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Rella SA, Kulikova YA, Minnegalieva AR, Kondrashov FA. Complex vaccination strategies prevent the emergence of vaccine resistance. Evolution 2024; 78:1722-1738. [PMID: 38990788 DOI: 10.1093/evolut/qpae106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 06/22/2024] [Accepted: 07/10/2024] [Indexed: 07/13/2024]
Abstract
Vaccination is the most effective tool to control infectious diseases. However, the evolution of vaccine resistance, exemplified by vaccine resistance in SARS-CoV-2, remains a concern. Here, we model complex vaccination strategies against a pathogen with multiple epitopes-molecules targeted by the vaccine. We found that a vaccine targeting one epitope was ineffective in preventing vaccine escape. Vaccine resistance in highly infectious pathogens was prevented by the full-epitope vaccine, that is, one targeting all available epitopes, but only when the rate of pathogen evolution was low. Strikingly, a bet-hedging strategy of random administration of vaccines targeting different epitopes was the most effective in preventing vaccine resistance in pathogens with the low rate of infection and high rate of evolution. Thus, complex vaccination strategies, when biologically feasible, may be preferable to the currently used single-vaccine approaches for long-term control of disease outbreaks, especially when applied to livestock with near 100% vaccination rates.
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Affiliation(s)
- Simon A Rella
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Yuliya A Kulikova
- International Institute for Applied Systems Analysis, Laxenburg, Austria
- Okinawa Institute of Science and Technology, Okinawa, Japan
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2
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Bell-Roberts L, Turner JFR, Werner GDA, Downing PA, Ross L, West SA. Larger colony sizes favoured the evolution of more worker castes in ants. Nat Ecol Evol 2024:10.1038/s41559-024-02512-7. [PMID: 39187609 PMCID: PMC7616618 DOI: 10.1038/s41559-024-02512-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 07/18/2024] [Indexed: 08/28/2024]
Abstract
The size-complexity hypothesis is a leading explanation for the evolution of complex life on earth. It predicts that in lineages that have undergone a major transition in organismality, larger numbers of lower-level subunits select for increased division of labour. Current data from multicellular organisms and social insects support a positive correlation between the number of cells and number of cell types and between colony size and the number of castes. However, the implication of these results is unclear, because colony size and number of cells are correlated with other variables which may also influence selection for division of labour, and causality could be in either direction. Here, to resolve this problem, we tested multiple causal hypotheses using data from 794 ant species. We found that larger colony sizes favoured the evolution of increased division of labour, resulting in more worker castes and greater variation in worker size. By contrast, our results did not provide consistent support for alternative hypotheses regarding either queen mating frequency or number of queens per colony explaining variation in division of labour. Overall, our results provide strong support for the size-complexity hypothesis.
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Affiliation(s)
| | | | - Gijsbert D A Werner
- Department of Biology, University of Oxford, Oxford, UK
- Netherlands Scientific Council for Government Policy, The Hague, The Netherlands
| | - Philip A Downing
- Ecology & Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Laura Ross
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, UK
| | - Stuart A West
- Department of Biology, University of Oxford, Oxford, UK
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3
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Esparza-Mora MA, Mazumdar T, Jiang S, Radek R, Thiem JN, Feng L, Petrašiūnaitė V, Banasiak R, Golian M, Gleske M, Lucas C, Springer A, Buellesbach J, McMahon DP. Defensive behavior is linked to altered surface chemistry following infection in a termite society. Sci Rep 2023; 13:20606. [PMID: 37996442 PMCID: PMC10667546 DOI: 10.1038/s41598-023-42947-9] [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: 05/22/2023] [Accepted: 09/16/2023] [Indexed: 11/25/2023] Open
Abstract
The care-kill response determines whether a sick individual will be treated or eliminated from an insect society, but little is known about the physiological underpinnings of this process. We exploited the stepwise infection dynamics of an entomopathogenic fungus in a termite to explore how care-kill transitions occur, and identify the chemical cues behind these shifts. We found collective responses towards pathogen-injected individuals to vary according to severity and timing of pathogen challenge, with elimination, via cannibalism, occurring sooner in response to a severe active infection. However, injection with inactivated fungal blastospores also resulted in increased albeit delayed cannibalism, even though it did not universally cause host death. This indicates that the decision to eliminate an individual is triggered before pathogen viability or terminal disease status has been established. We then compared the surface chemistry of differently challenged individuals, finding increased amounts of long-chained methyl-branched alkanes with similar branching patterns in individuals injected with both dead and viable fungal blastospores, with the latter showing the largest increase. This coincided with the highest amounts of observed cannibalism as well as signs of severe moribundity. Our study provides new mechanistic insight into the emergent collective behaviors involved in the disease defense of a termite society.
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Affiliation(s)
- M Alejandra Esparza-Mora
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
- Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin, Germany
| | - Tilottama Mazumdar
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
- Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin, Germany
| | - Shixiong Jiang
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
- Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin, Germany
| | - Renate Radek
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
| | - Julian N Thiem
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
| | - Linshan Feng
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
| | - Vesta Petrašiūnaitė
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
| | - Ronald Banasiak
- Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin, Germany
| | - Marek Golian
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstraße 1, 48149, Münster, Germany
| | - Melanie Gleske
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstraße 1, 48149, Münster, Germany
| | - Christophe Lucas
- Institut de Recherche sur la Biologie de l'Insecte (UMR7261), CNRS-University of Tours, Tours, France
| | - Andreas Springer
- Core Facility BioSupraMol, Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany
| | - Jan Buellesbach
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstraße 1, 48149, Münster, Germany
| | - Dino P McMahon
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany.
- Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205, Berlin, Germany.
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Metzler S, Kirchner J, Grasse AV, Cremer S. Trade-offs between immunity and competitive ability in fighting ant males. BMC Ecol Evol 2023; 23:37. [PMID: 37550612 PMCID: PMC10405452 DOI: 10.1186/s12862-023-02137-7] [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: 02/02/2023] [Accepted: 06/16/2023] [Indexed: 08/09/2023] Open
Abstract
BACKGROUND Fighting disease while fighting rivals exposes males to constraints and trade-offs during male-male competition. We here tested how both the stage and intensity of infection with the fungal pathogen Metarhizium robertsii interfere with fighting success in Cardiocondyla obscurior ant males. Males of this species have evolved long lifespans during which they can gain many matings with the young queens of the colony, if successful in male-male competition. Since male fights occur inside the colony, the outcome of male-male competition can further be biased by interference of the colony's worker force. RESULTS We found that severe, but not yet mild, infection strongly impaired male fighting success. In late-stage infection, this could be attributed to worker aggression directed towards the infected rather than the healthy male and an already very high male morbidity even in the absence of fighting. Shortly after pathogen exposure, however, male mortality was particularly increased during combat. Since these males mounted a strong immune response, their reduced fighting success suggests a trade-off between immune investment and competitive ability already early in the infection. Even if the males themselves showed no difference in the number of attacks they raised against their healthy rivals across infection stages and levels, severely infected males were thus losing in male-male competition from an early stage of infection on. CONCLUSIONS Males of the ant C. obscurior have a well-developed immune system that raises a strong immune response very fast after fungal exposure. This allows them to cope with mild pathogen exposures without compromising their success in male-male competition, and hence to gain multiple mating opportunities with the emerging virgin queens of the colony. Under severe infection, however, they are weak fighters and rarely survive a combat already at early infection when raising an immune response, as well as at progressed infection, when they are morbid and preferentially targeted by worker aggression. Workers thereby remove males that pose a future disease threat by biasing male-male competition. Our study thus reveals a novel social immunity mechanism how social insect workers protect the colony against disease risk.
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Affiliation(s)
- Sina Metzler
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria
| | - Jessica Kirchner
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria
| | - Anna V Grasse
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria
| | - Sylvia Cremer
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria.
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Felden A, Dobelmann J, Baty JW, McCormick J, Haywood J, Lester PJ. Can immune gene silencing via dsRNA feeding promote pathogenic viruses to control the globally invasive Argentine ant? ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2755. [PMID: 36196505 DOI: 10.1002/eap.2755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 06/27/2022] [Accepted: 08/03/2022] [Indexed: 06/16/2023]
Abstract
Pest control methods that can target pest species with limited environmental impacts are a conservation and economic priority. Species-specific pest control using RNA interference is a challenging but promising avenue in developing the next generation of pest management. We investigate the feasibility of manipulating a biological invader's immune system using double-stranded RNA (dsRNA) in order to increase susceptibility to naturally occurring pathogens. We used the invasive Argentine ant as a model, targeting the immunity-associated genes Spaetzle and Dicer-1 with dsRNA. We show that feeding with Spaetzle dsRNA can result in partial target gene silencing for up to 28 days in the laboratory and 5 days in the field. Dicer-1 dsRNA only resulted in partial gene knockdown after 2 days in the laboratory. Double-stranded RNA treatments were associated with significant gene expression disruptions across immune pathways in the laboratory and to a lower extent in the field. In total, 12 viruses and four bacteria were found in these ant populations. Some changes in viral loads in dsRNA-treated groups were observed. For example, Linepithema humile Polycipivirus 2 (LhuPCV2) loads increased after 2 days of treatment with Spaetzle and Dicer-1 dsRNA treatments in the laboratory. After treatment with the dsRNA in the field, after 5 days the virus Linepithema humile toti-like virus 1 (LhuTLV1) was significantly more abundant. However, immune pathway disruption did not result in a consistent increase in microbial infections, nor did it alter ant abundance in the field. Some viruses even declined in abundance after dsRNA treatment. Our study explored the feasibility of lowering a pest's immunity as a control tool. We demonstrate that it is possible to alter immune gene expression of pest species and pathogen loads, although in our specific system the affected pathogens did not appear to influence pest abundance. We provide suggestions on future directions for dsRNA-mediated immune disruption in pest species, including potential avenues to improve dsRNA delivery as well as the importance of pest and pathogen biology. Double-stranded RNA targeting immune function might be especially useful for pest control in systems in which viruses or other microorganisms are prevalent and have the potential to be pathogenic.
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Affiliation(s)
- Antoine Felden
- Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Jana Dobelmann
- Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Ulm, Germany
| | - James W Baty
- Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Joseph McCormick
- Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - John Haywood
- School of Mathematics and Statistics, Victoria University of Wellington, Wellington, New Zealand
| | - Philip J Lester
- Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
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Wiernasz DC, Cole BJ. The ontogeny of selection on genetic diversity in harvester ants. Proc Biol Sci 2022; 289:20220496. [PMID: 35673867 PMCID: PMC9174731 DOI: 10.1098/rspb.2022.0496] [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: 12/25/2022] Open
Abstract
Selection may favour traits throughout an individual's lifetime or at a particular life stage. In many species of social insects, established colonies that are more genetically diverse outperform less diverse colonies with respect to a variety of traits that contribute to fitness, but whether selection favours high diversity in small colonies is unknown. We tested the hypothesis that selection favours genetically diverse colonies during the juvenile period using a multi-year field experiment with the harvester ant, Pogonomyrmex occidentalis. We used controlled matings to generate colonies that varied in genetic diversity and transplanted them into the field. We monitored their survival for seven (the 2015 cohort, n = 149) and six (the 2016 cohort, n = 157) years. Genetically more diverse colonies had greater survival, resulting in significant viability selection. However, in both cohorts survival was not influenced by genetic diversity until colonies were three years old. We suggest that changes in their internal organization enabled colonies to use the benefits of multiple genotypes, and discuss possible mechanisms that can generate this pattern.
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Affiliation(s)
- Diane C. Wiernasz
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204-5001, USA
| | - Blaine J. Cole
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204-5001, USA
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7
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Detrain C, Leclerc JB. Spatial distancing by fungus-exposed Myrmica ants is prompted by sickness rather than contagiousness. JOURNAL OF INSECT PHYSIOLOGY 2022; 139:104384. [PMID: 35318040 DOI: 10.1016/j.jinsphys.2022.104384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 02/24/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
The ecological success of ants relies on their high level of sociality and cooperation between genetically related nestmates. However, these group-living insects suffer from elevated risks of disease outbreak in the whole nest. To face this sanitary challenge, social and spatial distancing of pathogen-exposed individuals from susceptible nestmates appear to be simple, although efficient, ways to limit the propagation of contact-transmitted pathogens. Here we question whether spatial distancing in Myrmica rubra ants is an active response of diseased individuals that correlates with their level of infectiousness. We contaminated foragers with spores of Metarhizium brunneum entomopathogenic fungus. We daily tracked the location of these pathogen-exposed individuals and we analyzed their movement patterns until their death on the 5th day post-contamination. Quite unexpectedly, we found that contagious individuals, whose body was covered with infectious spores, did not reduce their mobility nor stayed far away from larvae in order to limit pathogen transmission to healthy nestmates. Spatial distancing occurred later when diseased individuals were no longer contagious because spores had penetrated their body. These sick ants mainly stayed outside the nest, were less mobile and showed a shift from a superdiffusive to subdiffusive walking pattern. Furthermore, these diseased ants did not actively head towards directions that were opposite to the nest entrance. This study found no evidence for early spatial distancing by contaminated M.rubra workers that would fit to the actual risk of colony-wide contagion. Coupled to a lower mobility and area-reduced walking patterns, the late distancing of moribund individuals appears to be a symptom of sickness resulting from fungus-induced physical and physiological dysfunctions. Besides questioning the truly altruistic nature of death in isolation in this system (and potentially others), we discuss about the ecological and physiological constraints that explain the absence of early distancing when some ant species are exposed to pathogens.
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Affiliation(s)
- Claire Detrain
- Unit of Social Ecology CP 231, Université Libre de Bruxelles, 50 Avenue F Roosevelt, 1050 Brussels, Belgium.
| | - Jean-Baptiste Leclerc
- Unit of Social Ecology CP 231, Université Libre de Bruxelles, 50 Avenue F Roosevelt, 1050 Brussels, Belgium
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8
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Soper DM, Ekroth AKE, Martins MJF. Direct evidence for increased disease resistance in polyandrous broods exists only in eusocial Hymenoptera. BMC Ecol Evol 2021; 21:189. [PMID: 34670487 PMCID: PMC8527725 DOI: 10.1186/s12862-021-01925-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/24/2021] [Indexed: 11/25/2022] Open
Abstract
Background The ‘genetic diversity’ hypothesis posits that polyandry evolved as a mechanism to increase genetic diversity within broods. One extension of this hypothesis is the ‘genetic diversity for disease resistance’ hypothesis (GDDRH). Originally designed for eusocial Hymenoptera, GDDRH states that polyandry will evolve as an effect of lower parasite prevalence in genetically variable broods. However, this hypothesis has been broadly applied to several other taxa. It is unclear how much empirical evidence supports GDDRH specifically, especially outside eusocial Hymenoptera. Results This question was addressed by conducting a literature review and posteriorly conducting meta-analyses on the data available using Hedges’s g. The literature review found 10 direct and 32 indirect studies with both having a strong publication bias towards Hymenoptera. Two meta-analyses were conducted and both found increased polyandry (direct tests; n = 8, g = 0.2283, p = < 0.0001) and genetic diversity generated by other mechanisms (indirect tests; n = 10, g = 0.21, p = < 0.0001) reduced parasite load. A subsequent moderator analysis revealed that there were no differences among Orders, indicating there may be applicability outside of Hymenoptera. However, due to publication bias and low sample size we must exercise caution with these results. Conclusion Despite the fact that the GDDRH was developed for Hymenoptera, it is frequently applied to other taxa. This study highlights the low amount of direct evidence supporting GDDRH, particularly outside of eusocial Hymenoptera. It calls for future research to address species that have high dispersal rates and contain mixes of solitary and communal nesting. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01925-3.
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Affiliation(s)
- D M Soper
- Department of Biology, University of Dallas, 1845 E. Northgate Dr., Irving, TX, 75062, USA.
| | - A K E Ekroth
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - M J F Martins
- Interdisciplinary Center for Archaeology and Evolution of Human Behaviour (ICArEHB), Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.,Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20013-7012, USA
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Psalti MN, Gohlke D, Libbrecht R. Experimental increase of worker diversity benefits brood production in ants. BMC Ecol Evol 2021; 21:163. [PMID: 34461829 PMCID: PMC8404329 DOI: 10.1186/s12862-021-01890-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/18/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The reproductive division of labor of eusocial insects, whereby one or several queens monopolize reproduction, evolved in a context of high genetic relatedness. However, many extant eusocial species have developed strategies that decrease genetic relatedness in their colonies, suggesting some benefits of the increased diversity. Multiple studies support this hypothesis by showing positive correlations between genetic diversity and colony fitness, as well as finding effects of experimental manipulations of diversity on colony performance. However, alternative explanations could account for most of these reports, and the benefits of diversity on performance in eusocial insects still await validation. In this study, we experimentally increased worker diversity in small colonies of the ant Lasius niger while controlling for typical confounding factors. RESULTS We found that experimental colonies composed of workers coming from three different source colonies produced more larvae and showed more variation in size compared to groups of workers coming from a single colony. CONCLUSIONS We propose that the benefits of increased diversity stemmed from an improved division of labor. Our study confirms that worker diversity enhances colony performance, thus providing a possible explanation for the evolution of multiply mated queens and multiple-queen colonies in many species of eusocial insects.
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Affiliation(s)
- Marina N. Psalti
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Dustin Gohlke
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
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Lindström S, Timonen S, Sundström L. The bacterial and fungal community composition in time and space in the nest mounds of the ant Formica exsecta (Hymenoptera: Formicidae). Microbiologyopen 2021; 10:e1201. [PMID: 34459553 PMCID: PMC8289489 DOI: 10.1002/mbo3.1201] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/07/2021] [Accepted: 05/13/2021] [Indexed: 11/09/2022] Open
Abstract
In a subarctic climate, the seasonal shifts in temperature, precipitation, and plant cover drive the temporal changes in the microbial communities in the topsoil, forcing soil microbes to adapt or decline. Many organisms, such as mound-building ants, survive the cold winter owing to the favorable microclimate in their nest mounds. We have previously shown that the microbial communities in the nest of the ant Formica exsecta are significantly different from those in the surrounding bulk soil. In the current study, we identified taxa, which were consistently present in the nests over a study period of three years. Some taxa were also significantly enriched in the nest samples compared with spatially corresponding reference soils. We show that the bacterial communities in ant nests are temporally stable across years, whereas the fungal communities show greater variation. It seems that the activities of the ants contribute to unique biochemical processes in the secluded nest environment, and create opportunities for symbiotic interactions between the ants and the microbes. Over time, the microbial communities may come to diverge, due to drift and selection, especially given the long lifespan (up to 30 years) of the ant colonies.
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Affiliation(s)
- Stafva Lindström
- Organismal and Evolutionary Biology Research ProgrammeFaculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Tvärminne Zoological StationHankoFinland
- Department of MicrobiologyUniversity of HelsinkiHelsinkiFinland
| | - Sari Timonen
- Department of MicrobiologyUniversity of HelsinkiHelsinkiFinland
| | - Liselotte Sundström
- Organismal and Evolutionary Biology Research ProgrammeFaculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Tvärminne Zoological StationHankoFinland
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11
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Bensch HM, O'Connor EA, Cornwallis CK. Living with relatives offsets the harm caused by pathogens in natural populations. eLife 2021; 10:e66649. [PMID: 34309511 PMCID: PMC8313236 DOI: 10.7554/elife.66649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/19/2021] [Indexed: 01/23/2023] Open
Abstract
Living with relatives can be highly beneficial, enhancing reproduction and survival. High relatedness can, however, increase susceptibility to pathogens. Here, we examine whether the benefits of living with relatives offset the harm caused by pathogens, and if this depends on whether species typically live with kin. Using comparative meta-analysis of plants, animals, and a bacterium (nspecies = 56), we show that high within-group relatedness increases mortality when pathogens are present. In contrast, mortality decreased with relatedness when pathogens were rare, particularly in species that live with kin. Furthermore, across groups variation in mortality was lower when relatedness was high, but abundances of pathogens were more variable. The effects of within-group relatedness were only evident when pathogens were experimentally manipulated, suggesting that the harm caused by pathogens is masked by the benefits of living with relatives in nature. These results highlight the importance of kin selection for understanding disease spread in natural populations.
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The role of social structure and dynamics in the maintenance of endemic disease. Behav Ecol Sociobiol 2021; 75:122. [PMID: 34421183 PMCID: PMC8370858 DOI: 10.1007/s00265-021-03055-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/09/2021] [Accepted: 07/13/2021] [Indexed: 02/07/2023]
Abstract
Social interactions are required for the direct transmission of infectious diseases. Consequently, the social network structure of populations plays a key role in shaping infectious disease dynamics. A huge research effort has examined how specific social network structures make populations more (or less) vulnerable to damaging epidemics. However, it can be just as important to understand how social networks can contribute to endemic disease dynamics, in which pathogens are maintained at stable levels for prolonged periods of time. Hosts that can maintain endemic disease may serve as keystone hosts for multi-host pathogens within an ecological community, and also have greater potential to act as key wildlife reservoirs of agricultural and zoonotic diseases. Here, we examine combinations of social and demographic processes that can foster endemic disease in hosts. We synthesise theoretical and empirical work to demonstrate the importance of both social structure and social dynamics in maintaining endemic disease. We also highlight the importance of distinguishing between the local and global persistence of infection and reveal how different social processes drive variation in the scale at which infectious diseases appear endemic. Our synthesis provides a framework by which to understand how sociality contributes to the long-term maintenance of infectious disease in wildlife hosts and provides a set of tools to unpick the social and demographic mechanisms involved in any given host-pathogen system. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00265-021-03055-8.
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14
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Pull CD, McMahon DP. Superorganism Immunity: A Major Transition in Immune System Evolution. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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15
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Esparza-Mora MA, Davis HE, Meconcelli S, Plarre R, McMahon DP. Inhibition of a Secreted Immune Molecule Interferes With Termite Social Immunity. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00075] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Schläppi D, Chejanovsky N, Yañez O, Neumann P. Foodborne Transmission and Clinical Symptoms of Honey Bee Viruses in Ants Lasius spp. Viruses 2020; 12:E321. [PMID: 32192027 PMCID: PMC7150850 DOI: 10.3390/v12030321] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/11/2020] [Accepted: 03/12/2020] [Indexed: 01/10/2023] Open
Abstract
Emerging infectious diseases are often the products of host shifts, where a pathogen jumps from its original host to a novel species. Viruses in particular cross species barriers frequently. Acute bee paralysis virus (ABPV) and deformed wing virus (DWV) are viruses described in honey bees (Apis mellifera) with broad host ranges. Ants scavenging on dead honey bees may get infected with these viruses via foodborne transmission. However, the role of black garden ants, Lasius niger and Lasius platythorax, as alternative hosts of ABPV and DWV is not known and potential impacts of these viruses have not been addressed yet. In a laboratory feeding experiment, we show that L. niger can carry DWV and ABPV. However, negative-sense strand RNA, a token of virus replication, was only detected for ABPV. Therefore, additional L. niger colonies were tested for clinical symptoms of ABPV infections. Symptoms were detected at colony (fewer emerging workers) and individual level (impaired locomotion and movement speed). In a field survey, all L. platythorax samples carried ABPV, DWV-A and -B, as well as the negative-sense strand RNA of ABPV. These results show that L. niger and L. platythorax are alternative hosts of ABPV, possibly acting as a biological vector of ABPV and as a mechanical one for DWV. This is the first study showing the impact of honey bee viruses on ants. The common virus infections of ants in the field support possible negative consequences for ecosystem functioning due to host shifts.
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Affiliation(s)
- Daniel Schläppi
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, 3097 Bern, Switzerland; (N.C.); (O.Y.); (P.N.)
| | - Nor Chejanovsky
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, 3097 Bern, Switzerland; (N.C.); (O.Y.); (P.N.)
- Department of Entomology, Agricultural Research Organization, Volcani Center, 50250 Bet Dagan, Israel
| | - Orlando Yañez
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, 3097 Bern, Switzerland; (N.C.); (O.Y.); (P.N.)
- Swiss Bee Research Centre, Agroscope, 3097 Bern, Switzerland
| | - Peter Neumann
- Institute of Bee Health, Vetsuisse Faculty, University of Bern, 3097 Bern, Switzerland; (N.C.); (O.Y.); (P.N.)
- Swiss Bee Research Centre, Agroscope, 3097 Bern, Switzerland
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17
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Hunt ER. Phenotypic Plasticity Provides a Bioinspiration Framework for Minimal Field Swarm Robotics. Front Robot AI 2020; 7:23. [PMID: 33501192 PMCID: PMC7805735 DOI: 10.3389/frobt.2020.00023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 02/11/2020] [Indexed: 12/02/2022] Open
Abstract
The real world is highly variable and unpredictable, and so fine-tuned robot controllers that successfully result in group-level "emergence" of swarm capabilities indoors may quickly become inadequate outside. One response to unpredictability could be greater robot complexity and cost, but this seems counter to the "swarm philosophy" of deploying (very) large numbers of simple agents. Instead, here I argue that bioinspiration in swarm robotics has considerable untapped potential in relation to the phenomenon of phenotypic plasticity: when a genotype can produce a range of distinctive changes in organismal behavior, physiology and morphology in response to different environments. This commonly arises following a natural history of variable conditions; implying the need for more diverse and hazardous simulated environments in offline, pre-deployment optimization of swarms. This will generate-indicate the need for-plasticity. Biological plasticity is sometimes irreversible; yet this characteristic remains relevant in the context of minimal swarms, where robots may become mass-producible. Plasticity can be introduced through the greater use of adaptive threshold-based behaviors; more fundamentally, it can link to emerging technologies such as smart materials, which can adapt form and function to environmental conditions. Moreover, in social animals, individual heterogeneity is increasingly recognized as functional for the group. Phenotypic plasticity can provide meaningful diversity "for free" based on early, local sensory experience, contributing toward better collective decision-making and resistance against adversarial agents, for example. Nature has already solved the challenge of resilient self-organisation in the physical realm through phenotypic plasticity: swarm engineers can follow this lead.
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Affiliation(s)
- Edmund R. Hunt
- Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom
- Bristol Robotics Laboratory, University of the West of England, Bristol, United Kingdom
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18
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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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19
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Comparison of Twelve Ant Species and Their Susceptibility to Fungal Infection. INSECTS 2019; 10:insects10090271. [PMID: 31454953 PMCID: PMC6780858 DOI: 10.3390/insects10090271] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/18/2019] [Accepted: 08/19/2019] [Indexed: 02/02/2023]
Abstract
Eusocial insects, such as ants, have access to complex disease defenses both at the individual, and at the colony level. However, different species may be exposed to different diseases, and/or deploy different methods of coping with disease. Here, we studied and compared survival after fungal exposure in 12 species of ants, all of which inhabit similar habitats. We exposed the ants to two entomopathogenic fungi (Beauveria bassiana and Metarhizium brunneum), and measured how exposure to these fungi influenced survival. We furthermore recorded hygienic behaviors, such as autogrooming, allogrooming and trophallaxis, during the days after exposure. We found strong differences in autogrooming behavior between the species, but none of the study species performed extensive allogrooming or trophallaxis under the experimental conditions. Furthermore, we discuss the possible importance of the metapleural gland, and how the secondary loss of this gland in the genus Camponotus could favor a stronger behavioral response against pathogen threats.
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20
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Cremer S. Pathogens and disease defense of invasive ants. CURRENT OPINION IN INSECT SCIENCE 2019; 33:63-68. [PMID: 31358197 DOI: 10.1016/j.cois.2019.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 03/29/2019] [Indexed: 06/10/2023]
Abstract
Ant invasions are often harmful to native species communities. Their pathogens and host disease defense mechanisms may be one component of their devastating success. First, they can introduce harmful diseases to their competitors in the introduced range, to which they themselves are tolerant. Second, their supercolonial social structure of huge multi-queen nest networks means that they will harbor a broad pathogen spectrum and high pathogen load while remaining resilient, unlike the smaller, territorial colonies of the native species. Thus, it is likely that invasive ants act as a disease reservoir, promoting their competitive advantage and invasive success.
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Affiliation(s)
- Sylvia Cremer
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
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21
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Viljakainen L, Jurvansuu J, Holmberg I, Pamminger T, Erler S, Cremer S. Social environment affects the transcriptomic response to bacteria in ant queens. Ecol Evol 2018; 8:11031-11070. [PMID: 30519425 PMCID: PMC6262927 DOI: 10.1002/ece3.4573] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/06/2018] [Accepted: 09/07/2018] [Indexed: 01/05/2023] Open
Abstract
Social insects have evolved enormous capacities to collectively build nests and defend their colonies against both predators and pathogens. The latter is achieved by a combination of individual immune responses and sophisticated collective behavioral and organizational disease defenses, that is, social immunity. We investigated how the presence or absence of these social defense lines affects individual-level immunity in ant queens after bacterial infection. To this end, we injected queens of the ant Linepithema humile with a mix of gram+ and gram- bacteria or a control solution, reared them either with workers or alone and analyzed their gene expression patterns at 2, 4, 8, and 12 hr post-injection, using RNA-seq. This allowed us to test for the effect of bacterial infection, social context, as well as the interaction between the two over the course of infection and raising of an immune response. We found that social isolation per se affected queen gene expression for metabolism genes, but not for immune genes. When infected, queens reared with and without workers up-regulated similar numbers of innate immune genes revealing activation of Toll and Imd signaling pathways and melanization. Interestingly, however, they mostly regulated different genes along the pathways and showed a different pattern of overall gene up-regulation or down-regulation. Hence, we can conclude that the absence of workers does not compromise the onset of an individual immune response by the queens, but that the social environment impacts the route of the individual innate immune responses.
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Affiliation(s)
| | - Jaana Jurvansuu
- Ecology and Genetics Research UnitUniversity of OuluOuluFinland
| | - Ida Holmberg
- Ecology and Genetics Research UnitUniversity of OuluOuluFinland
| | | | - Silvio Erler
- Institute of Biology, Molecular EcologyMartin‐Luther‐University Halle‐WittenbergHalle (Saale)Germany
| | - Sylvia Cremer
- Institute of Science and Technology Austria (IST Austria)KlosterneuburgAustria
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22
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Townsend AK, Taff CC, Wheeler SS, Weis AM, Hinton MG, Jones ML, Logsdon RM, Reisen WK, Freund D, Sehgal RNM, Saberi M, Suh YH, Hurd J, Boyce WM. Low heterozygosity is associated with vector‐borne disease in crows. Ecosphere 2018. [DOI: 10.1002/ecs2.2407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
| | - Conor C. Taff
- Cornell University Laboratory of Ornithology Ithaca New York 14850 USA
| | - Sarah S. Wheeler
- Sacramento‐Yolo Mosquito and Vector Control District Elk Grove California 95624 USA
| | - Allison M. Weis
- Department of Population Health and Reproduction School of Veterinary Medicine 100K Pathogen Genome Project University of California Davis California 95616 USA
| | - Mitch G. Hinton
- Animal Behavior Graduate Group University of California Davis California 95616 USA
| | - Melissa L. Jones
- Avian Sciences Graduate Group University of California Davis California 95616 USA
| | - Ryane M. Logsdon
- Animal Behavior Graduate Group University of California Davis California 95616 USA
| | - William K. Reisen
- Department of Pathology, Microbiology, and Immunology School of Veterinary Medicine University of California Davis California 95616 USA
| | - David Freund
- Department of Biology San Francisco State University San Francisco California 94132 USA
| | - Ravinder N. M. Sehgal
- Department of Biology San Francisco State University San Francisco California 94132 USA
| | - Mojan Saberi
- Department of Wildlife, Fish, and Conservation Biology University of California Davis California 95616 USA
| | - Young Ha Suh
- Department of Ecology and Evolutionary Biology Cornell University Ithaca New York 14853 USA
| | - Jacqueline Hurd
- Department of Wildlife, Fish, and Conservation Biology University of California Davis California 95616 USA
| | - Walter M. Boyce
- Department of Pathology, Microbiology, and Immunology School of Veterinary Medicine University of California Davis California 95616 USA
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23
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Heinze J. Life-history evolution in ants: the case of Cardiocondyla. Proc Biol Sci 2018; 284:rspb.2016.1406. [PMID: 28298341 DOI: 10.1098/rspb.2016.1406] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/06/2016] [Indexed: 01/09/2023] Open
Abstract
Ants are important components of most terrestrial habitats, and a better knowledge of the diversity of their life histories is essential to understand many aspects of ecosystem functioning. The myrmicine genus Cardiocondyla shows a wide range of colony structures, reproductive behaviours, queen and male lifespans, and habitat use. Reconstructing the evolutionary pathways of individual and social phenotypic traits suggests that the ancestral life history of Cardiocondyla was characterized by the presence of multiple, short-lived queens in small-sized colonies and a male polyphenism with winged dispersers and wingless fighters, which engage in lethal combat over female sexuals within their natal nests. Single queening, queen polyphenism, the loss of winged males and tolerance among wingless males appear to be derived traits that evolved with changes in nesting habits, colony size and the spread from tropical to seasonal environments. The aim of this review is to bring together the information on life-history evolution in Cardiocondyla and to highlight the suitability of this genus for functional genomic studies of adaptation, phenotypic plasticity, senescence, invasiveness and other key life-history traits of ants.
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Affiliation(s)
- Jürgen Heinze
- Zoologie/Evolutionsbiologie, Universität Regensburg, 93040 Regensburg, Germany
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24
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Pull CD, Ugelvig LV, Wiesenhofer F, Grasse AV, Tragust S, Schmitt T, Brown MJF, Cremer S. Destructive disinfection of infected brood prevents systemic disease spread in ant colonies. eLife 2018; 7:e32073. [PMID: 29310753 PMCID: PMC5760203 DOI: 10.7554/elife.32073] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 11/17/2017] [Indexed: 01/19/2023] Open
Abstract
In social groups, infections have the potential to spread rapidly and cause disease outbreaks. Here, we show that in a social insect, the ant Lasius neglectus, the negative consequences of fungal infections (Metarhizium brunneum) can be mitigated by employing an efficient multicomponent behaviour, termed destructive disinfection, which prevents further spread of the disease through the colony. Ants specifically target infected pupae during the pathogen's non-contagious incubation period, utilising chemical 'sickness cues' emitted by pupae. They then remove the pupal cocoon, perforate its cuticle and administer antimicrobial poison, which enters the body and prevents pathogen replication from the inside out. Like the immune system of a metazoan body that specifically targets and eliminates infected cells, ants destroy infected brood to stop the pathogen completing its lifecycle, thus protecting the rest of the colony. Hence, in an analogous fashion, the same principles of disease defence apply at different levels of biological organisation.
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Affiliation(s)
- Christopher D Pull
- IST Austria (Institute of Science and Technology Austria)KlosterneuburgAustria
| | - Line V Ugelvig
- IST Austria (Institute of Science and Technology Austria)KlosterneuburgAustria
| | - Florian Wiesenhofer
- IST Austria (Institute of Science and Technology Austria)KlosterneuburgAustria
| | - Anna V Grasse
- IST Austria (Institute of Science and Technology Austria)KlosterneuburgAustria
| | - Simon Tragust
- IST Austria (Institute of Science and Technology Austria)KlosterneuburgAustria
- Evolution, Genetics and BehaviourUniversity of RegensburgRegensburgGermany
| | - Thomas Schmitt
- Department of Animal Ecology and Tropical BiologyUniversity of WürzburgWürzburgGermany
| | - Mark JF Brown
- School of Biological SciencesRoyal Holloway University of LondonEghamUnited Kingdom
| | - Sylvia Cremer
- IST Austria (Institute of Science and Technology Austria)KlosterneuburgAustria
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25
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Cremer S, Pull CD, Fürst MA. Social Immunity: Emergence and Evolution of Colony-Level Disease Protection. ANNUAL REVIEW OF ENTOMOLOGY 2018; 63:105-123. [PMID: 28945976 DOI: 10.1146/annurev-ento-020117-043110] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Social insect colonies have evolved many collectively performed adaptations that reduce the impact of infectious disease and that are expected to maximize their fitness. This colony-level protection is termed social immunity, and it enhances the health and survival of the colony. In this review, we address how social immunity emerges from its mechanistic components to produce colony-level disease avoidance, resistance, and tolerance. To understand the evolutionary causes and consequences of social immunity, we highlight the need for studies that evaluate the effects of social immunity on colony fitness. We discuss the roles that host life history and ecology have on predicted eco-evolutionary dynamics, which differ among the social insect lineages. Throughout the review, we highlight current gaps in our knowledge and promising avenues for future research, which we hope will bring us closer to an integrated understanding of socio-eco-evo-immunology.
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Affiliation(s)
- Sylvia Cremer
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg 3400, Austria; ,
| | - Christopher D Pull
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg 3400, Austria; ,
- Current affiliation: School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom;
| | - Matthias A Fürst
- IST Austria (Institute of Science and Technology Austria), Klosterneuburg 3400, Austria; ,
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26
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Impact of colony size on survival and sanitary strategies in fungus-infected ant colonies. Behav Ecol Sociobiol 2017. [DOI: 10.1007/s00265-017-2415-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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27
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Brütsch T, Avril A, Chapuisat M. No evidence for social immunity in co-founding queen associations. Sci Rep 2017; 7:16262. [PMID: 29176649 PMCID: PMC5701228 DOI: 10.1038/s41598-017-16368-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/31/2017] [Indexed: 12/02/2022] Open
Abstract
Ant queens often associate to found new colonies, yet the benefits of this behaviour remain unclear. A major hypothesis is that queens founding in groups are protected by social immunity and can better resist disease than solitary queens, due to mutual grooming, sharing of antimicrobials, or higher genetic diversity among their workers. We tested this hypothesis by manipulating the number of queens in incipient colonies of Lasius niger and measuring their resistance to the fungal entomopathogen Metarhizium brunneum. We found no evidence for social immunity in associations of founding queens. First, co-founding queens engaged in self-grooming, but performed very little allo-grooming or trophallaxis. Second, co-founding queens did not exhibit higher pathogen resistance than solitary queens, and their respective workers did not differ in disease resistance. Finally, queens founding in groups increased their investment in a component of individual immunity, as expected if they do not benefit from social immunity but respond to a higher risk of disease. Overall, our results provide no evidence that joint colony founding by L. niger queens increases their ability to resist fungal pathogens.
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Affiliation(s)
- Timothée Brütsch
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, 1015, Lausanne, Switzerland.
| | - Amaury Avril
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, 1015, Lausanne, Switzerland
| | - Michel Chapuisat
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, 1015, Lausanne, Switzerland
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28
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Kennedy P, Baron G, Qiu B, Freitak D, Helanterä H, Hunt ER, Manfredini F, O'Shea-Wheller T, Patalano S, Pull CD, Sasaki T, Taylor D, Wyatt CDR, Sumner S. Deconstructing Superorganisms and Societies to Address Big Questions in Biology. Trends Ecol Evol 2017; 32:861-872. [PMID: 28899581 DOI: 10.1016/j.tree.2017.08.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/31/2017] [Accepted: 08/03/2017] [Indexed: 12/19/2022]
Abstract
Social insect societies are long-standing models for understanding social behaviour and evolution. Unlike other advanced biological societies (such as the multicellular body), the component parts of social insect societies can be easily deconstructed and manipulated. Recent methodological and theoretical innovations have exploited this trait to address an expanded range of biological questions. We illustrate the broadening range of biological insight coming from social insect biology with four examples. These new frontiers promote open-minded, interdisciplinary exploration of one of the richest and most complex of biological phenomena: sociality.
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Affiliation(s)
- Patrick Kennedy
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
| | - Gemma Baron
- School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, United Kingdom
| | - Bitao Qiu
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark
| | - Dalial Freitak
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014 University of Helsinki, Finland
| | - Heikki Helanterä
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014 University of Helsinki, Finland
| | - Edmund R Hunt
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
| | - Fabio Manfredini
- School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, United Kingdom
| | - Thomas O'Shea-Wheller
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
| | | | - Christopher D Pull
- School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, United Kingdom; IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria
| | - Takao Sasaki
- Department of Zoology, University of Oxford, The Tinbergen Building, Parks Road, Oxford OX1 3PS, United Kingdom
| | - Daisy Taylor
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
| | - Christopher D R Wyatt
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Seirian Sumner
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom; Current address: Centre for Biodiversity & Environment Research, Department of Genetics, Evolution & Environment, University College London, Gower Street, London WC1E 6BT, United Kingdom.
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29
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Giehr J, Grasse AV, Cremer S, Heinze J, Schrempf A. Ant queens increase their reproductive efforts after pathogen infection. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170547. [PMID: 28791176 PMCID: PMC5541571 DOI: 10.1098/rsos.170547] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/01/2017] [Indexed: 05/31/2023]
Abstract
Infections with potentially lethal pathogens may negatively affect an individual's lifespan and decrease its reproductive value. The terminal investment hypothesis predicts that individuals faced with a reduced survival should invest more into reproduction instead of maintenance and growth. Several studies suggest that individuals are indeed able to estimate their body condition and to increase their reproductive effort with approaching death, while other studies gave ambiguous results. We investigate whether queens of a perennial social insect (ant) are able to boost their reproduction following infection with an obligate killing pathogen. Social insect queens are special with regard to reproduction and aging, as they outlive conspecific non-reproductive workers. Moreover, in the ant Cardiocondyla obscurior, fecundity increases with queen age. However, it remained unclear whether this reflects negative reproductive senescence or terminal investment in response to approaching death. Here, we test whether queens of C. obscurior react to infection with the entomopathogenic fungus Metarhizium brunneum by an increased egg-laying rate. We show that a fungal infection triggers a reinforced investment in reproduction in queens. This adjustment of the reproductive rate by ant queens is consistent with predictions of the terminal investment hypothesis and is reported for the first time in a social insect.
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Affiliation(s)
- Julia Giehr
- Zoology/Evolutionary Biology, University of Regensburg, 93053 Regensburg, Germany
| | - Anna V. Grasse
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Sylvia Cremer
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Jürgen Heinze
- Zoology/Evolutionary Biology, University of Regensburg, 93053 Regensburg, Germany
| | - Alexandra Schrempf
- Zoology/Evolutionary Biology, University of Regensburg, 93053 Regensburg, Germany
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30
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Cronin AL, Monnin T, Sillam-Dussès D, Aubrun F, Fédérici P, Doums C. Qualitative bias in offspring investment in a superorganism is linked to dispersal and nest inheritance. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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Leclerc JB, Detrain C. Ants detect but do not discriminate diseased workers within their nest. Naturwissenschaften 2016; 103:70. [PMID: 27475810 DOI: 10.1007/s00114-016-1394-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/06/2016] [Accepted: 07/11/2016] [Indexed: 12/23/2022]
Abstract
Social insects have evolved an array of individual and social behaviours that limit pathogen entrance and spread within the colony. The detection of ectoparasites or of fungal spores on a nestmate body triggers their removal by allogrooming and appears as a primary component of social prophylaxis. However, in the case of fungal infection, one may wonder whether ant workers are able to detect, discriminate and keep at bay diseased nestmates that have no spores over their cuticle but which constitute a latent sanitary risk due to post-mortem corpse sporulation. Here, we investigate the ability of Myrmica rubra workers to detect and discriminate a healthy from a diseased nestmate infected by the entomopathogen Metarhizium anisopliae. During dyadic encounters in a neutral location, workers were more aggressive towards isolated sick nestmates on the 3rd post-infection day. However, no such detection or discrimination of fungus-infected nestmates occurred in a social context inside the nest or at the nest entrance. Gatekeepers never actively rejected incoming diseased nestmates that rather spontaneously isolated themselves outside the nest. Our study reveals that ant workers may detect health-dependent cues and that their 'acceptance level' of sick nestmates is tunable depending on the social context. This raises questions about possible trade-offs between a social closure to pathogens and risks of erroneous rejection of healthy nestmates. Social isolation of moribund ants also appears as a widespread prophylactic strategy of social insects allowing them to reduce exposure to pathogens and to spare costs associated with the management of infected individuals.
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Affiliation(s)
- Jean-Baptiste Leclerc
- Unit of Social Ecology, Université Libre de Bruxelles, CP 231, Bd du Triomphe, 1050, Brussels, Belgium.
| | - Claire Detrain
- Unit of Social Ecology, Université Libre de Bruxelles, CP 231, Bd du Triomphe, 1050, Brussels, Belgium
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Armitage SAO, Fernández-Marín H, Boomsma JJ, Wcislo WT. Slowing them down will make them lose: a role for attine ant crop fungus in defending pupae against infections? J Anim Ecol 2016; 85:1210-21. [PMID: 27136600 PMCID: PMC6084299 DOI: 10.1111/1365-2656.12543] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 04/12/2016] [Indexed: 02/05/2023]
Abstract
Fungus-growing ants (Attini) have evolved an obligate dependency upon a basidiomycete fungus that they cultivate as their food. Less well known is that the crop fungus is also used by many attine species to cover their eggs, larvae and pupae. The adaptive functional significance of this brood covering is poorly understood. One hypothesis to account for this behaviour is that it is part of the pathogen protection portfolio when many thousands of sister workers live in close proximity and larvae and pupae are not protected by cells, as in bees and wasps, and are immobile. We performed behavioural observations on brood covering in the leaf-cutting ant Acromyrmex echinatior, and we experimentally manipulated mycelial cover on pupae and exposed them to the entomopathogenic fungus Metarhizium brunneum to test for a role in pathogen resistance. Our results show that active mycelial brood covering by workers is a behaviourally plastic trait that varies temporally, and across life stages and castes. The presence of a fungal cover on the pupae reduced the rate at which conidia appeared and the percentage of pupal surface that produced pathogen spores, compared to pupae that had fungal cover experimentally removed or naturally had no mycelial cover. Infected pupae with mycelium had higher survival rates than infected pupae without the cover, although this depended upon the time at which adult sister workers were allowed to interact with pupae. Finally, workers employed higher rates of metapleural gland grooming to infected pupae without mycelium than to infected pupae with mycelium. Our results imply that mycelial brood covering may play a significant role in suppressing the growth and subsequent spread of disease, thus adding a novel layer of protection to their defence portfolio.
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Affiliation(s)
- Sophie A O Armitage
- Department of Biology, Centre for Social Evolution, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark
| | - Hermógenes Fernández-Marín
- Department of Biology, Centre for Social Evolution, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark.,Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Edificio 219, Ciudad del Saber, Clayton, Panamá City, Panamá,Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panamá
| | - Jacobus J Boomsma
- Department of Biology, Centre for Social Evolution, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark
| | - William T Wcislo
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panamá
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Buechel SD, Schmid-Hempel P. Colony pace: a life-history trait affecting social insect epidemiology. Proc Biol Sci 2016; 283:rspb.2015.1919. [PMID: 26763696 DOI: 10.1098/rspb.2015.1919] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Among colonies of social insects, the worker turnover rate (colony 'pace') typically shows considerable variation. This has epidemiological consequences for parasites, because in 'fast-paced' colonies, with short-lived workers, the time of parasite residence in a given host will be reduced, and further transmission may thus get less likely. Here, we test this idea and ask whether pace is a life-history strategy against infectious parasites. We infected bumblebees (Bombus terrestris) with the infectious gut parasite Crithidia bombi, and experimentally manipulated birth and death rates to mimic slow and fast pace. We found that fewer workers and, importantly, fewer last-generation workers that are responsible for rearing sexuals were infected in colonies with faster pace. This translates into increased fitness in fast-paced colonies, as daughter queens exposed to fewer infected workers in the nest are less likely to become infected themselves, and have a higher chance of founding their own colonies in the next year. High worker turnover rate can thus act as a strategy of defence against a spreading infection in social insect colonies.
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Affiliation(s)
- Séverine Denise Buechel
- Institute of Integrative Biology (IBZ), ETH Zürich, ETH Zentrum CHN Universitätsstrasse 16, Zürich 8092, Switzerland
| | - Paul Schmid-Hempel
- Institute of Integrative Biology (IBZ), ETH Zürich, ETH Zentrum CHN Universitätsstrasse 16, Zürich 8092, Switzerland
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Liu L, Li G, Sun P, Lei C, Huang Q. Experimental verification and molecular basis of active immunization against fungal pathogens in termites. Sci Rep 2015; 5:15106. [PMID: 26458743 PMCID: PMC4602225 DOI: 10.1038/srep15106] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 09/15/2015] [Indexed: 01/30/2023] Open
Abstract
Termites are constantly exposed to many pathogens when they nest and forage in the field, so they employ various immune strategies to defend against pathogenic infections. Here, we demonstrate that the subterranean termite Reticulitermes chinensis employs active immunization to defend against the entomopathogen Metarhizium anisopliae. Our results showed that allogrooming frequency increased significantly between fungus-treated termites and their nestmates. Through active social contact, previously healthy nestmates only received small numbers of conidia from fungus-treated individuals. These nestmates experienced low-level fungal infections, resulting in low mortality and apparently improved antifungal defences. Moreover, infected nestmates promoted the activity of two antioxidant enzymes (SOD and CAT) and upregulated the expression of three immune genes (phenoloxidase, transferrin, and termicin). We found 20 differentially expressed proteins associated with active immunization in R. chinensis through iTRAQ proteomics, including 12 stress response proteins, six immune signalling proteins, and two immune effector molecules. Subsequently, two significantly upregulated (60S ribosomal protein L23 and isocitrate dehydrogenase) and three significantly downregulated (glutathione S-transferase D1, cuticle protein 19, and ubiquitin conjugating enzyme) candidate immune proteins were validated by MRM assays. These findings suggest that active immunization in termites may be regulated by different immune proteins.
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Affiliation(s)
- Long Liu
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Ganghua Li
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Pengdong Sun
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Chaoliang Lei
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Qiuying Huang
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
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36
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Genetic diversity within honey bee colonies affects pathogen load and relative virus levels in honey bees, Apis mellifera L. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-1965-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Freitak D, Bos N, Stucki D, Sundström L. Inbreeding-related trade-offs in stress resistance in the ant Formica exsecta. Biol Lett 2015; 10:20140805. [PMID: 25392316 DOI: 10.1098/rsbl.2014.0805] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Inbred individuals and populations are predicted to suffer from inbreeding depression, especially in times of stress. Under natural conditions, organisms are exposed to more than one stressor at any one time, highlighting the importance of stress resistance traits. We studied how inbreeding- and immunity-related traits are correlated under different dietary conditions in the ant Formica exsecta. Its natural diet varies in the amount and nature of plant secondary compounds and the level of free radicals, all of which require detoxification to maintain organismal homeostasis. We found that inbreeding decreased general antibacterial activity under dietary stress, suggesting inbreeding-related physiological trade-offs.
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Affiliation(s)
- D Freitak
- Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki 00014, Finland Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland Centre of Excellence in Biological Interactions, University of Jyväskylä, Jyväskylä 40014, Finland
| | - N Bos
- Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki 00014, Finland Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
| | - D Stucki
- Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki 00014, Finland Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
| | - L Sundström
- Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki 00014, Finland Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
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Theis FJ, Ugelvig LV, Marr C, Cremer S. Opposing effects of allogrooming on disease transmission in ant societies. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140108. [PMID: 25870394 PMCID: PMC4410374 DOI: 10.1098/rstb.2014.0108] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2015] [Indexed: 11/12/2022] Open
Abstract
To prevent epidemics, insect societies have evolved collective disease defences that are highly effective at curing exposed individuals and limiting disease transmission to healthy group members. Grooming is an important sanitary behaviour--either performed towards oneself (self-grooming) or towards others (allogrooming)--to remove infectious agents from the body surface of exposed individuals, but at the risk of disease contraction by the groomer. We use garden ants (Lasius neglectus) and the fungal pathogen Metarhizium as a model system to study how pathogen presence affects self-grooming and allogrooming between exposed and healthy individuals. We develop an epidemiological SIS model to explore how experimentally observed grooming patterns affect disease spread within the colony, thereby providing a direct link between the expression and direction of sanitary behaviours, and their effects on colony-level epidemiology. We find that fungus-exposed ants increase self-grooming, while simultaneously decreasing allogrooming. This behavioural modulation seems universally adaptive and is predicted to contain disease spread in a great variety of host-pathogen systems. In contrast, allogrooming directed towards pathogen-exposed individuals might both increase and decrease disease risk. Our model reveals that the effect of allogrooming depends on the balance between pathogen infectiousness and efficiency of social host defences, which are likely to vary across host-pathogen systems.
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Affiliation(s)
- Fabian J Theis
- Helmholtz Zentrum München-German Research Center for Environmental Health, Institute of Computational Biology, Ingolstädter Landstrasse 1, Neuherberg 85764, Germany Technische Universität München, Center for Mathematics, Chair of Mathematical Modeling of Biological Systems, Boltzmannstraße 3, Garching 85748, Germany
| | - Line V Ugelvig
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg 3400, Austria
| | - Carsten Marr
- Helmholtz Zentrum München-German Research Center for Environmental Health, Institute of Computational Biology, Ingolstädter Landstrasse 1, Neuherberg 85764, Germany
| | - Sylvia Cremer
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg 3400, Austria
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Meunier J. Social immunity and the evolution of group living in insects. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140102. [PMID: 25870389 PMCID: PMC4410369 DOI: 10.1098/rstb.2014.0102] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2014] [Indexed: 01/25/2023] Open
Abstract
The evolution of group living requires that individuals limit the inherent risks of parasite infection. To this end, group living insects have developed a unique capability of mounting collective anti-parasite defences, such as allogrooming and corpse removal from the nest. Over the last 20 years, this phenomenon (called social immunity) was mostly studied in eusocial insects, with results emphasizing its importance in derived social systems. However, the role of social immunity in the early evolution of group living remains unclear. Here, I investigate this topic by first presenting the definitions of social immunity and discussing their applications across social systems. I then provide an up-to-date appraisal of the collective and individual mechanisms of social immunity described in eusocial insects and show that they have counterparts in non-eusocial species and even solitary species. Finally, I review evidence demonstrating that the increased risks of parasite infection in group living species may both decrease and increase the level of personal immunity, and discuss how the expression of social immunity could drive these opposite effects. By highlighting similarities and differences of social immunity across social systems, this review emphasizes the potential importance of this phenomenon in the early evolution of the multiple forms of group living in insects.
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Affiliation(s)
- Joël Meunier
- Zoological Institute, Evolutionary Biology, Johannes Gutenberg University Mainz, Mainz, Germany
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Ho EKH, Frederickson ME. Alate susceptibility in ants. Ecol Evol 2014; 4:4209-19. [PMID: 25540683 PMCID: PMC4267860 DOI: 10.1002/ece3.1291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 09/22/2014] [Indexed: 12/02/2022] Open
Abstract
Pathogens are predicted to pose a particular threat to eusocial insects because infections can spread rapidly in colonies with high densities of closely related individuals. In ants, there are two major castes: workers and reproductives. Sterile workers receive no direct benefit from investing in immunity, but can gain indirect fitness benefits if their immunity aids the survival of their fertile siblings. Virgin reproductives (alates), on the other hand, may be able to increase their investment in reproduction, rather than in immunity, because of the protection they receive from workers. Thus, we expect colonies to have highly immune workers, but relatively more susceptible alates. We examined the survival of workers, gynes, and males of nine ant species collected in Peru and Canada when exposed to the entomopathogenic fungus Beauveria bassiana. For the seven species in which treatment with B. bassiana increased ant mortality relative to controls, we found workers were significantly less susceptible compared with both alate sexes. Female and male alates did not differ significantly in their immunocompetence. Our results suggest that, as with other nonreproductive tasks in ant colonies like foraging and nest maintenance, workers have primary responsibility for colony immunity, allowing alates to specialize on reproduction. We highlight the importance of colony-level selection on individual immunity in ants and other eusocial organisms.
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Affiliation(s)
- Eddie K H Ho
- Department of Ecology and Evolutionary Biology, University of Toronto 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto 25 Harbord Street, Toronto, ON, M5S 3G5, Canada
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Abstract
Senescence, the decline in physiological and behavioral function with increasing age, has been the focus of significant theoretical and empirical research in a broad array of animal taxa. Preeminent among invertebrate social models of aging are ants, a diverse and ecologically dominant clade of eusocial insects characterized by reproductive and sterile phenotypes. In this review, we critically examine selection for worker lifespan in ants and discuss the relationship between functional senescence, longevity, task performance, and colony fitness. We did not find strong or consistent support for the hypothesis that demographic senescence in ants is programmed, or its corollary prediction that workers that do not experience extrinsic mortality die at an age approximating their lifespan in nature. We present seven hypotheses concerning how selection could favor extended worker lifespan through its positive relationship to colony size and predict that large colony size, under some conditions, should confer multiple and significant fitness advantages. Fitness benefits derived from long worker lifespan could be mediated by increased resource acquisition, efficient division of labor, accuracy of collective decision-making, enhanced allomaternal care and colony defense, lower infection risk, and decreased energetic costs of workforce maintenance. We suggest future avenues of research to examine the evolution of worker lifespan and its relationship to colony fitness, and conclude that an innovative fusion of sociobiology, senescence theory, and mechanistic studies of aging can improve our understanding of the adaptive nature of worker lifespan in ants.
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Affiliation(s)
| | - James F A Traniello
- Department of Biology, Boston University, 5 Cummington Mall, Boston MA, 02215
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Purcell J, Chapuisat M. Foster carers influence brood pathogen resistance in ants. Proc Biol Sci 2014; 281:20141338. [PMID: 25143036 PMCID: PMC4150324 DOI: 10.1098/rspb.2014.1338] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/28/2014] [Indexed: 01/28/2023] Open
Abstract
Social organisms face a high risk of epidemics, and respond to this threat by combining efficient individual and collective defences against pathogens. An intriguing and little studied feature of social animals is that individual pathogen resistance may depend not only on genetic or maternal factors, but also on the social environment during development. Here, we used a cross-fostering experiment to investigate whether the pathogen resistance of individual ant workers was shaped by their own colony of origin or by the colony of origin of their carers. The origin of care-giving workers significantly influenced the ability of newly eclosed cross-fostered Formica selysi workers to resist the fungal entomopathogen Beauveria bassiana. In particular, carers that were more resistant to the fungal entomopathogen reared more resistant workers. This effect occurred in the absence of post-infection social interactions, such as trophallaxis and allogrooming. The colony of origin of eggs significantly influenced the survival of the resulting individuals in both control and pathogen treatments. There was no significant effect of the social organization (i.e. whether colonies contain a single or multiple queens) of the colony of origin of either carers or eggs. Our experiment reveals that social interactions during development play a central role in moulding the resistance of emerging workers.
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Affiliation(s)
- Jessica Purcell
- Department of Ecology and Evolution, University of Lausanne, Biophore, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne, Biophore, UNIL-Sorge, 1015 Lausanne, Switzerland
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43
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Masri L, Cremer S. Individual and social immunisation in insects. Trends Immunol 2014; 35:471-82. [DOI: 10.1016/j.it.2014.08.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 08/18/2014] [Accepted: 08/18/2014] [Indexed: 01/03/2023]
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44
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Increased grooming after repeated brood care provides sanitary benefits in a clonal ant. Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-014-1778-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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45
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Slaa EJ, Chappell P, Hughes WOH. Colony genetic diversity affects task performance in the red ant Myrmica rubra. Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-014-1703-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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46
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Boos S, Meunier J, Pichon S, Kölliker M. Maternal care provides antifungal protection to eggs in the European earwig. Behav Ecol 2014. [DOI: 10.1093/beheco/aru046] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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47
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Short independent lives and selection for maximal sperm survival make investment in immune defences unprofitable for leaf-cutting ant males. Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-014-1707-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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48
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Post-mortem Changes in Chemical Profile and their Influence on Corpse Removal in Ants. J Chem Ecol 2013; 39:1424-32. [DOI: 10.1007/s10886-013-0365-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/24/2013] [Accepted: 11/01/2013] [Indexed: 12/20/2022]
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49
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Pull CD, Hughes WOH, Brown MJF. Tolerating an infection: an indirect benefit of co-founding queen associations in the ant Lasius niger. Naturwissenschaften 2013; 100:1125-36. [DOI: 10.1007/s00114-013-1115-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/22/2013] [Accepted: 10/25/2013] [Indexed: 10/26/2022]
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50
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Grooming Behavior as a Mechanism of Insect Disease Defense. INSECTS 2013; 4:609-30. [PMID: 26462526 PMCID: PMC4553506 DOI: 10.3390/insects4040609] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/20/2013] [Accepted: 10/22/2013] [Indexed: 11/17/2022]
Abstract
Grooming is a well-recognized, multipurpose, behavior in arthropods and vertebrates. In this paper, we review the literature to highlight the physical function, neurophysiological mechanisms, and role that grooming plays in insect defense against pathogenic infection. The intricate relationships between the physical, neurological and immunological mechanisms of grooming are discussed to illustrate the importance of this behavior when examining the ecology of insect-pathogen interactions.
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