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Bieber BV, Lockett SG, Glasser SK, St Clair FA, Portillo NO, Adler LS, Povelones ML. Genetic modification of the bee parasite Crithidia bombi for improved visualization and protein localization. Exp Parasitol 2024; 262:108789. [PMID: 38762201 DOI: 10.1016/j.exppara.2024.108789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 05/02/2024] [Accepted: 05/15/2024] [Indexed: 05/20/2024]
Abstract
Crithidia bombi is a trypanosomatid parasite that infects several species of bumble bees (Bombus spp.), by adhering to their intestinal tract. Crithidia bombi infection impairs learning and reduces survival of workers and the fitness of overwintering queens. Although there is extensive research on the ecology of this host-pathogen system, we understand far less about the mechanisms that mediate internal infection dynamics. Crithidia bombi infects hosts by attaching to the hindgut via the flagellum, and one previous study found that a nectar secondary compound removed the flagellum, preventing attachment. However, approaches that allow more detailed observation of parasite attachment and growth would allow us to better understand factors mediating this host-pathogen relationship. We established techniques for genetic manipulation and visualization of cultured C. bombi. Using constructs established for Crithidia fasciculata, we successfully generated C. bombi cells expressing ectopic fluorescent transgenes using two different selectable markers. To our knowledge, this is the first genetic modification of this species. We also introduced constructs that label the mitochondrion and nucleus of the parasite, showing that subcellular targeting signals can function across parasite species to highlight specific organelles. Finally, we visualized fluorescently tagged parasites in vitro in both their swimming and attached forms, and in vivo in bumble bee (Bombus impatiens) hosts. Expanding our cell and molecular toolkit for C. bombi will help us better understand how factors such as host diet, immune system, and physiology mediate outcomes of infection by these common parasites.
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Affiliation(s)
| | - Sarah G Lockett
- Department of Biology, Villanova University, Villanova, PA, 19085, USA
| | - Sonja K Glasser
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Faith A St Clair
- Department of Biology, Villanova University, Villanova, PA, 19085, USA
| | - Neida O Portillo
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Megan L Povelones
- Department of Biology, Villanova University, Villanova, PA, 19085, USA.
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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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Erler S, Cotter SC, Freitak D, Koch H, Palmer-Young EC, de Roode JC, Smilanich AM, Lattorff HMG. Insects' essential role in understanding and broadening animal medication. Trends Parasitol 2024; 40:338-349. [PMID: 38443305 DOI: 10.1016/j.pt.2024.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 03/07/2024]
Abstract
Like humans, animals use plants and other materials as medication against parasites. Recent decades have shown that the study of insects can greatly advance our understanding of medication behaviors. The ease of rearing insects under laboratory conditions has enabled controlled experiments to test critical hypotheses, while their spectrum of reproductive strategies and living arrangements - ranging from solitary to eusocial communities - has revealed that medication behaviors can evolve to maximize inclusive fitness through both direct and indirect fitness benefits. Studying insects has also demonstrated in some cases that medication can act through modulation of the host's innate immune system and microbiome. We highlight outstanding questions, focusing on costs and benefits in the context of inclusive host fitness.
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Affiliation(s)
- Silvio Erler
- Institute for Bee Protection, Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Braunschweig, Germany; Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.
| | | | - Dalial Freitak
- Institute for Biology, University of Graz, Graz, Austria
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4
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Motta EVS, Moran NA. The honeybee microbiota and its impact on health and disease. Nat Rev Microbiol 2024; 22:122-137. [PMID: 38049554 PMCID: PMC10998682 DOI: 10.1038/s41579-023-00990-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2023] [Indexed: 12/06/2023]
Abstract
Honeybees (Apis mellifera) are key pollinators that support global agriculture and are long-established models for developmental and behavioural research. Recently, they have emerged as models for studying gut microbial communities. Earlier research established that hindguts of adult worker bees harbour a conserved set of host-restricted bacterial species, each showing extensive strain variation. These bacteria can be cultured axenically and introduced to gnotobiotic hosts, and some have basic genetic tools available. In this Review, we explore the most recent research showing how the microbiota establishes itself in the gut and impacts bee biology and health. Microbiota members occupy specific niches within the gut where they interact with each other and the host. They engage in cross-feeding and antagonistic interactions, which likely contribute to the stability of the community and prevent pathogen invasion. An intact gut microbiota provides protection against diverse pathogens and parasites and contributes to the processing of refractory components of the pollen coat and dietary toxins. Absence or disruption of the microbiota results in altered expression of genes that underlie immunity, metabolism, behaviour and development. In the field, such disruption by agrochemicals may negatively impact bees. These findings demonstrate a key developmental and protective role of the microbiota, with broad implications for bee health.
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Affiliation(s)
- Erick V S Motta
- Department of Integrative Biology, University of Texas, Austin, TX, USA
| | - Nancy A Moran
- Department of Integrative Biology, University of Texas, Austin, TX, USA.
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5
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Dahake A, Raguso RA, Goyret J. Context and the functional use of information in insect sensory ecology. CURRENT OPINION IN INSECT SCIENCE 2023; 58:101058. [PMID: 37217002 DOI: 10.1016/j.cois.2023.101058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/26/2023] [Accepted: 05/18/2023] [Indexed: 05/24/2023]
Abstract
Context-specific behaviors emerge from the interaction between an animal's internal state and its external environment. Although the importance of context is acknowledged in the field of insect sensory ecology, there is a lack of synthesis on this topic stemming from challenges in conceptualizing 'context'. We address this challenge by gleaning over the recent findings on the sensory ecology of mosquitoes and other insect pollinators. We discuss internal states and their temporal dynamics, from those lasting minutes to hours (host-seeking) to those lasting days to weeks (diapause, migration). Of the many patterns reviewed, at least three were common to all taxa studied. First, different sensory cues gain prominence depending on the insect's internal state. Second, similar sensory circuits between related species can result in different behavioral outcomes. And third, ambient conditions can dramatically alter internal states and behaviors.
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Affiliation(s)
- Ajinkya Dahake
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Joaquin Goyret
- Department of Biological Sciences, University of Tennessee Martin, Martin, TN, USA.
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Seidenath D, Weig AR, Mittereder A, Hillenbrand T, Brüggemann D, Opel T, Langhof N, Riedl M, Feldhaar H, Otti O. Diesel exhaust particles alter gut microbiome and gene expression in the bumblebee Bombus terrestris. Ecol Evol 2023; 13:e10180. [PMID: 37351478 PMCID: PMC10283033 DOI: 10.1002/ece3.10180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 04/13/2023] [Accepted: 05/29/2023] [Indexed: 06/24/2023] Open
Abstract
Insect decline is a major threat to ecosystems around the world as they provide many important functions, such as pollination or pest control. Pollution is one of the main reasons for the decline, alongside changes in land use, global warming, and invasive species. While negative impacts of pesticides are well-studied, there is still a lack of knowledge about the effects of other anthropogenic pollutants, such as airborne particulate matter, on insects. To address this, we exposed workers of the bumblebee Bombus terrestris to sublethal doses of diesel exhaust particles (DEPs) and brake dust, orally or via air. After 7 days, we looked at the composition of the gut microbiome and tracked changes in gene expression. While there were no changes in the other treatments, oral DEP exposure significantly altered the structure of the gut microbiome. In particular, the core bacterium Snodgrassella had a decreased abundance in the DEP treatment. Similarly, transcriptome analysis revealed changes in gene expression after oral DEP exposure, but not in the other treatments. The changes are related to metabolism and signal transduction, which indicates a general stress response. Taken together, our results suggest potential health effects of DEP exposure on insects, here shown in bumblebees, as gut dysbiosis may increase the susceptibility of bumblebees to pathogens, while a general stress response may lower available energy resources. Those effects may exacerbate under natural conditions where insects face a multiple-stressor environment.
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Affiliation(s)
- Dimitri Seidenath
- Animal Ecology I, Bayreuth Center of Ecology and Environmental Research (BayCEER)University of BayreuthBayreuthGermany
| | - Alfons R. Weig
- Keylab Genomics and Bioinformatics, Bayreuth Center of Ecology and Environmental Research (BayCEER)University of BayreuthBayreuthGermany
| | - Andreas Mittereder
- Department of Engineering Thermodynamics and Transport ProcessesUniversity of BayreuthBayreuthGermany
| | - Thomas Hillenbrand
- Department of Engineering Thermodynamics and Transport ProcessesUniversity of BayreuthBayreuthGermany
| | - Dieter Brüggemann
- Department of Engineering Thermodynamics and Transport ProcessesUniversity of BayreuthBayreuthGermany
| | - Thorsten Opel
- Department of Ceramic Materials EngineeringUniversity of BayreuthBayreuthGermany
| | - Nico Langhof
- Department of Ceramic Materials EngineeringUniversity of BayreuthBayreuthGermany
| | - Marcel Riedl
- Animal Ecology I, Bayreuth Center of Ecology and Environmental Research (BayCEER)University of BayreuthBayreuthGermany
| | - Heike Feldhaar
- Animal Ecology I, Bayreuth Center of Ecology and Environmental Research (BayCEER)University of BayreuthBayreuthGermany
| | - Oliver Otti
- Animal Ecology I, Bayreuth Center of Ecology and Environmental Research (BayCEER)University of BayreuthBayreuthGermany
- Applied ZoologyTU DresdenDresdenGermany
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Fattorini R, Egan PA, Rosindell J, Farrell IW, Stevenson PC. Grayanotoxin I variation across tissues and species of Rhododendron suggest pollinator-herbivore defence trade-offs. PHYTOCHEMISTRY 2023; 212:113707. [PMID: 37149121 DOI: 10.1016/j.phytochem.2023.113707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/25/2023] [Accepted: 05/03/2023] [Indexed: 05/08/2023]
Abstract
Grayanotoxin I (GTX I) is a major toxin in leaves of Rhododendron species, where it provides a defence against insect and vertebrate herbivores. Surprisingly, it is also present in R. ponticum nectar, and this can hold important implications for plant-pollinator mutualisms. However, knowledge of GTX I distributions across the genus Rhododendron and in different plant materials is currently limited, despite the important ecological function of this toxin. Here we characterise GTX I expression in the leaves, petals, and nectar of seven Rhododendron species. Our results indicated interspecific variation in GTX I concentration across all species. GTX I concentrations were consistently higher in leaves compared to petals and nectar. Our findings provide preliminary evidence for phenotypic correlation between GTX I concentrations in defensive tissues (leaves and petals) and floral rewards (nectar), suggesting that Rhododendron species may commonly experience functional trade-offs between herbivore defence and pollinator attraction.
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Affiliation(s)
- Róisín Fattorini
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, UK; Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK.
| | - Paul A Egan
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences, PO Box 102, Alnarp 23053, Sweden
| | - James Rosindell
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, UK
| | - Iain W Farrell
- Royal Botanic Gardens, Kew Green, Kew, Richmond, Surrey, TW9 3AE UK
| | - Philip C Stevenson
- Royal Botanic Gardens, Kew Green, Kew, Richmond, Surrey, TW9 3AE UK; Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
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8
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Giacomini JJ, Adler LS, Reading BJ, Irwin RE. Differential bumble bee gene expression associated with pathogen infection and pollen diet. BMC Genomics 2023; 24:157. [PMID: 36991318 DOI: 10.1186/s12864-023-09143-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/18/2023] [Indexed: 03/31/2023] Open
Abstract
BACKGROUND Diet and parasitism can have powerful effects on host gene expression. However, how specific dietary components affect host gene expression that could feed back to affect parasitism is relatively unexplored in many wild species. Recently, it was discovered that consumption of sunflower (Helianthus annuus) pollen reduced severity of gut protozoan pathogen Crithidia bombi infection in Bombus impatiens bumble bees. Despite the dramatic and consistent medicinal effect of sunflower pollen, very little is known about the mechanism(s) underlying this effect. However, sunflower pollen extract increases rather than suppresses C. bombi growth in vitro, suggesting that sunflower pollen reduces C. bombi infection indirectly via changes in the host. Here, we analyzed whole transcriptomes of B. impatiens workers to characterize the physiological response to sunflower pollen consumption and C. bombi infection to isolate the mechanisms underlying the medicinal effect. B. impatiens workers were inoculated with either C. bombi cells (infected) or a sham control (un-infected) and fed either sunflower or wildflower pollen ad libitum. Whole abdominal gene expression profiles were then sequenced with Illumina NextSeq 500 technology. RESULTS Among infected bees, sunflower pollen upregulated immune transcripts, including the anti-microbial peptide hymenoptaecin, Toll receptors and serine proteases. In both infected and un-infected bees, sunflower pollen upregulated putative detoxification transcripts and transcripts associated with the repair and maintenance of gut epithelial cells. Among wildflower-fed bees, infected bees downregulated immune transcripts associated with phagocytosis and the phenoloxidase cascade. CONCLUSIONS Taken together, these results indicate dissimilar immune responses between sunflower- and wildflower-fed bumble bees infected with C. bombi, a response to physical damage to gut epithelial cells caused by sunflower pollen, and a strong detoxification response to sunflower pollen consumption. Identifying host responses that drive the medicinal effect of sunflower pollen in infected bumble bees may broaden our understanding of plant-pollinator interactions and provide opportunities for effective management of bee pathogens.
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Affiliation(s)
- Jonathan J Giacomini
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, 27695, USA.
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Benjamin J Reading
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, 27695, USA
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9
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Vanderplanck M, Marin L, Michez D, Gekière A. Pollen as Bee Medicine: Is Prevention Better than Cure? BIOLOGY 2023; 12:497. [PMID: 37106698 PMCID: PMC10135463 DOI: 10.3390/biology12040497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/20/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023]
Abstract
To face environmental stressors such as infection, animals may display behavioural plasticity to improve their physiological status through ingestion of specific food. In bees, the significance of medicating pollen may be limited by their ability to exploit it. Until now, studies have focused on the medicinal effects of pollen and nectar after forced-feeding experiments, overlooking spontaneous intake. Here, we explored the medicinal effects of different pollen on Bombus terrestris workers infected by the gut parasite Crithidia bombi. First, we used a forced-feeding experimental design allowing for the distinction between prophylactic and therapeutic effects of pollen, considering host tolerance and resistance. Then, we assessed whether bumble bees favoured medicating resources when infected to demonstrate potential self-medicative behaviour. We found that infected bumble bees had a lower fitness but higher resistance when forced to consume sunflower or heather pollen, and that infection dynamics was more gradual in therapeutic treatments. When given the choice between resources, infected workers did not target medicating pollen, nor did they consume more medicating pollen than uninfected ones. These results emphasize that the access to medicating resources could impede parasite dynamics, but that the cost-benefit trade-off could be detrimental when fitness is highly reduced.
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Affiliation(s)
| | - Lucie Marin
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium
| | - Denis Michez
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium
| | - Antoine Gekière
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium
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10
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Palmer-Young EC, Malfi R, Zhou Y, Joyce B, Whitehead H, Van Wyk JI, Baylis K, Grubbs K, Boncristiani DL, Evans JD, Irwin RE, Adler LS. Sunflower-Associated Reductions in Varroa Mite Infestation of Honey Bee Colonies. JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:68-77. [PMID: 36573405 DOI: 10.1093/jee/toac196] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Indexed: 06/18/2023]
Abstract
Landscapes can affect parasite epidemiology in wild and agricultural animals. Honey bees are threatened by loss of floral resources and by parasites, principally the mite Varroa destructor and the viruses it vectors. Existing mite control relies heavily on chemical treatments that can adversely affect bees. Alternative, pesticide-free control methods are needed to mitigate infestation with these ectoparasites. Many flowering plants provide nectar and pollen that confer resistance to parasites. Enrichment of landscapes with antiparasitic floral resources could therefore provide a sustainable means of parasite control in pollinators. Floral rewards of Asteraceae plants can reduce parasitic infection in diverse bee species, including honey and bumble bees. Here, we tested the effects of sunflower (Helianthus annuus) cropland and pollen supplementation on honey bee resistance to macro- and microparasites. Although sunflower had nonsignificant effects on microparasites, We found that increased sunflower pollen availability correlated with reduced Varroa mite infestation in landscapes and pollen-supplemented colonies. At the landscape level, each doubling of sunflower crop area was associated with a 28% reduction in mite infestation. In field trials, late-summer supplementation of colonies with sunflower pollen reduced mite infestation by 2.75-fold relative to artificial pollen. United States sunflower crop acreage has declined by 2% per year since 1980, however, suggesting reduced availability of this floral resource. Although further research is needed to determine whether the observed effects represent direct inhibition of mite fecundity or mite-limiting reductions in honey bee brood-rearing, our findings suggest the potential for sunflower plantings or pollen supplements to counteract a major driver of honey bee losses worldwide.
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Affiliation(s)
| | - Rosemary Malfi
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Yujun Zhou
- Department of Agricultural & Consumer Economics, University of Illinois at Urbana-Champaign, Urbana and Champaign, IL, USA
| | - Bryanna Joyce
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Hannah Whitehead
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Jennifer I Van Wyk
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Kathy Baylis
- Department of Agricultural & Consumer Economics, University of Illinois at Urbana-Champaign, Urbana and Champaign, IL, USA
| | - Kyle Grubbs
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA
| | | | - Jay D Evans
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, USA
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA
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11
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Motta EVS, Gage A, Smith TE, Blake KJ, Kwong WK, Riddington IM, Moran N. Host-microbiome metabolism of a plant toxin in bees. eLife 2022; 11:82595. [PMID: 36472498 PMCID: PMC9897726 DOI: 10.7554/elife.82595] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
While foraging for nectar and pollen, bees are exposed to a myriad of xenobiotics, including plant metabolites, which may exert a wide range of effects on their health. Although the bee genome encodes enzymes that help in the metabolism of xenobiotics, it has lower detoxification gene diversity than the genomes of other insects. Therefore, bees may rely on other components that shape their physiology, such as the microbiota, to degrade potentially toxic molecules. In this study, we show that amygdalin, a cyanogenic glycoside found in honey bee-pollinated almond trees, can be metabolized by both bees and members of the gut microbiota. In microbiota-deprived bees, amygdalin is degraded into prunasin, leading to prunasin accumulation in the midgut and hindgut. In microbiota-colonized bees, on the other hand, amygdalin is degraded even further, and prunasin does not accumulate in the gut, suggesting that the microbiota contribute to the full degradation of amygdalin into hydrogen cyanide. In vitro experiments demonstrated that amygdalin degradation by bee gut bacteria is strain-specific and not characteristic of a particular genus or species. We found strains of Bifidobacterium, Bombilactobacillus, and Gilliamella that can degrade amygdalin. The degradation mechanism appears to vary since only some strains produce prunasin as an intermediate. Finally, we investigated the basis of degradation in Bifidobacterium wkB204, a strain that fully degrades amygdalin. We found overexpression and secretion of several carbohydrate-degrading enzymes, including one in glycoside hydrolase family 3 (GH3). We expressed this GH3 in Escherichia coli and detected prunasin as a byproduct when cell lysates were cultured with amygdalin, supporting its contribution to amygdalin degradation. These findings demonstrate that both host and microbiota can act together to metabolize dietary plant metabolites.
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Affiliation(s)
- Erick VS Motta
- Department of Integrative Biology, The University of Texas at AustinAustinUnited States
| | - Alejandra Gage
- Department of Integrative Biology, The University of Texas at AustinAustinUnited States
| | - Thomas E Smith
- Department of Integrative Biology, The University of Texas at AustinAustinUnited States
| | - Kristin J Blake
- Mass Spectrometry Facility, Department of Chemistry, The University of Texas at AustinAustinUnited States
| | | | - Ian M Riddington
- Mass Spectrometry Facility, Department of Chemistry, The University of Texas at AustinAustinUnited States
| | - Nancy Moran
- Department of Integrative Biology, The University of Texas at AustinAustinUnited States
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12
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Barribeau SM, Schmid-Hempel P, Walser JC, Zoller S, Berchtold M, Schmid-Hempel R, Zemp N. Genetic variation and microbiota in bumble bees cross-infected by different strains of C. bombi. PLoS One 2022; 17:e0277041. [PMID: 36441679 PMCID: PMC9704641 DOI: 10.1371/journal.pone.0277041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 10/18/2022] [Indexed: 11/29/2022] Open
Abstract
The bumblebee Bombus terrestris is commonly infected by a trypanosomatid gut parasite Crithidia bombi. This system shows a striking degree of genetic specificity where host genotypes are susceptible to different genotypes of parasite. To a degree, variation in host gene expression underlies these differences, however, the effects of standing genetic variation has not yet been explored. Here we report on an extensive experiment where workers of twenty colonies of B. terrestris were each infected by one of twenty strains of C. bombi. To elucidate the host's genetic bases of susceptibility to infection (measured as infection intensity), we used a low-coverage (~2 x) genome-wide association study (GWAS), based on angsd, and a standard high-coverage (~15x) GWAS (with a reduced set from a 8 x 8 interaction matrix, selected from the full set of twenty). The results from the low-coverage approach remained ambiguous. The high-coverage approach suggested potentially relevant genetic variation in cell surface and adhesion processes. In particular, mucin, a surface mucoglycoprotein, potentially affecting parasite binding to the host gut epithelia, emerged as a candidate. Sequencing the gut microbial community of the same bees showed that the abundance of bacterial taxa, such as Gilliamella, Snodgrassella, or Lactobacillus, differed between 'susceptible' and 'resistant' microbiota, in line with earlier studies. Our study suggests that the constitutive microbiota and binding processes at the cell surface are candidates to affect infection intensity after the first response (captured by gene expression) has run its course. We also note that a low-coverage approach may not be powerful enough to analyse such complex traits. Furthermore, testing large interactions matrices (as with the full 20 x 20 combinations) for the effect of interaction terms on infection intensity seems to blur the specific host x parasite interaction effects, likely because the outcome of an infection is a highly non-linear process dominated by variation in individually different pathways of host defence (immune) responses.
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Affiliation(s)
- Seth M. Barribeau
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
| | - Paul Schmid-Hempel
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
- * E-mail: (NZ); (PSH)
| | | | - Stefan Zoller
- Genetic Diversity Centre, ETH Zürich, Zürich, Switzerland
| | - Martina Berchtold
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
| | | | - Niklaus Zemp
- Genetic Diversity Centre, ETH Zürich, Zürich, Switzerland
- * E-mail: (NZ); (PSH)
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13
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Palmer-Young EC, Markowitz LM, Grubbs K, Zhang Y, Corona M, Schwarz R, Chen Y, Evans JD. Antiparasitic effects of three floral volatiles on trypanosomatid infection in honey bees. J Invertebr Pathol 2022; 194:107830. [PMID: 36174749 DOI: 10.1016/j.jip.2022.107830] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/07/2022] [Accepted: 09/21/2022] [Indexed: 11/18/2022]
Abstract
Trypanosomatid gut parasites are common in pollinators and costly for social bees. The recently described honey bee trypanosomatid Lotmaria passim is widespread, abundant, and correlated with colony losses in some studies. The potential for amelioration of infection by antimicrobial plant compounds has been thoroughly studied for closely related trypanosomatids of humans and is an area of active research in bumble bees, but remains relatively unexplored in honey bees. We recently identified several floral volatiles that inhibited growth of L. passim in vitro. Here, we tested the dose-dependent effects of four such compounds on infection, mortality, and food consumption in parasite-inoculated honey bees. We found that diets containing the monoterpenoid carvacrol and the phenylpropanoids cinnamaldehyde and eugenol at >10-fold the inhibitory concentrations for cell cultures reduced infection, with parasite numbers decreased by >90% for carvacrol and cinnamaldehyde and >99% for eugenol; effects of the carvacrol isomer thymol were non-significant. However, both carvacrol and eugenol also reduced bee survival, whereas parasite inoculation did not, indicating costs of phytochemical exposure that could exceed those of infection itself. To our knowledge, this is the first controlled screening of phytochemicals for effects on honey bee trypanosomatid infection, identifying potential treatments for managed bees afflicted with a newly characterized, cosmopolitan intestinal parasite.
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Affiliation(s)
| | - Lindsey M Markowitz
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA; Department of Biology, University of Maryland, College Park, MD, USA
| | - Kyle Grubbs
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA
| | - Yi Zhang
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA; Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, PR China
| | - Miguel Corona
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA
| | - Ryan Schwarz
- Department of Biology, Fort Lewis College, Durango, CO, USA
| | - Yanping Chen
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA
| | - Jay D Evans
- USDA-ARS Bee Research Laboratory, Beltsville, MD, USA
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14
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Stevenson PC, Koch H, Nicolson SW, Brown MJF. Natural processes influencing pollinator health. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210154. [PMID: 35491596 PMCID: PMC9062705 DOI: 10.1098/rstb.2021.0154] [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: 01/06/2023] Open
Abstract
Evidence from the last few decades indicates that pollinator abundance and diversity are at risk, with many species in decline. Anthropogenic impacts have been the focus of much recent work on the causes of these declines. However, natural processes, from plant chemistry, nutrition and microbial associations to landscape and habitat change, can also profoundly influence pollinator health. Here, we argue that these natural processes require greater attention and may even provide solutions to the deteriorating outlook for pollinators. Existing studies also focus on the decline of individuals and colonies and only occasionally at population levels. In the light of this we redefine pollinator health and argue that a top-down approach is required focusing at the ecological level of communities. We use examples from the primary research, opinion and review articles published in this special issue to illustrate how natural processes influence pollinator health, from community to individuals, and highlight where some of these processes could mitigate the challenges of anthropogenic and natural drivers of change. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Philip C Stevenson
- Royal Botanic Gardens, Kew, Kew Green, Richmond, Surrey TW9 3AE, UK.,Natural Resources Institute, University of Greenwich, Kent ME4 4TB, UK
| | - Hauke Koch
- Royal Botanic Gardens, Kew, Kew Green, Richmond, Surrey TW9 3AE, UK
| | - Susan W Nicolson
- Department of Zoology & Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - Mark J F Brown
- Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
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15
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Martin VN, Schaeffer RN, Fukami T. Potential effects of nectar microbes on pollinator health. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210155. [PMID: 35491594 DOI: 10.1098/rstb.2021.0155] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Floral nectar is prone to colonization by nectar-adapted yeasts and bacteria via air-, rain-, and animal-mediated dispersal. Upon colonization, microbes can modify nectar chemical constituents that are plant-provisioned or impart their own through secretion of metabolic by-products or antibiotics into the nectar environment. Such modifications can have consequences for pollinator perception of nectar quality, as microbial metabolism can leave a distinct imprint on olfactory and gustatory cues that inform foraging decisions. Furthermore, direct interactions between pollinators and nectar microbes, as well as consumption of modified nectar, have the potential to affect pollinator health both positively and negatively. Here, we discuss and integrate recent findings from research on plant-microbe-pollinator interactions and their consequences for pollinator health. We then explore future avenues of research that could shed light on the myriad ways in which nectar microbes can affect pollinator health, including the taxonomic diversity of vertebrate and invertebrate pollinators that rely on this reward. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
| | | | - Tadashi Fukami
- Department of Biology, Stanford University, Stanford, CA, USA
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16
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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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17
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Brown MJF. Complex networks of parasites and pollinators: moving towards a healthy balance. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210161. [PMID: 35491603 DOI: 10.1098/rstb.2021.0161] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Parasites are viewed as a major threat to wild pollinator health. While this may be true for epidemics driven by parasite spillover from managed or invasive species, the picture is more complex for endemic parasites. Wild pollinator species host and share a species-rich, generalist parasite community. In contrast to the negative health impacts that these parasites impose on individual hosts, at a community level they may act to reduce competition from common and abundant pollinator species. By providing rare species with space in which to exist, this will act to support and maintain a diverse and thus healthier pollinator community. At this level, and perhaps paraxodically, parasites may be good for pollinators. This stands in clear contrast to the obvious negative impacts of epidemic and spillover parasites on wild pollinator communities. Research into floral resources that control parasites could be best employed to help design landscapes that provide pollinators with the opportunity to moderate their parasite community, rather than attempting to eliminate specific parasites from wild pollinator communities. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Mark J F Brown
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, School of Life Sciences and the Environment, Royal Holloway University of London, Egham TW20 0EX, UK
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18
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Koch H, Welcome V, Kendal-Smith A, Thursfield L, Farrell IW, Langat MK, Brown MJF, Stevenson PC. Host and gut microbiome modulate the antiparasitic activity of nectar metabolites in a bumblebee pollinator. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210162. [PMID: 35491601 PMCID: PMC9058528 DOI: 10.1098/rstb.2021.0162] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Antimicrobial nectar secondary metabolites can support pollinator health by preventing or reducing parasite infections. To better understand the outcome of nectar metabolite-parasite interactions in pollinators, we determined whether the antiparasitic activity was altered through chemical modification by the host or resident microbiome during gut passage. We investigated this interaction with linden (Tilia spp.) and strawberry tree (Arbutus unedo) nectar compounds. Unedone from A. unedo nectar inhibited the common bumblebee gut parasite Crithidia bombi in vitro and in Bombus terrestris gynes. A compound in Tilia nectar, 1-[4-(1-hydroxy-1-methylethyl)-1,3-cyclohexadiene-1-carboxylate]-6-O-β-d-glucopyranosyl-β-d-glucopyranose (tiliaside), showed no inhibition in vitro at naturally occurring concentrations but reduced C. bombi infections of B. terrestris workers. Independent of microbiome status, tiliaside was deglycosylated during gut passage, thereby increasing its antiparasitic activity in the hindgut, the site of C. bombi infections. Conversely, unedone was first glycosylated in the midgut without influence of the microbiome to unedone-8-O-β-d-glucoside, rendering it inactive against C. bombi, but subsequently deglycosylated by the microbiome in the hindgut, restoring its activity. We therefore show that conversion of nectar metabolites by either the host or the microbiome modulates antiparasitic activity of nectar metabolites. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Hauke Koch
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK
| | - Vita Welcome
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK.,Imperial College, South Kensington, London SW7 2BX, UK
| | - Amy Kendal-Smith
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK.,Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Lucy Thursfield
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK.,John Innes Centre, Norwich, Norfolk NR4 7UH, UK
| | - Iain W Farrell
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK
| | - Moses K Langat
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK
| | - Mark J F Brown
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Philip C Stevenson
- Royal Botanic Gardens Kew, Kew Green, Richmond, Surrey TW9 3AE, UK.,Natural Resources Institute, University of Greenwich, Greenwich, Kent ME4 4TB, UK
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19
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Fowler AE, Sadd BM, Bassingthwaite T, Irwin RE, Adler LS. Consuming sunflower pollen reduced pathogen infection but did not alter measures of immunity in bumblebees. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210160. [PMID: 35491606 DOI: 10.1098/rstb.2021.0160] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Certain diets can benefit bee health by reducing pathogens, but the mechanism(s) driving these medicinal effects are largely unexplored. Recent research found that sunflower (Helianthus annuus) pollen reduces the gut pathogen Crithidia bombi in the common eastern bumblebee (Bombus impatiens). Here, we tested the effects of sunflower pollen and infection on two bee immune metrics to determine whether sunflower pollen diet drives changes in host immunity that can explain this medicinal effect. Bees were infected with C. bombi or not and given either sunflower or wildflower pollen. Subsequently, bees received a benign immune challenge or were left naive to test the induced and constitutive immune responses, respectively. We measured haemolymph phenoloxidase activity, involved in the melanization cascade, and antibacterial activity. Sunflower pollen reduced C. bombi infection, but we found no significant pollen diet effect on either immune measure. Phenoloxidase activity was also not affected by C. bombi infection status; however, uninfected bees were more likely to have measurable constitutive antibacterial activity, while infected bees had higher induced antibacterial activity. Overall, we found that sunflower pollen does not significantly affect the immune responses we measured, suggesting that the mechanisms underlying its medicinal effect do not involve these bee immune parameters. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Alison E Fowler
- Department of Biology, University of Massachusetts Amherst, 221 Morrill Science Center South, 611 North Pleasant Street, Amherst, MA 01003, USA
| | - Ben M Sadd
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Toby Bassingthwaite
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695, USA
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, 221 Morrill Science Center South, 611 North Pleasant Street, Amherst, MA 01003, USA
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20
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Palmer-Young EC, Schwarz RS, Chen Y, Evans JD. Can floral nectars reduce transmission of Leishmania? PLoS Negl Trop Dis 2022; 16:e0010373. [PMID: 35551517 PMCID: PMC9098005 DOI: 10.1371/journal.pntd.0010373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 03/29/2022] [Indexed: 11/19/2022] Open
Abstract
Background Insect-vectored Leishmania are responsible for loss of more disability-adjusted life years than any parasite besides malaria. Elucidation of the environmental factors that affect parasite transmission by vectors is essential to develop sustainable methods of parasite control that do not have off-target effects on beneficial insects or environmental health. Many phytochemicals that inhibit growth of sand fly-vectored Leishmania—which have been exhaustively studied in the search for phytochemical-based drugs—are abundant in nectars, which provide sugar-based meals to infected sand flies. Principle findings In a quantitative meta-analysis, we compare inhibitory phytochemical concentrations for Leishmania to concentrations present in floral nectar and pollen. We show that nectar concentrations of several flowering plant species exceed those that inhibit growth of Leishmania cell cultures, suggesting an unexplored, landscape ecology-based approach to reduce Leishmania transmission. Significance If nectar compounds are as effective against parasites in the sand fly gut as predicted from experiments in vitro, strategic planting of antiparasitic phytochemical-rich floral resources or phytochemically enriched baits could reduce Leishmania loads in vectors. Such interventions could provide an environmentally friendly complement to existing means of disease control. Leishmania parasites infect over a million people each year—including over 200,000 infections with deadly visceral leishmaniasis—resulting in a greater health burden than any human parasite besides malaria. Leishmania infections of humans are transmitted by blood-feeding sand flies, which also consume floral nectar. Nectar contains many chemicals that inhibit Leishmania growth and are candidate treatments for infection of humans. However, these same compounds could also reduce infection in nectar-consuming sand flies. By combining existing data on the chemistry of nectar and sensitivity of Leishmania to plant compounds, we show that some floral nectars contain sufficient chemical concentrations to inhibit growth of insect-stage Leishmania. Our results suggest that consumption of these nectars could reduce parasite loads in sand flies and transmission of parasites to new human hosts. In contrast to insecticide-based methods of sand fly control, incorporation of antiparasitic nectar sources into landscapes and domestic settings could benefit public health without threatening beneficial insects. These findings suggest an unexplored, landscape-based approach to reduce transmission of a major neglected tropical disease worldwide.
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Affiliation(s)
- Evan C. Palmer-Young
- USDA-ARS Bee Research Laboratory, Beltsville, Maryland, United States of America
- * E-mail: ,
| | - Ryan S. Schwarz
- Department of Biology, Fort Lewis College, Durango, Colorado, United States of America
| | - Yanping Chen
- USDA-ARS Bee Research Laboratory, Beltsville, Maryland, United States of America
| | - Jay D. Evans
- USDA-ARS Bee Research Laboratory, Beltsville, Maryland, United States of America
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21
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Siviter H, Matthews AJ, Brown MJF. A Combined LD50 for Agrochemicals and Pathogens in Bumblebees (Bombus terrestris [Hymenoptera: Apidae]). ENVIRONMENTAL ENTOMOLOGY 2022; 51:378-384. [PMID: 35021185 PMCID: PMC9032631 DOI: 10.1093/ee/nvab139] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Indexed: 06/04/2023]
Abstract
Neonicotinoid insecticides are the most commonly used insecticide in the world and can have significant sub-lethal impacts on beneficial insects, including bumblebees, which are important pollinators of agricultural crops and wild-flowers. This has led to bans on neonicotinoid use in the EU and has resulted in repeated calls for the agrochemical regulatory process to be modified. For example, there is increasing concern about 1) the underrepresentation of wild bees, such as bumblebees, in the regulatory process, and 2) the failure to determine how agrochemicals, such as neonicotinoids, interact with other commonly occurring environmental stressors, such as parasites. Here, we modify an OECD approved lethal dose (LD50) experimental design and coexpose bumblebees (Bombus terrestris) to the neonicotinoid thiamethoxam and the highly prevalent trypanosome parasite Crithidia bombi, in a fully crossed design. We found no difference in the LD50 of thiamethoxam on bumblebees that had or had not been inoculated with the parasite (Crithidia bombi). Furthermore, thiamethoxam dosage did not appear to influence the parasite intensity of surviving bumblebees, and there was no effect of either parasite or insecticide on sucrose consumption. The methodology used demonstrates how existing ring-tested experimental designs can be effectively modified to include other environmental stressors such as parasites. Moving forward, the regulatory process should implement methodologies that assess the interactions between agrochemicals and parasites on non-Apis bees and, in cases when this is not practical, should implement post-regulatory monitoring to better understand the real-world consequences of agrochemical use.
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Affiliation(s)
| | | | - Mark J F Brown
- Department of Biological Sciences, Centre for Ecology, Evolution, and Behaviour, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, Surrey, TW20 0EX, United Kingdom
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22
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Fitch G, Figueroa LL, Koch H, Stevenson PC, Adler LS. Understanding effects of floral products on bee parasites: Mechanisms, synergism, and ecological complexity. Int J Parasitol Parasites Wildl 2022; 17:244-256. [PMID: 35299588 PMCID: PMC8920997 DOI: 10.1016/j.ijppaw.2022.02.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 12/27/2022]
Abstract
Floral nectar and pollen commonly contain diverse secondary metabolites. While these compounds are classically thought to play a role in plant defense, recent research indicates that they may also reduce disease in pollinators. Given that parasites have been implicated in ongoing bee declines, this discovery has spurred interest in the potential for 'medicinal' floral products to aid in pollinator conservation efforts. We review the evidence for antiparasitic effects of floral products on bee diseases, emphasizing the importance of investigating the mechanism underlying antiparasitic effects, including direct or host-mediated effects. We discuss the high specificity of antiparasitic effects of even very similar compounds, and highlight the need to consider how nonadditive effects of multiple compounds, and the post-ingestion transformation of metabolites, mediate the disease-reducing capacity of floral products. While the bulk of research on antiparasitic effects of floral products on bee parasites has been conducted in the lab, we review evidence for the impact of such effects in the field, and highlight areas for future research at the floral product-bee disease interface. Such research has great potential both to enhance our understanding of the role of parasites in shaping plant-bee interactions, and the role of plants in determining bee-parasite dynamics. This understanding may in turn reveal new avenues for pollinator conservation.
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Affiliation(s)
- Gordon Fitch
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
- Corresponding author.
| | - Laura L. Figueroa
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
- Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Hauke Koch
- Royal Botanic Gardens, Kew Green, Kew, Richmond, Surrey, TW9 3AE, UK
| | - Philip C. Stevenson
- Royal Botanic Gardens, Kew Green, Kew, Richmond, Surrey, TW9 3AE, UK
- Natural Resources Institute, University of Greenwich, Kent, ME4 4TB, UK
| | - Lynn S. Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
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23
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Gekière A, Semay I, Gérard M, Michez D, Gerbaux P, Vanderplanck M. Poison or Potion: Effects of Sunflower Phenolamides on Bumble Bees and Their Gut Parasite. BIOLOGY 2022; 11:biology11040545. [PMID: 35453744 PMCID: PMC9030180 DOI: 10.3390/biology11040545] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 03/28/2022] [Accepted: 03/30/2022] [Indexed: 11/29/2022]
Abstract
Simple Summary Bee declines have been reported worldwide, partly due to parasite spread induced by human activities. However, bees may forage on specific floral resources to face parasite infection. Such natural resources are comparable to ‘natural pharmacies’ and may be favoured in bee conservation strategies. Consumption of sunflower pollen, despite being detrimental for larval development, has been recently shown to reduce the load of a widespread bumble bee gut parasite in the common eastern bumble bee. Although the underlying mechanisms remain unknown, it has been suggested that sunflower phenolamides—a family of molecules found in most flowering plants—may be responsible for such a reduction in parasite load. Here, we tested the impacts of sunflower phenolamides on healthy and infected buff-tailed bumble bees. Expectedly, sunflower pollen had harmful consequences on bumble bee development but surprisingly, it did not alter parasite load. By contrast, sunflower phenolamides had milder effects on bumble bee development but unexpectedly increased parasite load. Phenolamide effects may stem from the physiological stress they induced or the gut microbial community alteration they may have triggered. Since biological models and experimental framework differ greatly in related studies tackling plant–bee–parasite interplays, we challenged the definition of medicinal effects and questioned the way to assess them in controlled conditions. Abstract Specific floral resources may help bees to face environmental challenges such as parasite infection, as recently shown for sunflower pollen. Whereas this pollen diet is known to be unsuitable for the larval development of bumble bees, it has been shown to reduce the load of a trypanosomatid parasite (Crithidia bombi) in the bumble bee gut. Recent studies suggested it could be due to phenolamides, a group of compounds commonly found in flowering plants. We, therefore, decided to assess separately the impacts of sunflower pollen and its phenolamides on a bumble bee and its gut parasite. We fed Crithidia-infected and -uninfected microcolonies of Bombus terrestris either with a diet of willow pollen (control), a diet of sunflower pollen (natural diet) or a diet of willow pollen supplemented with sunflower phenolamides (supplemented diet). We measured several parameters at both microcolony (i.e., food collection, parasite load, brood development and stress responses) and individual (i.e., fat body content and phenotypic variation) levels. As expected, the natural diet had detrimental effects on bumble bees but surprisingly, we did not observe any reduction in parasite load, probably because of bee species-specific outcomes. The supplemented diet also induced detrimental effects but by contrast to our a priori hypothesis, it led to an increase in parasite load in infected microcolonies. We hypothesised that it could be due to physiological distress or gut microbiota alteration induced by phenolamide bioactivities. We further challenged the definition of medicinal effects and questioned the way to assess them in controlled conditions, underlining the necessity to clearly define the experimental framework in this research field.
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Affiliation(s)
- Antoine Gekière
- Laboratoire de Zoologie, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium;
- Correspondence: (A.G.); (M.V.); Tel.: +32-65373436 (A.G.)
| | - Irène Semay
- Organic Synthesis and Mass Spectrometry Laboratory, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium; (I.S.); (P.G.)
| | - Maxence Gérard
- Insect Lab., Division of Functional Morphology, Department of Zoology, Stockholm University, 11418 Stockholm, Sweden;
| | - Denis Michez
- Laboratoire de Zoologie, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium;
| | - Pascal Gerbaux
- Organic Synthesis and Mass Spectrometry Laboratory, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium; (I.S.); (P.G.)
| | - Maryse Vanderplanck
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, 34293 Montpellier, France
- Correspondence: (A.G.); (M.V.); Tel.: +32-65373436 (A.G.)
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24
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Bartlett LJ. Frontiers in effective control of problem parasites in beekeeping. Int J Parasitol Parasites Wildl 2022; 17:263-272. [PMID: 35309040 PMCID: PMC8924282 DOI: 10.1016/j.ijppaw.2022.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/27/2022] [Accepted: 03/01/2022] [Indexed: 12/21/2022]
Abstract
Demand for better control of certain parasites in managed western honey bees (Apis mellifera L.) remains apparent amongst beekeepers in both Europe and North America, and is of widespread public, scientific, and agricultural concern. Academically, interest from numerous fields including veterinary sciences has led to many exemplary reviews of the parasites of honey bees and the treatment options available. However, summaries of current research frontiers in treating both novel and long-known parasites of managed honey bees are lacking. This review complements the currently comprehensive body of literature summarizing the effectiveness of parasite control in managed honey bees by outlining where significant gaps in development, implementation, and uptake lie, including integration into IPM frameworks and separation of cultural, biological, and chemical controls. In particular, I distinguish where challenges in identifying appropriate controls exist in the lab compared to where we encounter hurdles in technology transfer due to regulatory, economic, or cultural contexts. I overview how exciting frontiers in honey bee parasite control research are clearly demonstrated by the abundance of recent publications on novel control approaches, but also caution that temperance must be levied on the applied end of the research engine in believing that what can be achieved in a laboratory research environment can be quickly and effectively marketed for deployment in the field.
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Affiliation(s)
- Lewis J Bartlett
- Center for the Ecology of Infectious Disease, University of Georgia, Athens, GA, 30602, USA
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25
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Giacomini JJ, Moore N, Adler LS, Irwin RE. Sunflower pollen induces rapid excretion in bumble bees: Implications for host-pathogen interactions. JOURNAL OF INSECT PHYSIOLOGY 2022; 137:104356. [PMID: 35016876 DOI: 10.1016/j.jinsphys.2022.104356] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/08/2021] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
Host diet can have a profound effect on host-pathogen interactions, including indirect effects on pathogens mediated through host physiology. In bumble bees (Bombus impatiens), the consumption of sunflower (Helianthus annuus) pollen dramatically reduces infection by the gut protozoan pathogen Crithidia bombi. One hypothesis for the medicinal effect of sunflower pollen is that consumption changes host gut physiological function, causing rapid excretion that flushes C. bombi from the system. We tested the effect of pollen diet and C. bombi infection on gut transit properties using a 2x2 factorial experiment in which bees were infected with C. bombi or not and fed sunflower or wildflower pollen diet. We measured several non-mutually exclusive physiological processes that underlie the insect excretory system, including gut transit time, bi-hourly excretion rate, the total number of excretion events and the total volume of excrement. Sunflower pollen significantly reduced gut transit time in uninfected bees, and increased the total number of excretion events and volume of excrement by 66 % and 68 %, respectively, in both infected and uninfected bees. Here we show that a sunflower pollen diet can affect host physiology gut function, causing more rapid and greater excretion. These results provide important insight into a mechanism that could underlie the medicinal effect of sunflower pollen for bumble bees.
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Affiliation(s)
- Jonathan J Giacomini
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695 USA.
| | - Nicholas Moore
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695 USA
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003 USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695 USA
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26
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Parreño MA, Alaux C, Brunet JL, Buydens L, Filipiak M, Henry M, Keller A, Klein AM, Kuhlmann M, Leroy C, Meeus I, Palmer-Young E, Piot N, Requier F, Ruedenauer F, Smagghe G, Stevenson PC, Leonhardt SD. Critical links between biodiversity and health in wild bee conservation. Trends Ecol Evol 2021; 37:309-321. [PMID: 34955328 DOI: 10.1016/j.tree.2021.11.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/24/2021] [Accepted: 11/30/2021] [Indexed: 11/29/2022]
Abstract
Wild bee populations are declining due to human activities, such as land use change, which strongly affect the composition and diversity of available plants and food sources. The chemical composition of food (i.e., nutrition) in turn determines the health, resilience, and fitness of bees. For pollinators, however, the term 'health' is recent and is subject to debate, as is the interaction between nutrition and wild bee health. We define bee health as a multidimensional concept in a novel integrative framework linking bee biological traits (physiology, stoichiometry, and disease) and environmental factors (floral diversity and nutritional landscapes). Linking information on tolerated nutritional niches and health in different bee species will allow us to better predict their distribution and responses to environmental change, and thus support wild pollinator conservation.
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Affiliation(s)
- M A Parreño
- Plant-Insect Interactions, TUM School of Life Science Systems, Technical University of Munich (TUM), Freising, Germany.
| | - C Alaux
- INRAE, Abeilles et Environnement, Avignon, France
| | - J-L Brunet
- INRAE, Abeilles et Environnement, Avignon, France
| | - L Buydens
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - M Filipiak
- Faculty of Biology, Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - M Henry
- INRAE, Abeilles et Environnement, Avignon, France
| | - A Keller
- Center for Computational and Theoretical Biology, and Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - A-M Klein
- Chair of Nature Conservation and Landscape Ecology, University of Freiburg, Freiburg, Germany
| | - M Kuhlmann
- Zoological Museum of Kiel University, Kiel, Germany
| | - C Leroy
- INRAE, Abeilles et Environnement, Avignon, France
| | - I Meeus
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - E Palmer-Young
- US Department of Agriculture (USDA) Agricultural Research Service Bee Research Laboratory, Beltsville, MD, USA
| | - N Piot
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - F Requier
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement, et Écologie, 91198 Gif-sur-Yvette, France
| | - F Ruedenauer
- Plant-Insect Interactions, TUM School of Life Science Systems, Technical University of Munich (TUM), Freising, Germany
| | - G Smagghe
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - P C Stevenson
- Royal Botanic Gardens, Kew, Surrey TW9 3AE, UK; University of Greenwich, London, UK
| | - S D Leonhardt
- Plant-Insect Interactions, TUM School of Life Science Systems, Technical University of Munich (TUM), Freising, Germany.
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Abstract
Bumblebees (Bombus) are charismatic and important pollinators. They are one of the best studied insect groups, especially in terms of ecology, behavior, and social structure. As many species are declining, there is a clear need to understand more about them. Microbial symbionts, which can influence many dimensions of animal life, likely have an outsized role in bumblebee biology. Recent research has shown that a conserved set of beneficial gut bacterial symbionts is ubiquitous across bumblebees. These bacteria are related to gut symbionts of honeybees, but have not been studied as intensively. Here we synthesize studies of bumblebee gut microbiota, highlight major knowledge gaps, and suggest future directions. Several patterns emerge, such as symbiont-host specificity maintained by sociality, frequent symbiont loss from individual bees, symbiont-conferred protection from trypanosomatid parasites, and divergence between bumblebee and honeybee microbiota in several key traits. For many facets of bumblebee-microbe interactions, however, underlying mechanisms and ecological functions remain unclear. Such information is important if we are to understand how bumblebees shape, and are shaped by, their gut microbiota. Bumblebees may provide a useful system for microbiome scientists, providing insights into general principles of host-microbe interactions. We also note how microbiota could influence bumblebee traits and responses to stressors. Finally, we propose that tinkering with the microbiota could be one way to aid bumblebee resilience in the face of global change.
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Affiliation(s)
- Tobin J. Hammer
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78703
- Corresponding author:
| | - Eli Le
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78703
| | - Alexia N. Martin
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78703
| | - Nancy A. Moran
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78703
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28
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Hien DFDS, Paré PSL, Cooper A, Koama BK, Guissou E, Yaméogo KB, Yerbanga RS, Farrell IW, Ouédraogo JB, Gnankiné O, Ignell R, Cohuet A, Dabiré RK, Stevenson PC, Lefèvre T. Contrasting effects of the alkaloid ricinine on the capacity of Anopheles gambiae and Anopheles coluzzii to transmit Plasmodium falciparum. Parasit Vectors 2021; 14:479. [PMID: 34526119 PMCID: PMC8444468 DOI: 10.1186/s13071-021-04992-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 09/02/2021] [Indexed: 11/18/2022] Open
Abstract
Background Besides feeding on blood, females of the malaria vector Anopheles gambiae sensu lato readily feed on natural sources of plant sugars. The impact of toxic secondary phytochemicals contained in plant-derived sugars on mosquito physiology and the development of Plasmodium parasites remains elusive. The focus of this study was to explore the influence of the alkaloid ricinine, found in the nectar of the castor bean Ricinus communis, on the ability of mosquitoes to transmit Plasmodium falciparum. Methods Females of Anopheles gambiae and its sibling species Anopheles coluzzii were exposed to ricinine through sugar feeding assays to assess the effect of this phytochemical on mosquito survival, level of P. falciparum infection and growth rate of the parasite. Results Ricinine induced a significant reduction in the longevity of both Anopheles species. Ricinine caused acceleration in the parasite growth rate with an earlier invasion of the salivary glands in both species. At a concentration of 0.04 g l−1 in An. coluzzii, ricinine had no effect on mosquito infection, while 0.08 g l−1 ricinine-5% glucose solution induced a 14% increase in An. gambiae infection rate. Conclusions Overall, our findings reveal that consumption of certain nectar phytochemicals can have unexpected and contrasting effects on key phenotypic traits that govern the intensity of malaria transmission. Further studies will be required before concluding on the putative role of ricinine as a novel control agent, including the development of ricinine-based toxic and transmission-blocking sugar baits. Testing other secondary phytochemicals in plant nectar will provide a broader understanding of the impact which plants can have on the transmission of vector-borne diseases. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04992-z.
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Affiliation(s)
- Domonbabele F D S Hien
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso. .,Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso. .,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France.
| | - Prisca S L Paré
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso.,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France.,Université Joseph KI-ZERBO, Ougadougou, Burkina Faso
| | - Amanda Cooper
- Royal Botanic Gardens, Kew, Surrey, Richmond, TW9 3AE, UK
| | - Benjamin K Koama
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso.,Institut Des Sciences Et Techniques, Université Nazi Boni, Bobo-Dioulasso, Burkina Faso
| | - Edwige Guissou
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso.,Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso.,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France
| | - Koudraogo B Yaméogo
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso.,Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Rakiswendé S Yerbanga
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso.,Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Iain W Farrell
- Royal Botanic Gardens, Kew, Surrey, Richmond, TW9 3AE, UK
| | - Jean B Ouédraogo
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso
| | | | - Rickard Ignell
- Department of Plant Protection Biology, Unit of Chemical Ecology, Disease Vector Group, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Anna Cohuet
- Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso.,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France
| | - Roch K Dabiré
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo Dioulasso, Burkina Faso.,Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Philip C Stevenson
- Royal Botanic Gardens, Kew, Surrey, Richmond, TW9 3AE, UK.,Natural Resources Institute, University of Greenwich, Kent, ME4 4TB, UK
| | - Thierry Lefèvre
- Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso.,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France.,Centre de Recherche en Écologie Et Évolution de La Santé (CREES), Montpellier, France
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29
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Buendía-Abad M, García-Palencia P, de Pablos LM, Alunda JM, Osuna A, Martín-Hernández R, Higes M. First description of Lotmaria passim and Crithidia mellificae haptomonad stages in the honeybee hindgut. Int J Parasitol 2021; 52:65-75. [PMID: 34416272 DOI: 10.1016/j.ijpara.2021.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/22/2022]
Abstract
The remodelling of flagella into attachment structures is a common and important event in the trypanosomatid life cycle. Lotmaria passim and Crithidia mellificae can parasitize Apis mellifera, and as a result they might have a significant impact on honeybee health. However, there are details of their life cycle and the mechanisms underlying their pathogenicity in this host that remain unclear. Here we show that both L. passim promastigotes and C. mellificae choanomastigotes differentiate into haptomonad stages covering the ileum and rectum of honeybees. These haptomonad cells remain attached to the host surface via zonular hemidesmosome-like structures, as revealed by transmission electron microscopy. This work describes for the first known time the haptomonad morphotype of these species and their hemidesmosome-like attachments in A. mellifera, a key trait used by other trypanosomatid species to proliferate in the insect host hindgut.
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Affiliation(s)
- María Buendía-Abad
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), IRIAF - Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal, Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Marchamalo, Spain.
| | - Pilar García-Palencia
- Departamento de Medicina Veterinaria y Cirugía Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain
| | - Luis Miguel de Pablos
- Departamento de Parasitología, Grupo de Bioquímica y Parasitología Molecular CTS-183, Universidad de Granada, Granada, Spain
| | - José María Alunda
- Departamento de Sanidad Animal, Grupo ICPVet, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain
| | - Antonio Osuna
- Departamento de Parasitología, Grupo de Bioquímica y Parasitología Molecular CTS-183, Universidad de Granada, Granada, Spain
| | - Raquel Martín-Hernández
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), IRIAF - Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal, Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Marchamalo, Spain; Instituto de Recursos Humanos para la Ciencia y la Tecnología (INCRECYT-FEDER), Fundación Parque Científico y Tecnológico de Castilla - La Mancha, Albacete, Spain
| | - Mariano Higes
- Laboratorio de Patología Apícola, Centro de Investigación Apícola y Agroambiental (CIAPA), IRIAF - Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal, Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Marchamalo, Spain
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30
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Giacomini JJ, Connon SJ, Marulanda D, Adler LS, Irwin RE. The costs and benefits of sunflower pollen diet on bumble bee colony disease and health. Ecosphere 2021. [DOI: 10.1002/ecs2.3663] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jonathan J. Giacomini
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
| | - Sara J. Connon
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
| | - Daniel Marulanda
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
| | - Lynn S. Adler
- Department of Biology University of Massachusetts Amherst Amherst Massachusetts 01003 USA
| | - Rebecca E. Irwin
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
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31
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Folly AJ, Koch H, Farrell IW, Stevenson PC, Brown MJF. Agri-environment scheme nectar chemistry can suppress the social epidemiology of parasites in an important pollinator. Proc Biol Sci 2021; 288:20210363. [PMID: 34034519 PMCID: PMC8150011 DOI: 10.1098/rspb.2021.0363] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/05/2021] [Indexed: 12/20/2022] Open
Abstract
Emergent infectious diseases are one of the main drivers of species loss. Emergent infection with the microsporidian Nosema bombi has been implicated in the population and range declines of a suite of North American bumblebees, a group of important pollinators. Previous work has shown that phytochemicals found in pollen and nectar can negatively impact parasites in individuals, but how this relates to social epidemiology and by extension whether plants can be effectively used as pollinator disease management strategies remains unexplored. Here, we undertook a comprehensive screen of UK agri-environment scheme (AES) plants, a programme designed to benefit pollinators and wider biodiversity in agricultural settings, for phytochemicals in pollen and nectar using liquid chromatography and mass spectrometry. Caffeine, which occurs across a range of plant families, was identified in the nectar of sainfoin (Onobrychis viciifolia), a component of UK AES and a major global crop. We showed that caffeine significantly reduces N. bombi infection intensity, both prophylactically and therapeutically, in individual bumblebees (Bombus terrestris), and, for the first time, that such effects impact social epidemiology, with colonies reared from wild-caught queens having both lower prevalence and intensity of infection. Furthermore, infection prevalence was lower in foraging bumblebees from caffeine-treated colonies, suggesting a likely reduction in population-level transmission. Combined, these results show that N. bombi is less likely to be transmitted intracolonially when bumblebees consume naturally available caffeine, and that this may in turn reduce environmental prevalence. Consequently, our results demonstrate that floral phytochemicals at ecologically relevant concentrations can impact pollinator disease epidemiology and that planting strategies that increase floral abundance to support biodiversity could be co-opted as disease management tools.
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Affiliation(s)
- Arran J. Folly
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, UK
| | | | | | - Philip C. Stevenson
- Royal Botanic Gardens, Kew, UK
- Natural Resources Institute, University of Greenwich, Kent, UK
| | - Mark J. F. Brown
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, UK
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32
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Martin CD, Fountain MT, Brown MJF. The potential for parasite spill-back from commercial bumblebee colonies: a neglected threat to wild bees? JOURNAL OF INSECT CONSERVATION 2021; 25:531-539. [PMID: 34720661 PMCID: PMC8550768 DOI: 10.1007/s10841-021-00322-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 05/12/2021] [Indexed: 05/08/2023]
Abstract
Commercially-reared bumblebee colonies provide pollination services to numerous crop species globally. These colonies may harbour parasites which can spill-over to wild bee species. However, the potential for parasites to spread from wild to commercial bumblebees, which could then lead to parasite spill-back, is poorly understood. To investigate this, parasite-free commercial Bombus terrestris audax colonies, which are used commercially for strawberry pollination, were placed into seasonal strawberry crops for either 6- or 8-week blocks across two key time periods, early spring and early summer. Bumblebees were removed from colonies weekly and screened for the presence of parasites. In the early spring placement, only one parasite, the highly virulent neogregarine Apicystis bombi, was detected at a low prevalence (0.46% across all bees screened). In contrast, all colonies placed in the crop in the early summer became infected. A trypanosome, Crithidia bombi, and A. bombi were the most prevalent parasites across all samples, reaching peak prevalence in screened bees of 39.39% and 18.18% respectively at the end of the experimental period. The prevalence of A. bombi was greater than most UK records from wild bumblebees, suggesting that commercial colonies could enhance levels of A. bombi infection in wild bees through spill-back. Studies on larger geographical scales with different commercial colony densities are required to fully assess spill-back risk. However, seasonal management, to minimise spill-back opportunities, and treatment of commercial colonies to prevent infection, could be implemented to manage the potential risks of parasite spill-back to wild bees. Implications for insect conservation Our results show that commercial bumblebee populations do pick up infections, most likely from wild bees, and that these infections can reach prevalences where they may pose a threat to wild bees via parasite spill-back. More research is required to clarify the extent of this potential threat. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s10841-021-00322-x.
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Affiliation(s)
- Callum D. Martin
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX UK
| | | | - Mark J. F. Brown
- Centre for Ecology, Evolution and Behaviour, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX UK
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33
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Adler LS, Irwin RE, McArt SH, Vannette RL. Floral traits affecting the transmission of beneficial and pathogenic pollinator-associated microbes. CURRENT OPINION IN INSECT SCIENCE 2021; 44:1-7. [PMID: 32866657 PMCID: PMC7914268 DOI: 10.1016/j.cois.2020.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 05/22/2023]
Abstract
Flowers provide resources for pollinators, and can also be transmission venues for beneficial or pathogenic pollinator-associated microbes. Floral traits could mediate transmission similarly for beneficial and pathogenic microbes, although some beneficial microbes can grow in flowers while pathogenic microbes may only survive until acquired by a new host. In spite of conceptual similarities, research on beneficial and pathogenic pollinator-associated microbes has progressed mostly independently. Recent advances demonstrate that floral traits are associated with transmission of beneficial and pathogenic microbes, with consequences for pollinator populations and communities. However, there is a near-absence of experimental manipulations of floral traits to determine causal effects on transmission, and a need to understand how floral, microbe and host traits interact to mediate transmission.
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Affiliation(s)
- Lynn S Adler
- Department of Biology, University of Massachusetts, 221 Morrill Science Center, 611 N. Pleasant St., Amherst MA 01002 USA.
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, 127 David Clark Labs, 100 Eugene Brooks Ave., Raleigh, NC 27695 USA
| | - Scott H McArt
- Department of Entomology, Cornell University, 4132 Comstock Hall, 129 Garden Ave., Ithaca, NY 14853 USA
| | - Rachel L Vannette
- Department of Entomology and Nematology, University of California, 43 Briggs Hall, Davis CA 95616 USA
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34
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Schmitt A, Roy R, Carter CJ. Nectar antimicrobial compounds and their potential effects on pollinators. CURRENT OPINION IN INSECT SCIENCE 2021; 44:55-63. [PMID: 33771735 DOI: 10.1016/j.cois.2021.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/24/2021] [Accepted: 03/15/2021] [Indexed: 06/12/2023]
Abstract
Nectar is a sugary, aqueous solution that plants offer as a reward to animal mutualists for visitation. Since nectars are so nutrient-rich, they often harbor significant microbial communities, which can be pathogenic, benign, or even sometimes beneficial to plant fitness. Through recent advances, it is now clear that these microbes alter nectar chemistry, which in turn influences mutualist behavior (e.g. pollinator visitation). To counteract unwanted microbial growth, nectars often contain antimicrobial compounds, especially in the form of proteins, specialized (secondary) metabolites, and metals. This review covers our current understanding of nectar antimicrobials, as well as their interplay with both microbes and insect visitors.
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Affiliation(s)
- Anthony Schmitt
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Ave, St. Paul, MN 55108, USA
| | - Rahul Roy
- Biology Department, St. Catherine University, 2004 Randolph Ave, St. Paul, MN 55105, USA
| | - Clay J Carter
- Department of Plant & Microbial Biology, University of Minnesota, 1479 Gortner Ave, St. Paul, MN 55108, USA.
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35
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Tawich SK, Bargul JL, Masiga D, Getahun MN. Supplementing Blood Diet With Plant Nectar Enhances Egg Fertility in Stomoxys calcitrans. Front Physiol 2021; 12:646367. [PMID: 33859570 PMCID: PMC8042263 DOI: 10.3389/fphys.2021.646367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/25/2021] [Indexed: 11/19/2022] Open
Abstract
Stomoxys calcitrans (stable fly) is a cosmopolitan biting fly of both medical and veterinary importance. Unlike blood-feeding-related behavior of stable fly, its plant feeding, the fitness value, and the S. calcitrans-plant interaction are less understood. Here we show based on two chloroplast DNA genes, ribulose bisphosphate carboxylase large chain (rbcL) and the intergenic spacer gene trnH-psbA, that field-collected male and female stable flies fed on various plant species. We investigated the fitness cost of plant feeding using Parthenium hysterophorus, one of the plant species identified to have been fed on by the field-collected flies. Supplementation of blood feeding with a flowering P. hysterophorus plant as nectar source enhanced egg hatchability significantly as compared to blood alone, showing the fitness value of nectar supplementation. However, nectar supplementation did not affect the number of eggs laid or longevity of S. calcitrans as compared to flies that fed on blood alone. S. calcitrans maintained on sugar alone failed to lay eggs. The various plants stable flies fed on demonstrated chemodiversity with their own signature scent. The behavioral response of S. calcitrans to these signature compounds varied from strong attraction (γ-terpinene) to neutral (linalool oxide and myrcene) to repellency (butanoic acid). Our study demonstrated that stable flies feed on nectar, and plant nectar supplementation of blood feeding enhanced larval emergence. Thus, our result has implication in stable fly reproduction, survival, disease transmission, boosting laboratory colony, and the possibility of using plant-derived odors for mass trapping of stable fly, for instance, using γ-terpinene.
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Affiliation(s)
- Simon K. Tawich
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Joel L. Bargul
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Daniel Masiga
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Merid N. Getahun
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
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Foster K, Oyenihi O, Rademan S, Erhabor J, Matsabisa M, Barker J, Langat MK, Kendal-Smith A, Asemota H, Delgoda R. Selective cytotoxic and anti-metastatic activity in DU-145 prostate cancer cells induced by Annona muricata L. bark extract and phytochemical, annonacin. BMC Complement Med Ther 2020; 20:375. [PMID: 33302945 PMCID: PMC7727144 DOI: 10.1186/s12906-020-03130-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/22/2020] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Annona muricata L. was identified as a popular medicinal plant in treatment regimens among cancer patients in Jamaica by a previously conducted structured questionnaire. Ethnomedically used plant parts, were examined in this study against human prostate cancer cells for the first time and mechanisms of action elucidated for the most potent of them, along with the active phytochemical, annonacin. METHODS Nine extracts of varying polarity from the leaves and bark of A. muricata were assessed initially for cytotoxicity using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on PC-3 prostate cancer cells and the ethyl acetate bark (EAB) extract was identified as the most potent. EAB extract was then standardized for annonacin content using High-performance Liquid Chromatography - Mass Spectrometry (HPLC-MS) and shown to be effective against a second prostate cancer cell line (DU-145) also. The mode of cell death in DU-145 cells were assessed via several apoptotic assays including induction of increased reactive oxygen species (ROS) production, reduction of mitochondrial membrane potential, activation of caspases and annexin V externalization combined with morphological observations using confocal microscopy. In addition, the potential to prevent metastasis was examined via inhibition of cell migration, vascular endothelial growth factor (VEGF) and angiogenesis using the chorioallantoic membrane assay (CAM). RESULTS Annonacin and EAB extract displayed selective and potent cytotoxicity against the DU-145 prostate carcinoma cells with IC50 values of 0.1 ± 0.07 μM and 55.501 ± 0.55 μg/mL respectively, without impacting RWPE-1 normal prostate cells, in stark contrast to chemotherapeutic docetaxel which lacked such selectivity. Docetaxel's impact on the cancerous DU-145 was improved by 50% when used in combination with EAB extract. Insignificant levels of intracellular ROS content, depolarization of mitochondrial membrane, Caspase 3/7 activation, annexin V content, along with stained morphological evaluations, pointed to a non-apoptotic mode of cell death. The extract at 50 μg/mL deterred cell migration in the wound-healing assay, while inhibition of angiogenesis was displayed in the CAM and VEGF inhibition assays for both EAB (100 μg /mL) and annonacin (0.5 μM). CONCLUSIONS Taken together, the standardized EAB extract and annonacin appear to induce selective and potent cell death via a necrotic pathway in DU-145 cells, while also preventing cell migration and angiogenesis, which warrant further examinations for mechanistic insights and validity in-vivo.
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Affiliation(s)
- Kimberley Foster
- Natural Products Institute, University of the West Indies, Mona, Kingston 7, Jamaica
- Biotechnolgy Centre, University of the West Indies, Mona, Kingston 7, Jamaica
| | - Omolola Oyenihi
- Pharmacology Department, School of Clinical Medicine, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| | - Sunelle Rademan
- Pharmacology Department, School of Clinical Medicine, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| | - Joseph Erhabor
- Pharmacology Department, School of Clinical Medicine, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| | - Motlalepula Matsabisa
- Pharmacology Department, School of Clinical Medicine, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| | - James Barker
- School of Life Sciences, Pharmacy and Chemistry, Kingston University, Penrhyn Road, Kingston-upon-Thames, Surrey, UK
| | - Moses K Langat
- Jodrell Laboratory, Department of Natural Capital and Plant Health, Royal Botanic Gardens, Kew, Richmond, TW9 3DS, UK
| | - Amy Kendal-Smith
- Jodrell Laboratory, Department of Natural Capital and Plant Health, Royal Botanic Gardens, Kew, Richmond, TW9 3DS, UK
- Faculty of Biological Sciences, University of Leeds, Leeds, England
| | - Helen Asemota
- Biotechnolgy Centre, University of the West Indies, Mona, Kingston 7, Jamaica
| | - Rupika Delgoda
- Natural Products Institute, University of the West Indies, Mona, Kingston 7, Jamaica.
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37
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OneHealth implications of infectious diseases of wild and managed bees. J Invertebr Pathol 2020; 186:107506. [PMID: 33249062 DOI: 10.1016/j.jip.2020.107506] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/27/2020] [Accepted: 11/20/2020] [Indexed: 01/23/2023]
Abstract
The OneHealth approach aims to further our understanding of the drivers of human, animal and environmental health, and, ultimately, to improve them by combining approaches and knowledge from medicine, biology and fields beyond. Wild and managed bees are essential pollinators of crops and wild flowers. Their health thus directly impacts on human and environmental health. At the same time, these bee species represent highly amenable and relevant model organisms for a OneHealth approach that aims to study fundamental epidemiological questions. In this review, we focus on how infectious diseases of wild and managed bees can be used as a OneHealth model system, informing fundamental questions on ecological immunology and disease transmission, while addressing how this knowledge can be used to tackle the issues facing pollinator health.
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Vannette RL. The Floral Microbiome: Plant, Pollinator, and Microbial Perspectives. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-013401] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Flowers at times host abundant and specialized communities of bacteria and fungi that influence floral phenotypes and interactions with pollinators. Ecological processes drive variation in microbial abundance and composition at multiple scales, including among plant species, among flower tissues, and among flowers on the same plant. Variation in microbial effects on floral phenotype suggests that microbial metabolites could cue the presence or quality of rewards for pollinators, but most plants are unlikely to rely on microbes for pollinator attraction or reproduction. From a microbial perspective, flowers offer opportunities to disperse between habitats, but microbial species differ in requirements for and benefits received from such dispersal. The extent to which floral microbes shape the evolution of floral traits, influence fitness of floral visitors, and respond to anthropogenic change is unclear. A deeper understanding of these phenomena could illuminate the ecological and evolutionary importance of floral microbiomes and their role in the conservation of plant–pollinator interactions.
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Affiliation(s)
- Rachel L. Vannette
- Department of Entomology and Nematology, University of California, Davis, California 95616, USA
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39
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Aguirre LA, Davis JK, Stevenson PC, Adler LS. Herbivory and Time Since Flowering Shape Floral Rewards and Pollinator-Pathogen Interactions. J Chem Ecol 2020; 46:978-986. [PMID: 32876829 DOI: 10.1007/s10886-020-01213-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/07/2020] [Accepted: 08/24/2020] [Indexed: 10/23/2022]
Abstract
Herbivory can induce chemical changes throughout plant tissues including flowers, which could affect pollinator-pathogen interactions. Pollen is highly defended compared to nectar, but no study has examined whether herbivory affects pollen chemistry. We assessed the effects of leaf herbivory on nectar and pollen alkaloids in Nicotiana tabacum, and how herbivory-induced changes in nectar and pollen affect pollinator-pathogen interactions. We damaged leaves of Nicotiana tabacum using the specialist herbivore Manduca sexta and compared nicotine and anabasine concentrations in nectar and pollen. We then pooled nectar and pollen by collection periods (within and after one month of flowering), fed them in separate experiments to bumble bees (Bombus impatiens) infected with the gut pathogen Crithidia bombi, and assessed infections after seven days. We did not detect alkaloids in nectar, and leaf damage did not alter the effect of nectar on Crithidia counts. In pollen, herbivory induced higher concentrations of anabasine but not nicotine, and alkaloid concentrations rose and then fell as a function of days since flowering. Bees fed pollen from damaged plants had Crithidia counts 15 times higher than bees fed pollen from undamaged plants, but only when pollen was collected after one month of flowering, indicating that both damage and time since flowering affected interaction outcomes. Within undamaged treatments, bees fed late-collected pollen had Crithidia counts 10 times lower than bees fed early-collected pollen, also indicating the importance of time since flowering. Our results emphasize the role of herbivores in shaping pollen chemistry, with consequences for interactions between pollinators and their pathogens.
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Affiliation(s)
- Luis A Aguirre
- Department of Biology, University of Massachusetts, Amherst, MA, 01003, USA.
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA, 01003, USA.
| | - Julie K Davis
- Department of Entomology, Cornell University, Ithaca, NY, 14850, USA
| | - Philip C Stevenson
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey, TW9 3AB, UK
- Natural Resources Institute, University of Greenwich, Chatham, Kent, ME4 4TB, UK
| | - Lynn S Adler
- Department of Biology, University of Massachusetts, Amherst, MA, 01003, USA
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Scott-Brown A, Koch H. New directions in pollinator research: diversity, conflict and response to global change. Emerg Top Life Sci 2020; 4:ETLS20200123. [PMID: 32556155 DOI: 10.1042/etls20200123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/01/2020] [Accepted: 06/01/2020] [Indexed: 11/17/2022]
Abstract
Interactions between pollinators and their plant hosts are central to maintaining global biodiversity and ensuring our food security. In this special issue, we compile reviews that summarize existing knowledge and point out key outstanding research areas to understand and safeguard pollinators, pollinators-host plant interactions and the pollination ecosystem services they provide. The vast diversity of the pollinator-plant interactions that exists on this planet still remains poorly explored, with many being associations involving a specialist pollinator partner, although historically most focus has been given to generalist pollinators, such as the honeybee. Two areas highlighted here are the ecology and evolution of oligolectic bee species, and the often-neglected groups of pollinators that forage solely at night. Advances in automated detection technologies could offer potential and complementary solutions to the current shortfall in knowledge on interactions occurring between less well-documented plant-pollinator associations, by increasing the collection range and capacity of flower visitation data over space and time. Pollinator-host plant interactions can be affected by external biotic factors, with herbivores and pathogens playing particularly important roles. Such interactions can be disrupted by modifying plant volatile and reward chemistry, with possible effects on pollinator attraction and pollination success. Mechanisms which underpin interactions between plants and their pollinators also face many anthropogenic disturbances. Reviews in this issue discuss threats from parasites and climate change to pollinator populations and plant-pollinator networks, and suggest new ways to mitigate these threats. While the protection of existing plant-pollinator networks will be a crucial goal for conservation biology, more research is needed to understand how lost interactions in degraded habitats may be restored with mutual benefits to plants and pollinators.
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Affiliation(s)
- Alison Scott-Brown
- Department of Natural Capital and Plant Health, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, U.K
| | - Hauke Koch
- Department of Natural Capital and Plant Health, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, U.K
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Abstract
Recent declines of wild pollinators and infections in honey, bumble and other bee species have raised concerns about pathogen spillover from managed honey and bumble bees to other pollinators. Parasites of honey and bumble bees include trypanosomatids and microsporidia that often exhibit low host specificity, suggesting potential for spillover to co-occurring bees via shared floral resources. However, experimental tests of trypanosomatid and microsporidial cross-infectivity outside of managed honey and bumble bees are scarce. To characterize potential cross-infectivity of honey and bumble bee-associated parasites, we inoculated three trypanosomatids and one microsporidian into five potential hosts – including four managed species – from the apid, halictid and megachilid bee families. We found evidence of cross-infection by the trypanosomatids Crithidia bombi and C. mellificae, with evidence for replication in 3/5 and 3/4 host species, respectively. These include the first reports of experimental C. bombi infection in Megachile rotundata and Osmia lignaria, and C. mellificae infection in O. lignaria and Halictus ligatus. Although inability to control amounts inoculated in O. lignaria and H. ligatus hindered estimates of parasite replication, our findings suggest a broad host range in these trypanosomatids, and underscore the need to quantify disease-mediated threats of managed social bees to sympatric pollinators.
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Folly AJ, Stevenson PC, Brown MJF. Age-related pharmacodynamics in a bumblebee-microsporidian system mirror similar patterns in vertebrates. ACTA ACUST UNITED AC 2020; 223:jeb.217828. [PMID: 32107305 DOI: 10.1242/jeb.217828] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/23/2020] [Indexed: 12/27/2022]
Abstract
Immune systems provide a key defence against diseases. However, they are not a panacea and so both vertebrates and invertebrates co-opt naturally occurring bioactive compounds to treat themselves against parasites and pathogens. In vertebrates, this co-option is complex, with pharmacodynamics leading to differential effects of treatment at different life stages, which may reflect age-linked differences in the immune system. However, our understanding of pharmacodynamics in invertebrates is almost non-existent. Critically, this knowledge may elucidate broad parallels across animals in regard to the requirement for the co-option of bioactive compounds to ameliorate disease. Here, we used biochanin A, an isoflavone found in the pollen of red clover (Trifolium pratense), to therapeutically treat Nosema bombi (Microsporidia) infection in bumblebee (Bombus terrestris) larvae and adults, and thus examine age-linked pharmacodynamics in an invertebrate. Therapeutic treatment of larvae with biochanin A did not reduce the infection intensity of N. bombi in adults. In contrast, therapeutic treatment of adults did reduce the infection intensity of N. bombi This transition in parasite resistance to bioactive compounds mirrors the age-linked pharmacodynamics of vertebrates. Understanding how different life-history stages respond to therapeutic compounds will provide novel insights into the evolution of foraging and self-medication behaviour in natural systems more broadly.
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Affiliation(s)
- Arran J Folly
- Department of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EY, UK .,Animal and Plant Health Agency, Addlestone, Surrey KT15 3NB, UK
| | - Philip C Stevenson
- Royal Botanic Gardens, Kew, Richmond, London TW9 3AE, UK.,Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK
| | - Mark J F Brown
- Department of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EY, UK
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Adler LS, Fowler AE, Malfi RL, Anderson PR, Coppinger LM, Deneen PM, Lopez S, Irwin RE, Farrell IW, Stevenson PC. Assessing Chemical Mechanisms Underlying the Effects of Sunflower Pollen on a Gut Pathogen in Bumble Bees. J Chem Ecol 2020; 46:649-658. [DOI: 10.1007/s10886-020-01168-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/04/2020] [Accepted: 03/06/2020] [Indexed: 12/16/2022]
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Bailes EJ, Bagi J, Coltman J, Fountain MT, Wilfert L, Brown MJF. Host density drives viral, but not trypanosome, transmission in a key pollinator. Proc Biol Sci 2020; 287:20191969. [PMID: 31910787 PMCID: PMC7003466 DOI: 10.1098/rspb.2019.1969] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Supplemental feeding of wildlife populations can locally increase the density of individuals, which may in turn impact disease dynamics. Flower strips are a widely used intervention in intensive agricultural systems to nutritionally support pollinators such as bees. Using a controlled experimental semi-field design, we asked how density impacts transmission of a virus and a trypanosome parasite in bumblebees. We manipulated bumblebee density by using different numbers of colonies within the same area of floral resource. In high-density compartments, slow bee paralysis virus was transmitted more quickly, resulting in higher prevalence and level of infection in bumblebee hosts. By contrast, there was no impact of density on the transmission of the trypanosome Crithidia bombi, which may reflect the ease with which this parasite is transmitted. These results suggest that agri-environment schemes such as flower strips, which are known to enhance the nutrition and survival of bumblebees, may also have negative impacts on pollinators through enhanced disease transmission. Future studies should assess how changing the design of these schemes could minimize disease transmission and thus maximise their health benefits to wild pollinators.
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Affiliation(s)
- Emily J Bailes
- Department of Biological Sciences, Royal Holloway University of London, Bourne Building, Egham TW20 0EX, UK.,Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Sheffield S10 2TN, UK
| | - Judit Bagi
- Department of Biological Sciences, Royal Holloway University of London, Bourne Building, Egham TW20 0EX, UK.,Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Jake Coltman
- Expedia Group, Angel Building, 407 St John Street, London EC1V 4AD, UK
| | | | - Lena Wilfert
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, 89069 Ulm, Germany
| | - Mark J F Brown
- Department of Biological Sciences, Royal Holloway University of London, Bourne Building, Egham TW20 0EX, UK
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45
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A Horizon Scan of Emerging Global Biological Conservation Issues for 2020. Trends Ecol Evol 2020; 35:81-90. [DOI: 10.1016/j.tree.2019.10.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 01/10/2023]
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46
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Schmid-Hempel P. Bee Parasites: Don't Lose Your Flagellum. Curr Biol 2019; 29:R1077-R1079. [PMID: 31639351 DOI: 10.1016/j.cub.2019.08.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bees can protect themselves from infection by accumulating specific nectars in the honey crop. A new study shows that as parasites pass through the crop, their flagellum is thereby removed, which prevents host infection.
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Affiliation(s)
- Paul Schmid-Hempel
- ETH Zürich, Institute of Integrative Biology (IBZ), Universitätsstrasse 16, CH-8092 Zürich, Switzerland.
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Abstract
In this study, we sequenced and analyzed the genomes of 40 strains, in addition to the already-reported two type strains, of two Crithidia species infecting bumblebees in Alaska and Central Europe and demonstrated that different strains of Crithidia bombi and C. expoeki vary considerably in terms of single nucleotide polymorphisms and gene copy number. Based on the genomic structure, phylogenetic analyses, and the pattern of copy number variation, we confirmed the status of C. expoeki as a separate species. The Alaskan populations appear to be clearly separated from those of Central Europe. This pattern fits a scenario of rapid host-parasite coevolution, where the selective advantage of a given parasite strain is only temporary. This study provides helpful insights into possible scenarios of selection and diversification of trypanosomatid parasites.IMPORTANCE A group of trypanosomatid flagellates includes several well-studied medically and economically important parasites of vertebrates and plants. Nevertheless, the vast majority of trypanosomatids infect only insects (mostly flies and true bugs) and, because of that, has attracted little research attention in the past. Of several hundred trypanosomatid species, only four can infect bees (honeybees and bumblebees). Because of such scarcity, these parasites are severely understudied. We analyzed whole-genome information for a total of 42 representatives of bee-infecting trypanosomatids collected in Central Europe and Alaska from a population genetics point of view. Our data shed light on the evolution, selection, and diversification in this important group of trypanosomatid parasites.
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