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Peng T, Kennedy A, Wu Y, Foitzik S, Grüter C. Early life exposure to queen mandibular pheromone mediates persistent transcriptional changes in the brain of honey bee foragers. J Exp Biol 2024; 227:jeb247516. [PMID: 38725404 DOI: 10.1242/jeb.247516] [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: 02/13/2024] [Accepted: 04/28/2024] [Indexed: 06/25/2024]
Abstract
Behavioural regulation in insect societies remains a fundamental question in sociobiology. In hymenopteran societies, the queen plays a crucial role in regulating group behaviour by affecting individual behaviour and physiology through modulation of worker gene expression. Honey bee (Apis mellifera) queens signal their presence via queen mandibular pheromone (QMP). While QMP has been shown to influence behaviour and gene expression of young workers, we know little about how these changes translate in older workers. The effects of the queen pheromone could have prolonged molecular impacts on workers that depend on an early sensitive period. We demonstrate that removal of QMP impacts long-term gene expression in the brain and antennae in foragers that were treated early in life (1 day post emergence), but not when treated later in life. Genes important for division of labour, learning, chemosensory perception and ageing were among those differentially expressed in the antennae and brain tissues, suggesting that QMP influences diverse physiological and behavioural processes in workers. Surprisingly, removal of QMP did not have an impact on foraging behaviour. Overall, our study suggests a sensitive period early in the life of workers, where the presence or absence of a queen has potentially life-long effects on transcriptional activity.
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Affiliation(s)
- Tianfei Peng
- Institute of Molecular and Organismic Evolution, Johannes Gutenberg University of Mainz, Biozentrum I, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
- College of Plant Science, Jilin University, Changchun 130062, PR China
| | - Anissa Kennedy
- Institute of Molecular and Organismic Evolution, Johannes Gutenberg University of Mainz, Biozentrum I, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Yongqiang Wu
- Institute of Molecular and Organismic Evolution, Johannes Gutenberg University of Mainz, Biozentrum I, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Susanne Foitzik
- Institute of Molecular and Organismic Evolution, Johannes Gutenberg University of Mainz, Biozentrum I, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
| | - Christoph Grüter
- Institute of Molecular and Organismic Evolution, Johannes Gutenberg University of Mainz, Biozentrum I, Hanns Dieter Hüsch Weg 15, 55128 Mainz, Germany
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2
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Moyano A, Croce AC, Scolari F. Pathogen-Mediated Alterations of Insect Chemical Communication: From Pheromones to Behavior. Pathogens 2023; 12:1350. [PMID: 38003813 PMCID: PMC10675518 DOI: 10.3390/pathogens12111350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/10/2023] [Accepted: 11/11/2023] [Indexed: 11/26/2023] Open
Abstract
Pathogens can influence the physiology and behavior of both animal and plant hosts in a manner that promotes their own transmission and dispersal. Recent research focusing on insects has revealed that these manipulations can extend to the production of pheromones, which are pivotal in chemical communication. This review provides an overview of the current state of research and available data concerning the impacts of bacterial, viral, fungal, and eukaryotic pathogens on chemical communication across different insect orders. While our understanding of the influence of pathogenic bacteria on host chemical profiles is still limited, viral infections have been shown to induce behavioral changes in the host, such as altered pheromone production, olfaction, and locomotion. Entomopathogenic fungi affect host chemical communication by manipulating cuticular hydrocarbons and pheromone production, while various eukaryotic parasites have been observed to influence insect behavior by affecting the production of pheromones and other chemical cues. The effects induced by these infections are explored in the context of the evolutionary advantages they confer to the pathogen. The molecular mechanisms governing the observed pathogen-mediated behavioral changes, as well as the dynamic and mutually influential relationships between the pathogen and its host, are still poorly understood. A deeper comprehension of these mechanisms will prove invaluable in identifying novel targets in the perspective of practical applications aimed at controlling detrimental insect species.
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Affiliation(s)
- Andrea Moyano
- Institute of Molecular Genetics, Italian National Research Council (CNR), Via Abbiategrasso 207, I-27100 Pavia, Italy; (A.M.); (A.C.C.)
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, I-27100 Pavia, Italy
| | - Anna Cleta Croce
- Institute of Molecular Genetics, Italian National Research Council (CNR), Via Abbiategrasso 207, I-27100 Pavia, Italy; (A.M.); (A.C.C.)
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, I-27100 Pavia, Italy
| | - Francesca Scolari
- Institute of Molecular Genetics, Italian National Research Council (CNR), Via Abbiategrasso 207, I-27100 Pavia, Italy; (A.M.); (A.C.C.)
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, I-27100 Pavia, Italy
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3
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Wang Z, Receveur JP, Pu J, Cong H, Richards C, Liang M, Chung H. Desiccation resistance differences in Drosophila species can be largely explained by variations in cuticular hydrocarbons. eLife 2022; 11:e80859. [PMID: 36473178 PMCID: PMC9757832 DOI: 10.7554/elife.80859] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
Maintaining water balance is a universal challenge for organisms living in terrestrial environments, especially for insects, which have essential roles in our ecosystem. Although the high surface area to volume ratio in insects makes them vulnerable to water loss, insects have evolved different levels of desiccation resistance to adapt to diverse environments. To withstand desiccation, insects use a lipid layer called cuticular hydrocarbons (CHCs) to reduce water evaporation from the body surface. It has long been hypothesized that the water-proofing capability of this CHC layer, which can confer different levels of desiccation resistance, depends on its chemical composition. However, it is unknown which CHC components are important contributors to desiccation resistance and how these components can determine differences in desiccation resistance. In this study, we used machine-learning algorithms, correlation analyses, and synthetic CHCs to investigate how different CHC components affect desiccation resistance in 50 Drosophila and related species. We showed that desiccation resistance differences across these species can be largely explained by variation in CHC composition. In particular, length variation in a subset of CHCs, the methyl-branched CHCs (mbCHCs), is a key determinant of desiccation resistance. There is also a significant correlation between the evolution of longer mbCHCs and higher desiccation resistance in these species. Given that CHCs are almost ubiquitous in insects, we suggest that evolutionary changes in insect CHC components can be a general mechanism for the evolution of desiccation resistance and adaptation to diverse and changing environments.
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Affiliation(s)
- Zinan Wang
- Department of Entomology, Michigan State UniversityEast LansingUnited States
- Ecology, Evolution, and Behavior Program, Michigan State UniversityEast LansingUnited States
| | - Joseph P Receveur
- Department of Entomology, Michigan State UniversityEast LansingUnited States
- Ecology, Evolution, and Behavior Program, Michigan State UniversityEast LansingUnited States
- Institute for Genome Sciences, University of MarylandBaltimoreUnited States
| | - Jian Pu
- Department of Entomology, Michigan State UniversityEast LansingUnited States
- College of Agriculture, Sichuan Agricultural UniversitySichuanChina
| | - Haosu Cong
- Department of Entomology, Michigan State UniversityEast LansingUnited States
| | - Cole Richards
- Department of Entomology, Michigan State UniversityEast LansingUnited States
| | - Muxuan Liang
- Department of Biostatistics, University of FloridaGainesvilleUnited States
| | - Henry Chung
- Department of Entomology, Michigan State UniversityEast LansingUnited States
- Ecology, Evolution, and Behavior Program, Michigan State UniversityEast LansingUnited States
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4
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Chung CY, Shigenobu S. Reproductive constraint in the social aphid Ceratovacuna japonica: Sterility regulation in the soldier caste of a viviparous insect. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 145:103756. [PMID: 35367587 DOI: 10.1016/j.ibmb.2022.103756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 06/14/2023]
Abstract
Differentiation of the non-reproductive caste is a unique feature of eusocial insects. Apoptosis in oocytes plays a major role in constraining the reproductivity of the eusocial insects including bees, ants, and termites. However, the regulation of reproductive constraint in non-reproductives of primitively eusocial insects other than hymenopterans and blattodeans is almost unknown. Here, we investigated the soldier sterility in a hemipteran insect, the social aphid Ceratovacuna japonica. We compared the gonads of soldiers, that are completely sterile, with those of reproductives in their viviparous development. We found that soldiers possess a pair of ovaries and the same number of germaria as reproductives, but soldiers' ovarioles were small and lacking gastrulating embryos. Unlike in most model social insects, the staining of cleaved Caspase-3 showed apoptosis in the maternal nutritive cells, rather in the oocyte, of soldier ovaries. In addition, the ubiquitous C. japonica vasa1 and piwi2a expression indicates the developmental failure of embryos in soldier ovaries. The absence of posterior nos1, an insect posterior determinant, indicates deficient posterior patterning in soldier ovarioles. Our findings suggest a different mode of reproductive constraint, which regulates both oogenesis and embryogenesis in a viviparous insect ovary. This is the first report of the reproductive constraint in a viviparous social insect at the molecular level.
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Affiliation(s)
- Chen-Yo Chung
- Laboratory of Evolutionary Genomics, National Institute for Basic Biology, Okazaki, 444-8585, Aichi, Japan
| | - Shuji Shigenobu
- Laboratory of Evolutionary Genomics, National Institute for Basic Biology, Okazaki, 444-8585, Aichi, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8585, Japan.
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5
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Effects of juvenile hormone in fertility and fertility-signaling in workers of the common wasp Vespula vulgaris. PLoS One 2021; 16:e0250720. [PMID: 33999926 PMCID: PMC8128253 DOI: 10.1371/journal.pone.0250720] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/12/2021] [Indexed: 02/07/2023] Open
Abstract
In the highly eusocial wasp, Vespula vulgaris, queens produce honest signals to alert their subordinate workers of their fertility status, and therefore they are reproductively suppressed and help in the colony. The honesty of the queen signals is likely maintained due to hormonal regulation, which affects fertility and fertility cue expression. Here, we tested if hormonal pleiotropy could support the hypothesis that juvenile hormone controls fertility and fertility signaling in workers. In addition, we aimed to check oocyte size as a proxy of fertility. To do that, we treated V. vulgaris workers with synthetic versions of juvenile hormone (JH) analogue and a JH inhibitor, methoprene and precocene, respectively. We dissected the treated females to check ovary activation and analyzed their chemical profile. Our results showed that juvenile hormone has an influence on the abundance of fertility linked compounds produced by workers, and it also showed to increase oocyte size in workers. Our results corroborate the hypothesis that juvenile hormone controls fertility and fertility signaling in workers, whereby workers are unable to reproduce without alerting other colony members of their fertility. This provides supports the hypothesis that hormonal pleiotropy contributes to keeping the queen fertility signals honest.
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6
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dos Santos Conceição Lopes B, Campbell AJ, Contrera FAL. Queen loss changes behavior and increases longevity in a stingless bee. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-2811-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Tsuchida K, Saigo T, Asai K, Okamoto T, Ando M, Ando T, Sasaki K, Yokoi K, Watanabe D, Sugime Y, Miura T. Reproductive workers insufficiently signal their reproductive ability in a paper wasp. Behav Ecol 2020. [DOI: 10.1093/beheco/arz212] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Abstract
Why workers forfeit direct reproduction is a crucial question in eusocial evolution. Worker reproduction provides an excellent opportunity to understand the mechanism of kin conflict resolution between the queen and workers. We evaluated behavioral and physiological differences among females in the paper wasp Polistes chinensis antennalis to examine why some workers reproduce under queenright conditions. Reproductive workers were old and foraged less early in the season; their cuticular hydrocarbon (CHC) profiles overlapped with those of queens but were significantly different. The distinct CHC profile of the eggs of the queen likely represented a cue for policing against those by workers. Juvenile hormone (JH) and dopamine seemed to be associated with gonadotropic function, and the JH level of reproductive workers was similar to that of the queen. The high JH level of reproductive workers likely facilitated their reproduction even under queenright conditions. Gene expression levels of the queen and reproductive workers differed only in vitellogenin. These results suggest that worker reproduction is facilitated by an increase in JH level; however, CHC is not a fertility-linked signal, but a queen-linked signal; consequently, reproductive workers without a queen-linked signal might be allowed to stay within the colony.
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Affiliation(s)
- Koji Tsuchida
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Takaharu Saigo
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Kazuyuki Asai
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Tomoko Okamoto
- Laboratory of Insect Ecology, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Masaki Ando
- Laboratory of Forest Wildlife Management, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Tetsu Ando
- Graduate School of Bio-Applications and Systems Engineering (BASE), Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan
| | - Ken Sasaki
- Graduate School of Agriculture, Honeybee Science Research Center, Tamagawa University, Machida, Tokyo, Japan
| | - Kakeru Yokoi
- Insect Genome Research Unit, Division of Applied Genetics, The National Agriculture and Research Organization, Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Dai Watanabe
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
| | - Yasuhiro Sugime
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
| | - Toru Miura
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Kanagawa, Japan
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8
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Silva-Junior EA, Paludo CR, Amaral JG, Gallon ME, Gobbo-Neto L, Nascimento FS, Lopes NP. Chemical Diversity in a Stingless Bee-Plant Symbiosis. ACS OMEGA 2019; 4:15208-15214. [PMID: 31552366 PMCID: PMC6751719 DOI: 10.1021/acsomega.9b02096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 08/20/2019] [Indexed: 06/10/2023]
Abstract
Bees are essential pollinators on earth, supporting forest equilibrium and human agriculture. The chemistry of the stingless bee-plant symbiosis is a complex and not completely understood phenomenon. Here, we combined untargeted tandem mass spectrometry, molecular networking, and multivariate statistical analysis to investigate the chemical diversity in colonies of the stingless bee Scaptotrigona depilis. Flavonoids were the most representative and diverse group of plant metabolites detected, indicating the importance of these biologically active natural products to the bees. We unveiled the metabolome, mapped the distribution of plant metabolites in stingless bee colonies, and digitized the chemical data into a public database.
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Affiliation(s)
- Eduardo A Silva-Junior
- NPPNS, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil
- Centro Universitário de Vale do Araguaia, Barra do Garças, MT 78600-000, Brazil
| | - Camila R Paludo
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
- Campus Universitário do Araguaia, Universidade Federal de Mato Grosso, Barra do Garças, MT 78600-000, Brazil
| | - Juliano G Amaral
- NPPNS, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil
- Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista, BA 45029-094, Brazil
| | - Marília E Gallon
- NPPNS, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil
| | - Leonardo Gobbo-Neto
- NPPNS, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil
| | - Fabio S Nascimento
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
| | - Norberto P Lopes
- NPPNS, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil
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9
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Gloag RS, Christie JR, Ding G, Stephens RE, Buchmann G, Oldroyd BP. Workers' sons rescue genetic diversity at the sex locus in an invasive honey bee population. Mol Ecol 2019; 28:1585-1592. [DOI: 10.1111/mec.15031] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/11/2018] [Accepted: 01/10/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Rosalyn S. Gloag
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environment Sciences University of Sydney Sydney New South Wales Australia
| | - Joshua R. Christie
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environment Sciences University of Sydney Sydney New South Wales Australia
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zürich Switzerland
| | - Guiling Ding
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environment Sciences University of Sydney Sydney New South Wales Australia
- Key Laboratory of Pollinating Insect Biology of the Ministry of Agriculture, Institute of Apicultural Research Chinese Academy of Agricultural Sciences Beijing China
| | - Ruby E. Stephens
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environment Sciences University of Sydney Sydney New South Wales Australia
| | - Gabriele Buchmann
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environment Sciences University of Sydney Sydney New South Wales Australia
| | - Benjamin P. Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, School of Life and Environment Sciences University of Sydney Sydney New South Wales Australia
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10
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Preface: Pheromone-Mediation of Female Reproduction and Reproductive Dominance in Social Species. J Chem Ecol 2019; 44:747-749. [PMID: 30009328 DOI: 10.1007/s10886-018-0992-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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11
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Combs PA, Krupp JJ, Khosla NM, Bua D, Petrov DA, Levine JD, Fraser HB. Tissue-Specific cis-Regulatory Divergence Implicates eloF in Inhibiting Interspecies Mating in Drosophila. Curr Biol 2018; 28:3969-3975.e3. [PMID: 30503619 DOI: 10.1016/j.cub.2018.10.036] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/06/2018] [Accepted: 10/12/2018] [Indexed: 12/30/2022]
Abstract
Reproductive isolation is a key component of speciation. In many insects, a major driver of this isolation is cuticular hydrocarbon pheromones, which help to identify potential intraspecific mates [1-3]. When the distributions of related species overlap, there may be strong selection on mate choice for intraspecific partners [4-9] because interspecific hybridization carries significant fitness costs [10]. Drosophila has been a key model for the investigation of reproductive isolation; although both male and female mate choices have been extensively investigated [6, 11-16], the genes underlying species recognition remain largely unknown. To explore the molecular mechanisms underlying Drosophila speciation, we measured tissue-specific cis-regulatory divergence using RNA sequencing (RNA-seq) in D. simulans × D. sechellia hybrids. By focusing on cis-regulatory changes specific to female oenocytes, the tissue that produces cuticular hydrocarbons, we rapidly identified a small number of candidate genes. We found that one of these, the fatty acid elongase eloF, broadly affects the hydrocarbons present on D. sechellia and D. melanogaster females, as well as the propensity of D. simulans males to mate with them. Therefore, cis-regulatory changes in eloF may be a major driver in the sexual isolation of D. simulans from multiple other species. Our RNA-seq approach proved to be far more efficient than quantitative trait locus (QTL) mapping in identifying candidate genes; the same framework can be used to pinpoint candidate drivers of cis-regulatory divergence in traits differing between any interfertile species.
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Affiliation(s)
- Peter A Combs
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
| | - Joshua J Krupp
- Department of Biology, University of Toronto, Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Neil M Khosla
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Dennis Bua
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Dmitri A Petrov
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Joel D Levine
- Department of Biology, University of Toronto, Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Hunter B Fraser
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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12
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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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