for host immune priming during Spiroplasma infection. Interestingly, we recovered sequence for putative toxins encoded by Spiroplasma, including a novel putative ribosome-inactivating protein, transcripts of which are up-regulated in response to nematode exposure. Protection via the production of toxins may be a widely used and important mechanism in heritable defensive symbioses in insects.
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Affiliation(s)
- Phineas T Hamilton
- Department of Biology, University of Victoria, PO Box 1800, STN CSC, Victoria, British Columbia, Canada, V8W 2Y2
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