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Liu Y, Dunker S, Durka W, Dominik C, Heuschele JM, Honchar H, Hoffmann P, Musche M, Paxton RJ, Settele J, Schweiger O. Eco-evolutionary processes shaping floral nectar sugar composition. Sci Rep 2024; 14:13856. [PMID: 38879632 PMCID: PMC11180116 DOI: 10.1038/s41598-024-64755-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 06/12/2024] [Indexed: 06/19/2024] Open
Abstract
Floral nectar sugar composition is assumed to reflect the nutritional demands and foraging behaviour of pollinators, but the relative contributions of evolutionary and abiotic factors to nectar sugar composition remain largely unknown across the angiosperms. We compiled a comprehensive dataset on nectar sugar composition for 414 insect-pollinated plant species across central Europe, along with phylogeny, paleoclimate, flower morphology, and pollinator dietary demands, to disentangle their relative effects. We found that phylogeny was strongly related with nectar sucrose content, which increased with the phylogenetic age of plant families, but even more strongly with historic global surface temperature. Nectar sugar composition was also defined by floral morphology, though it was not related to our functional measure of pollinator dietary demands. However, specialist pollinators of current plant-pollinator networks predominantly visited plant species with sucrose-rich nectar. Our results suggest that both physiological mechanisms related to plant water balance and evolutionary effects related to paleoclimatic changes have shaped floral nectar sugar composition during the radiation and specialisation of plants and pollinators. As a consequence, the high velocity of current climate change may affect plant-pollinator interaction networks due to a conflicting combination of immediate physiological responses and phylogenetic conservatism.
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Affiliation(s)
- Yicong Liu
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany.
- Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
| | - Susanne Dunker
- Department of Physiological Diversity, Helmholtz-Centre for Environmental Research-UFZ, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Walter Durka
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Christophe Dominik
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Jonna M Heuschele
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
- Department of Biodiversity and People, German Centre for Integrative Biodiversity Research-Jena-Leipzig, Leipzig, Germany
| | - Hanna Honchar
- Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research-UFZ, Halle (Saale), Germany
- Department of Ecological Monitoring, Institute for Evolutionary Ecology, NAS Ukraine, Kyiv, Ukraine
| | - Petra Hoffmann
- Department of Physiological Diversity, Helmholtz-Centre for Environmental Research-UFZ, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Martin Musche
- Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research-UFZ, Halle (Saale), Germany
| | - Robert J Paxton
- Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Josef Settele
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research-UFZ, Halle (Saale), Germany
| | - Oliver Schweiger
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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2
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Magner ET, Freund Saxhaug K, Zambre A, Bruns K, Carroll P, Snell-Rood EC, Hegeman AD, Carter CJ. A multifunctional role for riboflavin in the yellow nectar of Capsicum baccatum and Capsicum pubescens. THE NEW PHYTOLOGIST 2024. [PMID: 38874372 DOI: 10.1111/nph.19886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 05/14/2024] [Indexed: 06/15/2024]
Abstract
A few Capsicum (pepper) species produce yellow-colored floral nectar, but the chemical identity and biological function of the yellow pigment are unknown. A combination of analytical biochemistry techniques was used to identify the pigment that gives Capsicum baccatum and Capsicum pubescens nectars their yellow color. Microbial growth assays, visual modeling, and honey bee preference tests for artificial nectars containing riboflavin were used to assess potential biological roles for the nectar pigment. High concentrations of riboflavin (vitamin B2) give the nectars their intense yellow color. Nectars containing riboflavin generate reactive oxygen species when exposed to light and reduce microbial growth. Visual modeling also indicates that the yellow color is highly conspicuous to bees within the context of the flower. Lastly, field experiments demonstrate that honey bees prefer artificial nectars containing riboflavin. Some Capsicum nectars contain a yellow-colored vitamin that appears to play roles in (1) limiting microbial growth, (2) the visual attraction of bees, and (3) as a reward to nectar-feeding flower visitors (potential pollinators), which is especially interesting since riboflavin is an essential nutrient for brood rearing in insects. These results cumulatively suggest that the riboflavin found in some Capsicum nectars has several functions.
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Affiliation(s)
- Evin T Magner
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
| | | | - Amod Zambre
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
| | - Kaitlyn Bruns
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
| | - Patrick Carroll
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
| | - Emilie C Snell-Rood
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
| | - Adrian D Hegeman
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
- Department of Horticultural Science, University of Minnesota, St. Paul, MN, 55108, USA
| | - Clay J Carter
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
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3
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Francis JS, Mueller TG, Vannette RL. Intraspecific variation in realized dispersal probability and host quality shape nectar microbiomes. THE NEW PHYTOLOGIST 2023; 240:1233-1245. [PMID: 37614102 DOI: 10.1111/nph.19195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/16/2023] [Indexed: 08/25/2023]
Abstract
Epiphytic microbes frequently affect plant phenotype and fitness, but their effects depend on microbe abundance and community composition. Filtering by plant traits and deterministic dispersal-mediated processes can affect microbiome assembly, yet their relative contribution to predictable variation in microbiome is poorly understood. We compared the effects of host-plant filtering and dispersal on nectar microbiome presence, abundance, and composition. We inoculated representative bacteria and yeast into 30 plants across four phenotypically distinct cultivars of Epilobium canum. We compared the growth of inoculated communities to openly visited flowers from a subset of the same plants. There was clear evidence of host selection when we inoculated flowers with synthetic communities. However, plants with the highest microbial densities when inoculated did not have the highest microbial densities when openly visited. Instead, plants predictably varied in the presence of bacteria, which was correlated with pollen receipt and floral traits, suggesting a role for deterministic dispersal. These findings suggest that host filtering could drive plant microbiome assembly in tissues where species pools are large and dispersal is high. However, deterministic differences in microbial dispersal to hosts may be equally or more important when microbes rely on an animal vector, dispersal is low, or arrival order is important.
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Affiliation(s)
- Jacob S Francis
- Department of Entomology and Nematology, University of California Davis, Davis, CA, 95616, USA
| | - Tobias G Mueller
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Rachel L Vannette
- Department of Entomology and Nematology, University of California Davis, Davis, CA, 95616, USA
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4
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Jones PL, Martin KR, Prachand SV, Hastings AP, Duplais C, Agrawal AA. Compound-Specific Behavioral and Enzymatic Resistance to Toxic Milkweed Cardenolides in a Generalist Bumblebee Pollinator. J Chem Ecol 2023; 49:418-427. [PMID: 36745328 DOI: 10.1007/s10886-023-01408-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/07/2023]
Abstract
Plant secondary metabolites that defend leaves from herbivores also occur in floral nectar. While specialist herbivores often have adaptations providing resistance to these compounds in leaves, many social insect pollinators are generalists, and therefore are not expected to be as resistant to such compounds. The milkweeds, Asclepias spp., contain toxic cardenolides in all tissues including floral nectar. We compared the concentrations and identities of cardenolides between tissues of the North American common milkweed Asclepias syriaca, and then studied the effect of the predominant cardenolide in nectar, glycosylated aspecioside, on an abundant pollinator. We show that a generalist bumblebee, Bombus impatiens, a common pollinator in eastern North America, consumes less nectar with experimental addition of ouabain (a standard cardenolide derived from Apocynacid plants native to east Africa) but not with addition of glycosylated aspecioside from milkweeds. At a concentration matching that of the maximum in the natural range, both cardenolides reduced activity levels of bees after four days of consumption, demonstrating toxicity despite variation in behavioral deterrence (i.e., consumption). In vitro enzymatic assays of Na+/K+-ATPase, the target site of cardenolides, showed lower toxicity of the milkweed cardenolide than ouabain for B. impatiens, indicating that the lower deterrence may be due to greater tolerance to glycosylated aspecioside. In contrast, there was no difference between the two cardenolides in toxicity to the Na+/K+-ATPase from a control insect, the fruit fly Drosophila melanogaster. Accordingly, this work reveals that even generalist pollinators such as B. impatiens may have adaptations to reduce the toxicity of specific plant secondary metabolites that occur in nectar, despite visiting flowers from a wide variety of plants over the colony's lifespan.
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Affiliation(s)
| | - Kyle R Martin
- Department of Biology, Bowdoin College, Brunswick, ME, USA
| | | | - Amy P Hastings
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Christophe Duplais
- Department of Entomology, Cornell AgriTech, Cornell University, Geneva, NY, USA
| | - Anurag A Agrawal
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA
- Department of Entomology, Cornell AgriTech, Cornell University, Geneva, NY, USA
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5
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Mueller TG, Francis JS, Vannette RL. Nectar compounds impact bacterial and fungal growth and shift community dynamics in a nectar analog. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023; 15:170-180. [PMID: 36779256 PMCID: PMC10464699 DOI: 10.1111/1758-2229.13139] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 12/04/2022] [Indexed: 05/06/2023]
Abstract
Floral nectar is frequently colonised by microbes. However, nectar microbial communities are typically species-poor and dominated by few cosmopolitan genera. One hypothesis is that nectar constituents may act as environmental filters. We tested how five non-sugar nectar compounds as well as elevated sugar impacted the growth of 12 fungal and bacterial species isolated from nectar, pollinators, and the environment. We hypothesised that nectar isolated microbes would have the least growth suppression. Additionally, to test if nectar compounds could affect the outcome of competition between microbes, we grew a subset of microbes in co-culture across a subset of treatments. We found that some compounds such as H2 O2 suppressed microbial growth across many but not all microbes tested. Other compounds were more specialised in the microbes they impacted. As hypothesised, the nectar specialist yeast Metschnikowia reukaufii was unaffected by most nectar compounds assayed. However, many non-nectar specialist microbes remained unaffected by nectar compounds thought to reduce microbial growth. Our results show that nectar chemistry can influence microbial communities but that microbe-specific responses to nectar compounds are common. Nectar chemistry also affected the outcome of species interactions among microbial taxa, suggesting that non-sugar compounds can affect microbial community assembly in flowers.
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Affiliation(s)
- Tobias G. Mueller
- Department of Entomology and NematologyUniversity of California, DavisDavisCaliforniaUSA
- Department of EntomologyCornell UniversityIthacaNew YorkUSA
| | - Jacob S. Francis
- Department of Entomology and NematologyUniversity of California, DavisDavisCaliforniaUSA
| | - Rachel L. Vannette
- Department of Entomology and NematologyUniversity of California, DavisDavisCaliforniaUSA
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6
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Villegas LEM, Radl J, Dimopoulos G, Short SM. Bacterial communities of Aedes aegypti mosquitoes differ between crop and midgut tissues. PLoS Negl Trop Dis 2023; 17:e0011218. [PMID: 36989328 PMCID: PMC10085046 DOI: 10.1371/journal.pntd.0011218] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 04/10/2023] [Accepted: 03/06/2023] [Indexed: 03/30/2023] Open
Abstract
Microbiota studies of Aedes aegypti and other mosquitoes generally focus on the bacterial communities found in adult female midguts. However, other compartments of the digestive tract maintain communities of bacteria which remain almost entirely unstudied. For example, the Dipteran crop is a food storage organ, but few studies have looked at the microbiome of crops in mosquitoes, and only a single previous study has investigated the crop in Ae. aegypti. In this study, we used both culture-dependent and culture-independent methods to compare the bacterial communities in midguts and crops of laboratory reared Ae. aegypti. Both methods revealed a trend towards higher abundance, but also higher variability, of bacteria in the midgut than the crop. When present, bacteria from the genus Elizabethkingia (family Weeksellaceae) dominated midgut bacterial communities. In crops, we found a higher diversity of bacteria, and these communities were generally dominated by acetic acid bacteria (family Acetobacteriaceae) from the genera Tanticharoenia and Asaia. These three taxa drove significant community structure differences between the tissues. We used FAPROTAX to predict the metabolic functions of these communities and found that crop bacterial communities were significantly more likely to contain bacteria capable of methanol oxidation and methylotrophy. Both the presence of acetic acid bacteria (which commonly catabolize sugar to produce acetic acid) and the functional profile that includes methanol oxidation (which is correlated with bacteria found with natural sources like nectar) may relate to the presence of sugar, which is stored in the mosquito crop. A better understanding of what bacteria are present in the digestive tract of mosquitoes and how these communities assemble will inform how the microbiota impacts mosquito physiology and the full spectrum of functions provided by the microbiota. It may also facilitate better methods of engineering the mosquito microbiome for vector control or prevention of disease transmission.
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Affiliation(s)
| | - James Radl
- Department of Entomology, The Ohio State University, Columbus, Ohio, United States of America
| | - George Dimopoulos
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Sarah M. Short
- Department of Entomology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
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7
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Nicolson SW. Sweet solutions: nectar chemistry and quality. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210163. [PMID: 35491604 PMCID: PMC9058545 DOI: 10.1098/rstb.2021.0163] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/07/2021] [Indexed: 12/22/2022] Open
Abstract
Nectar, the main floral reward for pollinators, varies greatly in composition and concentration. The assumption that nectar quality is equivalent to its sugar (energy) concentration is too simple. Diverse non-sugar components, especially amino acids and secondary metabolites, play various roles in nutrition and health of pollinators. Many nectar compounds have indirect effects by altering the foraging behaviour of pollinators or protecting them from disease. This review also emphasizes the water component of nectar, often ignored because of evaporative losses and difficulties in sampling small nectar volumes. Nectar properties vary with environmental factors, pollinator visits and microbial contamination. Pollination mutualisms depend on the ability of insect and vertebrate pollinators to cope with and benefit from the variation and diversity in nectar chemistry. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Susan W. Nicolson
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
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8
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Matilla MA, Roca A. Multi-host lifestyle in plant-beneficial bacteria: an evolutionary advantage for survival and dispersal? Environ Microbiol 2022; 24:3307-3309. [PMID: 35411622 PMCID: PMC9541277 DOI: 10.1111/1462-2920.16002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 04/05/2022] [Indexed: 11/27/2022]
Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Amalia Roca
- Department of Microbiology, Facultad de Farmacia, Campus Universitario de Cartuja, Universidad de Granada, Granada, 18071, Spain
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9
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Missaoui K, Gonzalez-Klein Z, Pazos-Castro D, Hernandez-Ramirez G, Garrido-Arandia M, Brini F, Diaz-Perales A, Tome-Amat J. Plant non-specific lipid transfer proteins: An overview. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 171:115-127. [PMID: 34992048 DOI: 10.1016/j.plaphy.2021.12.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 05/26/2023]
Abstract
Plant non-specific lipid transfer proteins (nsLTPs) are usually defined as small, basic proteins, with a wide distribution in all orders of higher plants. Structurally, nsLTPs contain a conserved motif of eight cysteines, linked by four disulphide bonds, and a hydrophobic cavity in which the ligand is housed. This structure confers stability and enhances the ability to bind and transport a variety of hydrophobic molecules. Their highly conserved structural resemblance but low sequence identity reflects the wide variety of ligands they can carry, as well as the broad biological functions to which they are linked to, such as membrane stabilization, cell wall organization and signal transduction. In addition, they have also been described as essential in resistance to biotic and abiotic stresses, plant growth and development, seed development, and germination. Hence, there is growing interest in this family of proteins for their critical roles in plant development and for the many unresolved questions that need to be clarified, regarding their subcellular localization, transfer capacity, expression profile, biological function, and evolution.
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Affiliation(s)
- Khawla Missaoui
- Laboratory of Biotechnology and Plant Improvement, Centre of Biotechnology of Sfax (CBS), University of Sfax, Tunisia
| | - Zulema Gonzalez-Klein
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain; Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), Spain
| | - Diego Pazos-Castro
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain; Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), Spain
| | - Guadalupe Hernandez-Ramirez
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain; Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), Spain
| | - Maria Garrido-Arandia
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain; Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), Spain
| | - Faical Brini
- Laboratory of Biotechnology and Plant Improvement, Centre of Biotechnology of Sfax (CBS), University of Sfax, Tunisia
| | - Araceli Diaz-Perales
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain; Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), Spain
| | - Jaime Tome-Amat
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
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10
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Bartlett LJ, Martinez-Mejia C, Delaplane KS. Honey Bees (Apis mellifera Hymenoptera: Apidae) Preferentially Avoid Sugar Solutions Supplemented with Field-Relevant Concentrations of Hydrogen Peroxide Despite High Tolerance Limits. JOURNAL OF INSECT SCIENCE (ONLINE) 2022; 22:6484925. [PMID: 34958663 PMCID: PMC8711758 DOI: 10.1093/jisesa/ieab102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Indexed: 06/14/2023]
Abstract
Honey bees (Apis mellifera L. Hymeoptera: Apidae) use hydrogen peroxide (synthesized by excreted glucose oxidase) as an important component of social immunity. However, both tolerance of hydrogen peroxide and the production of glucose oxidase in honey is costly. Hydrogen peroxide may also be encountered by honey bees at high concentrations in nectar while foraging, however despite its presence both in their foraged and stored foods, it is unclear if and how bees monitor concentrations of, and their behavioral responses to, hydrogen peroxide. The costs of glucose oxidase production and the presence of hydrogen peroxide in both nectar and honey suggest hypotheses that honey bees preferentially forage on hydrogen peroxide supplemented feed syrups at certain concentrations, and avoid feed syrups supplemented with hydrogen peroxide at concentrations above some tolerance threshold. We test these hypotheses and find that, counter to expectation, honey bees avoid glucose solutions supplemented with field-relevant hydrogen peroxide concentrations and either avoid or don't differentiate supplemented sucrose solutions when given choice assays. This is despite honey bees showing high tolerance for hydrogen peroxide in feed solutions, with no elevated mortality until concentrations of hydrogen peroxide exceed 1% (v/v) in solution, with survival apparent even at concentrations up to 10%. The behavioral interaction of honey bees with hydrogen peroxide during both within-colony synthesis in honey and when foraging on nectar therefore likely relies on interactions with other indicator molecules, and maybe constrained evolutionarily in its plasticity, representing a constitutive immune mechanism.
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Affiliation(s)
- Lewis J Bartlett
- Center for the Ecology of Infectious Diseases, Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | | | - Keith S Delaplane
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
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11
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Crowley B, Russell A. Plant biology: Nectar bacteria grow by germinating and bursting pollen. Curr Biol 2021; 31:R1120-R1122. [PMID: 34637711 DOI: 10.1016/j.cub.2021.08.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microbial residents of floral nectar must survive in a carbohydrate-rich yet seemingly nitrogen-poor environment. A new study shows that Acinetobacter spp., common nectar-inhabiting bacteria, differentially induce the pollen commonly found in nectar to germinate and burst, releasing nutrients for microbial growth.
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Affiliation(s)
- Bailey Crowley
- Department of Biology, Utah State University, Logan, UT 84322, USA
| | - Avery Russell
- Department of Biology, Missouri State University, Springfield, MO 65897, USA.
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