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Bacteria associated with leaf-cutter ants drive natural antibiotic resistance in soil bacteria. JOURNAL OF TROPICAL ECOLOGY 2022. [DOI: 10.1017/s0266467422000323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Actinobacteria that live mutualistically with leaf-cutter ants secrete antibiotics that may induce antibiotic resistance in nearby soil bacteria. We tested for the first time whether soil bacteria near and inside Atta cephalotes nests in Costa Rica show higher levels of antibiotic resistance than bacteria collected farther away. We collected soil samples 0 m to 50 m away from ant nests and grew bacteria from them on agar with paper discs treated with antibiotics of common veterinary use. As a proxy for antibiotic resistance, we measured the distance from the edge of each disc to the closest bacterial colonies. In general, resistance to oxytetracycline increased with proximity to leaf-cutter ant nests. Antibiotic resistance to oxytetracycline was also higher in samples collected inside the nest than in samples from the nest mound; not all antibiotics demonstrated the same trend. A preliminary exploratory morphological analysis suggests bacterial communities between 0 m and 50 m from ant nests were similar in diversity and abundance, indicating the pattern of antibiotic resistance described above may not be caused by differences in community composition. We conclude that actinobacteria living mutualistically with A. cephalotes drive natural antibiotic resistance to tetracycline in proximal bacterial communities.
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Ruiz-González MX, Kelly M, Moret Y, Brown MJF. Parasite resistance and immunity across female castes in a social insect. Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03162-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Abstract
Living in a social group increases the risks of parasitism, especially in highly-related groups. In homogenous groups, with no reproductive division of labour, the impact of parasitism is unlikely to vary with host identity. Many social systems, however, do exhibit division of reproductive labour, most famously in social insects with their reproductive queens and generally infertile workers. In such systems, the impact of parasitism will differ for each group. Consequently, we predict that susceptibility to parasites will vary to reflect such differential impact. We tested this prediction using a trypanosome-bumble bee system, where Crithidia bombi infects both gynes and workers of Bombus terrestris. We studied both susceptibility to the parasite and relevant measures of the immune function. As predicted, gynes were significantly less susceptible to the parasite than workers, but while gynes and workers expressed different immune profiles, how these link to differential susceptibility remains unclear. In conclusion, our results suggest that differential selection pressures exerted by parasites may produce multiple phenotypes from a single genotype in order to maximise fitness in a social group context.
Significance statement
Social insect colonies dominate terrestrial ecology, and as such are targets for parasites. How they defend themselves against such threats is a key question. Here, we show that bumble bee gynes — the reproductive individuals that overwinter and found colonies in this annual social system — are more resistant to a parasite that disproportionately affects reproductive fitness than their sister workers. Differential patterns of susceptibility may help to explain the success of these social insects.
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Gandra LC, Amaral KD, Couceiro JC, Dângelo RAC, De Souza DJ, Della Lucia TMC. Immune Defense Strategies of Queens of the Social Parasite Ant Acromyrmex ameliae and Queens of Its Natural Hosts. NEOTROPICAL ENTOMOLOGY 2021; 50:229-236. [PMID: 33555562 DOI: 10.1007/s13744-020-00838-y] [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: 08/12/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
Social parasitism is well known in ants, but many aspects of this social phenomenon remain mysterious and unexplored. In some cases, parasite queens, who are able to mate very rarely end up producing brood and, thus, depend virtually on the labor of host ants. In this work, we sought to test the occurrence of grooming by host workers of Acromyrmex subterraneus subterraneus Forel, to their own queens and queens of the parasite Acromyrmex ameliae De Souza, Soares and Della Lucia and to compare the immune defense responses of parasite queens and queens of A. subterraneus subterraneus and Acromyrmex subterraneus brunneus Forel, the natural hosts. Duration and frequency of behavioral acts were recorded. The relative size of the bulla and the encapsulation response to a standardized antigen were analyzed. Regarding behavioral acts, self-grooming (duration and frequency) and allogrooming (duration) were statistically different between the species; the first is more frequent and lasted longer in parasite queens, while the second act lasted longer in host ants than in parasite ants. The bulla of A. ameliae was approximately 50% wider than those of its hosts. Parasite queens exhibited a stronger immune response than host queens. The results of this work contribute to elucidate potential mechanisms involved in the parasitism capacity of A. ameliae queens such as their strategies of immune defense.
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Affiliation(s)
- Lailla C Gandra
- Instituto de Ciências Biológicas e da Saúde, Univ Federal de Viçosa, Florestal, MG, Brazil.
| | | | - Joel C Couceiro
- Escola Superior de Agricultura Luiz de Queiroz, Univ de São Paulo, São Paulo, Brazil
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4
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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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5
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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: 143] [Impact Index Per Article: 23.8] [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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6
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Howe J, Schiøtt M, Boomsma JJ. Tachykinin Expression Levels Correlate with Caste-Specific Aggression in Workers of the Leaf-Cutting Ant Acromyrmex echinatior. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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7
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Fernández-Marín H, Nash DR, Higginbotham S, Estrada C, van Zweden JS, d'Ettorre P, Wcislo WT, Boomsma JJ. Functional role of phenylacetic acid from metapleural gland secretions in controlling fungal pathogens in evolutionarily derived leaf-cutting ants. Proc Biol Sci 2016; 282:20150212. [PMID: 25925100 DOI: 10.1098/rspb.2015.0212] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Fungus-farming ant colonies vary four to five orders of magnitude in size. They employ compounds from actinomycete bacteria and exocrine glands as antimicrobial agents. Atta colonies have millions of ants and are particularly relevant for understanding hygienic strategies as they have abandoned their ancestors' prime dependence on antibiotic-based biological control in favour of using metapleural gland (MG) chemical secretions. Atta MGs are unique in synthesizing large quantities of phenylacetic acid (PAA), a known but little investigated antimicrobial agent. We show that particularly the smallest workers greatly reduce germination rates of Escovopsis and Metarhizium spores after actively applying PAA to experimental infection targets in garden fragments and transferring the spores to the ants' infrabuccal cavities. In vitro assays further indicated that Escovopsis strains isolated from evolutionarily derived leaf-cutting ants are less sensitive to PAA than strains from phylogenetically more basal fungus-farming ants, consistent with the dynamics of an evolutionary arms race between virulence and control for Escovopsis, but not Metarhizium. Atta ants form larger colonies with more extreme caste differentiation relative to other attines, in societies characterized by an almost complete absence of reproductive conflicts. We hypothesize that these changes are associated with unique evolutionary innovations in chemical pest management that appear robust against selection pressure for resistance by specialized mycopathogens.
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Affiliation(s)
- Hermógenes Fernández-Marín
- Centro de Biodiversidad y Descubrimiento de Drogas, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Edificio 219, Ciudad del Saber, Clayton, Panamá Centre for Social Evolution, Department of Biology, University of Copenhagen Universitetsparken 15, Copenhagen 2100, Denmark Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panamá
| | - David R Nash
- Centre for Social Evolution, Department of Biology, University of Copenhagen Universitetsparken 15, Copenhagen 2100, Denmark
| | - Sarah Higginbotham
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panamá
| | - Catalina Estrada
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panamá
| | - Jelle S van Zweden
- Centre for Social Evolution, Department of Biology, University of Copenhagen Universitetsparken 15, Copenhagen 2100, Denmark Laboratory of Socioecology and Social Evolution, Zoological Institute, University of Leuven, Naamsestraat 59, box 2466, Leuven 3000, Belgium
| | - Patrizia d'Ettorre
- Centre for Social Evolution, Department of Biology, University of Copenhagen Universitetsparken 15, Copenhagen 2100, Denmark Laboratoire d'Ethologie Expérimentale et Comparée (LEEC), University of Paris 13, Sorbonne Paris Cité, France
| | - William T Wcislo
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panamá
| | - Jacobus J Boomsma
- Centre for Social Evolution, Department of Biology, University of Copenhagen Universitetsparken 15, Copenhagen 2100, Denmark
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8
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Tranter C, Fernández‐Marín H, Hughes WOH. Quality and quantity: transitions in antimicrobial gland use for parasite defense. Ecol Evol 2015; 5:5857-68. [PMID: 26811760 PMCID: PMC4717345 DOI: 10.1002/ece3.1827] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 10/09/2015] [Accepted: 10/09/2015] [Indexed: 11/09/2022] Open
Abstract
Parasites are a major force in evolution, and understanding how host life history affects parasite pressure and investment in disease resistance is a general problem in evolutionary biology. The threat of disease may be especially strong in social animals, and ants have evolved the unique metapleural gland (MG), which in many taxa produce antimicrobial compounds that have been argued to have been a key to their ecological success. However, the importance of the MG in the disease resistance of individual ants across ant taxa has not been examined directly. We investigate experimentally the importance of the MG for disease resistance in the fungus-growing ants, a group in which there is interspecific variation in MG size and which has distinct transitions in life history. We find that more derived taxa rely more on the MG for disease resistance than more basal taxa and that there are a series of evolutionary transitions in the quality, quantity, and usage of the MG secretions, which correlate with transitions in life history. These shifts show how even small clades can exhibit substantial transitions in disease resistance investment, demonstrating that host-parasite relationships can be very dynamic and that targeted experimental, as well as large-scale, comparative studies can be valuable for identifying evolutionary transitions.
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Affiliation(s)
| | - Hermógenes Fernández‐Marín
- Instituto de Investigaciones Científicas y Servicios de Alta TecnologíaEdificio 219, Panamá 5Ciudad del SaberClaytonPanama CityPO Box 0843‐01105Republic of Panama
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9
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10
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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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11
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Stürup M, Nash DR, Hughes WOH, Boomsma JJ. Sperm mixing in the polyandrous leaf-cutting ant Acromyrmex echinatior. Ecol Evol 2014; 4:3571-82. [PMID: 25478149 PMCID: PMC4224532 DOI: 10.1002/ece3.1176] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/25/2014] [Accepted: 07/02/2014] [Indexed: 11/08/2022] Open
Abstract
The insemination of queens by sperm from multiple males (polyandry) has evolved in a number of eusocial insect lineages despite the likely costs of the behavior. The selective advantages in terms of colony fitness must therefore also be significant and there is now good evidence that polyandry increases genetic variation among workers, thereby improving the efficiency of division of labor, resistance against disease, and diluting the impact of genetically incompatible matings. However, these advantages will only be maximized if the sperm of initially discrete ejaculates are mixed when stored in queen spermathecae and used for egg fertilization in a "fair raffle." Remarkably, however, very few studies have addressed the level of sperm mixing in social insects. Here we analyzed sperm use over time in the highly polyandrous leaf-cutting ant Acromyrmex echinatior. We genotyped cohorts of workers produced either 2 months apart or up to over a year apart, and batches of eggs laid up to over 2 years apart, and tested whether fluctuations in patriline distributions deviated from random. We show that the representation of father males in both egg and worker cohorts does not change over time, consistent with obligatorily polyandrous queens maximizing their fitness when workers are as genetically diverse as possible.
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Affiliation(s)
- Marlene Stürup
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark
| | - David R Nash
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark
| | - William O H Hughes
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark ; School of Life Sciences, University of Sussex Brighton, BN1 9QG, UK
| | - Jacobus J Boomsma
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark
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12
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Abstract
Transmission is a key determinant of parasite fitness, and understanding the dynamics of transmission is fundamental to the ecology and evolution of host-parasite interactions. Successful transmission is often reliant on contact between infected individuals and susceptible hosts. The social insects consist of aggregated groups of genetically similar hosts, making them particularly vulnerable to parasite transmission. Here we investigate how the ratio of infected to susceptible individuals impacts parasite transmission, using the honey bee, Apis mellifera and its microsporidian parasite Nosema ceranae. We used 2 types of infected hosts found simultaneously in colonies; sterile female workers and sexual males. We found a higher ratio of infected to susceptible individuals in groups resulted in a greater proportion of susceptibles becoming infected, but this effect was non-linear and interestingly, the ratio also affected the spore production of infected individuals. The transmission level was much greater in an experiment where the infected individuals were drones than in an experiment where they were workers, suggesting drones may act as intracolonial 'superspreaders'. Understanding the subtleties of transmission and how it is influenced by the phenotype of the infected/susceptible individuals is important for understanding pathogen transmission at population level, and for optimum targeting of parasite control strategies.
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13
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Arcuri SL, Pagnocca FC, Melo WGDP, Nagamoto NS, Komura DL, Rodrigues A. Yeasts found on an ephemeral reproductive caste of the leaf-cutting ant Atta sexdens rubropilosa. Antonie van Leeuwenhoek 2014; 106:475-87. [PMID: 25012689 DOI: 10.1007/s10482-014-0216-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 06/12/2014] [Indexed: 11/28/2022]
Abstract
Winged males of leaf-cutting ants are considered an ephemeral reproductive caste only produced before the mating flight season. Although much is known about the yeast diversity found in fungus gardens of attine ants, no study has focused on the yeasts associated with males of leaf-cutting ants. Here, we surveyed the yeasts on the integuments of males of Atta sexdens rubropilosa and assessed their potential role in the attine ant-microbe symbiosis. Using culture-dependent techniques, we found yeasts to be abundant on the integuments of males (54.5 %, n = 200 alates). A total of 242 yeast strains were obtained representing six orders, ten genera and 25 species. Strains of Aureobasidium, Cryptococcus, Hannaella and Rhodotorula were prevalent on the integuments and likely originated from the fungus garden of the parental nest or from the soil. The majority of strains (87.1 %) produced at least one of the evaluated enzymes: pectinase, polygalacturonase, cellulase, xylanase, ligninases and lipase. Aureobasidium pullulans accounted for the highest number of strains that produced all enzymes. In addition, yeasts showed the ability to assimilate the resulting oligosaccharides, supporting observations of other studies that yeasts may be involved in the plant biomass metabolism in the fungus gardens. Because winged males harbor several yeasts with putative functional roles, these fungi may take part and be beneficial in the microbial consortia of the new incipient nest.
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Affiliation(s)
- Silvio Lovato Arcuri
- Centro de Estudos de Insetos Sociais, UNESP - Univ Estadual Paulista, Campus Rio Claro, Rio Claro, SP, Brazil
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14
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Frost CL, Pollock SW, Smith JE, Hughes WOH. Wolbachia in the flesh: symbiont intensities in germ-line and somatic tissues challenge the conventional view of Wolbachia transmission routes. PLoS One 2014; 9:e95122. [PMID: 24988478 PMCID: PMC4079706 DOI: 10.1371/journal.pone.0095122] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 03/25/2014] [Indexed: 11/28/2022] Open
Abstract
Symbionts can substantially affect the evolution and ecology of their hosts. The investigation of the tissue-specific distribution of symbionts (tissue tropism) can provide important insight into host-symbiont interactions. Among other things, it can help to discern the importance of specific transmission routes and potential phenotypic effects. The intracellular bacterial symbiont Wolbachia has been described as the greatest ever panzootic, due to the wide array of arthropods that it infects. Being primarily vertically transmitted, it is expected that the transmission of Wolbachia would be enhanced by focusing infection in the reproductive tissues. In social insect hosts, this tropism would logically extend to reproductive rather than sterile castes, since the latter constitute a dead-end for vertically transmission. Here, we show that Wolbachia are not focused on reproductive tissues of eusocial insects, and that non-reproductive tissues of queens and workers of the ant Acromyrmex echinatior, harbour substantial infections. In particular, the comparatively high intensities of Wolbachia in the haemolymph, fat body, and faeces, suggest potential for horizontal transmission via parasitoids and the faecal-oral route, or a role for Wolbachia modulating the immune response of this host. It may be that somatic tissues and castes are not the evolutionary dead-end for Wolbachia that is commonly thought.
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Affiliation(s)
- Crystal L. Frost
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | | | - Judith E. Smith
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
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15
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Kay AD, Bruning AJ, van Alst A, Abrahamson TT, Hughes WOH, Kaspari M. A carbohydrate-rich diet increases social immunity in ants. Proc Biol Sci 2014; 281:20132374. [PMID: 24430844 DOI: 10.1098/rspb.2013.2374] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Increased potential for disease transmission among nest-mates means living in groups has inherent costs. This increased potential is predicted to select for disease resistance mechanisms that are enhanced by cooperative exchanges among group members, a phenomenon known as social immunity. One potential mediator of social immunity is diet nutritional balance because traits underlying immunity can require different nutritional mixtures. Here, we show how dietary protein-carbohydrate balance affects social immunity in ants. When challenged with a parasitic fungus Metarhizium anisopliae, workers reared on a high-carbohydrate diet survived approximately 2.8× longer in worker groups than in solitary conditions, whereas workers reared on an isocaloric, high-protein diet survived only approximately 1.3× longer in worker groups versus solitary conditions. Nutrition had little effect on social grooming, a potential mechanism for social immunity. However, experimentally blocking metapleural glands, which secrete antibiotics, completely eliminated effects of social grouping and nutrition on immunity, suggesting a causal role for secretion exchange. A carbohydrate-rich diet also reduced worker mortality rates when whole colonies were challenged with Metarhizium. These results provide a novel mechanism by which carbohydrate exploitation could contribute to the ecological dominance of ants and other social groups.
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Affiliation(s)
- Adam D Kay
- Department of Biology, University of St. Thomas, , St. Paul, MN, USA, School of Life Sciences, University of Sussex, , Brighton, UK, Graduate Program in EEB, Department of Zoology, University of Oklahoma, , Norman, OK, USA, Smithsonian Tropical Research Institute, , Balboa, Republic of Panama
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16
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Sanitizing the fortress: protection of ant brood and nest material by worker antibiotics. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1664-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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17
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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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18
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Biogenic amines are associated with worker task but not patriline in the leaf-cutting ant Acromyrmex echinatior. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2013; 199:1117-27. [PMID: 24072064 DOI: 10.1007/s00359-013-0854-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 08/31/2013] [Accepted: 09/02/2013] [Indexed: 10/26/2022]
Abstract
Division of labor among eusocial insect workers is a hallmark of advanced social organization, but its underlying neural mechanisms are not well understood. We investigated whether differences in whole-brain levels of the biogenic amines dopamine (DA), serotonin (5HT), and octopamine (OA) are associated with task specialization and genotype in similarly sized and aged workers of the leaf-cutting ant Acromyrmex echinatior, a polyandrous species in which genotype correlates with worker task specialization. We compared amine levels of foragers and waste management workers to test for an association with worker task, and young in-nest workers across patrilines to test for a genetic influence on brain amine levels. Foragers had higher levels of DA and OA and a higher OA:5HT ratio than waste management workers. Patrilines did not significantly differ in amine levels or their ratios, although patriline affected worker body size, which correlated with amine levels despite the small size range sampled. Levels of all three amines were correlated within individuals in both studies. Among patrilines, mean levels of DA and OA, and OA and 5HT were also correlated. Our results suggest that differences in biogenic amines could regulate worker task specialization, but may be not be significantly affected by genotype.
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19
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Evison SEF, Fazio G, Chappell P, Foley K, Jensen AB, Hughes WOH. Host-parasite genotypic interactions in the honey bee: the dynamics of diversity. Ecol Evol 2013; 3:2214-22. [PMID: 23919163 PMCID: PMC3728958 DOI: 10.1002/ece3.599] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/04/2013] [Accepted: 04/09/2013] [Indexed: 11/08/2022] Open
Abstract
Parasites are thought to be a major driving force shaping genetic variation in their host, and are suggested to be a significant reason for the maintenance of sexual reproduction. A leading hypothesis for the occurrence of multiple mating (polyandry) in social insects is that the genetic diversity generated within-colonies through this behavior promotes disease resistance. This benefit is likely to be particularly significant when colonies are exposed to multiple species and strains of parasites, but host-parasite genotypic interactions in social insects are little known. We investigated this using honey bees, which are naturally polyandrous and consequently produce genetically diverse colonies containing multiple genotypes (patrilines), and which are also known to host multiple strains of various parasite species. We found that host genotypes differed significantly in their resistance to different strains of the obligate fungal parasite that causes chalkbrood disease, while genotypic variation in resistance to the facultative fungal parasite that causes stonebrood disease was less pronounced. Our results show that genetic variation in disease resistance depends in part on the parasite genotype, as well as species, with the latter most likely relating to differences in parasite life history and host-parasite coevolution. Our results suggest that the selection pressure from genetically diverse parasites might be an important driving force in the evolution of polyandry, a mechanism that generates significant genetic diversity in social insects.
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Affiliation(s)
- Sophie E F Evison
- School of Biology, Faculty of Biological Sciences, University of Leeds LS2 9JT, U.K
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20
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Yek SH, Boomsma JJ, Schiøtt M. Differential gene expression in Acromyrmex leaf-cutting ants after challenges with two fungal pathogens. Mol Ecol 2013; 22:2173-87. [PMID: 23480581 DOI: 10.1111/mec.12255] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 01/03/2013] [Accepted: 01/15/2013] [Indexed: 11/30/2022]
Abstract
Social insects in general and leaf-cutting ants in particular have increased selection pressures on their innate immune system due to their social lifestyle and monoclonality of the symbiotic fungal cultivar. As this symbiosis is obligate for both parties, prophylactic behavioural defences against infections are expected to increase either ant survival or fungus-garden survival, but also to possibly trade off when specific infections differ in potential danger. We examined the effectiveness of prophylactic behaviours and modulations of innate immune defences by a combination of inoculation bioassays and genome-wide transcriptomic studies (RNA-Seq), using an ant pathogen (Metarhizium brunneum) and a fungus-garden pathogen (Escovopsis weberi) and administering inoculations both directly and indirectly (via the symbiotic partner). Upon detection of pathogen conidia, ant workers responded by increasing both general activity and the frequency of specific defence behaviours (self-grooming, allo-grooming, garden-grooming) independent of the pathogen encountered. This trend was also evident in the patterns of gene expression change. Both direct and indirect (via fungus garden) inoculations with Metarhizium induced a general up-regulation of gene expression, including a number of well-known immune-related genes. In contrast, direct inoculation of the fungus garden by Escovopsis induced an overall down-regulation of ant gene expression, whereas indirect inoculation (via the ants) did not, suggesting that increased activity of ants to remove this fungus-garden pathogen is costly and involves trade-offs with the activation of other physiological pathways.
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Affiliation(s)
- Sze H Yek
- Department of Biology, Centre for Social Evolution, University of Copenhagen, Copenhagen, Denmark
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Van Bael SA, Estrada C, Rehner SA, Santos JF, Wcislo WT. Leaf endophyte load influences fungal garden development in leaf-cutting ants. BMC Ecol 2012; 12:23. [PMID: 23140096 PMCID: PMC3537522 DOI: 10.1186/1472-6785-12-23] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 11/05/2012] [Indexed: 11/10/2022] Open
Abstract
Background Previous work has shown that leaf-cutting ants prefer to cut leaf material with relatively low fungal endophyte content. This preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in their host plants’ defense against leaf-cutting ants. To measure the long-term cost to the ant colony of fungal endophytes in their forage material, we conducted a 20-week laboratory experiment to measure fungal garden development for colonies that foraged on leaves with low or high endophyte content. Results Colony mass and the fungal garden dry mass did not differ significantly between the low and high endophyte feeding treatments. There was, however, a marginally significant trend toward greater mass of fungal garden per ant worker in the low relative to the high endophyte treatment. This trend was driven by differences in the fungal garden mass per worker from the earliest samples, when leaf-cutting ants had been foraging on low or high endophyte leaf material for only 2 weeks. At two weeks of foraging, the mean fungal garden mass per worker was 77% greater for colonies foraging on leaves with low relative to high endophyte loads. Conclusions Our data suggest that the cost of endophyte presence in ant forage material may be greatest to fungal colony development in its earliest stages, when there are few workers available to forage and to clean leaf material. This coincides with a period of high mortality for incipient colonies in the field. We discuss how the endophyte-leaf-cutter ant interaction may parallel constitutive defenses in plants, whereby endophytes reduce the rate of colony development when its risk of mortality is greatest.
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Affiliation(s)
- Sunshine A Van Bael
- Department of Ecology and Evolutionary Biology, Tulane University, 6823 St. Charles Avenue, New Orleans, LA 70118, USA.
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Constant N, Santorelli LA, Lopes JFS, Hughes WOH. The effects of genotype, caste, and age on foraging performance in leaf-cutting ants. Behav Ecol 2012. [DOI: 10.1093/beheco/ars116] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Yek SH, Nash DR, Jensen AB, Boomsma JJ. Regulation and specificity of antifungal metapleural gland secretion in leaf-cutting ants. Proc Biol Sci 2012; 279:4215-22. [PMID: 22915672 DOI: 10.1098/rspb.2012.1458] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ants have paired metapleural glands (MGs) to produce secretions for prophylactic hygiene. These exocrine glands are particularly well developed in leaf-cutting ants, but whether the ants can actively regulate MG secretion is unknown. In a set of controlled experiments using conidia of five fungi, we show that the ants adjust the amount of MG secretion to the virulence of the fungus with which they are infected. We further applied fixed volumes of MG secretion of ants challenged with constant conidia doses to agar mats of the same fungal species. This showed that inhibition halos were significantly larger for ants challenged with virulent and mild pathogens/weeds than for controls and Escovopsis-challenged ants. We conclude that the MG defence system of leaf-cutting ants has characteristics reminiscent of an additional cuticular immune system, with specific and non-specific components, of which some are constitutive and others induced.
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Affiliation(s)
- Sze Huei Yek
- Department of Biology, Centre for Social Evolution, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
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Graystock P, Hughes WOH. Disease resistance in a weaver ant, Polyrhachis dives, and the role of antibiotic-producing glands. Behav Ecol Sociobiol 2011. [DOI: 10.1007/s00265-011-1242-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Evison SEF, Hughes WOH. Genetic caste polymorphism and the evolution of polyandry in Atta leaf-cutting ants. Naturwissenschaften 2011; 98:643-9. [PMID: 21656003 DOI: 10.1007/s00114-011-0810-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 05/24/2011] [Accepted: 05/26/2011] [Indexed: 11/29/2022]
Abstract
Multiple mating by females with different males (polyandry) is difficult to explain in many taxa because it carries significant costs to females, yet benefits are often hard to identify. Polyandry is a derived trait in social insects, the evolutionary origins of which remain unclear. One of several leading hypotheses for its evolution is that it improves division of labour by increasing intra-colonial genetic diversity. Division of labour is a key player in the ecological success of social insects, and in many successful species of ants is based on morphologically distinct castes of workers, each with their own task specialisations. Atta leaf-cutting ants exhibit one of the most extreme and complicated forms of morphologically specialised worker castes and have been reported to be polyandrous but with relatively low mating frequencies (~2.5 on average). Here, we show for the first time that there is a significant genetic influence on worker size in Atta colombica leaf-cutting ants. We also provide the first estimate of the mating frequency of Atta cephalotes (four matings) and, by analysing much higher within-colony sample sizes, find that Atta are more polyandrous than previously thought (approximately six to seven matings). The results show that high polyandry and a genetic influence on worker caste are present in both genera of leaf-cutting ants and add weight to the hypothesis that division of labour is a potential driver of the evolution of polyandry in this clade of ants.
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Armitage SAO, Broch JF, Marín HF, Nash DR, Boomsma JJ. Immune defense in leaf-cutting ants: a cross-fostering approach. Evolution 2011; 65:1791-9. [PMID: 21644963 DOI: 10.1111/j.1558-5646.2011.01241.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To ameliorate the impact of disease, social insects combine individual innate immune defenses with collective social defenses. This implies that there are different levels of selection acting on investment in immunity, each with their own trade-offs. We present the results of a cross-fostering experiment designed to address the influences of genotype and social rearing environment upon individual and social immune defenses. We used a multiply mating leaf-cutting ant, enabling us to test for patriline effects within a colony, as well as cross-colony matriline effects. The worker's father influenced both individual innate immunity (constitutive antibacterial activity) and the size of the metapleural gland, which secretes antimicrobial compounds and functions in individual and social defense, indicating multiple mating could have important consequences for both defense types. However, the primarily social defense, a Pseudonocardia bacteria that helps to control pathogens in the ants' fungus garden, showed a significant colony of origin by rearing environment interaction, whereby ants that acquired the bacteria of a foster colony obtained a less abundant cover of bacteria: one explanation for this pattern would be co-adaptation between host colonies and their vertically transmitted mutualist. These results illustrate the complexity of the selection pressures that affect the expression of multilevel immune defenses.
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Affiliation(s)
- Sophie A O Armitage
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
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Ugelvig LV, Kronauer DJC, Schrempf A, Heinze J, Cremer S. Rapid anti-pathogen response in ant societies relies on high genetic diversity. Proc Biol Sci 2010; 277:2821-8. [PMID: 20444720 PMCID: PMC2981995 DOI: 10.1098/rspb.2010.0644] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 04/12/2010] [Indexed: 11/12/2022] Open
Abstract
Social organisms are constantly exposed to infectious agents via physical contact with conspecifics. While previous work has shown that disease susceptibility at the individual and group level is influenced by genetic diversity within and between group members, it remains poorly understood how group-level resistance to pathogens relates directly to individual physiology, defence behaviour and social interactions. We investigated the effects of high versus low genetic diversity on both the individual and collective disease defences in the ant Cardiocondyla obscurior. We compared the antiseptic behaviours (grooming and hygienic behaviour) of workers from genetically homogeneous and diverse colonies after exposure of their brood to the entomopathogenic fungus Metarhizium anisopliae. While workers from diverse colonies performed intensive allogrooming and quickly removed larvae covered with live fungal spores from the nest, workers from homogeneous colonies only removed sick larvae late after infection. This difference was not caused by a reduced repertoire of antiseptic behaviours or a generally decreased brood care activity in ants from homogeneous colonies. Our data instead suggest that reduced genetic diversity compromises the ability of Cardiocondyla colonies to quickly detect or react to the presence of pathogenic fungal spores before an infection is established, thereby affecting the dynamics of social immunity in the colony.
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Affiliation(s)
- Line V. Ugelvig
- Evolution, Behaviour and Genetics, Biology I, University of Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Daniel J. C. Kronauer
- Museum of Comparative Zoology Labs, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Alexandra Schrempf
- Evolution, Behaviour and Genetics, Biology I, University of Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Jürgen Heinze
- Evolution, Behaviour and Genetics, Biology I, University of Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Sylvia Cremer
- Evolution, Behaviour and Genetics, Biology I, University of Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
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Waddington SJ, Santorelli LA, Ryan FR, Hughes WO. Genetic polyethism in leaf-cutting ants. Behav Ecol 2010. [DOI: 10.1093/beheco/arq128] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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