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Barrajon-Santos V, Nepel M, Hausmann B, Voglmayr H, Woebken D, Mayer VE. Dynamics and drivers of fungal communities in a multipartite ant-plant association. BMC Biol 2024; 22:112. [PMID: 38745290 PMCID: PMC11093746 DOI: 10.1186/s12915-024-01897-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 04/18/2024] [Indexed: 05/16/2024] Open
Abstract
BACKGROUND Fungi and ants belong to the most important organisms in terrestrial ecosystems on Earth. In nutrient-poor niches of tropical rainforests, they have developed steady ecological relationships as a successful survival strategy. In tropical ant-plant mutualisms worldwide, where resident ants provide the host plants with defense and nutrients in exchange for shelter and food, fungi are regularly found in the ant nesting space, inhabiting ant-made dark-colored piles ("patches"). Unlike the extensively investigated fungus-growing insects, where the fungi serve as the primary food source, the purpose of this ant-fungi association is less clear. To decipher the roles of fungi in these structures within ant nests, it is crucial to first understand the dynamics and drivers that influence fungal patch communities during ant colony development. RESULTS In this study, we investigated how the ant colony age and the ant-plant species affect the fungal community in the patches. As model we selected one of the most common mutualisms in the Tropics of America, the Azteca-Cecropia complex. By amplicon sequencing of the internal transcribed spacer 2 (ITS2) region, we analyzed the patch fungal communities of 93 Azteca spp. colonies inhabiting Cecropia spp. trees. Our study demonstrates that the fungal diversity in patches increases as the ant colony grows and that a change in the prevalent fungal taxa occurs between initial and established patches. In addition, the ant species significantly influences the composition of the fungal community in established ant colonies, rather than the host plant species. CONCLUSIONS The fungal patch communities become more complex as the ant colony develops, due to an acquisition of fungi from the environment and a substrate diversification. Our results suggest a successional progression of the fungal communities in the patches during ant colony growth and place the ant colony as the main driver shaping such communities. The findings of this study demonstrate the unexpectedly complex nature of ant-plant mutualisms in tropical regions at a micro scale.
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Affiliation(s)
- Veronica Barrajon-Santos
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
- Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria.
| | - Maximilian Nepel
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
- Present Address: Plant Health and Environment Laboratory, Ministry for Primary Industries, Auckland, New Zealand
| | - Bela Hausmann
- Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria
- Department of Laboratory Medicine Division of Clinical Microbiology, Medical University of Vienna, Vienna, Austria
| | - Hermann Voglmayr
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Dagmar Woebken
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Veronika E Mayer
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.
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2
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Diehl JMC, Keller A, Biedermann PHW. Comparing the succession of microbial communities throughout development in field and laboratory nests of the ambrosia beetle Xyleborinus saxesenii. Front Microbiol 2023; 14:1151208. [PMID: 37152720 PMCID: PMC10159272 DOI: 10.3389/fmicb.2023.1151208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 03/31/2023] [Indexed: 05/09/2023] Open
Abstract
Some fungus-farming ambrosia beetles rely on multiple nutritional cultivars (Ascomycota: Ophiostomatales and/or yeasts) that seem to change in relative abundance over time. The succession of these fungi could benefit beetle hosts by optimal consumption of the substrate and extended longevity of the nest. However, abundances of fungal cultivars and other symbionts are poorly known and their culture-independent quantification over development has been studied in only a single species. Here, for the first time, we compared the diversity and succession of both fungal and bacterial communities of fungus gardens in the fruit-tree pinhole borer, Xyleborinus saxesenii, from field and laboratory nests over time. By amplicon sequencing of probed fungus gardens of both nest types at three development phases we showed an extreme reduction of diversity in both bacterial and fungal symbionts in laboratory nests. Furthermore, we observed a general transition from nutritional to non-beneficial fungal symbionts during beetle development. While one known nutritional mutualist, Raffaelea canadensis, was occurring more or less stable over time, the second mutualist R. sulphurea was dominating young nests and decreased in abundance at the expense of other secondary fungi. The quicker the succession proceeded, the slower offspring beetles developed, suggesting a negative role of these secondary symbionts. Finally, we found signs of transgenerational costs of late dispersal for daughters, possibly as early dispersers transmitted and started their own nests with less of the non-beneficial taxa. Future studies should focus on the functional roles of the few bacterial taxa that were present in both field and laboratory nests.
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Affiliation(s)
- Janina M. C. Diehl
- Chair of Forest Entomology and Protection, Institute of Forestry, University of Freiburg, Freiburg im Breisgau, Germany
- Insect-Fungus Interactions Research Group, Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
- *Correspondence: Janina M. C. Diehl,
| | - Alexander Keller
- Faculty of Biology, Cellular and Organismic Networks, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Peter H. W. Biedermann
- Chair of Forest Entomology and Protection, Institute of Forestry, University of Freiburg, Freiburg im Breisgau, Germany
- Peter H. W. Biedermann,
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3
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Guo W, Wang W, Tang J, Li T, Li X. Genome analysis and genomic comparison of a fungal cultivar of the nonsocial weevil Euops chinensis reveals its plant decomposition and protective roles in fungus-farming mutualism. Front Microbiol 2023; 14:1048910. [PMID: 36876094 PMCID: PMC9978505 DOI: 10.3389/fmicb.2023.1048910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/30/2023] [Indexed: 02/18/2023] Open
Abstract
Fungus-farming mutualisms are models for studying co-evolutionary among species. Compared to well-documented fungus-farming in social insects, the molecular aspects of fungus-farming mutualisms in nonsocial insects have been poorly explored. Euops chinensis is a solitary leaf-rolling weevil feeding on Japanese knotweed (Fallopia japonica). This pest has evolved a special proto-farming bipartite mutualism with the fungus Penicillium herquei, which provide nutrition and defensive protection for the E. chinensis larvae. Here, the genome of P. herquei was sequenced, and the structure and specific gene categories in the P. herquei genome were then comprehensively compared with the other two well-studied Penicillium species (P. decumbens and P. chrysogenum). The assembled P. herquei genome had a 40.25 Mb genome size with 46.7% GC content. A diverse set of genes associating with carbohydrate-active enzymes, cellulose and hemicellulose degradation, transporter, and terpenoid biosynthesis were detected in the P. herquei genome. Comparative genomics demonstrate that the three Penicillium species show similar metabolic and enzymatic potential, however, P. herquei has more genes associated with plant biomass degradation and defense but less genes associating with virulence pathogenicity. Our results provide molecular evidence for plant substrate breakdown and protective roles of P. herquei in E. chinensis mutualistic system. Large metabolic potential shared by Penicillium species at the genus level may explain why some Penicillium species are recruited by the Euops weevils as crop fungi.
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Affiliation(s)
- Wenfeng Guo
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, China.,Guangxi Crop Genetic Improvement and Biotechnology Lab, Guangxi Academy of Agricultural Sciences, Nanning, Guangxi, China
| | - Wei Wang
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, China
| | - Jun Tang
- Guangxi Crop Genetic Improvement and Biotechnology Lab, Guangxi Academy of Agricultural Sciences, Nanning, Guangxi, China
| | - Tianyu Li
- Wuhan Benagen Technology Company Limited, Wuhan, Hubei, China
| | - Xiaoqiong Li
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, China
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4
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Diehl JMC, Kowallik V, Keller A, Biedermann PHW. First experimental evidence for active farming in ambrosia beetles and strong heredity of garden microbiomes. Proc Biol Sci 2022; 289:20221458. [PMID: 36321493 PMCID: PMC9627711 DOI: 10.1098/rspb.2022.1458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Fungal cultivation is a defining feature for advanced agriculture in fungus-farming ants and termites. In a third supposedly fungus-farming group, wood-colonizing ambrosia beetles, an experimental proof for the effectiveness of beetle activity for selective promotion of their food fungi over others is lacking and farming has only been assumed based on observations of social and hygienic behaviours. Here, we experimentally removed mothers and their offspring from young nests of the fruit-tree pinhole borer, Xyleborinus saxesenii. By amplicon sequencing of bacterial and fungal communities of nests with and without beetles we could show that beetles are indeed able to actively shift symbiont communities. Although being consumed, the Raffaelea food fungi were more abundant when beetles were present while a weed fungus (Chaetomium sp.) as well as overall bacterial diversity were reduced in comparison to nests without beetles. Core symbiont communities were generally of low diversity and there were strong signs for vertical transmission not only for the cultivars, but also for secondary symbionts. Our findings verify the existence of active farming, even though the exact mechanisms underlying the selective promotion and/or suppression of symbionts need further investigation.
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Affiliation(s)
- Janina M. C. Diehl
- Chair of Forest Entomology and Protection, Institute of Forestry, University of Freiburg, Fohrenbühl 27, 79252 Stegen-Wittental, Germany
| | - Vienna Kowallik
- Chair of Forest Entomology and Protection, Institute of Forestry, University of Freiburg, Fohrenbühl 27, 79252 Stegen-Wittental, Germany
| | - Alexander Keller
- Cellular and Organismic Networks, Faculty of Biology, Ludwig-Maximilians-Universität München, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| | - Peter H. W. Biedermann
- Chair of Forest Entomology and Protection, Institute of Forestry, University of Freiburg, Fohrenbühl 27, 79252 Stegen-Wittental, Germany
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5
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Barcoto MO, Rodrigues A. Lessons From Insect Fungiculture: From Microbial Ecology to Plastics Degradation. Front Microbiol 2022; 13:812143. [PMID: 35685924 PMCID: PMC9171207 DOI: 10.3389/fmicb.2022.812143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Anthropogenic activities have extensively transformed the biosphere by extracting and disposing of resources, crossing boundaries of planetary threat while causing a global crisis of waste overload. Despite fundamental differences regarding structure and recalcitrance, lignocellulose and plastic polymers share physical-chemical properties to some extent, that include carbon skeletons with similar chemical bonds, hydrophobic properties, amorphous and crystalline regions. Microbial strategies for metabolizing recalcitrant polymers have been selected and optimized through evolution, thus understanding natural processes for lignocellulose modification could aid the challenge of dealing with the recalcitrant human-made polymers spread worldwide. We propose to look for inspiration in the charismatic fungal-growing insects to understand multipartite degradation of plant polymers. Independently evolved in diverse insect lineages, fungiculture embraces passive or active fungal cultivation for food, protection, and structural purposes. We consider there is much to learn from these symbioses, in special from the community-level degradation of recalcitrant biomass and defensive metabolites. Microbial plant-degrading systems at the core of insect fungicultures could be promising candidates for degrading synthetic plastics. Here, we first compare the degradation of lignocellulose and plastic polymers, with emphasis in the overlapping microbial players and enzymatic activities between these processes. Second, we review the literature on diverse insect fungiculture systems, focusing on features that, while supporting insects' ecology and evolution, could also be applied in biotechnological processes. Third, taking lessons from these microbial communities, we suggest multidisciplinary strategies to identify microbial degraders, degrading enzymes and pathways, as well as microbial interactions and interdependencies. Spanning from multiomics to spectroscopy, microscopy, stable isotopes probing, enrichment microcosmos, and synthetic communities, these strategies would allow for a systemic understanding of the fungiculture ecology, driving to application possibilities. Detailing how the metabolic landscape is entangled to achieve ecological success could inspire sustainable efforts for mitigating the current environmental crisis.
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Affiliation(s)
- Mariana O. Barcoto
- Center for the Study of Social Insects, São Paulo State University (UNESP), Rio Claro, Brazil
- Department of General and Applied Biology, São Paulo State University (UNESP), Rio Claro, Brazil
| | - Andre Rodrigues
- Center for the Study of Social Insects, São Paulo State University (UNESP), Rio Claro, Brazil
- Department of General and Applied Biology, São Paulo State University (UNESP), Rio Claro, Brazil
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6
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Abstract
Beetles are hosts to a remarkable diversity of bacterial symbionts. In this article, we review the role of these partnerships in promoting beetle fitness following a surge of recent studies characterizing symbiont localization and function across the Coleoptera. Symbiont contributions range from the supplementation of essential nutrients and digestive or detoxifying enzymes to the production of bioactive compounds providing defense against natural enemies. Insights on this functional diversity highlight how symbiosis can expand the host's ecological niche, but also constrain its evolutionary potential by promoting specialization. As bacterial localization can differ within and between beetle clades, we discuss how it corresponds to the microbe's beneficial role and outline the molecular and behavioral mechanisms underlying symbiont translocation and transmission by its holometabolous host. In reviewing this literature, we emphasize how the study of symbiosis can inform our understanding of the phenotypic innovations behind the evolutionary success of beetles.
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Affiliation(s)
- Hassan Salem
- Mutualisms Research Group, Max Planck Institute for Biology, Tübingen 72076, Germany;
| | - Martin Kaltenpoth
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena 07745, Germany;
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz 55128, Germany
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7
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Unique Attributes of the Laurel Wilt Fungal Pathogen, Raffaelea lauricola, as Revealed by Metabolic Profiling. Pathogens 2021; 10:pathogens10050528. [PMID: 33925553 PMCID: PMC8146198 DOI: 10.3390/pathogens10050528] [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: 03/31/2021] [Revised: 04/22/2021] [Accepted: 04/24/2021] [Indexed: 11/18/2022] Open
Abstract
Raffaelea lauricola is the causative agent of laurel wilt, a devastating disease of lauraceous trees. R. lauricola is also an obligate nutritional symbiont of several ambrosia beetle species who act as vectors for the pathogen. Here, we sought to establish the baseline “phenome” of R. lauricola with knowledge concerning its metabolic capability, expanding our understanding of how these processes are impacted by environmental and host nutrients. Phenotypic screening using a microarray of over one thousand compounds was used to generate a detailed profile of R. lauricola substrate utilization and chemical sensitivity. These data revealed (i) relatively restricted carbon utilization, (ii) broad sulfur and phosphate utilization, and (iii) pH and osmotic sensitivities that could be rescued by specific compounds. Additional growth profiling on fatty acids revealed toxicity on C10 substrates and lower, with robust growth on C12–C18 fatty acids. Conditions for lipid droplet (LD) visualization and LD dynamics were examined using a series of lipid dyes. These data provide unique insights regarding R. lauricola metabolism and physiology, and identify distinct patterns of substrate usage and sensitivity which likely reflect important aspects of the host-microbe interface and can be exploited for the development of strategies for mitigating the spread of laurel wilt.
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8
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Lehenberger M, Foh N, Göttlein A, Six D, Biedermann PHW. Nutrient-Poor Breeding Substrates of Ambrosia Beetles Are Enriched With Biologically Important Elements. Front Microbiol 2021; 12:664542. [PMID: 33981292 PMCID: PMC8107399 DOI: 10.3389/fmicb.2021.664542] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/30/2021] [Indexed: 11/13/2022] Open
Abstract
Fungus-farming within galleries in the xylem of trees has evolved independently in at least twelve lineages of weevils (Curculionidae: Scolytinae, Platypodinae) and one lineage of ship-timber beetles (Lymexylidae). Jointly these are termed ambrosia beetles because they actively cultivate nutritional “ambrosia fungi” as their main source of food. The beetles are obligately dependent on their ambrosia fungi as they provide them a broad range of essential nutrients ensuring their survival in an extremely nutrient-poor environment. While xylem is rich in carbon (C) and hydrogen (H), various elements essential for fungal and beetle growth, such as nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), magnesium (Mg), and manganese (Mn) are extremely low in concentration. Currently it remains untested how both ambrosia beetles and their fungi meet their nutritional requirements in this habitat. Here, we aimed to determine for the first time if galleries of ambrosia beetles are generally enriched with elements that are rare in uncolonized xylem tissue and whether these nutrients are translocated to the galleries from the xylem by the fungal associates. To do so, we examined natural galleries of three ambrosia beetle species from three independently evolved farming lineages, Xyleborinus saxesenii (Scolytinae: Xyleborini), Trypodendron lineatum (Scolytinae: Xyloterini) and Elateroides dermestoides (Lymexylidae), that cultivate unrelated ambrosia fungi in the ascomycete orders Ophiostomatales, Microascales, and Saccharomycetales, respectively. Several elements, in particular Ca, N, P, K, Mg, Mn, and S, were present in high concentrations within the beetles’ galleries but available in only very low concentrations in the surrounding xylem. The concentration of elements was generally highest with X. saxesenii, followed by T. lineatum and E. dermestoides, which positively correlates with the degree of sociality and productivity of brood per gallery. We propose that the ambrosia fungal mutualists are translocating essential elements through their hyphae from the xylem to fruiting structures they form on gallery walls. Moreover, the extremely strong enrichment observed suggests recycling of these elements from the feces of the insects, where bacteria and yeasts might play a role.
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Affiliation(s)
- Maximilian Lehenberger
- Research Group Insect-Fungus Symbiosis, Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany.,Chair of Forest Entomology and Protection, University of Freiburg, Freiburg im Breisgau, Germany
| | - Nina Foh
- Center for Medical Physics and Engineering, Max Schaldach Endowed Professorship for Biomedical Engineering, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Axel Göttlein
- Forest Nutrition and Water Resources, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Diana Six
- Department of Ecosystem and Conservation Sciences, W. A. Franke College of Forestry and Conservation, University of Montana, Missoula, MT, United States
| | - Peter H W Biedermann
- Research Group Insect-Fungus Symbiosis, Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany.,Chair of Forest Entomology and Protection, University of Freiburg, Freiburg im Breisgau, Germany
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9
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Fungal mutualisms and pathosystems: life and death in the ambrosia beetle mycangia. Appl Microbiol Biotechnol 2021; 105:3393-3410. [PMID: 33837831 DOI: 10.1007/s00253-021-11268-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/26/2021] [Accepted: 04/04/2021] [Indexed: 02/06/2023]
Abstract
Ambrosia beetles and their microbial communities, housed in specialized structures termed mycangia, represent one of the oldest and most diverse systems of mutualism and parasitism described thus far. Comprised of core filamentous fungal members, but also including bacteria and yeasts, the mycangia represent a unique adaptation that allows beetles to store and transport their source of nutrition. Although perhaps the most ancient of "farmers," the nature of these interactions remains largely understudied, with the exception of a handful of emerging pathosystems, where the fungal partner acts as a potentially devastating tree pathogen. Such virulence is often seen during "invasions," where (invasive) beetles carrying the fungal symbiont/plant pathogen expand into new territories and presumably "naïve" trees. Here, we summarize recent findings on the phylogenetic relationships between beetles and their symbionts and advances in the developmental and genetic characterization of the mechanisms that underlie insect-fungal-plant interactions. Results on genomic, transcriptomic, and metabolomic aspects of these relationships are described. Although many members of the fungal Raffaelea-beetle symbiont genera are relatively harmless to host trees, specialized pathosystems including wilt diseases of laurel and oak, caused by specific subspecies (R. lauricola and R. quercus, in the USA and East Asia, respectively), have emerged as potent plant pathogens capable of killing healthy trees. With the development of genetic tools, coupled to biochemical and microscopic techniques, the ambrosia beetle-fungal symbiont is establishing itself as a unique model system to study the molecular determinants and mechanisms that underlie the convergences of symbioses, mutualism, parasitism, and virulence. KEY POINTS: • Fungal-beetle symbioses are diverse and ancient examples of microbial farming. • The mycangium is a specialized structure on insects that houses microbial symbionts. • Some beetle symbiotic fungi are potent plant pathogens vectored by the insect.
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10
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Nel WJ, Wingfield MJ, de Beer ZW, Duong TA. Ophiostomatalean fungi associated with wood boring beetles in South Africa including two new species. Antonie Van Leeuwenhoek 2021; 114:667-686. [PMID: 33677752 DOI: 10.1007/s10482-021-01548-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/17/2021] [Indexed: 12/27/2022]
Abstract
Ambrosia beetles are small wood inhabiting members of the Curculionidae that have evolved obligate symbioses with fungi. The fungal symbionts concentrate nutrients from within infested trees into a usable form for their beetle partners, which then utilize the fungi as their primary source of nutrition. Ambrosia beetle species associate with one or more primary symbiotic fungal species, but they also vector auxiliary symbionts, which may provide the beetle with developmental or ecological advantages. In this study we isolated and identified ophiostomatalean fungi associated with ambrosia beetles occurring in a native forest area in South Africa. Using a modified Bambara beetle trap, living ambrosia beetle specimens were collected and their fungal symbionts isolated. Four beetle species, three Scolytinae and one Bostrichidae, were collected. Five species of ophiostomatalean fungi were isolated from the beetles and were identified using both morphological characters and DNA sequence data. One of these species, Raffaelea sulphurea, was recorded from South Africa for the first time and two novel species were described as Ceratocystiopsis lunata sp. nov. and Raffaelea promiscua sp. nov.
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Affiliation(s)
- Wilma J Nel
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa.
| | - Michael J Wingfield
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Z Wilhelm de Beer
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Tuan A Duong
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
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11
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Li H, Young SE, Poulsen M, Currie CR. Symbiont-Mediated Digestion of Plant Biomass in Fungus-Farming Insects. ANNUAL REVIEW OF ENTOMOLOGY 2021; 66:297-316. [PMID: 32926791 DOI: 10.1146/annurev-ento-040920-061140] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Feeding on living or dead plant material is widespread in insects. Seminal work on termites and aphids has provided profound insights into the critical nutritional role that microbes play in plant-feeding insects. Some ants, beetles, and termites, among others, have evolved the ability to use microbes to gain indirect access to plant substrate through the farming of a fungus on which they feed. Recent genomic studies, including studies of insect hosts and fungal and bacterial symbionts, as well as metagenomics and proteomics, have provided important insights into plant biomass digestion across insect-fungal mutualisms. Not only do advances in understanding of the divergent and complementary functions of complex symbionts reveal the mechanism of how these herbivorous insects catabolize plant biomass, but these symbionts also represent a promising reservoir for novel carbohydrate-active enzyme discovery, which is of considerable biotechnological interest.
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Affiliation(s)
- Hongjie Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo 315211, China;
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; ,
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA
| | - Soleil E Young
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; ,
| | - Michael Poulsen
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, 2100 Copenhagen East, Denmark;
| | - Cameron R Currie
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; ,
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA
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12
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Biedermann PHW. Cooperative Breeding in the Ambrosia Beetle Xyleborus affinis and Management of Its Fungal Symbionts. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.518954] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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13
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Ibarra-Juarez LA, Burton MAJ, Biedermann PHW, Cruz L, Desgarennes D, Ibarra-Laclette E, Latorre A, Alonso-Sánchez A, Villafan E, Hanako-Rosas G, López L, Vázquez-Rosas-Landa M, Carrion G, Carrillo D, Moya A, Lamelas A. Evidence for Succession and Putative Metabolic Roles of Fungi and Bacteria in the Farming Mutualism of the Ambrosia Beetle Xyleborus affinis. mSystems 2020; 5:e00541-20. [PMID: 32934115 PMCID: PMC7498683 DOI: 10.1128/msystems.00541-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/28/2020] [Indexed: 02/07/2023] Open
Abstract
The bacterial and fungal community involved in ambrosia beetle fungiculture remains poorly studied compared to the famous fungus-farming ants and termites. Here we studied microbial community dynamics of laboratory nests, adults, and brood during the life cycle of the sugarcane shot hole borer, Xyleborus affinis We identified a total of 40 fungal and 428 bacterial operational taxonomic units (OTUs), from which only five fungi (a Raffaelea fungus and four ascomycete yeasts) and four bacterial genera (Stenotrophomonas, Enterobacter, Burkholderia, and Ochrobactrum) can be considered the core community playing the most relevant symbiotic role. Both the fungal and bacterial populations varied significantly during the beetle's life cycle. While the ascomycete yeasts were the main colonizers of the gallery early on, the Raffaelea and other filamentous fungi appeared after day 10, at the time when larval hatching happened. Regarding bacteria, Stenotrophomonas and Enterobacter dominated overall but decreased in foundresses and brood with age. Finally, inferred analyses of the putative metabolic capabilities of the bacterial microbiome revealed that they are involved in (i) degradation of fungal and plant polymers, (ii) fixation of atmospheric nitrogen, and (iii) essential amino acid, cofactor, and vitamin provisioning. Overall, our results suggest that yeasts and bacteria are more strongly involved in supporting the beetle-fungus farming symbiosis than previously thought.IMPORTANCE Ambrosia beetles farm their own food fungi within tunnel systems in wood and are among the three insect lineages performing agriculture (the others are fungus-farming ants and termites). In ambrosia beetles, primary ambrosia fungus cultivars have been regarded essential, whereas other microbes have been more or less ignored. Our KEGG analyses suggest so far unknown roles of yeasts and bacterial symbionts, by preparing the tunnel walls for the primary ambrosia fungi. This preparation includes enzymatic degradation of wood, essential amino acid production, and nitrogen fixation. The latter is especially exciting because if it turns out to be present in vivo in ambrosia beetles, all farming animals (including humans) are dependent on atmospheric nitrogen fertilization of their crops. As previous internal transcribed spacer (ITS) metabarcoding approaches failed on covering the primary ambrosia fungi, our 18S metabarcoding approach can also serve as a template for future studies on the ambrosia beetle-fungus symbiosis.
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Affiliation(s)
- L A Ibarra-Juarez
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | - M A J Burton
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | - P H W Biedermann
- Chair of Forest Entomology and Protection, University of Freiburg, Freiburg, Germany
| | - L Cruz
- Tropical Research and Education Center, University of Florida, Homestead, Florida, USA
| | - D Desgarennes
- Red de Biodiversidad y Sistemática, Instituto de Ecología A. C., Xalapa, México
| | - E Ibarra-Laclette
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | - A Latorre
- Institute for Integrative Systems Biology (Universitat de València and CSIC), València, Spain
- Foundation for the Promotion of Sanitary and Biomedical Research in the Valencian Community (FISABIO), València, Spain
| | - A Alonso-Sánchez
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | - E Villafan
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | - G Hanako-Rosas
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | - L López
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
| | | | - G Carrion
- Red de Biodiversidad y Sistemática, Instituto de Ecología A. C., Xalapa, México
| | - D Carrillo
- Red de Biodiversidad y Sistemática, Instituto de Ecología A. C., Xalapa, México
| | - A Moya
- Institute for Integrative Systems Biology (Universitat de València and CSIC), València, Spain
- Foundation for the Promotion of Sanitary and Biomedical Research in the Valencian Community (FISABIO), València, Spain
| | - A Lamelas
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Xalapa, México
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14
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Griffin LH, Reed LK. Effect of gut microbiota on α-amanitin tolerance in Drosophila tripunctata. Ecol Evol 2020; 10:9419-9427. [PMID: 32953071 PMCID: PMC7487225 DOI: 10.1002/ece3.6630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 01/07/2023] Open
Abstract
The bacterial gut microbiota of many animals is known to be important for many physiological functions including detoxification. The selective pressures imposed on insects by exposure to toxins may also be selective pressures on their symbiotic bacteria, who thus may contribute to the mechanism of toxin tolerance for the insect. Amatoxins are a class of cyclopeptide mushroom toxins that primarily act by binding to RNA polymerase II and inhibiting transcription. Several species of mycophagous Drosophila are tolerant to amatoxins found in mushrooms of the genus Amanita, despite these toxins being lethal to most other known eukaryotes. These species can tolerate amatoxins in natural concentrations to utilize toxic mushrooms as larval hosts, but the mechanism by which these species are tolerant remains unknown. Previous data have shown that a local population of D. tripunctata exhibits significant genetic variation in toxin tolerance. This study assesses the potential role of the microbiome in α-amanitin tolerance in six wild-derived strains of Drosophila tripunctata. Normal and antibiotic-treated samples of six strains were reared on diets with and without α-amanitin, and then scored for survival from the larval stage to adulthood and for development time to pupation. Our results show that a substantial reduction in bacterial load does not influence toxin tolerance in this system, while confirming genotype and toxin-specific effects on survival are independent of the microbiome composition. Thus, we conclude that this adaptation to exploit toxic mushrooms as a host is likely intrinsic to the fly's genome and not a property of their microbiome.
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Affiliation(s)
- Logan H. Griffin
- Department of Biological SciencesUniversity of AlabamaTuscaloosaALUSA
| | - Laura K. Reed
- Department of Biological SciencesUniversity of AlabamaTuscaloosaALUSA
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15
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Fungus-growing insects host a distinctive microbiota apparently adapted to the fungiculture environment. Sci Rep 2020; 10:12384. [PMID: 32709946 PMCID: PMC7381635 DOI: 10.1038/s41598-020-68448-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 06/24/2020] [Indexed: 01/09/2023] Open
Abstract
Some lineages of ants, termites, and beetles independently evolved a symbiotic association with lignocellulolytic fungi cultivated for food, in a lifestyle known as fungiculture. Fungus-growing insects' symbiosis also hosts a bacterial community thought to integrate their physiology. Similarities in taxonomic composition support the microbiota of fungus-growing insects as convergent, despite differences in fungus-rearing by these insects. Here, by comparing fungus-growing insects to several hosts ranging diverse dietary patterns, we investigate whether the microbiota taxonomic and functional profiles are characteristic of the fungiculture environment. Compared to other hosts, the microbiota associated with fungus-growing insects presents a distinctive taxonomic profile, dominated by Gammaproteobacteria at class level and by Pseudomonas at genera level. Even with a functional profile presenting similarities with the gut microbiota of herbivorous and omnivorous hosts, some differentially abundant features codified by the microbiota of fungus-growing insects suggest these communities occupying microhabitats that are characteristic of fungiculture. These features include metabolic pathways involved in lignocellulose breakdown, detoxification of plant secondary metabolites, metabolism of simple sugars, fungal cell wall deconstruction, biofilm formation, antimicrobials biosynthesis, and metabolism of diverse nutrients. Our results suggest that the microbiota could be functionally adapted to the fungiculture environment, codifying metabolic pathways potentially relevant to the fungus-growing insects' ecosystems functioning.
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Skelton J, Loyd A, Smith JA, Blanchette RA, Held BW, Hulcr J. Fungal symbionts of bark and ambrosia beetles can suppress decomposition of pine sapwood by competing with wood-decay fungi. FUNGAL ECOL 2020. [DOI: 10.1016/j.funeco.2020.100926] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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17
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Sakai K, Yamaguchi A, Tsutsumi S, Kawai Y, Tsuzuki S, Suzuki H, Jindou S, Suzuki Y, Kajimura H, Kato M, Shimizu M. Characterization of FsXEG12A from the cellulose-degrading ectosymbiotic fungus Fusarium spp. strain EI cultured by the ambrosia beetle. AMB Express 2020; 10:96. [PMID: 32449090 PMCID: PMC7246284 DOI: 10.1186/s13568-020-01030-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/16/2020] [Indexed: 12/02/2022] Open
Abstract
Despite the threat of Fusarium dieback posed due to ambrosia fungi cultured by ambrosia beetles such as Euwallacea spp., the wood-degradation mechanisms utilized by ambrosia fungi are not fully understood. In this study, we analyzed the 16S rRNA and 18S rRNA genes of the microbial community from the Ficus tree tunnel excavated by Euwallacea interjectus and isolated the cellulose-degrading fungus, Fusarium spp. strain EI, by enrichment culture with carboxymethyl cellulose as the sole carbon source. The cellulolytic enzyme secreted by the fungus was identified and expressed in Pichia pastoris, and its enzymatic properties were characterized. The cellulolytic enzyme, termed FsXEG12A, could hydrolyze carboxymethyl cellulose, microcrystalline cellulose, xyloglucan, lichenan, and glucomannan, indicating that the broad substrate specificity of FsXEG12A could be beneficial for degrading complex wood components such as cellulose, xyloglucan, and galactoglucomannan in angiosperms. Inhibition of FsXEG12A function is, thus, an effective target for Fusarium dieback caused by Euwallacea spp.
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Affiliation(s)
- Kiyota Sakai
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Aya Yamaguchi
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Seitaro Tsutsumi
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Yuto Kawai
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Sho Tsuzuki
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Hiromitsu Suzuki
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Sadanari Jindou
- Faculty of Science and Technology, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Yoshihito Suzuki
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Hisashi Kajimura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Masashi Kato
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan
| | - Motoyuki Shimizu
- Faculty of Agriculture, Meijo University, Nagoya, Aichi, 468-8502, Japan.
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18
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Huang YT, Skelton J, Hulcr J. Lipids and small metabolites provisioned by ambrosia fungi to symbiotic beetles are phylogeny-dependent, not convergent. ISME JOURNAL 2020; 14:1089-1099. [PMID: 31988472 DOI: 10.1038/s41396-020-0593-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 12/27/2022]
Abstract
Long-term symbiotic associations often lead to reciprocal adaptation between the involved entities. One of the main challenges for studies of such symbioses is differentiating adaptation from neutral processes and phylogenetic background. Ambrosia fungi, cultivated by ambrosia beetles as their sole food source, provide an excellent model to study evolutionary adaptation in a comparative framework because they evolved many times, and each origin bears features seemingly convergently adapted to the symbiosis. We tested whether the symbiotic lifestyle of unrelated ambrosia fungi has led to convergence in the key feature of the symbiotic phenotype-nutrition provisioning to the vector beetles. We compared conidia and mycelium content in three phylogenetic pairs of ambrosia fungi and their closely related nonambrosia relatives using an untargeted metabolomic assay. Multivariate analysis of 311 polar metabolites and 14063 lipid features revealed no convergence of nutrient content across ambrosia lineages. Instead, most variation of the metabolome composition was explained by phylogenetic relationships among the fungi. Thus the overall metabolome evolution of each ambrosia fungus is mostly driven by its inherited metabolism rather than the transition toward symbiosis. We identified eight candidate lipid compounds with expression levels different between the swollen ambrosia spores and other tissues, but they were not consistently elevated across ambrosia fungi. We conclude that ambrosia provisions consist either of nonspecific nutrients in elevated amounts, or of metabolites that are specific to each of the ambrosia symbioses.
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Affiliation(s)
- Yin-Tse Huang
- School of Forest Resources and Conservation, University of Florida, Gainesville, FL, 32603, USA.,Center for Ecological Research, Kyoto University, Hirano 2-509-3, Otsu, Shiga Prefecture, 520-2113, Japan
| | - James Skelton
- School of Forest Resources and Conservation, University of Florida, Gainesville, FL, 32603, USA
| | - Jiri Hulcr
- School of Forest Resources and Conservation, University of Florida, Gainesville, FL, 32603, USA. .,Entomology and Nematology Department, University of Florida, Gainesville, FL, 32603, USA.
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19
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Abstract
The evolution of a mutualism requires reciprocal interactions whereby one species provides a service that the other species cannot perform or performs less efficiently. Services exchanged in insect-fungus mutualisms include nutrition, protection, and dispersal. In ectosymbioses, which are the focus of this review, fungi can be consumed by insects or can degrade plant polymers or defensive compounds, thereby making a substrate available to insects. They can also protect against environmental factors and produce compounds antagonistic to microbial competitors. Insects disperse fungi and can also provide fungal growth substrates and protection. Insect-fungus mutualisms can transition from facultative to obligate, whereby each partner is no longer viable on its own. Obligate dependency has (a) resulted in the evolution of morphological adaptations in insects and fungi, (b) driven the evolution of social behaviors in some groups of insects, and (c) led to the loss of sexuality in some fungal mutualists.
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Affiliation(s)
- Peter H W Biedermann
- Research Group Insect-Fungus Symbiosis, Department of Animal Ecology and Tropical Biology, University of Würzburg, 97074 Würzburg, Germany;
| | - Fernando E Vega
- Sustainable Perennial Crops Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA;
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20
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Nuotclà JA, Biedermann PHW, Taborsky M. Pathogen defence is a potential driver of social evolution in ambrosia beetles. Proc Biol Sci 2019; 286:20192332. [PMID: 31847779 PMCID: PMC6939916 DOI: 10.1098/rspb.2019.2332] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 11/27/2019] [Indexed: 12/20/2022] Open
Abstract
Social immunity-the collective behavioural defences against pathogens-is considered a crucial evolutionary force for the maintenance of insect societies. It has been described and investigated primarily in eusocial insects, but its role in the evolutionary trajectory from parental care to eusociality is little understood. Here, we report on the existence, plasticity, effectiveness and consequences of social pathogen defence in experimental nests of cooperatively breeding ambrosia beetles. After an Aspergillus spore buffer solution or a control buffer solution had been injected in laboratory nests, totipotent adult female workers increased their activity and hygienic behaviours like allogrooming and cannibalism. Such social immune responses had not been described for a non-eusocial, cooperatively breeding insect before. Removal of beetles from Aspergillus-treated nests in a paired experimental design revealed that the hygienic behaviours of beetles significantly reduced pathogen prevalence in the nest. Furthermore, in response to pathogen injections, female helpers delayed dispersal and thus prolonged their cooperative phase within their mother's nest. Our findings of appropriate social responses to an experimental immune challenge in a cooperatively breeding beetle corroborate the view that social immunity is not an exclusive attribute of eusocial insects, but rather a concomitant and presumably important feature in the evolutionary transitions towards complex social organization.
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Affiliation(s)
- Jon A. Nuotclà
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Peter H. W. Biedermann
- Research Group Insect-Fungus Symbiosis, Department of Animal Ecology and Tropical Biology, Am Hubland, Biocenter, 97074 Wuerzburg, Germany
| | - Michael Taborsky
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
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21
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Veselská T, Skelton J, Kostovčík M, Hulcr J, Baldrian P, Chudíčková M, Cajthaml T, Vojtová T, Garcia-Fraile P, Kolařík M. Adaptive traits of bark and ambrosia beetle-associated fungi. FUNGAL ECOL 2019. [DOI: 10.1016/j.funeco.2019.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Horváthová T, Bauchinger U. Biofilm Improves Isopod Growth Independent of the Dietary Cellulose Content. Physiol Biochem Zool 2019; 92:531-543. [PMID: 31556843 DOI: 10.1086/705441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cellulose is an abundant source of carbon, accounting for more than 50% of foliage and 90% of woody tissues of plants. Despite the diversity of species that include living or dead plant tissue in their diets, the ability to digest cellulose through self-produced enzymatic machinery is considered rare in the animal kingdom. The majority of animals studied to date rely on the cellulolytic activity of symbiotic microorganisms in their digestive tract, with some evidence for a complementary action of endogenous cellulases. Terrestrial isopods have evolved a lifestyle including feeding on a lignocellulose diet. Whether isopods utilize both external and internal cellulases for digestion of a diet is still not understood. We experimentally manipulated the content of cellulose (30%, 60%, or 90%) and the amount of biofilm (small or large) in the offered food source and quantified growth and cellulolytic activity in the gut of the isopod Porcellio scaber. The presence of a visible biofilm significantly promoted isopod growth, regardless of the cellulose content in the diet. The activity of gut cellulases was not significantly affected by the amount of biofilm or the cellulose content. Our results do not support a significant contribution of either ingested or host enzymes to cellulose utilization in P. scaber. Cellulose might not represent a key nutrient for isopods and does not seem to affect the nutritional value of the diet-associated biofilm. We propose that it is the biofilm community that determines the quality of plant diet in terrestrial isopods and potentially also in other detrital plant feeders.
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23
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24
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Hu H, da Costa RR, Pilgaard B, Schiøtt M, Lange L, Poulsen M. Fungiculture in Termites Is Associated with a Mycolytic Gut Bacterial Community. mSphere 2019; 4:e00165-19. [PMID: 31092601 PMCID: PMC6520439 DOI: 10.1128/msphere.00165-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 04/09/2019] [Indexed: 11/20/2022] Open
Abstract
Termites forage on a range of substrates, and it has been suggested that diet shapes the composition and function of termite gut bacterial communities. Through comparative analyses of gut metagenomes in nine termite species with distinct diets, we characterize bacterial community compositions and use peptide-based functional annotation method to determine biomass-degrading enzymes and the bacterial taxa that encode them. We find that fungus-growing termite guts have relatively more fungal cell wall-degrading enzyme genes, while wood-feeding termite gut communities have relatively more plant cell wall-degrading enzyme genes. Interestingly, wood-feeding termite gut bacterial genes code for abundant chitinolytic enzymes, suggesting that fungal biomass within the decaying wood likely contributes to gut bacterial or termite host nutrition. Across diets, the dominant biomass-degrading enzymes are predominantly coded for by the most abundant bacterial taxa, suggesting tight links between diet and gut community composition, with the most marked difference being the communities coding for the mycolytic capacity of the fungus-growing termite gut.IMPORTANCE Understanding functional capacities of gut microbiomes is important to improve our understanding of symbiotic associations. Here, we use peptide-based functional annotation to show that the gut microbiomes of fungus-farming termites code for a wealth of enzymes that likely target the fungal diet the termites eat. Comparisons to other termites showed that fungus-growing termite guts have relatively more fungal cell wall-degrading enzyme genes, whereas wood-feeding termite gut communities have relatively more plant cell wall-degrading enzyme genes. Across termites with different diets, the dominant biomass-degrading enzymes are predominantly coded for by the most abundant bacterial taxa, suggesting tight links between diet and gut community compositions.
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Affiliation(s)
- Haofu Hu
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rafael Rodrigues da Costa
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Bo Pilgaard
- Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Morten Schiøtt
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lene Lange
- Department of Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Michael Poulsen
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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25
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Lehenberger M, Biedermann PH, Benz JP. Molecular identification and enzymatic profiling of Trypodendron (Curculionidae: Xyloterini) ambrosia beetle-associated fungi of the genus Phialophoropsis (Microascales: Ceratocystidaceae). FUNGAL ECOL 2019. [DOI: 10.1016/j.funeco.2018.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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26
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27
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Saucedo-Carabez JR, Ploetz RC, Konkol JL, Carrillo D, Gazis R. Partnerships Between Ambrosia Beetles and Fungi: Lineage-Specific Promiscuity Among Vectors of the Laurel Wilt Pathogen, Raffaelea lauricola. MICROBIAL ECOLOGY 2018; 76:925-940. [PMID: 29675704 DOI: 10.1007/s00248-018-1188-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 04/10/2018] [Indexed: 05/25/2023]
Abstract
Nutritional mutualisms that ambrosia beetles have with fungi are poorly understood. Although these interactions were initially thought to be specific associations with a primary symbiont, there is increasing evidence that some of these fungi are associated with, and move among, multiple beetle partners. We examined culturable fungi recovered from mycangia of ambrosia beetles associated with trees of Persea humilis (silk bay, one site) and P. americana (avocado, six commercial orchards) that were affected by laurel wilt, an invasive disease caused by a symbiont, Raffaelea lauricola, of an Asian ambrosia beetle, Xyleborus glabratus. Fungi were isolated from 20 adult females of X. glabratus from silk bay and 70 each of Xyleborus affinis, Xyleborus bispinatus, Xyleborus volvulus, Xyleborinus saxesenii, and Xylosandrus crassiusculus from avocado. With partial sequences of ribosomal (LSU and SSU) and nuclear (β-tubulin) genes, one to several operational taxonomic units (OTUs) of fungi were identified in assayed individuals. Distinct populations of fungi were recovered from each of the examined beetle species. Raffaelea lauricola was present in all beetles except X. saxesenii and X. crassiusculus, and Raffaelea spp. predominated in Xyleborus spp. Raffaelea arxii, R. subalba, and R. subfusca were present in more than a single species of Xyleborus, and R. arxii was the most abundant symbiont in both X. affinis and X. volvulus. Raffaelea aguacate was detected for the first time in an ambrosia beetle (X. bispinatus). Yeasts (Ascomycota, Saccharomycotina) were found consistently in the mycangia of the examined beetles, and distinct, putatively co-adapted populations of these fungi were associated with each beetle species. Greater understandings are needed for how mycangia in ambrosia beetles interact with fungi, including yeasts which play currently underresearched roles in these insects.
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Affiliation(s)
- J R Saucedo-Carabez
- Tropical Research & Education Center, University of Florida, Homestead, FL, 33031-3314, USA
| | - Randy C Ploetz
- Tropical Research & Education Center, University of Florida, Homestead, FL, 33031-3314, USA.
| | - J L Konkol
- Tropical Research & Education Center, University of Florida, Homestead, FL, 33031-3314, USA
| | - D Carrillo
- Tropical Research & Education Center, University of Florida, Homestead, FL, 33031-3314, USA
| | - R Gazis
- Tropical Research & Education Center, University of Florida, Homestead, FL, 33031-3314, USA
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28
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Abstract
Ambrosia beetles are among the true fungus-farming insects and cultivate fungal gardens on which the larvae and adults feed. After invading new habitats, some species destructively attack living or weakened trees growing in managed and unmanaged settings. Ambrosia beetles adapted to weakened trees tunnel into stem tissues containing ethanol to farm their symbiotic fungi, even though ethanol is a potent antimicrobial agent that inhibits the growth of various fungi, yeasts, and bacteria. Here we demonstrate that ambrosia beetles rely on ethanol for host tree colonization because it promotes the growth of their fungal gardens while inhibiting the growth of “weedy” fungal competitors. We propose that ambrosia beetles use ethanol to optimize their food production. Animal–microbe mutualisms are typically maintained by vertical symbiont transmission or partner choice. A third mechanism, screening of high-quality symbionts, has been predicted in theory, but empirical examples are rare. Here we demonstrate that ambrosia beetles rely on ethanol within host trees for promoting gardens of their fungal symbiont and producing offspring. Ethanol has long been known as the main attractant for many of these fungus-farming beetles as they select host trees in which they excavate tunnels and cultivate fungal gardens. More than 300 attacks by Xylosandrus germanus and other species were triggered by baiting trees with ethanol lures, but none of the foundresses established fungal gardens or produced broods unless tree tissues contained in vivo ethanol resulting from irrigation with ethanol solutions. More X. germanus brood were also produced in a rearing substrate containing ethanol. These benefits are a result of increased food supply via the positive effects of ethanol on food-fungus biomass. Selected Ambrosiella and Raffaelea fungal isolates from ethanol-responsive ambrosia beetles profited directly and indirectly by (i) a higher biomass on medium containing ethanol, (ii) strong alcohol dehydrogenase enzymatic activity, and (iii) a competitive advantage over weedy fungal garden competitors (Aspergillus, Penicillium) that are inhibited by ethanol. As ambrosia fungi both detoxify and produce ethanol, they may maintain the selectivity of their alcohol-rich habitat for their own purpose and that of other ethanol-resistant/producing microbes. This resembles biological screening of beneficial symbionts and a potentially widespread, unstudied benefit of alcohol-producing symbionts (e.g., yeasts) in other microbial symbioses.
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Birkemoe T, Jacobsen RM, Sverdrup-Thygeson A, Biedermann PHW. Insect-Fungus Interactions in Dead Wood Systems. SAPROXYLIC INSECTS 2018. [DOI: 10.1007/978-3-319-75937-1_12] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Biedermann PH, Rohlfs M. Evolutionary feedbacks between insect sociality and microbial management. CURRENT OPINION IN INSECT SCIENCE 2017; 22:92-100. [PMID: 28805645 DOI: 10.1016/j.cois.2017.06.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/22/2017] [Accepted: 06/09/2017] [Indexed: 06/07/2023]
Abstract
Fitness-determining interactions with microbes-in particular fungi-have often been considered a by-product of social evolution in insects. Here, we take the view that both beneficial and harmful microbial consortia are major drivers of social behaviours in many insect systems-ranging from aggregation to eusociality. We propose evolutionary feedbacks between the insect sociality and microbial communities that strengthen mutualistic interactions with beneficial (dietary or defensive) microbes and simultaneously increase the capacity to defend against pathogens (i.e. social immunity). We identified variation in habitat stability-as determined by breeding site predictability and ephemerality-as a main ecological factor that constrains these feedbacks. To test this hypothesis we suggest following the evolution of insect social traits upon experimental manipulation of habitat stability and microbial consortia.
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Affiliation(s)
- Peter Hw Biedermann
- Department of Biochemistry, Max-Planck-Institute for Chemical Ecology, Jena, Germany; Institute for Animal Ecology and Tropical Biology, Julius-Maximilians-University of Würzburg, Germany.
| | - Marko Rohlfs
- University of Bremen, Institute of Ecology, Population- and Evolutionary Ecology Group, Germany; University of Goettingen, J.F. Blumenbach Institute of Zoology, Animal Ecology Group, Germany.
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Kasson MT, Wickert KL, Stauder CM, Macias AM, Berger MC, Simmons DR, Short DP, DeVallance DB, Hulcr J. Mutualism with aggressive wood-degrading Flavodon ambrosius (Polyporales) facilitates niche expansion and communal social structure in Ambrosiophilus ambrosia beetles. FUNGAL ECOL 2016. [DOI: 10.1016/j.funeco.2016.07.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Landvik M, Niemelä P, Roslin T. Mother knows the best mould: an essential role for non-wood dietary components in the life cycle of a saproxylic scarab beetle. Oecologia 2016; 182:163-75. [PMID: 27215637 DOI: 10.1007/s00442-016-3661-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 05/11/2016] [Indexed: 11/28/2022]
Abstract
Beetles living in tree hollows can feed on a wealth of substrates-e.g. the rotten wood surrounding the cavity, leaf humus falling into the hole, and larval frass accumulating in the cavity. In this paper, we examine the role of these main substrates in Finnish tree hollows in the female preference and larval growth of the hermit beetle Osmoderma barnabita. We rear larvae on diets consisting of wood material (as affected by brown-rot), leaf humus, and larval frass, in varying proportions. To pinpoint the effects of microbes, we contrast larval growth on sterilized versus unsterilized larval frass, and on pure mycelia of the cavity-creating fungus Laetiporus sulphureus. Finally, to relate larval performance to female preference, we examine female choice among the three main substrates used in the larval rearings. We found that the presence of one substrate modifies the influence of another, with larval growth and survival being highest on pure leaf humus. Microbes came with both positive and negative impacts on larval performance, as larvae grew quicker on unsterilized than on sterilized larval frass, but were also struck by higher mortality. On pure fungal mycelia, larvae neither grew nor survived. Female preference reflected larval performance, with leaf humus being preferred over other resources. Overall, our study suggests that organisms inhabiting tree holes may be dependent on subsidies entering the cavity from outside, and that ovipositing females may specifically respond to the presence of such subsidies. Thus, the quality of a microhabitat may depend on what enters it from outside.
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Affiliation(s)
- Matti Landvik
- Department of Biology, Section of Biodiversity and Environmental Science, University of Turku, 20014, Turku, Finland.
| | - Pekka Niemelä
- Herbarium, Department of Biology, University of Turku, 20014, Turku, Finland
| | - Tomas Roslin
- Spatial Foodweb Ecology Group, Department of Agricultural Sciences, University of Helsinki, Latokartanonkaari 5, 00014, Helsinki, Finland.,Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, 750 07, Uppsala, Sweden
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Freeman S, Sharon M, Dori-Bachash M, Maymon M, Belausov E, Maoz Y, Margalit O, Protasov A, Mendel Z. Symbiotic association of three fungal species throughout the life cycle of the ambrosia beetle Euwallacea nr. fornicatus. Symbiosis 2015. [DOI: 10.1007/s13199-015-0356-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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You L, Simmons DR, Bateman CC, Short DPG, Kasson MT, Rabaglia RJ, Hulcr J. New Fungus-Insect Symbiosis: Culturing, Molecular, and Histological Methods Determine Saprophytic Polyporales Mutualists of Ambrosiodmus Ambrosia Beetles. PLoS One 2015; 10:e0137689. [PMID: 26367271 PMCID: PMC4569427 DOI: 10.1371/journal.pone.0137689] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/19/2015] [Indexed: 12/28/2022] Open
Abstract
Ambrosia symbiosis is an obligate, farming-like mutualism between wood-boring beetles and fungi. It evolved at least 11 times and includes many notorious invasive pests. All ambrosia beetles studied to date cultivate ascomycotan fungi: early colonizers of recently killed trees with poor wood digestion. Beetles in the widespread genus Ambrosiodmus, however, colonize decayed wood. We characterized the mycosymbionts of three Ambrosiodmus species using quantitative culturing, high-throughput metabarcoding, and histology. We determined the fungi to be within the Polyporales, closely related to Flavodon flavus. Culture-independent sequencing of Ambrosiodmus minor mycangia revealed a single operational taxonomic unit identical to the sequences from the cultured Flavodon. Histological sectioning confirmed that Ambrosiodmus possessed preoral mycangia containing dimitic hyphae similar to cultured F. cf. flavus. The Ambrosiodmus-Flavodon symbiosis is unique in several aspects: it is the first reported association between an ambrosia beetle and a basidiomycotan fungus; the mycosymbiont grows as hyphae in the mycangia, not as budding pseudo-mycelium; and the mycosymbiont is a white-rot saprophyte rather than an early colonizer: a previously undocumented wood borer niche. Few fungi are capable of turning rotten wood into complete animal nutrition. Several thousand beetle-fungus symbioses remain unstudied and promise unknown and unexpected mycological diversity and enzymatic innovations.
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Affiliation(s)
- Li You
- School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - David Rabern Simmons
- School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Craig C. Bateman
- Department of Entomology and Nematology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Dylan P. G. Short
- Division of Plant and Soil Sciences, West Virginia University, Morgantown, West Virginia, United States of America
| | - Matthew T. Kasson
- Division of Plant and Soil Sciences, West Virginia University, Morgantown, West Virginia, United States of America
| | - Robert J. Rabaglia
- Forest Health Protection, State & Private Forestry, United States Department of Agriculture Forest Service, Washington, District of Columbia, United States of America
| | - Jiri Hulcr
- School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
- Department of Entomology and Nematology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
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Mayers CG, McNew DL, Harrington TC, Roeper RA, Fraedrich SW, Biedermann PHW, Castrillo LA, Reed SE. Three genera in the Ceratocystidaceae are the respective symbionts of three independent lineages of ambrosia beetles with large, complex mycangia. Fungal Biol 2015; 119:1075-1092. [PMID: 26466881 DOI: 10.1016/j.funbio.2015.08.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 07/28/2015] [Accepted: 08/03/2015] [Indexed: 12/24/2022]
Abstract
The genus Ambrosiella accommodates species of Ceratocystidaceae (Microascales) that are obligate, mutualistic symbionts of ambrosia beetles, but the genus appears to be polyphyletic and more diverse than previously recognized. In addition to Ambrosiella xylebori, Ambrosiella hartigii, Ambrosiella beaveri, and Ambrosiella roeperi, three new species of Ambrosiella are described from the ambrosia beetle tribe Xyleborini: Ambrosiella nakashimae sp. nov. from Xylosandrus amputatus, Ambrosiella batrae sp. nov. from Anisandrus sayi, and Ambrosiella grosmanniae sp. nov. from Xylosandrus germanus. The genus Meredithiella gen. nov. is created for symbionts of the tribe Corthylini, based on Meredithiella norrisii sp. nov. from Corthylus punctatissimus. The genus Phialophoropsis is resurrected to accommodate associates of the Xyloterini, including Phialophoropsis trypodendri from Trypodendron scabricollis and Phialophoropsis ferruginea comb. nov. from Trypodendron lineatum. Each of the ten named species was distinguished by ITS rDNA barcoding and morphology, and the ITS rDNA sequences of four other putative species were obtained with Ceratocystidaceae-specific primers and template DNA extracted from beetles or galleries. These results support the hypothesis that each ambrosia beetle species with large, complex mycangia carries its own fungal symbiont. Conidiophore morphology and phylogenetic analyses using 18S (SSU) rDNA and TEF1α DNA sequences suggest that these three fungal genera within the Ceratocystidaceae independently adapted to symbiosis with the three respective beetle tribes. In turn, the beetle genera with large, complex mycangia appear to have evolved from other genera in their respective tribes that have smaller, less selective mycangia and are associated with Raffaelea spp. (Ophiostomatales).
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Affiliation(s)
- Chase G Mayers
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey Hall, Ames, IA 50011, USA
| | - Douglas L McNew
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey Hall, Ames, IA 50011, USA
| | - Thomas C Harrington
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey Hall, Ames, IA 50011, USA.
| | | | | | - Peter H W Biedermann
- Research Group Insect Symbiosis, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Str. 8, 07745 Jena, Germany
| | - Louela A Castrillo
- Department of Entomology, Cornell University, R.W. Holley Center for Agriculture and Health, Ithaca, NY 14853, USA
| | - Sharon E Reed
- Division of Plant Sciences, University of Missouri, 52 Agriculture Lab, Columbia, MO 65211, USA
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Musvuugwa T, de Beer ZW, Duong TA, Dreyer LL, Oberlander KC, Roets F. New species of Ophiostomatales from Scolytinae and Platypodinae beetles in the Cape Floristic Region, including the discovery of the sexual state of Raffaelea. Antonie van Leeuwenhoek 2015; 108:933-50. [DOI: 10.1007/s10482-015-0547-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/24/2015] [Indexed: 01/21/2023]
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37
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Ulyshen MD. Wood decomposition as influenced by invertebrates. Biol Rev Camb Philos Soc 2014; 91:70-85. [PMID: 25424353 DOI: 10.1111/brv.12158] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 09/18/2014] [Accepted: 10/15/2014] [Indexed: 11/29/2022]
Abstract
The diversity and habitat requirements of invertebrates associated with dead wood have been the subjects of hundreds of studies in recent years but we still know very little about the ecological or economic importance of these organisms. The purpose of this review is to examine whether, how and to what extent invertebrates affect wood decomposition in terrestrial ecosystems. Three broad conclusions can be reached from the available literature. First, wood decomposition is largely driven by microbial activity but invertebrates also play a significant role in both temperate and tropical environments. Primary mechanisms include enzymatic digestion (involving both endogenous enzymes and those produced by endo- and ectosymbionts), substrate alteration (tunnelling and fragmentation), biotic interactions and nitrogen fertilization (i.e. promoting nitrogen fixation by endosymbiotic and free-living bacteria). Second, the effects of individual invertebrate taxa or functional groups can be accelerative or inhibitory but the cumulative effect of the entire community is generally to accelerate wood decomposition, at least during the early stages of the process (most studies are limited to the first 2-3 years). Although methodological differences and design limitations preclude meta-analysis, studies aimed at quantifying the contributions of invertebrates to wood decomposition commonly attribute 10-20% of wood loss to these organisms. Finally, some taxa appear to be particularly influential with respect to promoting wood decomposition. These include large wood-boring beetles (Coleoptera) and termites (Termitoidae), especially fungus-farming macrotermitines. The presence or absence of these species may be more consequential than species richness and the influence of invertebrates is likely to vary biogeographically.
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Affiliation(s)
- Michael D Ulyshen
- USDA Forest Service, Southern Research Station, Athens, GA, 30602, U.S.A
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Seal JN, Schiøtt M, Mueller UG. Ant-fungus species combinations engineer physiological activity of fungus gardens. ACTA ACUST UNITED AC 2014; 217:2540-7. [PMID: 24803469 DOI: 10.1242/jeb.098483] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fungus-gardening insects are among the most complex organisms because of their extensive co-evolutionary histories with obligate fungal symbionts and other microbes. Some fungus-gardening insect lineages share fungal symbionts with other members of their lineage and thus exhibit diffuse co-evolutionary relationships, while others exhibit little or no symbiont sharing, resulting in host-fungus fidelity. The mechanisms that maintain this symbiont fidelity are currently unknown. Prior work suggested that derived leaf-cutting ants in the genus Atta interact synergistically with leaf-cutter fungi (Attamyces) by exhibiting higher fungal growth rates and enzymatic activities than when growing a fungus from the sister-clade to Attamyces (so-called 'Trachymyces'), grown primarily by the non-leaf cutting Trachymyrmex ants that form, correspondingly, the sister-clade to leaf-cutting ants. To elucidate the enzymatic bases of host-fungus specialization in leaf-cutting ants, we conducted a reciprocal fungus-switch experiment between the ant Atta texana and the ant Trachymyrmex arizonensis and report measured enzymatic activities of switched and sham-switched fungus gardens to digest starch, pectin, xylan, cellulose and casein. Gardens exhibited higher amylase and pectinase activities when A. texana ants cultivated Attamyces compared with Trachymyces fungi, consistent with enzymatic specialization. In contrast, gardens showed comparable amylase and pectinase activities when T. arizonensis cultivated either fungal species. Although gardens of leaf-cutting ants are not known to be significant metabolizers of cellulose, T. arizonensis were able to maintain gardens with significant cellulase activity when growing either fungal species. In contrast to carbohydrate metabolism, protease activity was significantly higher in Attamyces than in Trachymyces, regardless of the ant host. Activity of some enzymes employed by this symbiosis therefore arises from complex interactions between the ant host and the fungal symbiont.
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Affiliation(s)
- J N Seal
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX 75799, USA Integrative Biology, University of Texas at Austin, 1 University Station C0930, Austin, TX 78712, USA
| | - M Schiøtt
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark
| | - U G Mueller
- Integrative Biology, University of Texas at Austin, 1 University Station C0930, Austin, TX 78712, USA
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Instability of novel ant-fungal associations constrains horizontal exchange of fungal symbionts. Evol Ecol 2013. [DOI: 10.1007/s10682-013-9665-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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40
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Biedermann PHW, Klepzig KD, Taborsky M, Six DL. Abundance and dynamics of filamentous fungi in the complex ambrosia gardens of the primitively eusocial beetle Xyleborinus saxesenii Ratzeburg (Coleoptera: Curculionidae, Scolytinae). FEMS Microbiol Ecol 2012; 83:711-23. [PMID: 23057948 DOI: 10.1111/1574-6941.12026] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 09/10/2012] [Accepted: 10/03/2012] [Indexed: 11/26/2022] Open
Abstract
Insect fungus gardens consist of a community of interacting microorganisms that can have either beneficial or detrimental effects to the farmers. In contrast to fungus-farming ants and termites, the fungal communities of ambrosia beetles and the effects of particular fungal species on the farmers are largely unknown. Here, we used a laboratory rearing technique for studying the filamentous fungal garden community of the ambrosia beetle, Xyleborinus saxesenii, which cultivates fungi in tunnels excavated within dead trees. Raffaelea sulfurea and Fusicolla acetilerea were transmitted in spore-carrying organs by gallery founding females and established first in new gardens. Raffaelea sulfurea had positive effects on egg-laying and larval numbers. Over time, four other fungal species emerged in the gardens. Prevalence of one of them, Paecilomyces variotii, correlated negatively with larval numbers and can be harmful to adults by forming biofilms on their bodies. It also comprised the main portion of garden material removed from galleries by adults. Our data suggest that two mutualistic, several commensalistic and one to two pathogenic filamentous fungi are associated with X. saxesenii. Fungal diversity in gardens of ambrosia beetles appears to be much lower than that in gardens of fungus-culturing ants, which seems to result from essential differences in substrates and behaviours.
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Affiliation(s)
- Peter H W Biedermann
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
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