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Muratore IB, Fandozzi EM, Traniello JFA. Behavioral performance and division of labor influence brain mosaicism in the leafcutter ant Atta cephalotes. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:325-344. [PMID: 35112161 DOI: 10.1007/s00359-021-01539-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 11/29/2022]
Abstract
Brain evolution is hypothesized to be driven by behavioral selection on neuroarchitecture. We developed a novel metric of relative neuroanatomical investments involved in performing tasks varying in sensorimotor and processing demands across polymorphic task-specialized workers of the leafcutter ant Atta cephalotes and quantified brain size and structure to examine their correlation with our computational approximations. Investment in multisensory and motor integration for task performance was estimated to be greatest for media workers, whose highly diverse repertoire includes leaf-quality discrimination and leaf-harvesting tasks that likely involve demanding sensory and motor processes. Confocal imaging revealed that absolute brain volume increased with worker size and functionally specialized compartmental scaling differed among workers. The mushroom bodies, centers of sensory integration and learning and memory, and the antennal lobes, olfactory input sites, were larger in medias than in minims (gardeners) and significantly larger than in majors ("soldiers"), both of which had lower scores for involvement of olfactory processing in the performance of their characteristic tasks. Minims had a proportionally larger central complex compared to other workers. These results support the hypothesis that variation in task performance influences selection for mosaic brain structure, the independent evolution of proportions of the brain composed of different neuropils.
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Affiliation(s)
- I B Muratore
- Department of Biology, Boston University, Boston, MA, 02215, USA.
| | - E M Fandozzi
- Department of Biology, Boston University, Boston, MA, 02215, USA
| | - J F A Traniello
- Department of Biology, Boston University, Boston, MA, 02215, USA.,Graduate Program in Neuroscience, Boston University, Boston, MA, 02215, USA
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2
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Crumière AJJ, James A, Lannes P, Mallett S, Michelsen A, Rinnan R, Shik JZ. The multidimensional nutritional niche of fungus-cultivar provisioning in free-ranging colonies of a neotropical leafcutter ant. Ecol Lett 2021; 24:2439-2451. [PMID: 34418263 PMCID: PMC9292433 DOI: 10.1111/ele.13865] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/01/2021] [Indexed: 11/29/2022]
Abstract
Foraging trails of leafcutter colonies are iconic scenes in the Neotropics, with ants collecting freshly cut plant fragments to provision a fungal food crop. We hypothesised that the fungus‐cultivar's requirements for macronutrients and minerals govern the foraging niche breadth of Atta colombica leafcutter ants. Analyses of plant fragments carried by foragers showed how nutrients from fruits, flowers and leaves combine to maximise cultivar performance. While the most commonly foraged leaves delivered excess protein relative to the cultivar's needs, in vitro experiments showed that the minerals P, Al and Fe may expand the leafcutter foraging niche by enhancing the cultivar's tolerance to protein‐biased substrates. A suite of other minerals reduces cultivar performance in ways that may render plant fragments with optimal macronutrient blends unsuitable for provisioning. Our approach highlights how the nutritional challenges of provisioning a mutualist can govern the multidimensional realised niche available to a generalist insect herbivore.
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Affiliation(s)
- Antonin J J Crumière
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Aidan James
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Pol Lannes
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Sophie Mallett
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Anders Michelsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Riikka Rinnan
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jonathan Z Shik
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
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From Plants to Ants: Fungal Modification of Leaf Lipids for Nutrition and Communication in the Leaf-Cutter Ant Fungal Garden Ecosystem. mSystems 2021; 6:6/2/e01307-20. [PMID: 33758033 PMCID: PMC8547007 DOI: 10.1128/msystems.01307-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipids are essential to all living organisms, as an energy source, as an important cellular structural component, and as a communication tool. In this study, we used global lipidomic methods to evaluate the lipids in leaf-cutter ant fungal gardens. Leaf-cutter ants and their coevolved fungal cultivar, Leucoagaricus gongylophorus, are a model mutualistic system. The fungus enzymatically digests fresh plant material that the ants cut and deliver, converting energy and nutrients from plants and providing them to the ants through specialized hyphal swellings called gongylidia. Using combined liquid chromatography, ion mobility spectrometry, and tandem mass spectrometry, we evaluated differences between the molecular species of lipids in the leaf-cutter ant fungal garden ecosystem. This lipidomic study characterized leaves that are fed to the gardens, gongylidia that are produced by the fungus to feed the ants, and spatially resolved regions of the fungal garden through stages of leaf degradation. Lipids containing alpha-linolenic acid (18:3) were enriched in leaves and the top of the gardens but not dominant in the middle or bottom regions. Gongylidia were dominated by lipids containing linoleic acid (18:2). To evaluate the communicative potential of the lipids in fungal gardens, we conducted a behavioral experiment that showed Atta leaf-cutter ants responded differently to 18:3 and 18:2 fatty acids, with aggression toward 18:3 and attraction for 18:2. This work demonstrates the role of lipids in both the transfer of energy and as an interkingdom communication tool in leaf-cutter ant fungal gardens. IMPORTANCE In this work, we examined the role of lipids in the mutualism between leaf-cutter ants and fungus. These ants cut fresh leaf material, which they provide to their fungal cultivar, that converts energy and nutrients from the plants and provides it to the ants in specialized hyphal swellings called gongylidia. This work constitutes the first example of a global lipidomics study of a symbiotic system and provides insights as to how the fungus modifies plant lipids into a usable source for the ants. Through a behavioral experiment, this work also demonstrates how lipids can be used as an interkingdom communication tool, in this case, as an attractant rather than as a repellant, which is more often seen. Author Video: An author video summary of this article is available.
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Goes AC, Barcoto MO, Kooij PW, Bueno OC, Rodrigues A. How Do Leaf-Cutting Ants Recognize Antagonistic Microbes in Their Fungal Crops? Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00095] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Crumière AJJ, Stephenson CJ, Nagel M, Shik JZ. Using Nutritional Geometry to Explore How Social Insects Navigate Nutritional Landscapes. INSECTS 2020; 11:E53. [PMID: 31952303 PMCID: PMC7022258 DOI: 10.3390/insects11010053] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/11/2020] [Accepted: 01/11/2020] [Indexed: 12/15/2022]
Abstract
Insects face many cognitive challenges as they navigate nutritional landscapes that comprise their foraging environments with potential food items. The emerging field of nutritional geometry (NG) can help visualize these challenges, as well as the foraging solutions exhibited by insects. Social insect species must also make these decisions while integrating social information (e.g., provisioning kin) and/or offsetting nutrients provisioned to, or received from unrelated mutualists. In this review, we extend the logic of NG to make predictions about how cognitive challenges ramify across these social dimensions. Focusing on ants, we outline NG predictions in terms of fundamental and realized nutritional niches, considering when ants interact with related nestmates and unrelated bacterial, fungal, plant, and insect mutualists. The nutritional landscape framework we propose provides new avenues for hypothesis testing and for integrating cognition research with broader eco-evolutionary principles.
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Affiliation(s)
- Antonin J. J. Crumière
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Calum J. Stephenson
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Manuel Nagel
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Jonathan Z. Shik
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
- Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Balboa, Ancon, Panama
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Nelson AS, Carvajal Acosta N, Mooney KA. Plant chemical mediation of ant behavior. CURRENT OPINION IN INSECT SCIENCE 2019; 32:98-103. [PMID: 31113639 DOI: 10.1016/j.cois.2018.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/23/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
Ants are ecologically dominant members of terrestrial communities. Ant foraging is often strongly associated with plants and depends upon associative learning of chemicals in the environment. As a result, plant chemicals can affect ant behaviors and, in so doing, have strong multi-trophic indirect effects. Plant chemicals mediate ant behaviors in the contexts of floral visitation, seed dispersal and predation, leaf cutting, interactions with ant-mutualist host plants, interactions with mutualist and prey insects in plant canopies, and plant predation of ants by carnivorous plants. Here, we review what is known about these differing contexts in which plant chemicals influence ant behavior, the mechanisms by which ants are affected by plant chemicals, and future directions within these topics.
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Affiliation(s)
- Annika S Nelson
- Department of Ecology and Evolutionary Biology, University of California at Irvine, 321 Steinhaus Hall, Irvine, CA 92697, United States; Rocky Mountain Biological Laboratory, PO Box 319, Crested Butte, CO 81224, United States
| | - Nalleli Carvajal Acosta
- Department of Ecology and Evolutionary Biology, University of California at Irvine, 321 Steinhaus Hall, Irvine, CA 92697, United States
| | - Kailen A Mooney
- Department of Ecology and Evolutionary Biology, University of California at Irvine, 321 Steinhaus Hall, Irvine, CA 92697, United States; Rocky Mountain Biological Laboratory, PO Box 319, Crested Butte, CO 81224, United States.
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Arenas A, Roces F. Appetitive and aversive learning of plants odors inside different nest compartments by foraging leaf-cutting ants. JOURNAL OF INSECT PHYSIOLOGY 2018; 109:85-92. [PMID: 29981324 DOI: 10.1016/j.jinsphys.2018.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/21/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
Cues inside the nest provide social insect foragers with information about resources currently exploited that may influence their decisions outside. Leaf-cutting ants harvest leaf fragments that are either further processed as substrate for their symbiotic fungus, or disposed of if unsuitable. We investigated whether Acromyrmex ambiguus foragers develop learned preferences for olfactory cues they experienced either in the fungus or in the waste chamber of the nest. Foragers' olfactory preferences were quantified as a choice between sugared papers disks scented with a novel odor and with the odor experienced in one of the nest compartments, before and after odor addition. Odors incorporated in the fungus chamber led to preferences towards paper disks smelling of them. Conversely, odors experienced in the waste chambers led to avoidance of similarly-scented disks. To investigate context-specificity of responses, we quantified learned preferences towards an odor that occurred first in the fungus chamber, and 14 h later in the waste chamber. Foragers initially developed a preference for the odor added in the fungus chamber that turned into avoidance when the same odor solely occurred later in the waste chamber. Avoidance of plants could also be induced in a more natural context, when fresh leaf disks of novel plants, privet or firethorn, were presented in the waste chamber. We conclude that learned acceptance or rejection of suitable plants by foragers depend on the learning context: smells can lead to appetitive learning when present in the fungus garden, or to avoidance learning when they occur at the dump.
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Affiliation(s)
- Andrés Arenas
- Department of Behavioral Physiology and Sociobiology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Flavio Roces
- Department of Behavioral Physiology and Sociobiology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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