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Ren Q, Ma L, Zhang X, Chen L, Mao Z, Li D, Zhang L, Jiang X. Effect of Juvenile Hormone on Worker Behavioral Transition in the Red Imported Fire Ant, Solenopsis invicta (Hymenoptera: Formicidae). INSECTS 2023; 14:934. [PMID: 38132607 PMCID: PMC10743645 DOI: 10.3390/insects14120934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023]
Abstract
The division of labor among workers is a defining characteristic of social insects and plays a pivotal role in enhancing the competitive advantage of their colony. Juvenile hormone (JH) has long been hypothesized to be the essential driver in regulating the division of labor due to its ability to accelerate behavioral transitions in social insects, such as honeybees. The regulation of behavioral transitions by JH in the red imported fire ant (RIFA), Solenopsis invicta, a typical social pest, is unclear. Through video capture and analysis, we investigated the effects of the juvenile hormone analogue (JHA) methoprene on brood care, phototaxis behavior, and threat responsiveness of RIFA nurse workers. Our results showed that the JHA application significantly reduced the time and frequency of brood care behavior by nurse workers while increasing their walking distance and activity time in the light area. Additionally, the application of JHA made ants become excited, indicating a significant improvement in their activity level (movement distance, time, and speed). Furthermore, it was observed that the application of JHA did not affect the threat responsiveness of nurse workers towards stimuli (nestmates or non-nestmates). Our study demonstrates that the application of JHA reduced brood care behavior and enhanced phototaxis in nurse workers, which may reveal the role of JH in facilitating behavioral transitions in RIFA from intranidal tasks to extranidal activity. This study provides an experimental basis for further elucidating the mechanism underlying the division of labor in social insects.
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Affiliation(s)
- Qilin Ren
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100193, China; (Q.R.); (L.M.); (X.Z.)
| | - Lin Ma
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100193, China; (Q.R.); (L.M.); (X.Z.)
| | - Xiaolong Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100193, China; (Q.R.); (L.M.); (X.Z.)
| | - Libiao Chen
- Guangxi Green City Pest Control Technology Co., Ltd., Nanning 530007, China;
| | - Zhigang Mao
- Guangxi Beitou Urban Environmental Governance Group Co., Ltd., Nanning 530000, China; (Z.M.); (D.L.)
| | - Dongdong Li
- Guangxi Beitou Urban Environmental Governance Group Co., Ltd., Nanning 530000, China; (Z.M.); (D.L.)
| | - Lei Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100193, China; (Q.R.); (L.M.); (X.Z.)
| | - Xingfu Jiang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100193, China; (Q.R.); (L.M.); (X.Z.)
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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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Wynants E, Van Dun C, Lenaerts N, Princen SA, Tuyttens E, Shpigler HY, Wenseleers T, Van Oystaeyen A. Uncovering the role of juvenile hormone in ovary development and egg laying in bumble bees. JOURNAL OF INSECT PHYSIOLOGY 2023; 150:104557. [PMID: 37625783 DOI: 10.1016/j.jinsphys.2023.104557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/18/2023] [Accepted: 08/21/2023] [Indexed: 08/27/2023]
Abstract
Juvenile hormone (JH) regulates developmental and physiological processes in insects. In bumble bees, the hormone acts as a gonadotropin that mediates ovary development, but the exact physiological pathways involved in ovary activation and subsequent egg laying are poorly understood. In this study, we examine how queen hibernation state, caste, and species impact the gonadotropic effect of JH in bumble bee queens through methoprene (JH analogue) application. We extend previous research by assessing queen egg laying and colony initiation, alongside ovary development. Furthermore, we compared sensitivity of workers of both species to the juvenile hormone's gonadotropic effect. In both bumble bee species, the ovaries of hibernated queens were developed five to six days after breaking diapause, regardless of methoprene treatment. By contrast, methoprene did have a stimulatory effect on ovary development in non-hibernated queens. The dose needed to obtain this effect was higher in B. impatiens. Methoprene did not have gonadotropic effects in callow workers of both species. These results indicate that the physiological effect of exogenous methoprene application varies according to species, caste and hibernation status. Interestingly, despite gonadotropic effects in non-hibernated queens, oviposition was not accelerated by JH. This suggests that JH alone is insufficient to induce egg laying and that an additional stimulus, which is naturally present in hibernated queens, is required. Consequently, our findings indicate that other physiological processes, beyond a rise in JH alone, are required for oviposition and colony initiation.
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Affiliation(s)
- Enya Wynants
- Biobest Group NV, Research and Development, 2260 Westerlo, Belgium
| | - Cédric Van Dun
- Laboratory of Socio-ecology and Social Evolution, University of Leuven, 3000 Leuven, Belgium
| | - Nancy Lenaerts
- Biobest Group NV, Research and Development, 2260 Westerlo, Belgium
| | - Sarah A Princen
- Biobest Group NV, Research and Development, 2260 Westerlo, Belgium
| | - Ella Tuyttens
- Biobest Group NV, Research and Development, 2260 Westerlo, Belgium
| | - Hagai Y Shpigler
- Department of Entomology, Agricultural Research Organization, The Volcani Institute, Rishon LeZion, Israel
| | - Tom Wenseleers
- Laboratory of Socio-ecology and Social Evolution, University of Leuven, 3000 Leuven, Belgium
| | - Annette Van Oystaeyen
- Biobest Group NV, Research and Development, 2260 Westerlo, Belgium; Laboratory of Socio-ecology and Social Evolution, University of Leuven, 3000 Leuven, Belgium.
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4
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Starkey J, Hawkings C, Tamborindeguy C. Influence of juvenile hormone analog on behavior in the red imported fire ant, Solenopsis invicta. Sci Rep 2023; 13:14726. [PMID: 37679373 PMCID: PMC10485025 DOI: 10.1038/s41598-023-41540-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 08/28/2023] [Indexed: 09/09/2023] Open
Abstract
Division of labor is a hallmark characteristic of social insect colonies. While it is understood that worker differentiation is regulated through either the queen or her brood, the understanding of the physiology behind task regulation varies within social species. Studies in eusocial insects have shown that juvenile hormone (JH) is associated with division of labor and the onset of foraging tasks. Although, outside of a few key species, this interaction has yet to be elucidated in the red imported fire ant, Solenopsis invicta. In this study, we evaluated the role of a JH analog, S-hydroprene in worker task transition in Solenopsis invicta. S-hydroprene was applied to nurses to observe behavioral changes. S-hyroprene application to nurses did not affect phototaxis, but there was a shift in behavior from internal, nest-based behaviors to external, foraging-based behaviors. These results show that JH may be implicated in worker task transition in S. invicta and may function similarly as it does in other eusocial insects.
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Affiliation(s)
- Jesse Starkey
- Department of Entomology, Texas A&M University, 412 Heep Center, College Station, TX, 77843, USA
| | - Chloe Hawkings
- Department of Entomology, Texas A&M University, 412 Heep Center, College Station, TX, 77843, USA
- Department of Entomology, Rutgers University, Thompson Hall, New Brunswick, NJ, 08901, USA
| | - Cecilia Tamborindeguy
- Department of Entomology, Texas A&M University, 412 Heep Center, College Station, TX, 77843, USA.
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5
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Collins DH, Prince DC, Donelan JL, Chapman T, Bourke AFG. Costs of reproduction are present but latent in eusocial bumblebee queens. BMC Biol 2023; 21:153. [PMID: 37430246 DOI: 10.1186/s12915-023-01648-5] [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: 08/25/2022] [Accepted: 06/12/2023] [Indexed: 07/12/2023] Open
Abstract
BACKGROUND The standard evolutionary theory of ageing proposes that ageing occurs because of a trade-off between reproduction and longevity. Eusocial insect queens exhibit positive fecundity-longevity associations and so have been suggested to be counter-examples through not expressing costs of reproduction and through remodelling conserved genetic and endocrine networks regulating ageing and reproduction. If so, eusocial evolution from solitary ancestors with negative fecundity-longevity associations must have involved a stage at which costs of reproduction were suppressed and fecundity and longevity became positively associated. Using the bumblebee (Bombus terrestris), we experimentally tested whether queens in annual eusocial insects at an intermediate level of eusocial complexity experience costs of reproduction, and, using mRNA-seq, the extent to which they exhibit a remodelling of relevant genetic and endocrine networks. Specifically, we tested whether costs of reproduction are present but latent, or whether a remodelling of relevant genetic and endocrine networks has already occurred allowing queens to reproduce without costs. RESULTS We experimentally increased queens' costs of reproduction by removing their eggs, which caused queens to increase their egg-laying rate. Treatment queens had significantly reduced longevity relative to control queens whose egg-laying rate was not increased. Reduced longevity in treatment queens was not caused by increased worker-to-queen aggression or by increased overall activity in queens. In addition, treatment and control queens differed in age-related gene expression based on mRNA-seq in both their overall expression profiles and the expression of ageing-related genes. Remarkably, these differences appeared to occur principally with respect to relative age, not chronological age. CONCLUSIONS This study represents the first simultaneously phenotypic and transcriptomic experimental test for a longevity cost of reproduction in eusocial insect queens. The results support the occurrence of costs of reproduction in annual eusocial insects of intermediate social complexity and suggest that reproductive costs are present but latent in queens of such species, i.e. that these queens exhibit condition-dependent positive fecundity-longevity associations. They also raise the possibility that a partial remodelling of genetic and endocrine networks underpinning ageing may have occurred in intermediately eusocial species such that, in unmanipulated conditions, age-related gene expression depends more on chronological than relative age.
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Affiliation(s)
- David H Collins
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - David C Prince
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Jenny L Donelan
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Tracey Chapman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Andrew F G Bourke
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
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Lu J, Zhang H, Wang Q, Huang X. Genome-Wide Identification and Expression Pattern of Cytochrome P450 Genes in the Social Aphid Pseudoregma bambucicola. INSECTS 2023; 14:212. [PMID: 36835781 PMCID: PMC9966863 DOI: 10.3390/insects14020212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/10/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
Cytochrome P450 monooxygenases (P450s) have a variety of functions, including involvement in the metabolism of exogenous substances and the synthesis and degradation of endogenous substances, which are important for the growth and development of insects. Pseudoregma bambucicola is a social aphid that produces genetically identical but morphologically and behaviorally distinct first-instar soldiers and normal nymphs within colonies. In this study, we identified 43 P450 genes based on P. bambucicola genome data. Phylogenetic analysis showed that these genes were classified into 4 clans, 13 families, and 23 subfamilies. The CYP3 and CYP4 clans had a somewhat decreased number of genes. In addition, differential gene expression analysis based on transcriptome data showed that several P450 genes, including CYP18A1, CYP4G332, and CYP4G333, showed higher expression levels in soldiers compared to normal nymphs and adult aphids. These genes may be candidates for causing epidermal hardening and developmental arrest in soldiers. This study provides valuable data and lays the foundation for the study of functions of P450 genes in the social aphid P. bambucicola.
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Affiliation(s)
- Jianjun Lu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Hui Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qing Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaolei Huang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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Cressman A, Amsalem E. Impacts and mechanisms of CO2 narcosis in bumble bees: narcosis depends on dose, caste and mating status and is not induced by anoxia. J Exp Biol 2023; 226:286149. [PMID: 36541091 DOI: 10.1242/jeb.244746] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022]
Abstract
Carbon dioxide (CO2) is commonly used to immobilize insects and to induce reproduction in bees. However, despite its wide use and potential off-target impacts, its underlying mechanisms are not fully understood. Here, we used Bombus impatiens to examine whether CO2 impacts are mediated by anoxia and whether these mechanisms differ between female castes or following mating in queens. We examined the behavior, physiology and gene expression of workers, mated queens and virgin queens following exposure to anoxia, hypoxia, full and partial hypercapnia, and controls. Hypercapnia and anoxia caused immobilization, but only hypercapnia resulted in behavioral, physiological and molecular impacts in bees. Recovery from hypercapnia resulted in increased abdominal contractions and took longer in queens. Additionally, hypercapnia activated the ovaries of queens, but inhibited those of workers in a dose-dependent manner and caused a depletion of fat-body lipids in both castes. All responses to hypercapnia were weaker following mating in queens. Analysis of gene expression related to hypoxia and hypercapnia supported the physiological findings in queens, demonstrating that the overall impacts of CO2, excluding virgin queen ovaries, were unique and were not induced by anoxia. This study contributes to our understanding of the impacts and the mechanistic basis of CO2 narcosis in insects and its impacts on bee physiology. This article has an associated ECR Spotlight interview with Anna Cressman.
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Affiliation(s)
- Anna Cressman
- Department of Entomology, Center for Chemical Ecology, Center for Pollination Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Etya Amsalem
- Department of Entomology, Center for Chemical Ecology, Center for Pollination Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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8
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Jensen MA, Blatz DJ, LaLone CA. Defining the Biologically Plausible Taxonomic Domain of Applicability of an Adverse Outcome Pathway: A Case Study Linking Nicotinic Acetylcholine Receptor Activation to Colony Death. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2023; 42:71-87. [PMID: 36263952 PMCID: PMC10100214 DOI: 10.1002/etc.5501] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/30/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
For the majority of developed adverse outcome pathways (AOPs), the taxonomic domain of applicability (tDOA) is typically narrowly defined with a single or a handful of species. Defining the tDOA of an AOP is critical for use in regulatory decision-making, particularly when considering protection of untested species. Structural and functional conservation are two elements that can be considered when defining the tDOA. Publicly accessible bioinformatics approaches, such as the Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS) tool, take advantage of existing and growing databases of protein sequence and structural information to provide lines of evidence toward structural conservation of key events (KEs) and KE relationships (KERs) of an AOP. It is anticipated that SeqAPASS results could readily be combined with data derived from empirical toxicity studies to provide evidence of both structural and functional conservation, to define the tDOA for KEs, KERs, and AOPs. Such data could be incorporated in the AOP-Wiki as lines of evidence toward biological plausibility for the tDOA. We present a case study describing the process of using bioinformatics to define the tDOA of an AOP using an AOP linking the activation of the nicotinic acetylcholine receptor to colony death/failure in Apis mellifera. Although the AOP was developed to gain a particular biological understanding relative to A. mellifera health, applicability to other Apis bees, as well as non-Apis bees, has yet to be defined. The present study demonstrates how bioinformatics can be utilized to rapidly take advantage of existing protein sequence and structural knowledge to enhance and inform the tDOA of KEs, KERs, and AOPs, focusing on providing evidence of structural conservation across species. Environ Toxicol Chem 2023;42:71-87. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Marissa A. Jensen
- Department of Biology, Swenson College of Science and EngineeringUniversity of Minnesota DuluthDuluthMinnesotaUSA
- US Environmental Protection Agency, Center for Computational Toxicology and ExposureGreat Lakes Toxicology and Ecology DivisionDuluthMinnesotaUSA
| | | | - Carlie A. LaLone
- US Environmental Protection Agency, Center for Computational Toxicology and ExposureGreat Lakes Toxicology and Ecology DivisionDuluthMinnesotaUSA
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Favreau E, Geist KS, Wyatt CDR, Toth AL, Sumner S, Rehan SM. Co-expression Gene Networks and Machine-learning Algorithms Unveil a Core Genetic Toolkit for Reproductive Division of Labour in Rudimentary Insect Societies. Genome Biol Evol 2022; 15:6926469. [PMID: 36527688 PMCID: PMC9830183 DOI: 10.1093/gbe/evac174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 12/06/2022] [Accepted: 12/10/2022] [Indexed: 12/23/2022] Open
Abstract
The evolution of eusociality requires that individuals forgo some or all their own reproduction to assist the reproduction of others in their group, such as a primary egg-laying queen. A major open question is how genes and genetic pathways sculpt the evolution of eusociality, especially in rudimentary forms of sociality-those with smaller cooperative nests when compared with species such as honeybees that possess large societies. We lack comprehensive comparative studies examining shared patterns and processes across multiple social lineages. Here we examine the mechanisms of molecular convergence across two lineages of bees and wasps exhibiting such rudimentary societies. These societies consist of few individuals and their life histories range from facultative to obligately social. Using six species across four independent origins of sociality, we conduct a comparative meta-analysis of publicly available transcriptomes. Standard methods detected little similarity in patterns of differential gene expression in brain transcriptomes among reproductive and non-reproductive individuals across species. By contrast, both supervised machine learning and consensus co-expression network approaches uncovered sets of genes with conserved expression patterns among reproductive and non-reproductive phenotypes across species. These sets overlap substantially, and may comprise a shared genetic "toolkit" for sociality across the distantly related taxa of bees and wasps and independently evolved lineages of sociality. We also found many lineage-specific genes and co-expression modules associated with social phenotypes and possible signatures of shared life-history traits. These results reveal how taxon-specific molecular mechanisms complement a core toolkit of molecular processes in sculpting traits related to the evolution of eusociality.
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Affiliation(s)
| | | | - Christopher D R Wyatt
- Department of Genetics, Environment, Evolution, University College London, London WC1E 6BT, United Kingdom
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10
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Guo N, Ma H, Han H, Yan F, Gao H, Zhang Y, Gao S. Phenotypic and Differential Gene Expression Analyses of Phase Transition in Oedaleus asiaticus under High-Density Population Stress. INSECTS 2022; 13:1034. [PMID: 36354858 PMCID: PMC9697361 DOI: 10.3390/insects13111034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/02/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
The high-density-dependent phase change from solitary to gregarious individuals in locusts is a typical example of phenotypic plasticity. However, the underlying molecular mechanism is not clear. In this study, first, Oedaleus asiaticus were treated with high-density population stress and then analyzed by Illumina sequencing on days 1, 3, 5, and 7 of the body color change to identify the stage-specific differentially expressed genes (DEGs). The KEGG pathway enrichment analysis of the identified DEGs revealed their role in metabolic pathways. Furthermore, the expression patterns of the nine key DEGs were studied in detail; this showed that the material change in locusts began on the third day of the high-density treatment, with the number of DEGs being the largest, indicating the importance of this period in the phase transition. In addition, the phenotypic change involved several key genes of important regulatory pathways, possibly working in a complex network. Phenotypic plasticity in locusts is multifactorial, involving multilevel material network interactions. This study improves the mechanistic understanding of phenotypic variation in insects at the genetic level.
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Affiliation(s)
- Na Guo
- Institute of Grassland Research, Chinese Academy of Agricultural Science, Hohhot 010010, China
| | - Hongyue Ma
- Research Center for Grassland Entomology, Inner Mongolia University for Nationalities, Tongliao 028000, China
| | - Haibin Han
- Institute of Grassland Research, Chinese Academy of Agricultural Science, Hohhot 010010, China
| | - Feng Yan
- Forest Pest Management and Quarantine Station of Ordos, Ordos 017010, China
| | - Haiyan Gao
- Institute of Grassland Research, Chinese Academy of Agricultural Science, Hohhot 010010, China
| | - Yuanyuan Zhang
- Institute of Grassland Research, Chinese Academy of Agricultural Science, Hohhot 010010, China
| | - Shujing Gao
- Institute of Grassland Research, Chinese Academy of Agricultural Science, Hohhot 010010, China
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11
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Juvenile hormone regulates reproductive physiology and the production of fertility cues in the swarm-founding wasp Polybia occidentalis. CHEMOECOLOGY 2022. [DOI: 10.1007/s00049-022-00376-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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12
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Effect of Insulin Receptor on Juvenile Hormone Signal and Fecundity in Spodoptera litura (F.). INSECTS 2022; 13:insects13080701. [PMID: 36005325 PMCID: PMC9409390 DOI: 10.3390/insects13080701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/23/2022] [Accepted: 08/02/2022] [Indexed: 02/01/2023]
Abstract
Simple Summary The tobacco cutworm, Spodoptera litura (F.), exemplifies strong reproductive capacities and damages many agricultural crops. The insulin signaling pathway is known as a key determinant of female reproduction in insects. However, the detailed molecular mechanisms in these processes are poorly studied. Here, we injected bovine insulin into the newly emerged moth, resulting in gene expression changes in the insulin pathway, while knockdown of SlInR caused an inverse gene expression change involved in the insulin pathway. Further studies indicated that the content of JH-III, Vg, total proteins and triacylgycerol could be suppressed by SlInR dsRNA injection. Furthermore, stunted ovaries and lower fecundity were observed by RNAi. Our studies indicated that SlInR plays a key role in JH-III synthesis and the ovarian development in S. litura. Abstract Insulin signaling can regulate various physiological functions, such as energy metabolism and reproduction and so on, in many insects, including mosquito and locust. However, the molecular mechanism of this physiological process remains elusive. The tobacco cutworm, Spodoptera litura, is one of the most important pests of agricultural crops around the world. In this study, phosphoinositide 3-kinase (SlPI3K), protein kinase B (SlAKT), target of rapamycin (SlTOR), ribosomal protein S6 kinase (SlS6K) and transcription factor cAMP-response element binding protein (SlCREB) genes, except transcription factor forkhead box class O (SlFoxO), can be activated by bovine insulin injection. Then, we studied the influence of the insulin receptor gene (SlInR) on the reproduction of S. litura using RNA interference technology. qRT-PCR analysis revealed that SlInR was most abundant in the head. The SlPI3K, SlAKT, SlTOR, SlS6K and SlCREB genes were decreased, except SlFoxO, after the SlInR gene knockdown. Further studies revealed that the expression of vitellogenin mRNA and protein, Methoprene-tolerant gene (SlMet), could be down-regulated by the injection of dsRNA of SlInR significantly. Furthermore, a depletion in the insulin receptor by RNAi significantly decreased the content of juvenile hormone III (JH-III), total proteins and triacylgycerol. These changes indicated that a lack of SlInR could impair ovarian development and decrease fecundity in S. litura. Our studies contribute to a comprehensive insight into reproduction, regulated by insulin and the juvenile hormone signaling pathway through nutrition, and a provide theoretical basis for the reproduction process in pest insects.
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Santos PKF, Galbraith DA, Starkey J, Amsalem E. The effect of the brood and the queen on early gene expression in bumble bee workers' brains. Sci Rep 2022; 12:3018. [PMID: 35194064 PMCID: PMC8863840 DOI: 10.1038/s41598-022-06715-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/04/2022] [Indexed: 11/12/2022] Open
Abstract
Worker reproduction in social insects is often regulated by the queen, but can be regulated by the brood and nestmates, who may use different mechanisms to induce the same outcomes in subordinates. Analysis of brain gene expression patterns in bumble bee workers (Bombus impatiens) in response to the presence of the queen, the brood, both or neither, identified 18 differentially expressed genes, 17 of them are regulated by the queen and none are regulated by the brood. Overall, brain gene expression differences in workers were driven by the queen’s presence, despite recent studies showing that brood reduces worker egg laying and provides context to the queen pheromones. The queen affected important regulators of reproduction and brood care across insects, such as neuroparsin and vitellogenin, and a comparison with similar datasets in the honey bee and the clonal raider ant revealed that neuroparsin is differentially expressed in all species. These data emphasize the prominent role of the queen in regulating worker physiology and behavior. Genes that serve as key regulators of workers’ reproduction are likely to play an important role in the evolution of sociality.
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Affiliation(s)
- Priscila K F Santos
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA.
| | - David A Galbraith
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Jesse Starkey
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Etya Amsalem
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
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14
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Sarro E, Tripodi A, Woodard SH. Bumble Bee ( Bombus vosnesenskii) Queen Nest Searching Occurs Independent of Ovary Developmental Status. INTEGRATIVE ORGANISMAL BIOLOGY (OXFORD, ENGLAND) 2022; 4:obac007. [PMID: 35274079 PMCID: PMC8902787 DOI: 10.1093/iob/obac007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Studies on the physiological states of wild-caught organisms are essential to uncovering the links between ecological and physiological processes. Bumble bee queens emerge from overwintering in the spring. At this time, queens develop their ovaries and search for a nest site in which to start a colony. Whether these two processes, ovary development and nest-searching, interact with or influence one another remains an unresolved question in behavioral physiology. We explored the hypothesis that ovary development and nest-searching might be mechanistically connected, by testing whether (1) ovary development precedes nest-searching behavior; (2) nest occupation precedes ovary development; or (3) ovary development and nest-searching occur independently, in bumble bee (Bombus vosnesenskii) queens. We collected queens either nest-searching (and thus prior to occupying a nest) or pollen-collecting (and thus provisioning an occupied nest) and measured their degree of ovary activation. We further screened these queens for parasites or other symbionts, to identify additional factors that may impact their reproductive success at this time. We found that queens searched for and occupied nests at all stages of ovary development, indicating that these processes occur independently in this system. Nest-searching queens were more likely to have substantial mite loads than pollen-collecting queens, who had already located and occupied a nest. However, mite loads did not significantly predict ovary developmental status. Collectively, our work shows that nesting status and symbionts alone are insufficient to explain the variation in spring bumble bee queen ovary development. We propose that ovary development and nest-searching occur opportunistically, which may enable queens to begin laying eggs earlier in the season than if these processes occurred in discrete succession.
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Affiliation(s)
- Erica Sarro
- Department of Entomology, University of California Riverside, 900 University Ave, Riverside, CA 92521, USA
| | - Amber Tripodi
- Department of Entomology, University of California Riverside, 900 University Ave, Riverside, CA 92521, USA
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15
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Shpigler HY, Magory Cohen T, Ben-Shimol E, Ben-Betzalel R, Levin E. Juvenile hormone functions as a metabolic rate accelerator in bumble bees (Bombus terrestris). Horm Behav 2021; 136:105073. [PMID: 34634696 DOI: 10.1016/j.yhbeh.2021.105073] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 11/23/2022]
Abstract
Juvenile hormone (JH) is a modulator of many physiological transitions in insects, including molting, metamorphosis, diapause, and reproduction. These processes often include metabolic changes. Here we show that JH accelerates metabolic rate in bumble bees (Bombus terrestris). We reduced JH levels in worker bumble bees by removing their corpora allata (allatectomy) and elevated JH levels in queens through a topical application of JH-III. Natural and high JH levels increased the metabolic rate in both workers and queens and triggered an increased protein turnover rate. Following the treatments, JH also caused an increase in food consumption and a reduction in lipid levels and flight muscle mass of queens, and a reduction in lipids levels in workers. Furthermore, the topical application of a JH analog to queens prior to their diapause caused a decline in their survival of diapause. These findings support the hypothesis that JH acts as a metabolic rate accelerator, initiating a resource shift in bumble bees, and thereby reducing diapause survival in queens. Based on previous studies on JH we suggest that, additional to its behavioral or physiological effects, JH's function as an accelerator of metabolic processes is conserved across different life stages and insect species.
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Affiliation(s)
| | - Tali Magory Cohen
- School of Zoology, Faculty of Life Sciences, Tel-Aviv, Israel; Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel
| | | | | | - Eran Levin
- School of Zoology, Faculty of Life Sciences, Tel-Aviv, Israel.
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16
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Sarro E, Sun P, Mauck K, Rodriguez-Arellano D, Yamanaka N, Woodard SH. An organizing feature of bumble bee life history: worker emergence promotes queen reproduction and survival in young nests. CONSERVATION PHYSIOLOGY 2021; 9:coab047. [PMID: 34221405 PMCID: PMC8242224 DOI: 10.1093/conphys/coab047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/13/2021] [Accepted: 06/10/2021] [Indexed: 05/14/2023]
Abstract
Bumble bee queens initiate nests solitarily and transition to living socially once they successfully rear their first cohort of offspring. Bumble bees are disproportionately important for early season pollination, and many populations are experiencing dramatic declines. In this system, the onset of the social stage is critical for nest survival, yet the mechanisms that facilitate this transition remain understudied. Further, the majority of conservation efforts target the social stage of the bumble bee life cycle and do not address the solitary founding stage. We experimentally manipulated the timing of worker emergence in young nests of bumble bee (Bombus impatiens) queens to determine whether and how queen fecundity and survival are impacted by the emergence of workers in the nest. We found that queens with workers added to the nest exhibit increased ovary activation, accelerated egg laying, elevated juvenile hormone (JH) titres and also lower mortality relative to solitary queens. We also show that JH is more strongly impacted by the social environment than associated with queen reproductive state, suggesting that this key regulator of insect reproduction has expanded its function in bumble bees to also influence social organization. We further demonstrate that these effects are independent of queen social history, suggesting that this underlying mechanism promoting queen fecundity is reversible and short lived. Synchronization between queen reproductive status and emergence of workers in the nest may ultimately increase the likelihood of early nesting success in social systems with solitary nest founding. Given that bumble bee workers regulate queen physiology as we have demonstrated, the timing of early worker emergence in the nest likely impacts queen fitness, colony developmental trajectories and ultimately nesting success. Collectively, our findings underline the importance of conservation interventions for bumble bees that support the early nesting period and facilitate the production and maintenance of workers in young nests.
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Affiliation(s)
- Erica Sarro
- Department of Entomology, The University of California Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - Penglin Sun
- Department of Entomology, The University of California Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - Kerry Mauck
- Department of Entomology, The University of California Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - Damaris Rodriguez-Arellano
- Department of Entomology, The University of California Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - Naoki Yamanaka
- Department of Entomology, The University of California Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - S Hollis Woodard
- Department of Entomology, The University of California Riverside, 900 University Ave., Riverside, CA 92521, USA
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17
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Cardoso-Júnior CAM, Oldroyd BP, Ronai I. Vitellogenin expression in the ovaries of adult honeybee workers provides insights into the evolution of reproductive and social traits. INSECT MOLECULAR BIOLOGY 2021; 30:277-286. [PMID: 33427366 DOI: 10.1111/imb.12694] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 12/10/2020] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Social insects are notable for having two female castes that exhibit extreme differences in their reproductive capacity. The molecular basis of these differences is largely unknown. Vitellogenin (Vg) is a powerful antioxidant and insulin-signalling regulator used in oocyte development. Here we investigate how Royal Jelly (the major food of honeybee queens) and queen mandibular pheromone (a major regulator of worker fertility), affect the longevity and reproductive status of honey bee workers, the expression of Vg, its receptor VgR and associated regulatory proteins. We find that Vg is expressed in the ovaries of workers and that workers fed a queen diet of Royal Jelly have increased Vg expression in the ovaries. Surprisingly, we find that expression of Vg is not associated with ovary activation in workers, suggesting that this gene has potentially acquired non-reproductive functions. Therefore, Vg expression in the ovaries of honeybee workers provides further support for the Ovarian Ground Plan Hypothesis, which argues that genes implicated in the regulation of reproduction have been co-opted to regulate behavioural differences between queens and workers.
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Affiliation(s)
- C A M Cardoso-Júnior
- Departamento de Biologia Celular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
- Behaviour and Genetics of Social Insects Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, New South Wales, Australia
| | - B P Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, New South Wales, Australia
| | - I Ronai
- Behaviour and Genetics of Social Insects Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, New South Wales, Australia
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18
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Korb J, Meusemann K, Aumer D, Bernadou A, Elsner D, Feldmeyer B, Foitzik S, Heinze J, Libbrecht R, Lin S, Majoe M, Monroy Kuhn JM, Nehring V, Negroni MA, Paxton RJ, Séguret AC, Stoldt M, Flatt T. Comparative transcriptomic analysis of the mechanisms underpinning ageing and fecundity in social insects. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190728. [PMID: 33678016 PMCID: PMC7938167 DOI: 10.1098/rstb.2019.0728] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2021] [Indexed: 12/13/2022] Open
Abstract
The exceptional longevity of social insect queens despite their lifelong high fecundity remains poorly understood in ageing biology. To gain insights into the mechanisms that might underlie ageing in social insects, we compared gene expression patterns between young and old castes (both queens and workers) across different lineages of social insects (two termite, two bee and two ant species). After global analyses, we paid particular attention to genes of the insulin/insulin-like growth factor 1 signalling (IIS)/target of rapamycin (TOR)/juvenile hormone (JH) network, which is well known to regulate lifespan and the trade-off between reproduction and somatic maintenance in solitary insects. Our results reveal a major role of the downstream components and target genes of this network (e.g. JH signalling, vitellogenins, major royal jelly proteins and immune genes) in affecting ageing and the caste-specific physiology of social insects, but an apparently lesser role of the upstream IIS/TOR signalling components. Together with a growing appreciation of the importance of such downstream targets, this leads us to propose the TI-J-LiFe (TOR/IIS-JH-Lifespan and Fecundity) network as a conceptual framework for understanding the mechanisms of ageing and fecundity in social insects and beyond. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'
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Affiliation(s)
- Judith Korb
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
| | - Karen Meusemann
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
- Australian National Insect Collection, CSIRO National Research Collections Australia, Clunies Ross Street, Canberra, Acton 2601, Australia
| | - Denise Aumer
- Developmental Zoology, Molecular Ecology Research Group, Hoher Weg 4, D-06099 Halle (Saale), Germany
| | - Abel Bernadou
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany
| | - Daniel Elsner
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
| | - Barbara Feldmeyer
- Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Molecular Ecology, Senckenberg, Georg-Voigt-Straße 14-16, D-60325 Frankfurt, Germany
| | - Susanne Foitzik
- Institute of Organismic and Molecular Evolution (IOME), Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 15, D-55128 Mainz, Germany
| | - Jürgen Heinze
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution (IOME), Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 15, D-55128 Mainz, Germany
| | - Silu Lin
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
| | - Megha Majoe
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
- Institute of Organismic and Molecular Evolution (IOME), Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 15, D-55128 Mainz, Germany
| | - José Manuel Monroy Kuhn
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
| | - Volker Nehring
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
| | - Matteo A. Negroni
- Institute of Organismic and Molecular Evolution (IOME), Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 15, D-55128 Mainz, Germany
| | - Robert J. Paxton
- Institute for Biology, Martin Luther University Halle-Wittenberg, Hoher Weg 8, 06120 Halle, Germany
| | - Alice C. Séguret
- Institute for Biology, Martin Luther University Halle-Wittenberg, Hoher Weg 8, 06120 Halle, Germany
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstraße 1, 48149 Münster, Germany
| | - Marah Stoldt
- Institute of Organismic and Molecular Evolution (IOME), Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 15, D-55128 Mainz, Germany
| | - Thomas Flatt
- Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - the So-Long consortium
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstraße 1, D-79104 Freiburg (Breisgau), Germany
- Australian National Insect Collection, CSIRO National Research Collections Australia, Clunies Ross Street, Canberra, Acton 2601, Australia
- Developmental Zoology, Molecular Ecology Research Group, Hoher Weg 4, D-06099 Halle (Saale), Germany
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany
- Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Molecular Ecology, Senckenberg, Georg-Voigt-Straße 14-16, D-60325 Frankfurt, Germany
- Institute of Organismic and Molecular Evolution (IOME), Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 15, D-55128 Mainz, Germany
- Institute for Biology, Martin Luther University Halle-Wittenberg, Hoher Weg 8, 06120 Halle, Germany
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstraße 1, 48149 Münster, Germany
- Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
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19
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Chen H, Wu G, Zhou H, Dai X, Steeghs NWF, Dong X, Zheng L, Zhai Y. Hormonal Regulation of Reproductive Diapause That Occurs in the Year-Round Mass Rearing of Bombus terrestris Queens. J Proteome Res 2021; 20:2240-2250. [PMID: 33779174 DOI: 10.1021/acs.jproteome.0c00776] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Adult reproductive diapause is an adaptive strategy under adverse environments for insects and other arthropod species, including bumblebees, which enables queens to survive through a harsh winter and then build new colonies in the following spring. Little research has been done on the molecular regulatory mechanism of reproductive diapause in Bombus terrestris, which is an important pollinator of wild plants and crops. Our previous research identified the conditions that induced reproductive diapause during the year-round mass rearing of B. terrestris. Here, we performed combined transcriptomics and proteomics analyses of reproductive diapause in B. terrestris during and after diapause at three different ecophysiological phases, diapause, postdiapause, and founder postdiapause. The analyses showed that differentially expressed proteins/genes acted in the citrate cycle, insect hormone biosynthesis, insulin and mTOR signaling pathway. To further understand the mechanisms that regulated the reproductive diapause, genes involved in the regulation of JH synthesis, insulin/TOR signal pathway were determined. The BtRheb, BtTOR, BtVg, and BtJHAMT had lower expression levels in diapause queens. The JH III titer levels and the activities of the metabolic enzymes were significantly up-regulated in postdiapause queens. Also, after the microinjection of insulin-like peptides (ILPs) and JH analogue (JHA), hormones, cold-tolerance metabolites, metabolic enzymes, and reproduction showed significant changes. Together with results from other related research, a model of the regulation of reproductive diapause during the year-round mass rearing of B. terrestris was proposed. This study contributes to a comprehensive insight into the molecular regulatory mechanism of reproductive diapause in eusocial insects.
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Affiliation(s)
- Hao Chen
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Guang'an Wu
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China.,College of Agriculture, Yangtze University, Jingzhou 434000, China
| | - Hao Zhou
- Shandong Lubao Technology Co. Ltd., Jinan 250100, China
| | - Xiaoyan Dai
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | | | - Xiaolin Dong
- College of Agriculture, Yangtze University, Jingzhou 434000, China
| | - Li Zheng
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Yifan Zhai
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China.,College of Agriculture, Yangtze University, Jingzhou 434000, China.,College of Life Sciences, Shandong Normal University, Jinan 250100, China
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20
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Sasaki K, Yokoi K, Toga K. Bumble bee queens activate dopamine production and gene expression in nutritional signaling pathways in the brain. Sci Rep 2021; 11:5526. [PMID: 33750862 PMCID: PMC7943803 DOI: 10.1038/s41598-021-84992-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/24/2021] [Indexed: 11/08/2022] Open
Abstract
To explore the neuroendocrine mechanisms underlying caste-specific behavior and its evolution from primitive to advanced eusocial bees, the monoamine levels and expression of genes involved in monoamine production and signaling in the brain were compared between the castes of Bombus ignitus. Higher levels of dopamine and its related substances were found in the brains of newly emerged queens than in the brains of emerged workers. The degree of caste differences in B. ignitus was smaller than that reported in Apis mellifera, indicating a link to different social stages in the two species. There was no differential expression in genes involved in dopamine biosynthesis between castes, suggesting that the high dopamine production in queens was not largely influenced by the expression of these genes at emergence, rather it might be influenced by tyrosine supply. Genome-wide analyses of gene expression by RNA-sequencing indicated that a greater number of genes involved in nutrition were actively expressed in the brains of newly emerged queens in comparison to the emerged workers. Some of the expression was confirmed by real-time quantitative PCR. The signaling pathways driven by the expression of these genes may be associated with dopamine signaling or the parallel activation of dopamine production.
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Affiliation(s)
- Ken Sasaki
- Graduate School of Agriculture, Honeybee Science Research Center, Tamagawa University, Machida, Tokyo, 194-8610, Japan.
| | - Kakeru Yokoi
- Insect Genome Research Unit, Division of Applied Genetics, The National Agriculture and Research Organization, Institute of Agrobiological Sciences, Owashi 1-2, Tsukuba, Ibaraki, 305-8634, Japan
| | - Kouhei Toga
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Sakurajyosui 3-25-40, Setagaya-Ku, Tokyo, 156-8550, Japan
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21
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Araujo NDS, Arias MC. Gene expression and epigenetics reveal species-specific mechanisms acting upon common molecular pathways in the evolution of task division in bees. Sci Rep 2021; 11:3654. [PMID: 33574391 PMCID: PMC7878513 DOI: 10.1038/s41598-020-75432-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 10/05/2020] [Indexed: 01/30/2023] Open
Abstract
A striking feature of advanced insect societies is the existence of workers that forgo reproduction. Two broad types of workers exist in eusocial bees: nurses who care for their young siblings and the queen, and foragers who guard the nest and forage for food. Comparisons between these two worker subcastes have been performed in honeybees, but data from other bees are scarce. To understand whether similar molecular mechanisms are involved in nurse-forager differences across distinct species, we compared gene expression and DNA methylation profiles between nurses and foragers of the buff-tailed bumblebee Bombus terrestris and the stingless bee Tetragonisca angustula. These datasets were then compared to previous findings from honeybees. Our analyses revealed that although the expression pattern of genes is often species-specific, many of the biological processes and molecular pathways involved are common. Moreover, the correlation between gene expression and DNA methylation was dependent on the nucleotide context, and non-CG methylation appeared to be a relevant factor in the behavioral changes of the workers. In summary, task specialization in worker bees is characterized by a plastic and mosaic molecular pattern, with species-specific mechanisms acting upon broad common pathways across species.
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Affiliation(s)
- Natalia de Souza Araujo
- Department of Genetics and Evolutionary Biology, Universidade de São Paulo, Rua Do Matão, 277, São Paulo, SP, 05508-090, Brazil.
- Department of Evolutionary Biology and Ecology, Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles, Avenue F.D. Roosevelt, 50, 1050, Brussels, Belgium.
| | - Maria Cristina Arias
- Department of Genetics and Evolutionary Biology, Universidade de São Paulo, Rua Do Matão, 277, São Paulo, SP, 05508-090, Brazil
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22
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Awde DN, Skandalis A, Richards MH. Vitellogenin expression corresponds with reproductive status and caste in a primitively eusocial bee. JOURNAL OF INSECT PHYSIOLOGY 2020; 127:104113. [PMID: 32890626 DOI: 10.1016/j.jinsphys.2020.104113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Vitellogenin (vg) expression is consistently associated with variation in insect phenotypes, particularly egg-laying. Primitively eusocial species, such as eusocial sweat bees, have behaviourally totipotent castes, in which each female is capable of high levels of ovarian development. Few studies have investigated vg expression patterns in primitively eusocial insects, and only one study has focused on a primitively eusocial bee. Here we use a primitively eusocial sweat bee, Lasioglossum laevissimum, and Real Time quantitative PCR (RT-qPCR) to investigate the relationship between vg expression, castes, and variation in phenotypes associated with castes differences. These assays showed that females with high ovarian development had the highest levels of vg expression, and that vg expression levels reflected the reproductive status of females first and caste second. This is in contrast to vg expression patterns observed in advanced eusocial queens and workers, which differ in vg expression based on caste and have caste-specific vg expression patterns. Furthermore, future queens (gynes) do not have ovarian development and had similar vg expression levels to early spring foundresses, which do have ovarian development, supporting Vg's function as a transporter of lipids and amino acids before diapause.
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Affiliation(s)
- David N Awde
- Department of Entomology, University of Kentucky, KY, USA; Department of Biological Sciences, Brock University, ON, Canada.
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23
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Built to change: dominance strategy changes with life stage in a primitively eusocial bee. Behav Ecol 2020. [DOI: 10.1093/beheco/araa093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Abstract
Access to reproduction is determined by an individual’s dominance rank in many species and is achieved through aggression and/or dominance signaling. In eusocial insects, one or several dominant females (queens) monopolize reproduction but to what extent queens rely on aggression and signaling remains obscure. Aggression is costly and its efficiency depends on the group size, whereas signaling may reduce the risks and costs of aggression. Both strategies are used to regulate reproduction in social taxa, with aggression being more common in small social groups, compared to signaling in larger societies. Here, we examine the use of aggression and chemical signaling in a social species (Bombus impatiens) where the dominant queen interacts with increasing numbers of workers as she ages. We found that the queen’s strategy to monopolize reproduction changes with life stage, shifting from overt aggression to chemical signaling as the queen gets older. Particularly, old queens exhibited a higher ratio of short to long cuticular hydrocarbons compared to young queens, an endogenous shift that was attributed to age, as all egg-laying queens were fecund and kept with the same number of workers. Our findings contribute to the understanding of reproductive dominance in the context of an individual’s life history.
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Ge J, Ge Z, Zhu D, Wang X. Pheromonal Regulation of the Reproductive Division of Labor in Social Insects. Front Cell Dev Biol 2020; 8:837. [PMID: 32974354 PMCID: PMC7468439 DOI: 10.3389/fcell.2020.00837] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/05/2020] [Indexed: 11/13/2022] Open
Abstract
The reproductive altruism in social insects is an evolutionary enigma that has been puzzling scientists starting from Darwin. Unraveling how reproductive skew emerges and maintains is crucial to understand the reproductive altruism involved in the consequent division of labor. The regulation of adult worker reproduction involves conspecific inhibitory signals, which are thought to be chemical signals by numerous studies. Despite the primary identification of few chemical ligands, the action modes of primer pheromones that regulate reproduction and their molecular causes and effects remain challenging. Here, these questions were elucidated by comprehensively reviewing recent advances. The coordination with other modalities of queen pheromones (QPs) and its context-dependent manner to suppress worker reproduction were discussed under the vast variation and plasticity of reproduction during colony development and across taxa. In addition to the effect of QPs, special attention was paid to recent studies revealing the regulatory effect of brood pheromones. Considering the correlation between pheromone and hormone, this study focused on the production and perception of pheromones under the endocrine control and highlighted the pivotal roles of nutrition-related pathways. The novel chemicals and gene pathways discovered by recent works provide new insights into the understanding of social regulation of reproductive division of labor in insects.
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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, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Zhuxi Ge
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Dan Zhu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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25
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Ortiz-Alvarado Y, Rivera-Marchand B. Worker Queens? Behavioral Flexibility of Queens in the Little Fire Ant Wasmannia auropunctata. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00241] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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26
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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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27
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Tibbetts EA, Laub EC, Mathiron AGE, Goubault M. The challenge hypothesis in insects. Horm Behav 2020; 123:104533. [PMID: 31185222 DOI: 10.1016/j.yhbeh.2019.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/09/2019] [Accepted: 05/16/2019] [Indexed: 11/23/2022]
Abstract
The 'challenge hypothesis' provides a predictive framework for how the social environment influences within-species variation in hormone titers. High testosterone levels are beneficial during reproduction and competition, but they also impose costs because they may suppress traits like parental care and immunity. As a result, the challenge hypothesis predicts that individuals will change their testosterone levels to match the current social environment. Although the vast majority of work on the challenge hypothesis has focused on androgens in vertebrates, there is growing evidence that insect hormones, especially juvenile hormone (JH), may respond to social stimuli in ways that parallel androgens in vertebrates. Many insects rapidly upregulate JH titers during social competition with rivals. Some insects also modulate JH titers based on contest outcomes, with winners upregulating JH and losers downregulating JH. This review will integrate work on social modulation of hormone titers in vertebrates and insects. First, we provide background on insect hormones and describe the functional parallels between androgens and JH. Second, we review evidence that insects rapidly change JH titers in response to social competition. Finally, we highlight opportunities for future work on social modulation of hormones in insects. Overall, the challenge hypothesis provides a useful conceptual framework for hypothesis-driven research in insect endocrinology. Comparing vertebrates and insects provides insight into how selection has shaped patterns of hormone responsiveness as well as the generality of hypotheses originally developed for vertebrates.
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Affiliation(s)
- Elizabeth A Tibbetts
- Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Emily C Laub
- Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anthony G E Mathiron
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, Université de Tours, Parc Grandmont, 37200 Tours, France
| | - Marlene Goubault
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, Université de Tours, Parc Grandmont, 37200 Tours, France
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Treanore ED, Kiner JM, Kerner ME, Amsalem E. Shift in worker physiology and gene expression pattern from reproductive to diapause-like with colony age in the bumble bee Bombus impatiens. J Exp Biol 2020; 223:jeb218768. [PMID: 32205359 DOI: 10.1242/jeb.218768] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/17/2020] [Indexed: 08/26/2023]
Abstract
Insects maximize their fitness by exhibiting predictable and adaptive seasonal patterns in response to changing environmental conditions. These seasonal patterns are often expressed even when insects are kept in captivity, suggesting they are functionally and evolutionarily important. In this study, we examined whether workers of the eusocial bumble bee Bombus impatiens maintained a seasonal signature when kept in captivity. We used an integrative approach and compared worker egg laying, ovarian activation, body size and mass, lipid content in the fat body, cold tolerance and expression of genes related to cold tolerance, metabolism and stress throughout colony development. We found that bumble bee worker physiology and gene expression patterns shift from reproductive-like to diapause-like as the colony ages. Workers eclosing early in the colony cycle had increased egg laying and ovarian activation, and reduced cold tolerance, body size, mass and lipid content in the fat body, in line with a reproductive-like profile, while late-eclosing workers exhibited the opposite characteristics. Furthermore, expression patterns of genes associated with reproduction and diapause differed between early- and late-eclosing workers, partially following the physiological patterns. We suggest that a seasonal signature, innate to individual workers, the queen or the colony, is used by workers as a social cue determining the phenology of the colony and discuss possible implications for understanding reproductive division of labor in bumble bee colonies and the evolutionary divergence of female castes in the genus Bombus.
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Affiliation(s)
- Erin D Treanore
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Jacklyn M Kiner
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Mackenzie E Kerner
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Etya Amsalem
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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29
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Orlova M, Starkey J, Amsalem E. A small family business: synergistic and additive effects of the queen and the brood on worker reproduction in a primitively eusocial bee. J Exp Biol 2020; 223:jeb217547. [PMID: 31953359 DOI: 10.1242/jeb.217547] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/08/2020] [Indexed: 01/04/2023]
Abstract
The mechanisms that maintain reproductive division of labor in social insects are still incompletely understood. Most studies focus on the relationship between adults, overlooking another important stakeholder - the juveniles. Recent studies show that not only the queen but also the brood regulate worker reproduction. However, how the two coordinate to maintain reproductive monopoly remained unexplored. Here, we disentangled the roles of the brood and the queen in primitively eusocial bees (Bombus impatiens) by examining their separated and combined effects on worker behavioral, physiological and brain gene expression. We found that young larvae produce a releaser effect on workers, decreasing oviposition and aggression, while the queen produces both releaser and primer effects, modifying worker behavior and reproductive physiology. The expression of reproduction- and aggression-related genes was altered in the presence of both queen and brood but was stronger or the same in the presence of the queen. We identified two types of interactions between the queen and the brood in regulating worker reproduction: (1) synergistic interactions regulating worker physiology, where the combined effect of the queen and the brood on worker physiology was greater than their separate effects; (2) additive interactions, where the combined effect of the queen and the brood on worker behavior was similar to the sum of their separate effects. Our results suggest that the queen and the brood interact synergistically and additively to regulate worker behavior and reproduction, and this interaction exists at multiple regulatory levels.
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Affiliation(s)
- Margarita Orlova
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Jesse Starkey
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Etya Amsalem
- Department of Entomology, Center for Chemical Ecology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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30
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Pandey A, Motro U, Bloch G. Juvenile hormone interacts with multiple factors to modulate aggression and dominance in groups of orphan bumble bee (Bombus terrestris) workers. Horm Behav 2020; 117:104602. [PMID: 31647921 DOI: 10.1016/j.yhbeh.2019.104602] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/16/2019] [Accepted: 09/19/2019] [Indexed: 02/07/2023]
Abstract
Juvenile hormone (JH) is a key regulator of insect development and reproduction. Given that JH commonly affects adult insect fertility, it has been hypothesized to also regulate behaviors such as dominance and aggression that are associated with reproduction. We tested this hypothesis in the bumble bee Bombus terrestris for which JH has been shown to be the major gonadotropin. We used the allatoxin Precocene-I (P-I) to reduce hemolymph JH titers and replacement therapy with the natural JH to revert this effect. In small orphan groups of workers with similar body size but mixed treatment, P-I treated bees showed lower aggressiveness, oogenesis, and dominance rank compared with control and replacement therapy treated bees. In similar groups in which all bees were treated similarly, there was a clear dominance hierarchy, even in P-I and replacement therapy treatment groups in which the bees showed similar levels of ovarian activation. In a similar experiment in which bees differed in body size, larger bees were more likely to be dominant despite their similar JH treatment and ovarian state. In the last experiment, we show that JH manipulation does not affect dominance rank in groups that had already established a stable dominance hierarchy. These findings solve previous ambiguities concerning whether or not JH affects dominance in bumble bees. JH positively affects dominance, but bees with similar levels of JH can nevertheless establish dominance hierarchies. Thus, multiple factors including JH, body size, and previous experience affect dominance and aggression in social bumble bees.
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Affiliation(s)
- Atul Pandey
- Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Israel
| | - Uzi Motro
- Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Israel
| | - Guy Bloch
- Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Israel.
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31
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Marshall H, Lonsdale ZN, Mallon EB. Methylation and gene expression differences between reproductive and sterile bumblebee workers. Evol Lett 2019; 3:485-499. [PMID: 31636941 PMCID: PMC6791180 DOI: 10.1002/evl3.129] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 07/09/2019] [Accepted: 07/12/2019] [Indexed: 12/18/2022] Open
Abstract
Phenotypic plasticity is the production of multiple phenotypes from a single genome and is notably observed in social insects. Multiple epigenetic mechanisms have been associated with social insect plasticity, with DNA methylation being explored to the greatest extent. DNA methylation is thought to play a role in caste determination in Apis mellifera, and other social insects, but there is limited knowledge on its role in other bee species. In this study, we analyzed whole genome bisulfite sequencing and RNA-seq data sets from head tissue of reproductive and sterile castes of the eusocial bumblebee Bombus terrestris. We found that genome-wide methylation in B. terrestris is similar to other holometabolous insects and does not differ between reproductive castes. We did, however, find differentially methylated genes between castes, which are enriched for multiple biological processes including reproduction. However, we found no relationship between differential methylation and differential gene expression or differential exon usage between castes. Our results also indicate high intercolony variation in methylation. These findings suggest that methylation is associated with caste differences but may serve an alternate function, other than direct caste determination in this species. This study provides the first insights into the nature of a bumblebee caste-specific methylome as well as its interaction with gene expression and caste-specific alternative splicing, providing greater understanding of the role of methylation in phenotypic plasticity within social bee species. Future experimental work is needed to determine the function of methylation and other epigenetic mechanisms in insects.
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Affiliation(s)
- Hollie Marshall
- Department of Genetics and Genome BiologyThe University of LeicesterLeicesterUnited Kingdom
| | - Zoë N. Lonsdale
- Department of Genetics and Genome BiologyThe University of LeicesterLeicesterUnited Kingdom
| | - Eamonn B. Mallon
- Department of Genetics and Genome BiologyThe University of LeicesterLeicesterUnited Kingdom
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32
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Hawkings C, Calkins TL, Pietrantonio PV, Tamborindeguy C. Caste-based differential transcriptional expression of hexamerins in response to a juvenile hormone analog in the red imported fire ant (Solenopsis invicta). PLoS One 2019; 14:e0216800. [PMID: 31107891 PMCID: PMC6527210 DOI: 10.1371/journal.pone.0216800] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 04/29/2019] [Indexed: 01/10/2023] Open
Abstract
The reproductive ground plan hypothesis proposes that gene networks regulating foraging behavior and reproductive female physiology in social insects emerged from ancestral gene and endocrine factor networks. Expression of storage proteins such as vitellogenins and hexamerins is an example of this co-option. Hexamerins, through their role modulating juvenile hormone availability, are involved in caste determination in termites. The genome of the fire ant (Solenopsis invicta) encodes four hexamerin genes, hexamerin-like (LOC105192919, hereafter called hexamerin 1), hexamerin (LOC105204474, hereafter called hexamerin 2), arylphorin subunit alpha-like, and arylphorin subunit beta. In this study, a phylogenetic analysis of the S. invicta hexamerins determined that each predicted protein clustered with one of the orthologous Apis mellifera hexamerins. Gene expression analyses by RT-qPCR revealed differential expression of the hexamerins between queens and workers, and between specific task-allocated workers (nurses and foragers). Queens and nurses had significantly higher expression of all genes when compared to foragers. Hexamerin 1 was expressed at higher levels in queens, while hexamerin 2 and arylphorin subunit beta were expressed at significantly higher levels in nurses. Arylphorin subunit alpha-like showed no significant difference in expression between virgin queens and nurses. Additionally, we analyzed the relationship between the expression of hexamerin genes and S-hydroprene, a juvenile hormone analog. Significant changes in hexamerin expression were recorded in nurses, virgin queens, and foragers 12 h after application of the analog. Hexamerin 1 and arylphorin subunit alpha-like expression were significantly lower after analog application in virgin queens. In foragers, hexamerin 2 and arylphorin subunit beta were significantly lower after analog application, while in nurses expression of all genes were significantly lower after analog application. Our results suggest that in S. invicta hexamerin genes could be associated with reproductive division of labor and task-allocation of workers.
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Affiliation(s)
- Chloe Hawkings
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
| | - Travis L. Calkins
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
| | - Patricia V. Pietrantonio
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
| | - Cecilia Tamborindeguy
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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33
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Kohlmeier P, Alleman AR, Libbrecht R, Foitzik S, Feldmeyer B. Gene expression is more strongly associated with behavioural specialization than with age or fertility in ant workers. Mol Ecol 2019; 28:658-670. [PMID: 30525254 DOI: 10.1111/mec.14971] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 11/09/2018] [Accepted: 11/15/2018] [Indexed: 12/19/2022]
Abstract
The ecological success of social insects is based on division of labour, not only between queens and workers, but also among workers. Whether a worker tends the brood or forages is influenced by age, fertility and nutritional status, with brood carers being younger, more fecund and more corpulent. Here, we experimentally disentangle behavioural specialization from age and fertility in Temnothorax longispinosus ant workers and analyse how these parameters are linked to whole-body gene expression. A total of 3,644 genes were associated with behavioural specialization which is ten times more than associated with age and 50 times more than associated with fertility. Brood carers were characterized by an upregulation of three Vitellogenin (Vg) genes, one of which, Vg-like A, was the most differentially expressed gene that was recently shown experimentally to control the switch from brood to worker care. The expression of Conventional Vg was unlinked to behavioural specialization, age or fertility, which contrasts to studies on bees and some ants. Diversity in Vg/Vg-like copy number and expression bias across ants supports subfunctionalization of Vg genes and indicates that some regulatory mechanisms of division of labour diverged in different ant lineages. Simulations revealed that our experimental dissociation of co-varying factors reduced transcriptomic noise, suggesting that confounding factors could potentially explain inconsistencies across transcriptomic studies of behavioural specialization in ants. Thus, our study reveals that worker gene expression is mainly linked to the worker's function for the colony and provides novel insights into the evolution of sociality in ants.
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Affiliation(s)
- Philip Kohlmeier
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Austin R Alleman
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Susanne Foitzik
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Barbara Feldmeyer
- Senckenberg Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany
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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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35
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Molecular evolution of juvenile hormone esterase-like proteins in a socially exchanged fluid. Sci Rep 2018; 8:17830. [PMID: 30546082 PMCID: PMC6293014 DOI: 10.1038/s41598-018-36048-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 11/12/2018] [Indexed: 11/08/2022] Open
Abstract
Socially exchanged fluids are a direct means by which an organism can influence conspecifics. It was recently shown that when workers of the carpenter ant Camponotus floridanus feed larval offspring via trophallaxis, they transfer Juvenile Hormone III (JH), a key developmental regulator, as well as paralogs of JH esterase (JHE), an enzyme that catalyzes the hydrolysis of JH. Here we combine proteomic, phylogenetic and selection analyses to investigate the evolution of this esterase subfamily. We show that Camponotus JHE-like proteins have undergone multiple duplications, experienced positive selection, and changed tissue localization to become abundantly and selectively present in trophallactic fluid. The Camponotus trophallactic esterases have maintained their catalytic triads and contain a number of positively-selected amino acid changes distributed throughout the protein, which possibly reflect an adaptation to the highly acidic trophallactic fluid of formicine ants. To determine whether these esterases might regulate larval development, we fed workers with a JHE-specific pharmacological inhibitor to introduce it into the trophallactic network. This inhibitor increased the likelihood of pupation of the larvae reared by these workers, similar to the influence of food supplementation with JH. Together, these findings suggest that JHE-like proteins have evolved a new role in the inter-individual regulation of larval development in the Camponotus genus.
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36
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Zhen C, Yang H, Luo S, Huang J, Wu J. Broad-complex Z3 contributes to the ecdysone-mediated transcriptional regulation of the vitellogenin gene in Bombus lantschouensis. PLoS One 2018; 13:e0207275. [PMID: 30440013 PMCID: PMC6237364 DOI: 10.1371/journal.pone.0207275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/29/2018] [Indexed: 01/03/2023] Open
Abstract
During reproduction, vitellogenin (Vg), as an egg yolk precursor, is critical in sexually mature females of oviparous species including some insects. The transcription of Vg is usually mediated by hormones such as juvenile hormone (JH), ecdysteroids and some neuropeptides. In this study, the structure of the Vg gene from the bumblebee Bombus lantschouensis, (BlVg) was determined by sequencing and assembly. BlVg was found to be expressed at higher levels in reproductive queens than in virgins by quantitative real-time PCR analysis. Tissue-specific expression analysis showed that BlVg was expressed at the highest levels in the fat bodies of both virgin and reproductive queens. Prediction of the BlVg promoter revealed the presence of ecdysteroid-responsive cis-regulatory elements (CREs) containing one Broad-Complex zinc-finger isoform 3 (BR-C Z3), and one ecdysone-induced protein 74A (E74A). In addition, luciferase reporter expression, driven by the 5' -regulatory region of the BlVg gene, from -1517 bp to +895 bp downstream of the start codon, was induced by treatment with 20-hydroxyecdysone (20-E). Moreover, the luciferase activity of the BlVg promoter was elevated by only BlBrC-Z3 when Sf9 cells were cotransfected with four BlBrC isoforms respectively. BlVg promoter-mediated luciferase activation was significantly reduced when the putative BrC-Z3 CRE in the promoter was mutated. In summary, this report describes the first study of vitellogenin gene regulation at the transcriptional level in bumblebees and demonstrates that the ecdysone-induced transcription of the BlVg gene is mediated by the binding of BlBrC-Z3 to the BrC-Z3 CRE in the BlVg promoter in bumblebees.
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Affiliation(s)
- Congai Zhen
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Huipeng Yang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Shudong Luo
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Jiaxing Huang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
- * E-mail: (JW); (JH)
| | - Jie Wu
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
- * E-mail: (JW); (JH)
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37
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Libbrecht R, Oxley PR, Kronauer DJC. Clonal raider ant brain transcriptomics identifies candidate molecular mechanisms for reproductive division of labor. BMC Biol 2018; 16:89. [PMID: 30103762 PMCID: PMC6090591 DOI: 10.1186/s12915-018-0558-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/31/2018] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Division of labor between reproductive queens and workers that perform brood care is a hallmark of insect societies. However, studies of the molecular basis of this fundamental dichotomy are limited by the fact that the caste of an individual cannot typically be experimentally manipulated at the adult stage. Here we take advantage of the unique biology of the clonal raider ant, Ooceraea biroi, to study brain gene expression dynamics during experimentally induced transitions between reproductive and brood care behavior. RESULTS Introducing larvae that inhibit reproduction and induce brood care behavior causes much faster changes in adult gene expression than removing larvae. In addition, the general patterns of gene expression differ depending on whether ants transition from reproduction to brood care or vice versa, indicating that gene expression changes between phases are cyclic rather than pendular. Finally, we identify genes that could play upstream roles in regulating reproduction and behavior because they show large and early expression changes in one or both transitions. CONCLUSIONS Our analyses reveal that the nature and timing of gene expression changes differ substantially depending on the direction of the transition, and identify a suite of promising candidate molecular regulators of reproductive division of labor that can now be characterized further in both social and solitary animal models. This study contributes to understanding the molecular regulation of reproduction and behavior, as well as the organization and evolution of insect societies.
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Affiliation(s)
- Romain Libbrecht
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany.
| | - Peter R Oxley
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
- Samuel J. Wood Library, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
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Hawkings C, Tamborindeguy C. Expression analysis of vitellogenins in the workers of the red imported fire ant ( Solenopsis invicta). PeerJ 2018; 6:e4875. [PMID: 29868280 PMCID: PMC5978388 DOI: 10.7717/peerj.4875] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/09/2018] [Indexed: 01/27/2023] Open
Abstract
Vitellogenin has been proposed to regulate division of labor and social organization in social insects. The red imported fire ant (Solenopsis invicta) harbors four distinct, adjacent vitellogenin genes (Vg1, Vg2, Vg3, and Vg4). Contrary to honey bees that have a single Vg ortholog as well as potentially fertile nurses, and to other ant species that lay trophic eggs, S. invicta workers completely lack ovaries or the ability to lay eggs. This provides a unique model to investigate whether Vg duplication in S. invicta was followed by subfunctionalization to acquire non-reproductive functions and whether Vg was co-opted to regulate behavior within the worker caste. To investigate these questions, we compared the expression patterns of S. invicta Vg genes among workers from different morphological subcastes or performing different tasks. RT-qPCRs revealed higher relative expression of Vg1 in major workers compared to both medium and minor workers, and of Vg2 in major workers when compared to minor workers. Relative expression of Vg1 was also higher in carbohydrate foragers when compared to nurses and protein foragers. By contrast, the level of expression of Vg2, Vg3, and Vg4 were not significantly different among the workers performing the specific tasks. Additionally, we analyzed the relationship between the expression of the Vg genes and S-hydroprene, a juvenile hormone analog. No changes in Vg expression were recorded in workers 12 h after application of the analog. Our results suggest that in S. invicta the Vg gene underwent subfunctionalization after duplication to new functions based on the expression bias observed in these data. This may suggest an alternative and still unknown function for Vg in the workers that needs to be investigated further.
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Affiliation(s)
- Chloe Hawkings
- Department of Entomology, Texas A&M University, College Station, TX, USA
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39
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Manfredini F, Brown MJF, Toth AL. Candidate genes for cooperation and aggression in the social wasp Polistes dominula. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2018; 204:449-463. [PMID: 29488013 PMCID: PMC5907630 DOI: 10.1007/s00359-018-1252-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/09/2018] [Accepted: 02/10/2018] [Indexed: 11/28/2022]
Abstract
Cooperation and aggression are ubiquitous in social groups, and the genetic mechanisms underlying these behaviours are of great interest for understanding how social group formation is regulated and how it evolves. In this study, we used a candidate gene approach to investigate the patterns of expression of key genes for cooperation and aggression in the brain of a primitively eusocial wasp, Polistes dominula, during colony founding, when multiple foundresses can join the same nest and establish subtle hierarchies of dominance. We used a comparative approach to select candidate genes for cooperation and aggression looking at two previously published studies on global gene expression in wasps and ants. We tested the expression of these genes in P. dominula wasps that were either displaying aggressive behaviour (dominant and single foundresses) or cooperation (subordinate foundresses and workers) towards nestmates. One gene in particular, the egg yolk protein vitellogenin, known for its reproductive role in insects, displayed patterns of expression that strongly matched wasp social rank. We characterize the genomic context of vitellogenin by building a head co-expression gene network for P. dominula, and we discuss a potential role for vitellogenin as a mediator of social interactions in wasps.
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Affiliation(s)
- Fabio Manfredini
- School of Biological Sciences, Royal Holloway University of London, Egham, UK.
| | - Mark J F Brown
- School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Amy L Toth
- Departments of Ecology, Evolution, and Organismal Biology and Entomology, Iowa State University, Ames, IA, USA
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40
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Nevoa JC, Mendes MT, da Silva MV, Soares SC, Oliveira CJF, Ribeiro JMC. An insight into the salivary gland and fat body transcriptome of Panstrongylus lignarius (Hemiptera: Heteroptera), the main vector of Chagas disease in Peru. PLoS Negl Trop Dis 2018; 12:e0006243. [PMID: 29462134 PMCID: PMC5834209 DOI: 10.1371/journal.pntd.0006243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 03/02/2018] [Accepted: 01/17/2018] [Indexed: 12/31/2022] Open
Abstract
Triatomines are hematophagous arthropod vectors of Trypanosoma cruzi, the causative agent of Chagas Disease. Panstrongylus lignarius, also known as Panstrongylus herreri, is considered one of the most versatile triatomines because it can parasitize different hosts, it is found in different habitats and countries, it has sylvatic, peridomestic and domestic behavior and it is a very important vector of Chagas disease, especially in Peru. Molecules produced and secreted by salivary glands and fat body are considered of important adaptational value for triatomines because, among other functions, they subvert the host haemostatic, inflammatory and immune systems and detoxify or protect them against environmental aggressors. In this context, the elucidation of the molecules produced by these tissues is highly valuable to understanding the ability of this species to adapt and transmit pathogens. Here, we use high-throughput sequencing techniques to assemble and describe the coding sequences resulting from the transcriptome of the fat body and salivary glands of P. lignarius. The final assembly of both transcriptomes together resulted in a total of 11,507 coding sequences (CDS), which were mapped from a total of 164,676,091 reads. The CDS were subdivided according to their 10 folds overexpression on salivary glands (513 CDS) or fat body (2073 CDS). Among the families of proteins found in the salivary glands, lipocalins were the most abundant. Other ubiquitous families of proteins present in other sialomes were also present in P. lignarius, including serine protease inhibitors, apyrase and antigen-5. The unique transcriptome of fat body showed proteins related to the metabolic function of this organ. Remarkably, nearly 20% of all reads mapped to transcripts coded by Triatoma virus. The data presented in this study improve the understanding on triatomines' salivary glands and fat body function and reveal important molecules used in the interplay between vectors and vertebrate hosts.
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Affiliation(s)
- Jessica C. Nevoa
- Institute of Natural and Biological Sciences, Laboratory of Immunology, Federal University of Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - Maria T. Mendes
- University of Texas at El Paso, El Paso, Texas, United States of America
| | - Marcos V. da Silva
- Institute of Natural and Biological Sciences, Laboratory of Immunology, Federal University of Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - Siomar C. Soares
- Institute of Natural and Biological Sciences, Laboratory of Immunology, Federal University of Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - Carlo J. F. Oliveira
- Institute of Natural and Biological Sciences, Laboratory of Immunology, Federal University of Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - José M. C. Ribeiro
- National Institute of Allergy and Infectious Diseases (NIAID), Laboratory of Malaria and Vector Research (LMVR), Rockville, Maryland, United States of America
- * E-mail:
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41
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Blacher P, Huggins TJ, Bourke AFG. Evolution of ageing, costs of reproduction and the fecundity-longevity trade-off in eusocial insects. Proc Biol Sci 2018; 284:rspb.2017.0380. [PMID: 28701554 PMCID: PMC5524490 DOI: 10.1098/rspb.2017.0380] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 06/07/2017] [Indexed: 01/04/2023] Open
Abstract
Eusocial insects provide special opportunities to elucidate the evolution of ageing as queens have apparently evaded costs of reproduction and reversed the fecundity–longevity trade-off generally observed in non-social organisms. But how reproduction affects longevity in eusocial insects has rarely been tested experimentally. In this study, we took advantage of the reproductive plasticity of workers to test the causal role of reproduction in determining longevity in eusocial insects. Using the eusocial bumblebee Bombus terrestris, we found that, in whole colonies, in which workers could freely ‘choose’ whether to become reproductive, workers' level of ovarian activation was significantly positively associated with longevity and ovary-active workers significantly outlived ovary-inactive workers. By contrast, when reproductivity was experimentally induced in randomly selected workers, thereby decoupling it from other traits, workers' level of ovarian activation was significantly negatively associated with longevity and ovary-active workers were significantly less long-lived than ovary-inactive workers. These findings show that workers experience costs of reproduction and suggest that intrinsically high-quality individuals can overcome these costs. They also raise the possibility that eusocial insect queens exhibit condition-dependent longevity and hence call into question whether eusociality entails a truly reversed fecundity–longevity trade-off involving a fundamental remodelling of conserved genetic and endocrine networks underpinning ageing.
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Affiliation(s)
- Pierre Blacher
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Timothy J Huggins
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Andrew F G Bourke
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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42
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Woodard SH. Bumble bee ecophysiology: integrating the changing environment and the organism. CURRENT OPINION IN INSECT SCIENCE 2017; 22:101-108. [PMID: 28805631 DOI: 10.1016/j.cois.2017.06.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/08/2017] [Accepted: 06/08/2017] [Indexed: 06/07/2023]
Abstract
Bumble bees are among the most ecologically and economically important pollinators worldwide, yet many of their populations are being threatened by a suite of interrelated, human-mediated environmental changes. Here, I discuss recent progress in our understanding of bumble bee ecophysiology, including advances related to thermal biology in light of global warming; nutritional biology in the context of declining food resources; and the capacity for bumble bees to exhibit physiological plasticity or adaptations to novel or extreme environments, with reference to their evolutionary history and current biogeography.
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Affiliation(s)
- S Hollis Woodard
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA
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43
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Amsalem E, Grozinger CM. Evaluating the molecular, physiological and behavioral impacts of CO 2 narcosis in bumble bees (Bombus impatiens). JOURNAL OF INSECT PHYSIOLOGY 2017; 101:57-65. [PMID: 28666863 DOI: 10.1016/j.jinsphys.2017.06.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/25/2017] [Accepted: 06/26/2017] [Indexed: 06/07/2023]
Abstract
Exposure to carbon dioxide (CO2) has pleiotropic effects in many insect species, ranging from eliciting rapid behavioral responses such as attraction, to dramatic physiological changes, including ovary activation. In bumble bees, CO2 narcosis causes queens to bypass diapause and initiate egg laying, but its mode of action is not well-understood. Here, we evaluated the effects of CO2 narcosis on the behavior, physiology and immune function of virgin bumble bee queens (Bombus impatiens). We tested the hypothesis that CO2 induces these changes by stimulating oxidative stress response pathways. We found that CO2 stimulates ovarian activation and egg production and suppresses lipid (but not glycogen) accumulation in virgin queens. Additionally, CO2 treated queens were more active (particularly in terms of flight) and performed, but did not receive, more aggressive behaviors compared to controls. Moreover, CO2 positively affected immune function in queens, reduced transcript levels of 5/6 antioxidant enzyme genes and had no effect on longevity. Thus, although CO2 treatment stimulated reproduction, we did not observe any evidence of a trade-off in queen health parameters, aside from a reduction in lipids. Overall CO2 narcosis does not appear to stimulate a typical stress response in virgin bumble bee queens. On the contrary, CO2 narcosis appears to stimulate changes that prepare queens to cope with the nutritional, metabolic and behavioral challenges associated with reproduction and colony-founding.
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Affiliation(s)
- Etya Amsalem
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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44
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Kapheim KM. Nutritional, endocrine, and social influences on reproductive physiology at the origins of social behavior. CURRENT OPINION IN INSECT SCIENCE 2017; 22:62-70. [PMID: 28805640 DOI: 10.1016/j.cois.2017.05.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/19/2017] [Accepted: 05/30/2017] [Indexed: 06/07/2023]
Abstract
Understanding the evolutionary origins of social behavior in insects requires understanding the physiological basis for reproductive plasticity. Solitary bees and wasps or those living in small, flexible societies will be key to understanding how conserved pathways have evolved to give rise to reproductive castes. Nutrient-sensing and endocrine pathways are decoupled from reproduction in some life stages of social insects. Heterochrony, particularly as it is related to diapause physiology, may be an important mechanism by which this decoupling occurs. Additional research is needed to understand how these pathways became sensitive to cues from the social environment. Future research targeting species with a diversity of social behaviors and diapause strategies will be key to understanding the physiological basis of social evolution.
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Affiliation(s)
- Karen M Kapheim
- Utah State University, Department of Biology, 5305 Old Main Hill, Logan, UT 84322, USA.
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45
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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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46
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Collins DH, Mohorianu I, Beckers M, Moulton V, Dalmay T, Bourke AFG. MicroRNAs Associated with Caste Determination and Differentiation in a Primitively Eusocial Insect. Sci Rep 2017; 7:45674. [PMID: 28361900 PMCID: PMC5374498 DOI: 10.1038/srep45674] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 03/02/2017] [Indexed: 01/08/2023] Open
Abstract
In eusocial Hymenoptera (ants, bees and wasps), queen and worker adult castes typically arise via environmental influences. A fundamental challenge is to understand how a single genome can thereby produce alternative phenotypes. A powerful approach is to compare the molecular basis of caste determination and differentiation along the evolutionary trajectory between primitively and advanced eusocial species, which have, respectively, relatively undifferentiated and strongly differentiated adult castes. In the advanced eusocial honeybee, Apis mellifera, studies suggest that microRNAs (miRNAs) play an important role in the molecular basis of caste determination and differentiation. To investigate how miRNAs affect caste in eusocial evolution, we used deep sequencing and Northern blots to isolate caste-associated miRNAs in the primitively eusocial bumblebee Bombus terrestris. We found that the miRNAs Bte-miR-6001-5p and -3p are more highly expressed in queen- than in worker-destined late-instar larvae. These are the first caste-associated miRNAs from outside advanced eusocial Hymenoptera, so providing evidence for caste-associated miRNAs occurring relatively early in eusocial evolution. Moreover, we found little evidence that miRNAs previously shown to be associated with caste in A. mellifera were differentially expressed across caste pathways in B. terrestris, suggesting that, in eusocial evolution, the caste-associated role of individual miRNAs is not conserved.
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Affiliation(s)
- David H Collins
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Irina Mohorianu
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.,School of Computing Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Matthew Beckers
- School of Computing Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Vincent Moulton
- School of Computing Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Tamas Dalmay
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Andrew F G Bourke
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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47
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Norman VC, Hughes WOH. Behavioural effects of juvenile hormone and their influence on division of labour in leaf-cutting ant societies. ACTA ACUST UNITED AC 2017; 219:8-11. [PMID: 26739685 DOI: 10.1242/jeb.132803] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Division of labour in social insects represents a major evolutionary transition, but the physiological mechanisms that regulate this are still little understood. Experimental work with honey bees, and correlational analyses in other social insects, have implicated juvenile hormone (JH) as a regulatory factor, but direct experimental evidence of behavioural effects of JH in social insects is generally lacking. Here, we used experimental manipulation of JH to show that raised JH levels in leaf-cutting ants results in workers becoming more active, phototactic and threat responsive, and engaging in more extranidal activity - behavioural changes that we show are all characteristic of the transition from intranidal work to foraging. These behavioural effects on division of labour suggest that the JH mediation of behaviour occurs across multiple independent evolutions of eusociality, and may be a key endocrine regulator of the division of labour which has produced the remarkable ecological and evolutionary success of social insects.
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Affiliation(s)
- Victoria C Norman
- School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9QG, UK
| | - William O H Hughes
- School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9QG, UK
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48
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LeBoeuf AC, Waridel P, Brent CS, Gonçalves AN, Menin L, Ortiz D, Riba-Grognuz O, Koto A, Soares ZG, Privman E, Miska EA, Benton R, Keller L. Oral transfer of chemical cues, growth proteins and hormones in social insects. eLife 2016; 5:e20375. [PMID: 27894417 PMCID: PMC5153251 DOI: 10.7554/elife.20375] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/14/2016] [Indexed: 01/02/2023] Open
Abstract
Social insects frequently engage in oral fluid exchange - trophallaxis - between adults, and between adults and larvae. Although trophallaxis is widely considered a food-sharing mechanism, we hypothesized that endogenous components of this fluid might underlie a novel means of chemical communication between colony members. Through protein and small-molecule mass spectrometry and RNA sequencing, we found that trophallactic fluid in the ant Camponotus floridanus contains a set of specific digestion- and non-digestion related proteins, as well as hydrocarbons, microRNAs, and a key developmental regulator, juvenile hormone. When C. floridanus workers' food was supplemented with this hormone, the larvae they reared via trophallaxis were twice as likely to complete metamorphosis and became larger workers. Comparison of trophallactic fluid proteins across social insect species revealed that many are regulators of growth, development and behavioral maturation. These results suggest that trophallaxis plays previously unsuspected roles in communication and enables communal control of colony phenotypes.
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Affiliation(s)
- Adria C LeBoeuf
- Center for Integrative GenomicsUniversity of LausanneLausanneSwitzerland
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Patrice Waridel
- Protein Analysis FacilityUniversity of LausanneLausanneSwitzerland
| | - Colin S Brent
- Arid Land Agricultural Research Center, USDA-ARSMaricopaUnited States
| | - Andre N Gonçalves
- Department of Biochemistry and ImmunologyInstituto de Ciências Biológicas, Universidade Federal de Minas GeraisMinas GeraisBrazil
- Gurdon InstituteUniversity of CambridgeCambridgeUnited Kingdom
| | - Laure Menin
- Institute of Chemical Sciences and EngineeringEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Daniel Ortiz
- Institute of Chemical Sciences and EngineeringEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Oksana Riba-Grognuz
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Akiko Koto
- The Department of Genetics, Graduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan
| | - Zamira G Soares
- Department of Biochemistry and ImmunologyInstituto de Ciências Biológicas, Universidade Federal de Minas GeraisMinas GeraisBrazil
- Gurdon InstituteUniversity of CambridgeCambridgeUnited Kingdom
| | - Eyal Privman
- Department of Evolutionary and Environmental Biology, Institute of EvolutionUniversity of HaifaHaifaIsrael
| | - Eric A Miska
- Gurdon InstituteUniversity of CambridgeCambridgeUnited Kingdom
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
- Wellcome Trust Sanger InstituteWellcome Trust Genome CampusCambridgeUnited Kingdom
| | - Richard Benton
- Center for Integrative GenomicsUniversity of LausanneLausanneSwitzerland
| | - Laurent Keller
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
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49
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Jedlička P, Ernst UR, Votavová A, Hanus R, Valterová I. Gene Expression Dynamics in Major Endocrine Regulatory Pathways along the Transition from Solitary to Social Life in a Bumblebee, Bombus terrestris. Front Physiol 2016; 7:574. [PMID: 27932998 PMCID: PMC5121236 DOI: 10.3389/fphys.2016.00574] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 11/10/2016] [Indexed: 01/28/2023] Open
Abstract
Understanding the social evolution leading to insect eusociality requires, among other, a detailed insight into endocrine regulatory mechanisms that have been co-opted from solitary ancestors to play new roles in the complex life histories of eusocial species. Bumblebees represent well-suited models of a relatively primitive social organization standing on the mid-way to highly advanced eusociality and their queens undergo both, a solitary and a social phase, separated by winter diapause. In the present paper, we characterize the gene expression levels of major endocrine regulatory pathways across tissues, sexes, and life-stages of the buff-tailed bumblebee, Bombus terrestris, with special emphasis on critical stages of the queen's transition from solitary to social life. We focused on fundamental genes of three pathways: (1) Forkhead box protein O and insulin/insulin-like signaling, (2) Juvenile hormone (JH) signaling, and (3) Adipokinetic hormone signaling. Virgin queens were distinguished by higher expression of forkhead box protein O and downregulated insulin-like peptides and JH signaling, indicated by low expression of methyl farnesoate epoxidase (MFE) and transcription factor Krüppel homolog 1 (Kr-h1). Diapausing queens showed the expected downregulation of JH signaling in terms of low MFE and vitellogenin (Vg) expressions, but an unexpectedly high expression of Kr-h1. By contrast, reproducing queens revealed an upregulation of MFE and Vg together with insulin signaling. Surprisingly, the insulin growth factor 1 (IGF-1) turned out to be a queen-specific hormone. Workers exhibited an expression pattern of MFE and Vg similar to that of reproducing queens. Males were characterized by high Kr-h1 expression and low Vg level. The tissue comparison unveiled an unexpected resemblance between the fat body and hypopharyngeal glands across all investigated genes, sexes, and life stages.
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Affiliation(s)
- Pavel Jedlička
- Department of Chemistry of Social Insects, The Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences Prague, Czechia
| | - Ulrich R Ernst
- Department of Chemistry of Social Insects, The Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences Prague, Czechia
| | | | - Robert Hanus
- Department of Chemistry of Social Insects, The Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences Prague, Czechia
| | - Irena Valterová
- Research Group of Infochemicals, The Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences Prague, Czechia
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50
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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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