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Navas-Zuloaga MG, Baudier KM, Fewell JH, Ben-Asher N, Pavlic TP, Kang Y. A modeling framework for adaptive collective defense: crisis response in social-insect colonies. J Math Biol 2023; 87:87. [PMID: 37966545 DOI: 10.1007/s00285-023-01995-5] [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: 10/25/2022] [Revised: 08/26/2023] [Accepted: 09/07/2023] [Indexed: 11/16/2023]
Abstract
Living systems, from cells to superorganismic insect colonies, have an organizational boundary between inside and outside and allocate resources to defend it. Whereas the micro-scale dynamics of cell walls can be difficult to study, the adaptive allocation of workers to defense in social-insect colonies is more conspicuous. This is particularly the case for Tetragonisca angustula stingless bees, which combine different defensive mechanisms found across other colonial animals: (1) morphological specialization (distinct soldiers (majors) are produced over weeks); (2) age-based polyethism (young majors transition to guarding tasks over days); and (3) task switching (small workers (minors) replace soldiers within minutes under crisis). To better understand how these timescales of reproduction, development, and behavior integrate to balance defensive demands with other colony needs, we developed a demographic Filippov ODE system to study the effect of these processes on task allocation and colony size. Our results show that colony size peaks at low proportions of majors, but colonies die if minors are too plastic or defensive demands are too high or if there is a high proportion of quickly developing majors. For fast maturation, increasing major production may decrease defenses. This model elucidates the demographic factors constraining collective defense regulation in social insects while also suggesting new explanations for variation in defensive allocation at smaller scales where the mechanisms underlying defensive processes are not easily observable. Moreover, our work helps to establish social insects as model organisms for understanding other systems where the transaction costs for component turnover are nontrivial, as in manufacturing systems and just-in-time supply chains.
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Affiliation(s)
| | - Kaitlin M Baudier
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Jennifer H Fewell
- School of Life Sciences, Arizona State University, Tempe, AZ, 85281, USA
| | - Noam Ben-Asher
- Data Science Directorate, SimSpace Cooperation, Boston, MA, USA
| | - Theodore P Pavlic
- School of Life Sciences, Arizona State University, Tempe, AZ, 85281, USA
- School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ, 85281, USA
- School of Sustainability, Arizona State University, Tempe, AZ, 85281, USA
- School of Complex Adaptive Systems, Arizona State University, Tempe, AZ, 85281, USA
| | - Yun Kang
- Sciences and Mathematics Faculty, College of Integrative Sciences and Arts, Arizona State University, Tempe, AZ, 85281, USA.
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2
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Grüter C, Balbuena MS, Valadares L. Mechanisms and adaptations that shape division of labour in stingless bees. CURRENT OPINION IN INSECT SCIENCE 2023; 58:101057. [PMID: 37230412 DOI: 10.1016/j.cois.2023.101057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/12/2023] [Accepted: 05/02/2023] [Indexed: 05/27/2023]
Abstract
Stingless bees are a diverse and ecologically important group of pollinators in the tropics. Division of labour allows bee colonies to meet the various demands of their social life, but has been studied in only ∼3% of all described stingless bee species. The available data suggest that division of labour shows both parallels and striking differences compared with other social bees. Worker age is a reliable predictor of worker behaviour in many species, while morphological variation in body size or differences in brain structure are important for specific worker tasks in some species. Stingless bees provide opportunities to confirm general patterns of division of labour, but they also offer prospects to discover and study novel mechanisms underlying the different lifestyles found in eusocial bees.
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Affiliation(s)
- Christoph Grüter
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, BS8 1TQ, UK.
| | - María Sol Balbuena
- Laboratorio de Insectos Sociales, Departamento de Biodiversidad y Biología Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina; Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET, Universidad de Ciencias Naturales y Exactas, Universidad de Buenos Aires, CABA, Argentina
| | - Lohan Valadares
- Evolution, Genomes, Behavior, and Ecology (EGCE), Université Paris-Saclay, CNRS, IRD, Gif-sur-Yvette, France
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3
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Almeida FCR, Magalhães DM, Favaris AP, Rodríguez J, Azevedo KEX, Bento JMS, Alves DA. Side effects of a fungus-based biopesticide on stingless bee guarding behaviour. CHEMOSPHERE 2022; 287:132147. [PMID: 34492415 DOI: 10.1016/j.chemosphere.2021.132147] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 06/13/2023]
Abstract
Pathogenic fungi have been used worldwide to control crop pests and are assumed to pose negligible threats to the survival of pollinators. Although eusocial stingless bees provide essential pollination services and might be exposed to these biopesticides in tropical agroecosystems, there is a substantial knowledge gap regarding the side effects of fungal pathogens on behavioural traits that are crucial for colony functioning, such as guarding behaviour. Here, we evaluated the effect of Beauveria bassiana on the sophisticated kin recognition system of Tetragonisca angustula, a bee with morphologically specialized entrance guards. By combining behavioural assays and chemical analyses, we show that guards detect pathogen-exposed nestmates, preventing them from accessing nests. Furthermore, cuticular profiles of pathogen-exposed foragers contained significantly lower amounts of linear alkanes than the unexposed ones. Such chemical cues associated with fungal conidia may potentially trigger aggression towards pathogen-exposed bees, preventing pathogen spread into and among colonies. This is the first demonstration that this highly abundant native bee seems to respond in a much more adaptive way to a potentially infectious threat, outweighing the costs of losing foraging workforce when reducing the chances of fungal pathogen outbreaks within their colonies, than honeybees do.
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Affiliation(s)
- Felipe Chagas Rocha Almeida
- Laboratory of Chemical Ecology and Insect Behaviour, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Diego Martins Magalhães
- Laboratory of Chemical Ecology and Insect Behaviour, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Arodí Prado Favaris
- Laboratory of Chemical Ecology and Insect Behaviour, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Jonathan Rodríguez
- Laboratory of Pathology and Microbial Control, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Kamila Emmanuella Xavier Azevedo
- Laboratory of Chemical Ecology and Insect Behaviour, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - José Maurício Simões Bento
- Laboratory of Chemical Ecology and Insect Behaviour, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Denise Araujo Alves
- Laboratory of Chemical Ecology and Insect Behaviour, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil.
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Wagner T, Bachenberg L, Glaser SM, Oikonomou A, Linn M, Grüter C. Large body size variation is associated with low communication success in tandem running ants. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02941-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Abstract
Diversity in animal groups is often assumed to increase group performance. In insect colonies, genetic, behavioural and morphological variation among workers can improve colony functioning and resilience. However, it has been hypothesized that during communication processes, differences between workers, e.g. in body size, could also have negative effects. Tandem running is a common recruitment strategy in ants and allows a leader to guide a nestmate follower to resources. A substantial proportion of tandem runs fail because leader and follower lose contact. Using the ant Temnothorax nylanderi as a model system, we tested the hypothesis that tandem running success is impaired if leader and follower differ in size. Indeed, we found that the success rate of tandem pairs drops considerably as size variation increases: tandem runs were unsuccessful when the leader–follower size difference exceeded 10%, whereas ~ 80% of tandem runs were successful when ants differed less than 5% in body length. Possible explanations are that size differences are linked to differences in walking speed or sensory perception. Ants did not choose partners of similar size, but extranidal workers were larger than intranidal workers, which could reduce recruitment mistakes because it reduced the chance that very large and very small ants perform tandem runs together. Our results suggest that phenotypic differences between interacting workers can have negative effects on the efficiency of communication processes. Whether phenotypic variation has positive or negative effects is likely to depend on the task and the phenotypic trait that shows variation.
Significance statement
Diversity is often assumed to increase colony performance in social insects. However, phenotypic differences among workers could also have negative effects, e.g. during communication. Tandem running is a common recruitment strategy in ants, but tandem runs often fail when ants lose contact. We used the ant Temnothorax nylanderi to test the hypothesis that body size differences between tandem leader and follower impair tandem communication. We show that the success rate of tandem pairs drops considerably as size variation increases, possibly because ants of varying size also differ in walking speed. Our study supports the hypothesis that phenotypic variation among workers might not always be beneficial and can negatively impact the efficiency of communication processes.
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Manipulation of worker size diversity does not affect colony fitness under natural conditions in the ant Temnothorax nylanderi. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02885-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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6
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Galvani GL, Soto EM, Canavoso LE, Settembrini BP. Fat body morphology, but not body size, changes in forager bees of Scaptotrigona jujuyensis (Apidae: Meliponini) during foraging season. ZOOL ANZ 2019. [DOI: 10.1016/j.jcz.2019.09.006] [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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Chole H, Woodard SH, Bloch G. Body size variation in bees: regulation, mechanisms, and relationship to social organization. CURRENT OPINION IN INSECT SCIENCE 2019; 35:77-87. [PMID: 31426016 DOI: 10.1016/j.cois.2019.07.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 07/03/2019] [Accepted: 07/15/2019] [Indexed: 06/10/2023]
Abstract
Size polymorphism is common in bees, and is determined by environmental factors such as temperature, brood cell size, and the diet provided to developing larvae. In social bees, these factors are further influenced by intricate interactions between the queen, workers, and the developing brood which eventually determine the final size and caste of developing larvae. Environmental and social factors act in part on juvenile hormone and ecdysteroids, which are key hormonal regulators of body size and caste determination. In some social bees, body size variation is central for social organization because it structures reproductive division of labor, task allocation among workers, or both. At ecological scales, body size also impacts bee-mediated pollination services in solitary and social species by influencing floral visitation and pollination efficacy.
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Affiliation(s)
- Hanna Chole
- Department of Ecology, Evolution, and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Sarah Hollis Woodard
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA
| | - Guy Bloch
- Department of Ecology, Evolution, and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Baudier KM, Ostwald MM, Grüter C, Segers FHID, Roubik DW, Pavlic TP, Pratt SC, Fewell JH. Changing of the guard: mixed specialization and flexibility in nest defense (Tetragonisca angustula). Behav Ecol 2019. [DOI: 10.1093/beheco/arz047] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Abstract
Task allocation is a central challenge of collective behavior in a variety of group-living species, and this is particularly the case for the allocation of social insect workers for group defense. In social insects, both benefits and considerable costs are associated with the production of specialized soldiers. We asked whether colonies mitigate costs of production of specialized soldiers by simultaneously employing behavioral flexibility in nonspecialist workers that can augment defense capabilities at short time scales. We studied colonies of the stingless bee Tetragonisca angustula, a species that has 2 discrete nest-guarding tasks typically performed by majors: hovering guarding and standing guarding. Majors showed age polyethism across nest-guarding tasks, first hovering and then changing to the task of standing guarding after 1 week. Colonies were also able to reassign minors to guarding tasks when majors were experimentally removed. Replacement guards persisted in nest defense tasks until colonies produced enough majors to return to their initial state. Tetragonisca angustula colonies thus employed a coordinated set of specialization strategies in nest defense: morphologically specialized soldiers, age polyethism among soldiers within specific guarding tasks, and rapid flexible reallocation of nonspecialists to guarding during soldier loss. This mixed strategy achieves the benefits of a highly specialized defensive force while maintaining the potential for rapid reinforcement when soldiers are lost or colonies face unexpectedly intense attack.
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Affiliation(s)
| | | | - Christoph Grüter
- Institute of Organismic and Molecular Evolution, Biozentrum I, University of Mainz, Mainz, Germany
| | - Francisca H I D Segers
- Department for Applied Bioinformatics, Institute of Cell Biology and Neuroscience, Goethe University, Frankfurt, Germany
| | - David W Roubik
- Smithsonian Tropical Research Institute, Balboa, Ancón, Panama, Republic of Panama
| | - Theodore P Pavlic
- Decision Systems Engineering, Arizona State University, Tempe, AZ
- School of Sustainability, Arizona State University, Wrigley Hall, Tempe, AZ, USA
| | - Stephen C Pratt
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
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9
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Grüter C. Repeated switches from cooperative to selfish worker oviposition during stingless bee evolution. J Evol Biol 2018; 31:1843-1851. [PMID: 30242940 DOI: 10.1111/jeb.13377] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 09/13/2018] [Accepted: 09/17/2018] [Indexed: 11/29/2022]
Abstract
Reproductive division of labour is a defining feature of insect societies. Stingless bees (Meliponini) are an interesting exception among the highly eusocial insects in that workers of many species contribute significantly to the production of males. Since workers remain sterile in other species of this large tropical tribe, it has been hypothesized that, in the latter species, ancestral queens have won the conflict over who produces the males. The fact that sterile workers of some species lay trophic eggs to feed the queen and display ritualized behaviours towards her during oviposition has been interpreted as an evolutionary relic of this ancient conflict. Here, I used ancestral state estimation to test whether worker reproduction is indeed the ancestral condition and worker sterility a derived state in stingless bees. Contrary to this hypothesis, data suggest that trophic egg laying was the ancestral condition, whereas selfish worker reproduction in queenright colonies evolved subsequently during stingless bee diversification. The appearance of worker reproduction in queenright conditions was tightly linked to the laying of trophic eggs, which suggests that having activated ovaries in queen presence facilitates the evolution of worker reproduction. Worker reproduction is also linked to brood cell architecture, but surprisingly not to colony size or queen-worker dimorphism. The reason for this association between brood cell architecture and worker oviposition is currently unknown. These results suggest that trophic eggs are not a relic of an ancient conflict, but a sign of overlapping interests between the queen and workers about who produces the males.
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Affiliation(s)
- Christoph Grüter
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
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10
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Norman VC, Pamminger T, Hughes WOH. The effects of disturbance threat on leaf-cutting ant colonies: a laboratory study. INSECTES SOCIAUX 2016; 64:75-85. [PMID: 28255181 PMCID: PMC5310565 DOI: 10.1007/s00040-016-0513-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 08/26/2016] [Accepted: 08/31/2016] [Indexed: 06/06/2023]
Abstract
The flexibility of organisms to respond plastically to their environment is fundamental to their fitness and evolutionary success. Social insects provide some of the most impressive examples of plasticity, with individuals exhibiting behavioral and sometimes morphological adaptations for their specific roles in the colony, such as large soldiers for nest defense. However, with the exception of the honey bee model organism, there has been little investigation of the nature and effects of environmental stimuli thought to instigate alternative phenotypes in social insects. Here, we investigate the effect of repeated threat disturbance over a prolonged (17 month) period on both behavioral and morphological phenotypes, using phenotypically plastic leaf-cutting ants (Atta colombica) as a model system. We found a rapid impact of threat disturbance on the behavioral phenotype of individuals within threat-disturbed colonies becoming more aggressive, threat responsive, and phototactic within as little as 2 weeks. We found no effect of threat disturbance on morphological phenotypes, potentially, because constraints such as resource limitation outweighed the benefit for colonies of producing larger individuals. The results suggest that plasticity in behavioral phenotypes can enable insect societies to respond to threats even when constraints prevent alteration of morphological phenotypes.
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Affiliation(s)
- V. C. Norman
- School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9QG UK
| | - T. Pamminger
- School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9QG UK
| | - W. O. H. Hughes
- School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9QG UK
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11
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Jandt JM, Gordon DM. The behavioral ecology of variation in social insects. CURRENT OPINION IN INSECT SCIENCE 2016; 15:40-44. [PMID: 27436730 DOI: 10.1016/j.cois.2016.02.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 02/22/2016] [Accepted: 02/23/2016] [Indexed: 06/06/2023]
Abstract
Understanding the ecological relevance of variation within and between colonies has been an important and recurring theme in social insect research. Recent research addresses the genomic and physiological factors and fitness effects associated with behavioral variation, within and among colonies, in regulation of activity, cognitive abilities, and aggression. Behavioral variation among colonies has consequences for survival and reproductive success that are the basis for evolutionary change.
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Affiliation(s)
- J M Jandt
- Iowa State University, Department of Ecology, Evolution, and Organismal Biology, 251 Bessey Hall, Ames, IA 50011, USA.
| | - D M Gordon
- Stanford University, Department of Biology, Gilbert Biological Sciences Building, rm 410, 371 Serra Mall, Stanford, CA 94305, USA
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12
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Segers FHID, von Zuben L, Grüter C. Local differences in parasitism and competition shape defensive investment in a polymorphic eusocial bee. Ecology 2016; 97:417-26. [PMID: 27145616 DOI: 10.1890/15-0793.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many colonial animals rely for their defense on a soldier caste. Adaptive colony demography theory predicts that colonies should flexibly adjust the investment in different worker castes depending on the colony needs. For example, colonies should invest more in defensive workers (e.g., soldiers) in dangerous environments. However, evidence for this prediction has been mixed. We combined descriptive and experimental approaches to examine whether defensive investment and worker size are adjusted to local ecology in the only known bee with polymorphic workers, Tetragonisca angustula. Colonies of this species are defended by a morphologically specialized soldier caste. Our study included three populations that differed in the density of food competition and the occurrence of a parasitic robber bee. We found that colonies coexisting with robber bees had on average 43% more soldiers defending the nest entrance, while colonies facing stronger foraging competition had soldiers that were -6-7% smaller. We then experimentally relocated colonies to areas with different levels of competition. When released from intense food competition, body sizes of guards and foragers increased. After introducing chemical robber bee cues at nest entrances, we found both a short-term and a long-term up-regulation of the number of soldiers defending the colony. Active soldier numbers remained high after the experiment for a duration equivalent to 2-3 worker life spans. How information about past parasite threat is stored in the colony is currently unknown. In summary, T. angustula adjusts both the number and the body size of active soldiers to local ecological conditions. Competitor density also affects forager (or minor) size, an important colony trait with potential community ecological consequences. Our study supports adaptive colony demography theory in a eusocial bee and highlights the importance of colony threats and competition as selective forces shaping colony phenotype.
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13
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Hammel B, Vollet-Neto A, Menezes C, Nascimento FS, Engels W, Grüter C. Soldiers in a Stingless Bee. Am Nat 2016; 187:120-9. [DOI: 10.1086/684192] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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