1
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Ge J, Shalem Y, Ge Z, Liu J, Wang X, Bloch G. Integration of information from multiple sources drives and maintains the division of labor in bumble bee colonies. CURRENT OPINION IN INSECT SCIENCE 2023; 60:101115. [PMID: 37704097 DOI: 10.1016/j.cois.2023.101115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/12/2023] [Accepted: 09/08/2023] [Indexed: 09/15/2023]
Abstract
Bumble bees are eusocial bees in which the division of labor (DoL) in reproduction and in task performance changes during their annual lifecycle. The queen monopolizes reproduction in young colonies, but at later stages, some workers start to challenge the queen and lay their own unfertilized eggs. The division of colony maintenance and growth tasks relates to worker body size. Reproduction and task performance are regulated by multiple social signals of the queen, the workers, and the brood. Here, we review recent studies suggesting that bumble bees use multiple sources of information to establish and maintain DoL in both reproduction and in task performance. Juvenile hormone (JH) is an important neuroendocrine signal involved in the regulation of DoL in reproduction but not in worker task performance. The reliance on multiple signals facilitates flexibility in face of changes in the social and geophysical environment.
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Affiliation(s)
- Jin Ge
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, PR China; CAS Centre for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, PR China
| | - Yuval Shalem
- Department of Ecology, Evolution, and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Zhuxi Ge
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, PR China; CAS Centre for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, PR China
| | - Jinpeng Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, PR China; CAS Centre for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, PR China
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, PR China; CAS Centre for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, PR China.
| | - 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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2
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Oi CA. Honeybee queen mandibular pheromone fails to regulate ovary activation in the common wasp. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:297-302. [PMID: 35028724 DOI: 10.1007/s00359-021-01531-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/21/2022]
Abstract
The queen mandibular pheromone (QMP) identified from the honeybee is responsible for maintaining reproductive division of labour in the colony, and affects multiple behaviours. Interestingly, QMP inhibits reproduction not only in honeybee workers, but also in distantly related insect species such as fruit flies and bumblebees. This study examines whether QMP also affects worker reproduction in the common wasp Vespula vulgaris. Wasp workers were exposed to one of the following treatments: QMP, wasp queen pheromone (the hydrocarbon heptacosane n-C27), or acetone (solvent-only control). After dissecting the workers, no evidence that QMP inhibits development in V. vulgaris could be found. However, this study could confirm the inhibitory effect of the hydrocarbon heptacosane on ovary activation. The reason why non-social species such as the fruit fly and social species such as bumblebees and ants respond to the QMP, while the social wasp V. vulgaris does not, is unclear. The investigation of whether olfaction is key to sensing QMP in other insect species, and the detailed study of odorant receptors in other social insects, may provide insights into the mechanisms of response to this pheromone.
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Affiliation(s)
- Cintia Akemi Oi
- Laboratory of Socioecology and Social Evolution, KU Leuven, Leuven, Belgium.
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3
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Princen SA, Van Oystaeyen A, van Zweden JS, Wenseleers T. Worker dominance and reproduction in the bumblebee Bombus terrestris: when does it pay to bare one's mandibles? Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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4
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Princen SA, Van Oystaeyen A, Petit C, van Zweden JS, Wenseleers T. Cross-activity of honeybee queen mandibular pheromone in bumblebees provides evidence for sensory exploitation. Behav Ecol 2019. [DOI: 10.1093/beheco/arz191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
AbstractThe evolutionary origin of queen pheromones (QPs), which regulate reproductive division of labor in insect societies, has been explained by two evolutionary scenarios: the sender-precursor hypothesis and the sensory exploitation hypothesis. These scenarios differ in terms of whether the signaling system was built on preadaptations on the part of either the sender queens or the receiver workers. While some social insect QPs—such as cuticular hydrocarbons—were likely derived from ancestral fertility cues and evolved according to the former theory, the honeybee’s queen mandibular pheromone (QMP) has been suggested to act directly on preexisting gene-regulatory networks linked with reproduction. This is evidenced by the fact that QMP has been shown to also inhibit ovary activation in fruit flies, thereby implying exploitation of conserved physiological pathways. To verify whether QMP has similar effects on more closely related eusocial species, we here tested for QMP cross-activity in the bumblebee Bombus terrestris. Interestingly, we found that the non-native QMP blend significantly inhibited egg laying in both worker and queen bumblebees and caused accompanying shifts in ovary activation. The native bumblebee QP pentacosane, by contrast, only inhibited the reproduction of the workers. Overall, these findings support the hypothesis that honeybee QMP likely evolved via a route of sensory exploitation. We argue that such exploitation could allow social insect queens to produce compounds that manipulate the workers to remain sterile, but that a major hurdle would be that the queens themselves would have to be immune to such compounds.
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Affiliation(s)
- Sarah A Princen
- Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution, Naamsestraat, Leuven, Belgium
| | - Annette Van Oystaeyen
- Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution, Naamsestraat, Leuven, Belgium
- Biobest Group NV, Westerlo, Belgium
| | - Clément Petit
- Biobest Group NV, Westerlo, Belgium
- Montpellier SupAgro, Montpellier, France
| | - Jelle S van Zweden
- Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution, Naamsestraat, Leuven, Belgium
| | - Tom Wenseleers
- Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution, Naamsestraat, Leuven, Belgium
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5
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Kelly CD. Rate and success of study replication in ecology and evolution. PeerJ 2019; 7:e7654. [PMID: 31565572 PMCID: PMC6743472 DOI: 10.7717/peerj.7654] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 08/10/2019] [Indexed: 01/06/2023] Open
Abstract
The recent replication crisis has caused several scientific disciplines to self-reflect on the frequency with which they replicate previously published studies and to assess their success in such endeavours. The rate of replication, however, has yet to be assessed for ecology and evolution. Here, I survey the open-access ecology and evolution literature to determine how often ecologists and evolutionary biologists replicate, or at least claim to replicate, previously published studies. I found that approximately 0.023% of ecology and evolution studies are described by their authors as replications. Two of the 11 original-replication study pairs provided sufficient statistical detail for three effects so as to permit a formal analysis of replication success. Replicating authors correctly concluded that they replicated an original effect in two cases; in the third case, my analysis suggests that the finding by the replicating authors was consistent with the original finding, contrary the conclusion of “replication failure” by the authors.
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Affiliation(s)
- Clint D Kelly
- Département des Sciences biologiques, Université du Québec à Montréal, Montréal, Quebec, Canada
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6
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Princen SA, Oliveira RC, Ernst UR, Millar JG, van Zweden JS, Wenseleers T. Honeybees possess a structurally diverse and functionally redundant set of queen pheromones. Proc Biol Sci 2019; 286:20190517. [PMID: 31213188 DOI: 10.1098/rspb.2019.0517] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Queen pheromones, which signal the presence of a fertile queen and induce workers to remain sterile, play a key role in regulating reproductive division of labour in insect societies. In the honeybee, volatiles produced by the queen's mandibular glands have been argued to act as the primary sterility-inducing pheromones. This contrasts with evidence from other groups of social insects, where specific queen-characteristic hydrocarbons present on the cuticle act as conserved queen signals. This led us to hypothesize that honeybee queens might also employ cuticular pheromones to stop workers from reproducing. Here, we support this hypothesis with the results of bioassays with synthetic blends of queen-characteristic alkenes, esters and carboxylic acids. We show that all these compound classes suppress worker ovary development, and that one of the blends of esters that we used was as effective as the queen mandibular pheromone (QMP) mix. Furthermore, we demonstrate that the two main QMP compounds 9-ODA and 9-HDA tested individually were as effective as the blend of all four major QMP compounds, suggesting considerable signal redundancy. Possible adaptive reasons for the observed complexity of the honeybee queen signal mix are discussed.
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Affiliation(s)
- Sarah A Princen
- 1 Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution , Leuven , Belgium
| | - Ricardo Caliari Oliveira
- 1 Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution , Leuven , Belgium
| | - Ulrich R Ernst
- 1 Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution , Leuven , Belgium.,2 Department of Biology, KU Leuven, Functional Genomics and Proteomics Group , Leuven , Belgium.,3 Institute for Evolution and Biodiversity, University of Münster, Molecular Evolution and Sociobiology Group , Münster , Germany
| | - Jocelyn G Millar
- 4 Departments of Entomology and Chemistry, University of California , Riverside, CA 92521 , USA
| | - Jelle S van Zweden
- 1 Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution , Leuven , Belgium
| | - Tom Wenseleers
- 1 Department of Biology, KU Leuven, Laboratory of Socioecology and Social Evolution , Leuven , Belgium
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7
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Comparative transcriptomics of social insect queen pheromones. Nat Commun 2019; 10:1593. [PMID: 30962449 PMCID: PMC6453924 DOI: 10.1038/s41467-019-09567-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 03/19/2019] [Indexed: 12/18/2022] Open
Abstract
Queen pheromones are chemical signals that mediate reproductive division of labor in eusocial animals. Remarkably, queen pheromones are composed of identical or chemically similar compounds in some ants, wasps and bees, even though these taxa diverged >150MYA and evolved queens and workers independently. Here, we measure the transcriptomic consequences of experimental exposure to queen pheromones in workers from two ant and two bee species (genera: Lasius, Apis, Bombus), and test whether they are similar across species. Queen pheromone exposure affected transcription and splicing at many loci. Many genes responded consistently in multiple species, and the set of pheromone-sensitive genes was enriched for functions relating to lipid biosynthesis and transport, olfaction, production of cuticle, oogenesis, and histone (de)acetylation. Pheromone-sensitive genes tend to be evolutionarily ancient, positively selected, peripheral in the gene coexpression network, hypomethylated, and caste-specific in their expression. Our results reveal how queen pheromones achieve their effects, and suggest that ants and bees use similar genetic modules to achieve reproductive division of labor.
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8
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Almond EJ, Huggins TJ, Crowther LP, Parker JD, Bourke AFG. Queen Longevity and Fecundity Affect Conflict with Workers over Resource Inheritance in a Social Insect. Am Nat 2018; 193:256-266. [PMID: 30720369 DOI: 10.1086/701299] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Resource inheritance is a major source of conflict in animal societies. However, the assumptions and predictions of models of conflict over resource inheritance have not been systematically tested within a single system. We developed an inclusive fitness model for annual eusocial Hymenoptera that predicts a zone of conflict in which future reproductive workers are selected to enforce nest inheritance before the queen is selected to cede the nest. We experimentally tested key elements of this model in the bumblebee Bombus terrestris. In colonies from which queens were sequentially removed, queen tenure was significantly negatively associated with worker male production, confirming that workers gain direct fitness by usurping the queen. In unmanipulated colonies, queen fecundity decreased significantly over the latter part of the colony cycle, confirming that workers' indirect fitness from maintaining queens declines over time. Finally, in an experiment simulating loss of queen fecundity by removal of queens' eggs, worker-to-queen aggression increased significantly and aggressive workers were significantly more likely to become egg layers, consistent with workers monitoring queen fecundity to assess the net benefit of future reproduction. Overall, by upholding key assumptions and predictions of the model, our results provide novel empirical support for kin-selected conflict over resource inheritance.
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9
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Amsalem E, Grozinger CM. The importance of holistically evaluating data: a comment on Holman. Behav Ecol 2018. [DOI: 10.1093/beheco/ary082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Etya Amsalem
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
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10
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Affiliation(s)
- Luke Holman
- School of BioSciences, University of Melbourne, Royal Parade, Melbourne, VIC 3010, Australia
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11
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Li B, Hou L, Zhu D, Xu X, An S, Wang X. Identification and caste-dependent expression patterns of DNA methylation associated genes in Bombus terrestris. Sci Rep 2018; 8:2332. [PMID: 29402971 PMCID: PMC5799256 DOI: 10.1038/s41598-018-20831-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 01/24/2018] [Indexed: 11/09/2022] Open
Abstract
DNA methylation has been proposed to play critical roles in caste fate and behavioral plasticity in bumblebees, however, there is little information on its regulatory mechanisms. Here, we identified six important genes mediating the modification of DNA methylation and determined their expression patterns in the bumblebee Bombus terrestris. There is a complete functional DNA methylation system, including four DNA methyltransferases (DNMT1a, DNMT1b, DNMT2, and DNMT3), a DNA demethylase (Ten-eleven translocation), and a methyl-CpG-binding domain protein in B. terrestris. Most of these genes were highly expressed in fat bodies and gonads but lowly expressed in antennae and brains of bumblebee adults. Besides, these genes exhibited caste-specific expression patterns in bumblebees, with higher transcription levels in queens than workers and drones. Whereas their expression levels showed no remarkable difference in queenright and queenless workers. These results suggested potential roles of DNA methylation-related genes in caste differentiation in bumblebees.
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Affiliation(s)
- Beibei Li
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Li Hou
- Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Dan Zhu
- Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xilian Xu
- Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
| | - Shiheng An
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China.
| | - Xianhui Wang
- Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
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12
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Olejarz J, Veller C, Nowak MA. The evolution of queen control over worker reproduction in the social Hymenoptera. Ecol Evol 2017; 7:8427-8441. [PMID: 29075460 PMCID: PMC5648666 DOI: 10.1002/ece3.3324] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 07/12/2017] [Accepted: 07/20/2017] [Indexed: 02/06/2023] Open
Abstract
A trademark of eusocial insect species is reproductive division of labor, in which workers forego their own reproduction while the queen produces almost all offspring. The presence of the queen is key for maintaining social harmony, but the specific role of the queen in the evolution of eusociality remains unclear. A long‐discussed scenario is that a queen either behaviorally or chemically sterilizes her workers. However, the demographic and ecological conditions that enable such manipulation are still debated. We study a simple model of evolutionary dynamics based on haplodiploid genetics. Our model is set in the commonly observed case where workers have lost the ability to lay female (diploid) eggs by mating, but retain the ability to lay male (haploid) eggs. We consider a mutation that acts in a queen, causing her to control the reproductive behavior of her workers. Our mathematical analysis yields precise conditions for the evolutionary emergence and stability of queen‐induced worker sterility. These conditions do not depend on the queen's mating frequency. We find that queen control is always established if it increases colony reproductive efficiency, but can evolve even if it decreases colony efficiency. We further derive the conditions under which queen control is evolutionarily stable against invasion by mutant workers who have recovered the ability to lay male eggs.
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Affiliation(s)
- Jason Olejarz
- Program for Evolutionary Dynamics Harvard University Cambridge MA USA
| | - Carl Veller
- Program for Evolutionary Dynamics Harvard University Cambridge MA USA.,Department of Organismic and Evolutionary Biology Harvard University Cambridge MA USA
| | - Martin A Nowak
- Program for Evolutionary Dynamics Harvard University Cambridge MA USA.,Department of Organismic and Evolutionary Biology Harvard University Cambridge MA USA.,Department of Mathematics Harvard University Cambridge MA USA
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13
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Gévar J, Bagnères AG, Christidès JP, Darrouzet E. Chemical Heterogeneity in Inbred European Population of the Invasive Hornet Vespa velutina nigrithorax. J Chem Ecol 2017; 43:763-777. [PMID: 28762003 DOI: 10.1007/s10886-017-0874-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 07/18/2017] [Accepted: 07/21/2017] [Indexed: 11/30/2022]
Abstract
Invasive social insect populations that have been introduced to a new environment through a limited number of introduction events generally exhibit reduced variability in their chemical signatures (cuticular hydrocarbons) compared to native populations of the same species. The reduced variability in these major recognition cues could be caused by a reduction of genetic diversity due to a genetic bottleneck. This hypothesis was tested in an inbred European population of the invasive hornet Vespa velutina nigrithorax. Our results show that, in spite of the limited amount of genetic diversity present in the European population, the chemical signatures of individuals were highly heterogeneous according to their caste, sex, and colony origin. In queens, some specific saturated and unsaturated hydrocarbons were identified. These results suggest that epigenetic and/or environmental factors could play a role in modifying cuticular hydrocarbon profiles in this introduced hornet population despite the observed reduction of genetic diversity.
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Affiliation(s)
- J Gévar
- IRBI, UMR CNRS 7261, University François Rabelais of Tours, Parc de Grandmont, 37200, Tours, France
| | - A-G Bagnères
- IRBI, UMR CNRS 7261, University François Rabelais of Tours, Parc de Grandmont, 37200, Tours, France
| | - J-P Christidès
- IRBI, UMR CNRS 7261, University François Rabelais of Tours, Parc de Grandmont, 37200, Tours, France
| | - E Darrouzet
- IRBI, UMR CNRS 7261, University François Rabelais of Tours, Parc de Grandmont, 37200, Tours, France.
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14
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Smith AA, Liebig J. The evolution of cuticular fertility signals in eusocial insects. CURRENT OPINION IN INSECT SCIENCE 2017; 22:79-84. [PMID: 28805643 DOI: 10.1016/j.cois.2017.05.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/17/2017] [Accepted: 05/19/2017] [Indexed: 05/19/2023]
Abstract
A reproductive division of labor is a definitive characteristic of eusocial insect societies and it requires a means through which colony members can assess the presence and productivity of reproductive individuals. Cuticular hydrocarbons are the primary means of doing so across eusocial hymenopterans. However, recent experimental work presents conflicting views on how these chemical signals function, are interpreted by workers, and evolve. These recent advances include demonstrations of hydrocarbons as evolutionarily conserved 'queen pheromones' and as species-divergent 'fertility signals' used by both queens and workers. In this review, we synthesize conflicting studies into an evolutionary framework suggesting a transition of reproductive communication from cue-like signature mixtures, to learned fertility signals, to innate queen pheromones that evolved across eusocial insects.
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Affiliation(s)
- Adrian A Smith
- Research & Collections, North Carolina Museum of Natural Sciences, 11 W. Jones St, Raleigh, NC 27601, USA; Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.
| | - Jürgen Liebig
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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15
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Abstract
Reproduction in social insect societies reflects a delicate balance between cooperation and conflict over offspring production, and worker reproduction is widespread even in species showing strong reproductive skew in favor of the queen. To navigate these conflicts, workers are predicted to develop the means to estimate the queen's fecundity - potentially through behavioral and/or chemical cues - and to adjust their reproduction to maximize their fitness. Here, we introduced bumble bee, Bombus impatiens, workers to queens of different mating and reproductive status and examined worker reproduction and expression levels of two genes which were previously shown to be sensitive to the presence of the queen, vitellogenin and Krüppel-homolog 1. We further explored whether the queen's chemical secretion alone is sufficient to regulate worker reproduction, aggression and gene expression. We found that worker ovary activation was inhibited only in the presence of egg-laying queens, regardless of their mating status. Workers reared in the presence of newly-mated queens showed intermediate vitellogenin expression levels relative to workers reared with mated egg-laying and virgin queens. However, none of the whole-body chemical extracts of any of the queen treatment groups affected ovary activation, aggressive behavior, or gene expression in workers. Our findings indicate that only the presence of a freely-behaving, egg-laying queen can fully inhibit worker reproduction. It remains to be determined if workers detect differences in queen mating status and fecundity through differences in the queens' behavior alone or through the queen's behavior in concert with fertility signals.
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16
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Holman L, van Zweden JS, Oliveira RC, van Oystaeyen A, Wenseleers T. Conserved queen pheromones in bumblebees: a reply to Amsalem et al. PeerJ 2017; 5:e3332. [PMID: 28533978 PMCID: PMC5436554 DOI: 10.7717/peerj.3332] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 04/18/2017] [Indexed: 11/25/2022] Open
Abstract
In a recent study, Amsalem, Orlova & Grozinger (2015) performed experiments with Bombus impatiens bumblebees to test the hypothesis that saturated cuticular hydrocarbons are evolutionarily conserved signals used to regulate reproductive division of labor in many Hymenopteran social insects. They concluded that the cuticular hydrocarbon pentacosane (C25), previously identified as a queen pheromone in a congeneric bumblebee, does not affect worker reproduction in B. impatiens. Here we discuss some shortcomings of Amsalem et al.’s study that make its conclusions unreliable. In particular, several confounding effects may have affected the results of both experimental manipulations in the study. Additionally, the study’s low sample sizes (mean n per treatment = 13.6, range: 4–23) give it low power, not 96–99% power as claimed, such that its conclusions may be false negatives. Inappropriate statistical tests were also used, and our reanalysis found that C25 substantially reduced and delayed worker egg laying in B. impatiens. We review the evidence that cuticular hydrocarbons act as queen pheromones, and offer some recommendations for future queen pheromone experiments.
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Affiliation(s)
- Luke Holman
- School of Biosciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Jelle S van Zweden
- Laboratory of Socioecology and Social Evolution, Zoological Institute, University of Leuven, Leuven, Belgium
| | - Ricardo C Oliveira
- Laboratory of Socioecology and Social Evolution, Zoological Institute, University of Leuven, Leuven, Belgium
| | | | - Tom Wenseleers
- Laboratory of Socioecology and Social Evolution, Zoological Institute, University of Leuven, Leuven, Belgium
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17
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Oliveira RC, Vollet-Neto A, Akemi Oi C, van Zweden JS, Nascimento F, Sullivan Brent C, Wenseleers T. Hormonal pleiotropy helps maintain queen signal honesty in a highly eusocial wasp. Sci Rep 2017; 7:1654. [PMID: 28490760 PMCID: PMC5431770 DOI: 10.1038/s41598-017-01794-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 04/10/2017] [Indexed: 01/17/2023] Open
Abstract
In insect societies, both queens and workers produce chemicals that reliably signal caste membership and reproductive status. The mechanisms that help to maintain the honesty of such queen and fertility signals, however, remain poorly studied. Here we test if queen signal honesty could be based on the shared endocrine control of queen fertility and the production of specific signals. In support of this “hormonal pleiotropy” hypothesis, we find that in the common wasp, application of methoprene (a juveline hormone analogue) caused workers to acquire a queen-like cuticular hydrocarbon profile, resulting in the overproduction of known queen pheromones as well as some compounds typically linked to worker fertility. By contrast, administration of precocene-I (a JH inhibitor) had a tendency to have the opposite effect. Furthermore, a clear gonadotropic effect of JH in queens was suggested by the fact that circulating levels of JH were ca. 2 orders of magnitude higher in queens than those in workers and virgin, non-egg-laying queens, even if methoprene or precocene treatment did not affect the ovary development of workers. Overall, these results suggest that queen signal honesty in this system is maintained by queen fertility and queen signal production being under shared endocrine control.
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Affiliation(s)
- Ricardo Caliari Oliveira
- Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Leuven, Belgium.
| | - Ayrton Vollet-Neto
- Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Leuven, Belgium.,Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Cintia Akemi Oi
- Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Leuven, Belgium
| | - Jelle S van Zweden
- Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Leuven, Belgium
| | - Fabio Nascimento
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Tom Wenseleers
- Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Leuven, Belgium
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18
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Holman L, Trontti K, Helanterä H. Queen pheromones modulate DNA methyltransferase activity in bee and ant workers. Biol Lett 2017; 12:20151038. [PMID: 26814223 DOI: 10.1098/rsbl.2015.1038] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
DNA methylation is emerging as an important regulator of polyphenism in the social insects. Research has concentrated on differences in methylation between queens and workers, though we hypothesized that methylation is involved in mediating other flexible phenotypes, including pheromone-dependent changes in worker behaviour and physiology. Here, we find that exposure to queen pheromone affects the expression of two DNA methyltransferase genes in Apis mellifera honeybees and in two species of Lasius ants, but not in Bombus terrestris bumblebees. These results suggest that queen pheromones influence the worker methylome, pointing to a novel proximate mechanism for these key social signals.
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Affiliation(s)
- Luke Holman
- Division of Ecology, Evolution & Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Kalevi Trontti
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki 00014, Finland Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, PO Box 65, Helsinki 00014, Finland
| | - Heikki Helanterä
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, PO Box 65, Helsinki 00014, Finland Tvärminne Zoological Station, J. A. Palménin tie 260, Hanko 10900, Finland
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19
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Conservation of Queen Pheromones Across Two Species of Vespine Wasps. J Chem Ecol 2016; 42:1175-1180. [PMID: 27722875 DOI: 10.1007/s10886-016-0777-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/21/2016] [Accepted: 09/19/2016] [Indexed: 02/05/2023]
Abstract
Social insects are known for their reproductive division of labor between queens and workers, whereby queens lay the majority of the colony's eggs, and workers engage mostly in non-reproductive tasks. Queens produce pheromones that signal their presence and fertility to workers, which in turn generally remain sterile. Recently, it has been discovered that specific queen-characteristic cuticular hydrocarbons (CHCs) function as queen pheromones across multiple lineages of social insects. In the common wasp, Vespula vulgaris, several long-chain linear alkanes and 3-methylalkanes were shown to act as queen signals. Here, we describe similar bioassays with a related species of highly eusocial vespine wasp, the Saxon wasp, Dolichovespula saxonica. We show that a blend of queen-characteristic hydrocarbons that are structurally related to those of the common wasp inhibit worker reproduction, suggesting conservation of queen pheromones across social wasps. Overall, our results highlight the central importance of CHCs in chemical communication among social insects in general, and as conserved queen pheromones in these social wasps in particular.
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20
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Padilla M, Amsalem E, Altman N, Hefetz A, Grozinger CM. Chemical communication is not sufficient to explain reproductive inhibition in the bumblebee Bombus impatiens. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160576. [PMID: 27853577 PMCID: PMC5099002 DOI: 10.1098/rsos.160576] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/12/2016] [Indexed: 05/29/2023]
Abstract
Reproductive division of labour is a hallmark of eusociality, but disentangling the underlying proximate mechanisms can be challenging. In bumblebees, workers isolated from the queen can activate their ovaries and lay haploid, male eggs. We investigated if volatile, contact, visual or behavioural cues produced by the queen or brood mediate reproductive dominance in Bombus impatiens. Exposure to queen-produced volatiles, brood-produced volatiles and direct contact with pupae did not reduce worker ovary activation; only direct contact with the queen could reduce ovary activation. We evaluated behaviour, physiology and gene expression patterns in workers that were reared in chambers with all stages of brood and a free queen, caged queen (where workers could contact the queen, but the queen was unable to initiate interactions) or no queen. Workers housed with a caged queen or no queen fully activated their ovaries, whereas ovary activation in workers housed with a free queen was completely inhibited. The caged queen marginally reduced worker aggression and expression of an aggression-associated gene relative to queenless workers. Thus, queen-initiated behavioural interactions appear necessary to establish reproductive dominance. Queen-produced chemical cues may function secondarily in a context-specific manner to augment behavioural cues, as reliable or honest signal.
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Affiliation(s)
- Mario Padilla
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Etya Amsalem
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Naomi Altman
- Department of Statistics, Huck Institutes of Life Sciences, Clinical and Translational Sciences Institute, The Pennsylvania State University, University Park, PA 16802, USA
| | - Abraham Hefetz
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Christina M. Grozinger
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA
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21
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Amsalem E, Orlova M, Grozinger CM. A conserved class of queen pheromones? Re-evaluating the evidence in bumblebees (Bombus impatiens). Proc Biol Sci 2016; 282:20151800. [PMID: 26490791 DOI: 10.1098/rspb.2015.1800] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The regulation of reproductive division of labour is a key component in the evolution of social insects. Chemical signals are important mechanisms to regulate worker reproduction, either as queen-produced pheromones that coercively inhibit worker reproduction or as queen signals that honestly advertise her fecundity. A recent study suggested that a conserved class of hydrocarbons serve as queen pheromones across three independent origins of eusociality. In bumblebees (Bombus terrestris), pentacosane (C25) was suggested to serve as a queen pheromone. Here, we repeat these studies using a different species of bumblebee (Bombus impatiens) with a more controlled experimental design. Instead of dequeened colonies, we used same-aged, three-worker queenless groups comprising either experienced or naive workers (with/without adult exposure to queen pheromone). We quantified three hydrocarbons (C23, C25 and C27) on the cuticular surfaces of females and tested their effects on the two worker types. Our results indicate differences in responses of naive and experienced workers, genetic effects on worker reproduction, and general effects of hydrocarbons and duration of egg laying on ovary resorption rates. However, we found no evidence to support the theory that a conserved class of hydrocarbons serve as queen pheromones or queen signals in Bombus impatiens.
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Affiliation(s)
- Etya Amsalem
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Margarita Orlova
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA
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22
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Caliari Oliveira R, Oi CA, do Nascimento MMC, Vollet-Neto A, Alves DA, Campos MC, Nascimento F, Wenseleers T. The origin and evolution of queen and fertility signals in Corbiculate bees. BMC Evol Biol 2015; 15:254. [PMID: 26573687 PMCID: PMC4647589 DOI: 10.1186/s12862-015-0509-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/12/2015] [Indexed: 12/13/2022] Open
Abstract
Background In social Hymenoptera (ants, bees and wasps), various chemical compounds present on the cuticle have been shown to act as fertility signals. In addition, specific queen-characteristic hydrocarbons have been implicated as sterility-inducing queen signals in ants, wasps and bumblebees. In Corbiculate bees, however, the chemical nature of queen-characteristic and fertility-linked compounds appears to be more diverse than in ants and wasps. Moreover, it remains unknown how queen signals evolved across this group and how they might have been co-opted from fertility signals in solitary ancestors. Results Here, we perform a phylogenetic analysis of fertility-linked compounds across 16 species of solitary and eusocial bee species, comprising both literature data as well as new primary data from a key solitary outgroup species, the oil-collecting bee Centris analis, and the highly eusocial stingless bee Scaptotrigona depilis. Our results demonstrate the presence of fertility-linked compounds belonging to 12 different chemical classes. In addition, we find that some classes of compounds (linear and branched alkanes, alkenes, esters and fatty acids) were already present as fertility-linked signals in the solitary ancestors of Corbiculate bees, while others appear to be specific to certain species. Conclusion Overall, our results suggest that queen signals in Corbiculate bees are likely derived from ancestral fertility-linked compounds present in solitary bees that lacked reproductive castes. These original fertility-linked cues or signals could have been produced either as a by-product of ovarian activation or could have served other communicative purposes, such as in mate recognition or the regulation of egg-laying. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0509-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ricardo Caliari Oliveira
- Department of Biology, Laboratory of Socioecology & Social Evolution, KU Leuven, Leuven, Belgium.
| | - Cintia Akemi Oi
- Department of Biology, Laboratory of Socioecology & Social Evolution, KU Leuven, Leuven, Belgium.
| | | | - Ayrton Vollet-Neto
- Department of Biology, Laboratory of Behavioral Ecology, FFCLRP, University of São Paulo, Ribeirão Preto, Brazil.
| | - Denise Araujo Alves
- Department of Entomology and Acarology, ESALQ, University of São Paulo, Piracicaba, Brazil.
| | - Maria Claudia Campos
- Department of Biology, Laboratory of Behavioral Ecology, FFCLRP, University of São Paulo, Ribeirão Preto, Brazil.
| | - Fabio Nascimento
- Department of Biology, Laboratory of Behavioral Ecology, FFCLRP, University of São Paulo, Ribeirão Preto, Brazil.
| | - Tom Wenseleers
- Department of Biology, Laboratory of Socioecology & Social Evolution, KU Leuven, Leuven, Belgium.
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23
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Oi CA, van Zweden JS, Oliveira RC, Van Oystaeyen A, Nascimento FS, Wenseleers T. The origin and evolution of social insect queen pheromones: Novel hypotheses and outstanding problems. Bioessays 2015; 37:808-21. [PMID: 25916998 DOI: 10.1002/bies.201400180] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Queen pheromones, which signal the presence of a fertile queen and induce daughter workers to remain sterile, are considered to play a key role in regulating the reproductive division of labor of insect societies. Although queen pheromones were long thought to be highly taxon-specific, recent studies have shown that structurally related long-chain hydrocarbons act as conserved queen signals across several independently evolved lineages of social insects. These results imply that social insect queen pheromones are very ancient and likely derived from an ancestral signalling system that was already present in their common solitary ancestors. Based on these new insights, we here review the literature and speculate on what signal precursors social insect queen pheromones may have evolved from. Furthermore, we provide compelling evidence that these pheromones should best be seen as honest signals of fertility as opposed to suppressive agents that chemically sterilize the workers against their own best interests.
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Affiliation(s)
- Cintia A Oi
- Department of Biology, Laboratory of Socioecology & Social Evolution, University of Leuven, Leuven, Belgium
| | - Jelle S van Zweden
- Department of Biology, Laboratory of Socioecology & Social Evolution, University of Leuven, Leuven, Belgium
| | - Ricardo C Oliveira
- Department of Biology, Laboratory of Socioecology & Social Evolution, University of Leuven, Leuven, Belgium
| | - Annette Van Oystaeyen
- Department of Biology, Laboratory of Socioecology & Social Evolution, University of Leuven, Leuven, Belgium
| | - Fabio S Nascimento
- Departamento de Biologia da Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil
| | - Tom Wenseleers
- Department of Biology, Laboratory of Socioecology & Social Evolution, University of Leuven, Leuven, Belgium
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