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Cama B, Heaton K, Thomas-Oates J, Schulz S, Dasmahapatra KK. Complexity of Chemical Emissions Increases Concurrently with Sexual Maturity in Heliconius Butterflies. J Chem Ecol 2024; 50:197-213. [PMID: 38478290 PMCID: PMC11233321 DOI: 10.1007/s10886-024-01484-z] [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: 06/04/2023] [Revised: 02/21/2024] [Accepted: 03/03/2024] [Indexed: 07/10/2024]
Abstract
Pheromone communication is widespread among animals. Since it is often involved in mate choice, pheromone production is often tightly controlled. Although male sex pheromones (MSPs) and anti-aphrodisiacs have been studied in some Heliconius butterfly species, little is known about the factors affecting their production and release in these long-lived butterflies. Here, we investigate the effect of post-eclosion age on chemical blends from pheromone-emitting tissues in Heliconius atthis and Heliconius charithonia, exhibiting respectively free-mating and pupal-mating strategies that are hypothesised to differently affect the timing of their pheromone emissions. We focus on two different tissues: the wing androconia, responsible for MSPs used in courtship, and the genital tip, the production site for anti-aphrodisiac pheromones that affect post-mating behaviour. Gas chromatography-mass spectrometric analysis of tissue extracts from virgin males and females of both species from day 0 to 8 post-eclosion demonstrates the following. Some ubiquitous fatty acid precursors are already detectable at day 0. The complexity of the chemical blends increases with age regardless of tissue or sex. No obvious difference in the time course of blend production was evident between the two species, but female tissues in H. charithonia were more affected by age than in H. atthis. We suggest that compounds unique to male androconia and genitals and whose amount increases with age are potential candidates for future investigation into their roles as pheromones. While this analysis revealed some of the complexity in Heliconius chemical ecology, the effects of other factors, such as the time of day, remain unknown.
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Affiliation(s)
- Bruna Cama
- Department of Biology, University of York, Wentworth Way, Heslington, YO10 5DD, UK.
| | - Karl Heaton
- Department of Chemistry, University of York, Heslington, YO10 5DD, UK
| | - Jane Thomas-Oates
- Department of Chemistry, University of York, Heslington, YO10 5DD, UK
| | - Stefan Schulz
- Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, Braunschweig, 38106, Germany
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Hart T, Lopes LE, Frank DD, Kronauer DJ. Pheromone representation in the ant antennal lobe changes with age. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.13.580193. [PMID: 38405746 PMCID: PMC10888935 DOI: 10.1101/2024.02.13.580193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
While the neural basis of age-related decline has been extensively studied (1-3), less is known about changes in neural function during the pre-senescent stages of adulthood. Adult neural plasticity is likely a key factor in social insect age polyethism, where individuals perform different tasks as they age and divide labor in an age-dependent manner (4-9). Primarily, workers transition from nursing to foraging tasks (5, 10), become more aggressive, and more readily display alarm behavior (11-16) as they get older. While it is unknown how these behavioral dynamics are neurally regulated, they could partially be generated by altered salience of behaviorally relevant stimuli (4, 6, 7). Here, we investigated how odor coding in the antennal lobe (AL) changes with age in the context of alarm pheromone communication in the clonal raider ant (Ooceraea biroi) (17). Similar to other social insects (11, 12, 16), older ants responded more rapidly to alarm pheromones, the chemical signals for danger. Using whole-AL calcium imaging (18), we then mapped odor representations for five general odorants and two alarm pheromones in young and old ants. Alarm pheromones were represented sparsely at all ages. However, alarm pheromone responses within individual glomeruli changed with age, either increasing or decreasing. Only two glomeruli became sensitized to alarm pheromones with age, while at the same time becoming desensitized to general odorants. Our results suggest that the heightened response to alarm pheromones in older ants occurs via increased sensitivity in these two core glomeruli, illustrating the importance of sensory modulation in social insect division of labor and age-associated behavioral plasticity.
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Affiliation(s)
- Taylor Hart
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Lindsey E. Lopes
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Dominic D. Frank
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Daniel J.C. Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
- Howard Hughes Medical Institute, New York, NY 10065, USA
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Lopes LE, Frank ET, Kárpáti Z, Schmitt T, Kronauer DJC. The Alarm Pheromone and Alarm Response of the Clonal Raider Ant. J Chem Ecol 2023; 49:1-10. [PMID: 36759430 PMCID: PMC9941220 DOI: 10.1007/s10886-023-01407-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 12/02/2022] [Accepted: 12/08/2022] [Indexed: 02/11/2023]
Abstract
Ants communicate via an arsenal of different pheromones produced in a variety of exocrine glands. For example, ants release alarm pheromones in response to danger to alert their nestmates and to trigger behavioral alarm responses. Here we characterize the alarm pheromone and the alarm response of the clonal raider ant Ooceraea biroi, a species that is amenable to laboratory studies but for which no pheromones have been identified. During an alarm response, ants quickly become unsettled, leave their nest pile, and are sometimes initially attracted to the source of alarm, but ultimately move away from it. We find that the alarm pheromone is released from the head of the ant and identify the putative alarm pheromone as a blend of two compounds found in the head, 4-methyl-3-heptanone and 4-methyl-3-heptanol. These compounds are sufficient to induce alarm behavior alone and in combination. They elicit similar, though slightly different behavioral features of the alarm response, with 4-methyl-3-heptanone being immediately repulsive and 4-methyl-3-heptanol being initially attractive before causing ants to move away. The behavioral response to these compounds in combination is dose-dependent, with ants becoming unsettled and attracted to the source of alarm pheromone at low concentrations and repulsed at high concentrations. While 4-methyl-3-heptanone and 4-methyl-3-heptanol are known alarm pheromones in other more distantly related ant species, this is the first report of the chemical identity of a pheromone in O. biroi, and the first alarm pheromone identified in the genus Ooceraea. Identification of a pheromone that triggers a robust, consistent, and conserved behavior, like the alarm pheromone, provides an avenue to dissect the behavioral and neuronal mechanisms underpinning chemical communication.
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Affiliation(s)
- Lindsey E Lopes
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
| | - Erik T Frank
- Biocentre, Department of Animal Ecology and Tropical Biology, University of Würzburg, D-97074, Würzburg, Germany
- Department of Ecology and Evolution, Biophore, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Zsolt Kárpáti
- Biocentre, Department of Animal Ecology and Tropical Biology, University of Würzburg, D-97074, Würzburg, Germany
- Department of Chemical Ecology, Plant Protection Institute, Centre of Agricultural Research, ELKH, Budapest, Hungary
| | - Thomas Schmitt
- Biocentre, Department of Animal Ecology and Tropical Biology, University of Würzburg, D-97074, Würzburg, Germany
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
- Howard Hughes Medical Institute, New York, NY, 10065, USA.
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Kannan K, Galizia CG, Nouvian M. Olfactory Strategies in the Defensive Behaviour of Insects. INSECTS 2022; 13:470. [PMID: 35621804 PMCID: PMC9145661 DOI: 10.3390/insects13050470] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/06/2022] [Accepted: 05/16/2022] [Indexed: 11/17/2022]
Abstract
Most animals must defend themselves in order to survive. Defensive behaviour includes detecting predators or intruders, avoiding them by staying low-key or escaping or deterring them away by means of aggressive behaviour, i.e., attacking them. Responses vary across insect species, ranging from individual responses to coordinated group attacks in group-living species. Among different modalities of sensory perception, insects predominantly use the sense of smell to detect predators, intruders, and other threats. Furthermore, social insects, such as honeybees and ants, communicate about danger by means of alarm pheromones. In this review, we focus on how olfaction is put to use by insects in defensive behaviour. We review the knowledge of how chemical signals such as the alarm pheromone are processed in the insect brain. We further discuss future studies for understanding defensive behaviour and the role of olfaction.
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Affiliation(s)
- Kavitha Kannan
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany;
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457 Konstanz, Germany
| | - C. Giovanni Galizia
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany;
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457 Konstanz, Germany
- Zukunftskolleg, University of Konstanz, 78457 Konstanz, Germany
| | - Morgane Nouvian
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany;
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457 Konstanz, Germany
- Zukunftskolleg, University of Konstanz, 78457 Konstanz, Germany
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Easter C, Leadbeater E, Hasenjager MJ. Behavioural variation among workers promotes feed-forward loops in a simulated insect colony. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220120. [PMID: 35316950 PMCID: PMC8889185 DOI: 10.1098/rsos.220120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/04/2022] [Indexed: 05/03/2023]
Abstract
Coordinated responses in eusocial insect colonies arise from worker interaction networks that enable collective processing of ecologically relevant information. Previous studies have detected a structural motif in these networks known as the feed-forward loop, which functions to process information in other biological regulatory networks (e.g. transcriptional networks). However, the processes that generate feed-forward loops among workers and the consequences for information flow within the colony remain largely unexplored. We constructed an agent-based model to investigate how individual variation in activity and movement shaped the production of feed-forward loops in a simulated insect colony. We hypothesized that individual variation along these axes would generate feed-forward loops by driving variation in interaction frequency among workers. We found that among-individual variation in activity drove over-representation of feed-forward loops in the interaction networks by determining the directionality of interactions. However, despite previous work linking feed-forward loops with efficient information transfer, activity variation did not promote faster or more efficient information flow, thus providing no support for the hypothesis that feed-forward loops reflect selection for enhanced collective functioning. Conversely, individual variation in movement trajectory, despite playing no role in generating feed-forward loops, promoted fast and efficient information flow by linking together otherwise unconnected regions of the nest.
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Affiliation(s)
- Carrie Easter
- School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Ellouise Leadbeater
- Department of Biological Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK
| | - Matthew J. Hasenjager
- Department of Biological Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK
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Abstract
Ants have outstanding capacity to mediate inter- and intraspecific interactions by producing structurally diverse metabolites from numerous secretory glands. Since Murray Blum's pioneering studies dating from the 1950s, there has been a growing interest in arthropod toxins as natural products. Over a dozen different alkaloid classes have been reported from approximately 40 ant genera in five subfamilies, with peak diversity within the Myrmicinae tribe Solenopsidini. Most ant alkaloids function as venom, but some derive from other glands with alternative functions. They are used in defense (e.g., alarm, repellants) or offense (e.g., toxins) but also serve as antimicrobials and pheromones. We provide an overview of ant alkaloid diversity and function with an evolutionary perspective. We conclude that more directed integrative research is needed. We suggest that comparative phylogenetics will illuminate compound diversification, while molecular approaches will elucidate genetic origins. Biological context, informed by natural history, remains critical not only for research about focal species, but also to guide applied research.
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Affiliation(s)
- Eduardo Gonçalves Paterson Fox
- Departamento de Parasitologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21044-020, Brazil;
| | - Rachelle M M Adams
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio 43210, USA;
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC 20560, USA
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