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Rivest S, Muralidhar M, Forrest JRK. Pollen chemical and mechanical defences restrict host-plant use by bees. Proc Biol Sci 2024; 291:20232298. [PMID: 38471551 PMCID: PMC10932708 DOI: 10.1098/rspb.2023.2298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/31/2024] [Indexed: 03/14/2024] Open
Abstract
Plants produce an array of chemical and mechanical defences that provide protection against many herbivores and pathogens. Putatively defensive compounds and structures can even occur in floral rewards: for example, the pollen of some plant taxa contains toxic compounds or possesses conspicuous spines. Yet little is known about whether pollen defences restrict host-plant use by bees. In other words, do bees, like other insect herbivores, tolerate the defences of their specific host plants while being harmed by non-host defences? To answer this question, we compared the effects of a chemical defence from Lupinus (Fabaceae) pollen and a putative mechanical defence (pollen spines) from Asteraceae pollen on larval survival of nine bee species in the tribe Osmiini (Megachilidae) varying in their pollen-host use. We found that both types of pollen defences reduce larval survival rate in some bee species. These detrimental effects were, however, mediated by host-plant associations, with bees being more tolerant of the pollen defences of their hosts, relative to the defences of plant taxa exploited by other species. This pattern strongly suggests that bees are adapted to the pollen defences of their hosts, and that host-plant use by bees is constrained by their ability to tolerate such defences.
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Affiliation(s)
- Sébastien Rivest
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N5
- Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
| | | | - Jessica R. K. Forrest
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N5
- Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
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Vaudo AD, Dyer LA, Leonard AS. Pollen nutrition structures bee and plant community interactions. Proc Natl Acad Sci U S A 2024; 121:e2317228120. [PMID: 38190523 PMCID: PMC10801918 DOI: 10.1073/pnas.2317228120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/19/2023] [Indexed: 01/10/2024] Open
Abstract
As bees' main source of protein and lipids, pollen is critical for their development, reproduction, and health. Plant species vary considerably in the macronutrient content of their pollen, and research in bee model systems has established that this variation both modulates performance and guides floral choice. Yet, how variation in pollen chemistry shapes interactions between plants and bees in natural communities is an open question, essential for both understanding the nutritional dynamics of plant-pollinator mutualisms and informing their conservation. To fill this gap, we asked how pollen nutrition (relative protein and lipid content) sampled from 109 co-flowering plant species structured visitation patterns observed among 75 subgenera of pollen-collecting bees in the Great Basin/Eastern Sierra region (USA). We found that the degree of similarity in co-flowering plant species' pollen nutrition predicted similarity among their visitor communities, even after accounting for floral morphology and phylogeny. Consideration of pollen nutrition also shed light on the structure of this interaction network: Bee subgenera and plant genera were arranged into distinct, interconnected groups, delineated by differences in pollen macronutrient values, revealing potential nutritional niches. Importantly, variation in pollen nutrition alone (high in protein, high in lipid, or balanced) did not predict the diversity of bee visitors, indicating that plant species offering complementary pollen nutrition may be equally valuable in supporting bee diversity. Nutritional diversity should thus be a key consideration when selecting plants for habitat restoration, and a nutritionally explicit perspective is needed when considering reward systems involved in the community ecology of pollination.
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Affiliation(s)
- Anthony D. Vaudo
- Department of Biology, University of Nevada, Reno, NV89557
- Rocky Mountain Research Station, United States Department of Agriculture Forest Service, Moscow, ID83843
| | - Lee A. Dyer
- Department of Biology, University of Nevada, Reno, NV89557
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Buttstedt A, Pirk CWW, Yusuf AA. Mandibular glands secrete 24-methylenecholesterol into honey bee (Apis mellifera) food jelly. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 161:104011. [PMID: 37716535 DOI: 10.1016/j.ibmb.2023.104011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/01/2023] [Accepted: 09/07/2023] [Indexed: 09/18/2023]
Abstract
Honey bee (Apis mellifera) workers feed their larvae with food jelly that is secreted by specialized glands in their heads - the hypopharyngeal and the mandibular glands. Food jelly contains all the nutrients the larvae need to develop into adult honey bees, including essential dietary sterols. The main sterol in food jelly, 24-methylenecholesterol (24MC), is pollen-derived and delivered in food jelly to the larvae in a complex with two proteins, major royal jelly protein 1 (MRJP1) and apisim. Whereas the proteins are synthesized in the hypopharyngeal glands, the sterol-secreting gland has not been identified. We here identified the mandibular glands as sterol-secreting gland for food jelly production by direct detection of the four main honey bee sterols (24MC, campesterol, β-sitosterol and isofucosterol). Furthermore, 24MC seems to be specifically enriched in the mandibular glands, thereby ensuring that food jelly contains the amounts of 24MC necessary for complex formation with MRJP1 and apisimin.
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Affiliation(s)
- Anja Buttstedt
- Social Insects Research Group, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, 0028, Hatfield, Pretoria, South Africa.
| | - Christian W W Pirk
- Social Insects Research Group, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, 0028, Hatfield, Pretoria, South Africa
| | - Abdullahi A Yusuf
- Social Insects Research Group, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, 0028, Hatfield, Pretoria, South Africa
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Furse S, Koch H, Wright GA, Stevenson PC. Sterol and lipid metabolism in bees. Metabolomics 2023; 19:78. [PMID: 37644282 PMCID: PMC10465395 DOI: 10.1007/s11306-023-02039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 07/27/2023] [Indexed: 08/31/2023]
Abstract
BACKGROUND Bees provide essential pollination services for many food crops and are critical in supporting wild plant diversity. However, the dietary landscape of pollen food sources for social and solitary bees has changed because of agricultural intensification and habitat loss. For this reason, understanding the basic nutrient metabolism and meeting the nutritional needs of bees is becoming an urgent requirement for agriculture and conservation. We know that pollen is the principal source of dietary fat and sterols for pollinators, but a precise understanding of what the essential nutrients are and how much is needed is not yet clear. Sterols are key for producing the hormones that control development and may be present in cell membranes, where fatty-acid-containing species are important structural and signalling molecules (phospholipids) or to supply, store and distribute energy (glycerides). AIM OF THE REVIEW In this critical review, we examine the current general understanding of sterol and lipid metabolism of social and solitary bees from a variety of literature sources and discuss implications for bee health. KEY SCIENTIFIC CONCEPTS OF REVIEW We found that while eusocial bees are resilient to some dietary variation in sterol supply the scope for this is limited. The evidence of both de novo lipogenesis and a dietary need for particular fatty acids (FAs) shows that FA metabolism in insects is analogous to mammals but with distinct features. Bees rely on their dietary intake for essential sterols and lipids in a way that is dependent upon pollen availability.
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Affiliation(s)
- Samuel Furse
- Royal Botanic Gardens, Kew Green, Kew, Surrey, TW9 3AB, UK.
| | - Hauke Koch
- Royal Botanic Gardens, Kew Green, Kew, Surrey, TW9 3AB, UK
| | | | - Philip C Stevenson
- Royal Botanic Gardens, Kew Green, Kew, Surrey, TW9 3AB, UK.
- Natural Resources Institute, University of Greenwich, Chatham, Kent, ME4 4TB, UK.
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Nebauer CA, Schleifer MC, Ruedenauer FA, Leonhardt SD, Spaethe J. Perception, regulation, and fitness effects of pollen phytosterols in the bumble bee, Bombus terrestris. AMERICAN JOURNAL OF BOTANY 2023:e16165. [PMID: 37071779 DOI: 10.1002/ajb2.16165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 06/19/2023]
Abstract
PREMISE Many flowering plants depend on insects for pollination and thus attract pollinators by offering rewards, mostly nectar and pollen. Bee pollinators rely on pollen as their main nutrient source. Pollen provides all essential micro- and macronutrients including substances that cannot be synthesized by bees themselves, such as sterols, which bees need for processes such as hormone production. Variations in sterol concentrations may consequently affect bee health and reproductive fitness. We therefore hypothesized that (1) these variations in pollen sterols affect longevity and reproduction in bumble bees and (2) can thus be perceived via the bees' antennae before consumption. METHODS We studied the effect of sterols on longevity and reproduction of Bombus terrestris workers in feeding experiments and investigated sterol perception using chemotactile proboscis extension response (PER) conditioning. RESULTS Workers could perceive several sterols (cholesterol, cholestenone, desmosterol, stigmasterol, β-sitosterol) via their antennae but not differentiate between them. However, when sterols were presented in pollen, and not as a single compound, the bees were unable to differentiate between pollen differing in sterol content. Additionally, different sterol concentrations in pollen neither affected pollen consumption nor brood development or worker longevity. CONCLUSIONS Since we used both natural concentrations and concentrations higher than those found in pollen, our results indicate that bumble bees may not need to pay specific attention to pollen sterol content beyond a specific threshold. Naturally encountered concentrations might fully support their sterol requirements and higher concentrations do not seem to have negative effects.
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Affiliation(s)
- Carmen A Nebauer
- Plant-Insect Interactions, Department of Life Science Systems, Technical University of Munich, Freising, Germany
| | - Marielle C Schleifer
- Department of Behavioral Physiology and Sociobiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Fabian A Ruedenauer
- Plant-Insect Interactions, Department of Life Science Systems, Technical University of Munich, Freising, Germany
| | - Sara D Leonhardt
- Plant-Insect Interactions, Department of Life Science Systems, Technical University of Munich, Freising, Germany
| | - Johannes Spaethe
- Department of Behavioral Physiology and Sociobiology, Biocenter, University of Würzburg, Würzburg, Germany
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Wang W, Zhang F, Zhang S, Xue Z, Xie L, Govers F, Liu X. Phytophthora capsici sterol reductase PcDHCR7 has a role in mycelium development and pathogenicity. Open Biol 2022; 12:210282. [PMID: 35382565 PMCID: PMC8984297 DOI: 10.1098/rsob.210282] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The de novo biosynthesis of sterols is critical for the majority of eukaryotes; however, some organisms lack this pathway, including most oomycetes. Phytophthora spp. are sterol auxotrophic but, remarkably, have retained a few genes encoding enzymes in the sterol biosynthesis pathway. Here, we show that PcDHCR7, a gene in Phytophthora capsici predicted to encode Δ7-sterol reductase, displays multiple functions. When expressed in Saccharomyces cerevisiae, PcDHCR7 showed the Δ7-sterol reductase activity. Knocking out PcDHCR7 in P. capsici resulted in loss of the capacity to transform ergosterol into brassicasterol, which means PcDHCR7 has the Δ7-sterol reductase activity in P. capsici itself. This enables P. capsici to transform sterols recruited from the environment for better use. The biological characteristics of ΔPcDHCR7 transformants were compared with those of the wild-type strain and a PcDHCR7 complemented transformant, and the results showed that PcDHCR7 plays a key role in mycelium development and pathogenicity of zoospores. Further analysis of the transcriptome indicated that the expression of many genes changed in the ΔPcDHCR7 transformant, which involve in different biological processes. It is possible that P. capsici compensates for the defects caused by the loss of PcDHCR7 by remodelling its transcriptome.
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Affiliation(s)
- Weizhen Wang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, People's Republic of China,Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
| | - Fan Zhang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, People's Republic of China
| | - Sicong Zhang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, People's Republic of China
| | - Zhaolin Xue
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, People's Republic of China
| | - Linfang Xie
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
| | - Francine Govers
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
| | - Xili Liu
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, People's Republic of China,State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, People's Republic of China
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Abstract
Optimal nutrition is crucial for honey bee colony growth and robust immune systems. Honey bee nutrition is complex and depends on the floral composition of the landscape. Foraging behavior of honey bees depends on both colony environment and external environment. There are significant gaps in knowledge regarding honey bee nutrition, and hence no optimal diet is available for honey bees, as there is for other livestock. In this review, we discuss (1) foraging behavior of honey bees, (2) nutritional needs, (3) nutritional supplements used by beekeepers, (4) probiotics, and (5) supplemental forage and efforts integrating floral diversity into cropping systems.
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Affiliation(s)
- Jennifer M Tsuruda
- University of Tennessee - Knoxville, 2505 E J Chapman Drive, Knoxville, TN 37996, USA
| | - Priyadarshini Chakrabarti
- Mississippi State University, P.O. Box 5307, Mississippi State, MS 39762, USA; Oregon State University, 4017 Agriculture and Life Science Building, Corvallis, OR 97331, USA
| | - Ramesh R Sagili
- Oregon State University, 4017 Agriculture and Life Science Building, Corvallis, OR 97331, USA.
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Zu P, Koch H, Schwery O, Pironon S, Phillips C, Ondo I, Farrell IW, Nes WD, Moore E, Wright GA, Farman DI, Stevenson PC. Pollen sterols are associated with phylogeny and environment but not with pollinator guilds. THE NEW PHYTOLOGIST 2021; 230:1169-1184. [PMID: 33484583 PMCID: PMC8653887 DOI: 10.1111/nph.17227] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/14/2021] [Indexed: 06/01/2023]
Abstract
Phytosterols are primary plant metabolites that have fundamental structural and regulatory functions. They are also essential nutrients for phytophagous insects, including pollinators, that cannot synthesize sterols. Despite the well-described composition and diversity in vegetative plant tissues, few studies have examined phytosterol diversity in pollen. We quantified 25 pollen phytosterols in 122 plant species (105 genera, 51 families) to determine their composition and diversity across plant taxa. We searched literature and databases for plant phylogeny, environmental conditions, and pollinator guilds of the species to examine the relationships with pollen sterols. 24-methylenecholesterol, sitosterol and isofucosterol were the most common and abundant pollen sterols. We found phylogenetic clustering of twelve individual sterols, total sterol content and sterol diversity, and of sterol groupings that reflect their underlying biosynthesis pathway (C-24 alkylation, ring B desaturation). Plants originating in tropical-like climates (higher mean annual temperature, lower temperature seasonality, higher precipitation in wettest quarter) were more likely to record higher pollen sterol content. However, pollen sterol composition and content showed no clear relationship with pollinator guilds. Our study is the first to show that pollen sterol diversity is phylogenetically clustered and that pollen sterol content may adapt to environmental conditions.
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Affiliation(s)
- Pengjuan Zu
- Royal Botanic GardensKew, Natural Capital and Plant Health DepartmentRichmondSurreyTW9 3ABUK
- Department Fish Ecology and EvolutionSwiss Federal Institute of Aquatic Science and TechnologySeestrasse 79KastanienbaumCH‐6047Switzerland
| | - Hauke Koch
- Royal Botanic GardensKew, Natural Capital and Plant Health DepartmentRichmondSurreyTW9 3ABUK
| | - Orlando Schwery
- New Mexico Consortium4200 W. Jemez Rd, Suite 301Los AlamosNM87544USA
| | - Samuel Pironon
- Royal Botanic GardensKew, Biodiversity Informatics and Spatial Analysis DepartmentRichmondSurreyTW9 3ABUK
| | - Charlotte Phillips
- Royal Botanic GardensKew, Biodiversity Informatics and Spatial Analysis DepartmentRichmondSurreyTW9 3ABUK
- Royal Botanic GardensKew, Conservation Science DepartmentWakehurst PlaceArdinglyWest SussexRH17 6TNUK
| | - Ian Ondo
- Royal Botanic GardensKew, Biodiversity Informatics and Spatial Analysis DepartmentRichmondSurreyTW9 3ABUK
| | - Iain W. Farrell
- Royal Botanic GardensKew, Natural Capital and Plant Health DepartmentRichmondSurreyTW9 3ABUK
| | - W. David Nes
- Department of Chemistry & BiochemistryTexas Tech UniversityLubbockTX79424USA
| | - Elynor Moore
- Department of ZoologyUniversity of Oxford11a Mansfield RoadOxfordOX1 3SZUK
| | | | - Dudley I. Farman
- Natural Resources InstituteUniversity of GreenwichChatham, KentME4 4TBUK
| | - Philip C. Stevenson
- Royal Botanic GardensKew, Natural Capital and Plant Health DepartmentRichmondSurreyTW9 3ABUK
- Natural Resources InstituteUniversity of GreenwichChatham, KentME4 4TBUK
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Pollen Protein: Lipid Macronutrient Ratios May Guide Broad Patterns of Bee Species Floral Preferences. INSECTS 2020; 11:insects11020132. [PMID: 32085627 PMCID: PMC7074338 DOI: 10.3390/insects11020132] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/03/2020] [Accepted: 02/15/2020] [Indexed: 11/26/2022]
Abstract
Pollinator nutritional ecology provides insights into plant–pollinator interactions, coevolution, and the restoration of declining pollinator populations. Bees obtain their protein and lipid nutrient intake from pollen, which is essential for larval growth and development as well as adult health and reproduction. Our previous research revealed that pollen protein to lipid ratios (P:L) shape bumble bee foraging preferences among pollen host-plant species, and these preferred ratios link to bumble bee colony health and fitness. Yet, we are still in the early stages of integrating data on P:L ratios across plant and bee species. Here, using a standard laboratory protocol, we present over 80 plant species’ protein and lipid concentrations and P:L values, and we evaluate the P:L ratios of pollen collected by three bee species. We discuss the general phylogenetic, phenotypic, behavioral, and ecological trends observed in these P:L ratios that may drive plant–pollinator interactions; we also present future research questions to further strengthen the field of pollination nutritional ecology. This dataset provides a foundation for researchers studying the nutritional drivers of plant–pollinator interactions as well as for stakeholders developing planting schemes to best support pollinators.
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