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Lynn S. Adler - One of the best experts on this subject based on the ideXlab platform.
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Assessing Chemical Mechanisms Underlying the Effects of Sunflower Pollen on a Gut Pathogen in Bumble Bees
Journal of Chemical Ecology, 2020Co-Authors: Lynn S. Adler, Rebecca E. Irwin, Alison E. Fowler, Rosemary L. Malfi, Patrick R. Anderson, Lily M. Coppinger, Pheobe M. Deneen, Stephanie Lopez, Iain W. Farrell, Philip C. StevensonAbstract:Many pollinator species are declining due to a variety of interacting stressors including pathogens, sparking interest in understanding factors that could mitigate these outcomes. Diet can affect host-pathogen interactions by changing nutritional reserves or providing bioactive secondary chemicals. Recent work found that sunflower pollen ( Helianthus annuus ) dramatically reduced cell counts of the gut pathogen Crithidia bombi in bumble bee workers ( Bombus impatiens ), but the mechanism underlying this effect is unknown. Here we analyzed methanolic extracts of sunflower pollen by LC-MS and identified triscoumaroyl spermidines as the major secondary metabolite components, along with a flavonoid quercetin-3- O -hexoside and a quercetin-3- O -(6- O -malonyl)-hexoside. We then tested the effect of triscoumaroyl spermidine and rutin (as a proxy for quercetin glycosides) on Crithidia infection in B. impatiens , compared to buckwheat pollen ( Fagopyrum esculentum ) as a negative control and sunflower pollen as a positive control. In addition, we tested the effect of nine fatty acids from sunflower pollen individually and in combination using similar methods. Although sunflower pollen consistently reduced Crithidia relative to control pollen, none of the compounds we tested had significant effects. In addition, diet treatments did not affect mortality, or sucrose or pollen consumption. Thus, the mechanisms underlying the medicinal effect of sunflower are still unknown; future work could use bioactivity-guided fractionation to more efficiently target compounds of interest, and explore non-chemical mechanisms. Ultimately, identifying the mechanism underlying the effect of sunflower pollen on pathogens will open up new avenues for managing bee health.
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README.R_Scripts from Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen
2019Co-Authors: George M. Locascio, Luis Aguirre, Rebecca Irwin, Lynn S. AdlerAbstract:Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) of Bombus impatiens previously, but the breadth of this effect was unknown. We tested whether pollen from nine H. annuus cultivars, four wild H. annuus populations, H. petiolarus, H. argophyllus and two Solidago spp., reduced Crithidia in B. impatiens compared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. All Helianthus and Solidago pollen reduced Crithidia by 20–40-fold compared to buckwheat pollen, and all but three taxa reduced Crithidia compared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduce Crithidia infection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease
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README_CSV from Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen
2019Co-Authors: George M. Locascio, Luis Aguirre, Rebecca Irwin, Lynn S. AdlerAbstract:Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) of Bombus impatiens previously, but the breadth of this effect was unknown. We tested whether pollen from nine H. annuus cultivars, four wild H. annuus populations, H. petiolarus, H. argophyllus and two Solidago spp., reduced Crithidia in B. impatiens compared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. All Helianthus and Solidago pollen reduced Crithidia by 20–40-fold compared to buckwheat pollen, and all but three taxa reduced Crithidia compared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduce Crithidia infection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease
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Death_by_Sflower from Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen
2019Co-Authors: George M. Locascio, Luis Aguirre, Rebecca Irwin, Lynn S. AdlerAbstract:Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) of Bombus impatiens previously, but the breadth of this effect was unknown. We tested whether pollen from nine H. annuus cultivars, four wild H. annuus populations, H. petiolarus, H. argophyllus and two Solidago spp., reduced Crithidia in B. impatiens compared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. All Helianthus and Solidago pollen reduced Crithidia by 20–40-fold compared to buckwheat pollen, and all but three taxa reduced Crithidia compared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduce Crithidia infection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease
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Sflower1 from Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen
2019Co-Authors: George M. Locascio, Luis Aguirre, Rebecca Irwin, Lynn S. AdlerAbstract:Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) of Bombus impatiens previously, but the breadth of this effect was unknown. We tested whether pollen from nine H. annuus cultivars, four wild H. annuus populations, H. petiolarus, H. argophyllus and two Solidago spp., reduced Crithidia in B. impatiens compared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. All Helianthus and Solidago pollen reduced Crithidia by 20–40-fold compared to buckwheat pollen, and all but three taxa reduced Crithidia compared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduce Crithidia infection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease
Rebecca E. Irwin - One of the best experts on this subject based on the ideXlab platform.
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Assessing Chemical Mechanisms Underlying the Effects of Sunflower Pollen on a Gut Pathogen in Bumble Bees
Journal of Chemical Ecology, 2020Co-Authors: Lynn S. Adler, Rebecca E. Irwin, Alison E. Fowler, Rosemary L. Malfi, Patrick R. Anderson, Lily M. Coppinger, Pheobe M. Deneen, Stephanie Lopez, Iain W. Farrell, Philip C. StevensonAbstract:Many pollinator species are declining due to a variety of interacting stressors including pathogens, sparking interest in understanding factors that could mitigate these outcomes. Diet can affect host-pathogen interactions by changing nutritional reserves or providing bioactive secondary chemicals. Recent work found that sunflower pollen ( Helianthus annuus ) dramatically reduced cell counts of the gut pathogen Crithidia bombi in bumble bee workers ( Bombus impatiens ), but the mechanism underlying this effect is unknown. Here we analyzed methanolic extracts of sunflower pollen by LC-MS and identified triscoumaroyl spermidines as the major secondary metabolite components, along with a flavonoid quercetin-3- O -hexoside and a quercetin-3- O -(6- O -malonyl)-hexoside. We then tested the effect of triscoumaroyl spermidine and rutin (as a proxy for quercetin glycosides) on Crithidia infection in B. impatiens , compared to buckwheat pollen ( Fagopyrum esculentum ) as a negative control and sunflower pollen as a positive control. In addition, we tested the effect of nine fatty acids from sunflower pollen individually and in combination using similar methods. Although sunflower pollen consistently reduced Crithidia relative to control pollen, none of the compounds we tested had significant effects. In addition, diet treatments did not affect mortality, or sucrose or pollen consumption. Thus, the mechanisms underlying the medicinal effect of sunflower are still unknown; future work could use bioactivity-guided fractionation to more efficiently target compounds of interest, and explore non-chemical mechanisms. Ultimately, identifying the mechanism underlying the effect of sunflower pollen on pathogens will open up new avenues for managing bee health.
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Tables S1 and S2 from Bee pathogen transmission dynamics: deposition, persistence and acquisition on flowers
2019Co-Authors: Laura L. Figueroa, Rebecca E. Irwin, Malcolm Blinder, Cali Grincavitch, Angus Jelinek, Emilia K. Mann, Liam A. Merva, Lucy E. Metz, Amy Y. Zhao, Scott H. McartAbstract:Experiment 1: Post-hoc analysis (Tukey's HSD) for flower species by part interaction on number of times feces were observed.; Experiment 2: Post-hoc analyses (Tukey's HSD) table for differences in Crithidia survival across parts on the flower for each plant species
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Medicinal value of sunflower pollen against bee pathogens
Scientific reports, 2018Co-Authors: Jonathan J Giacomini, Evan C. Palmer-young, Rebecca E. Irwin, Jessica M Leslie, David R. Tarpy, Lynn S. AdlerAbstract:Global declines in pollinators, including bees, can have major consequences for ecosystem services. Bees are dominant pollinators, making it imperative to mitigate declines. Pathogens are strongly implicated in the decline of native and honey bees. Diet affects bee immune responses, suggesting the potential for floral resources to provide natural resistance to pathogens. We discovered that sunflower (Helianthus annuus) pollen dramatically and consistently reduced a protozoan pathogen (Crithidia bombi) infection in bumble bees (Bombus impatiens) and also reduced a microsporidian pathogen (Nosema ceranae) of the European honey bee (Apis mellifera), indicating the potential for broad anti-parasitic effects. In a field survey, bumble bees from farms with more sunflower area had lower Crithidia infection rates. Given consistent effects of sunflower in reducing pathogens, planting sunflower in agroecosystems and native habitat may provide a simple solution to reduce disease and improve the health of economically and ecologically important pollinators.
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Effects of 5 ppm anabasine treatment on Crithidia infection intensity in Bombus impatiens across three experiments.
2017Co-Authors: Evan C. Palmer-young, Rebecca E. Irwin, Jonathan Andicoechea, Alison Hogeboom, Alexander J. Kaye, Dash Donnelly, Sara June Connon, Ian Weston, Kimberly Skyrm, Lynn S. AdlerAbstract:(A) Parasite Variation Experiment that tested effects of anabasine on infection of individual bees with one of four Crithidia lineages and reared individually. (B) Life History Experiment in which bees were reared in microcolonies of three workers. (C) Pollen Deprivation Experiment in which individual bees were deprived of pollen. Significance of terms in generalized linear mixed-effects models were tested by χ2 tests. Crithidia cell counts were ln(x+1)-transformed to better conform to model assumptions. Marginal cell length refers to length of the right forewing marginal cell, used to estimate bee size (see Materials and Methods). Colony refers to the bee’s experimental colony of origin.
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RESEARCH ARTICLE Possible Synergistic Effects of Thymol and Nicotine against Crithidia bombi Parasitism in Bumble Bees
2016Co-Authors: Olivia Masi Biller, Lynn S. Adler, Rebecca E. Irwin, Caitlin Mcallister, C. Palmer-youngAbstract:Floral nectar contains secondary compounds with antimicrobial properties that can affect not only plant-pollinator interactions, but also interactions between pollinators and their par-asites. Although recent work has shown that consumption of plant secondary compounds can reduce pollinator parasite loads, little is known about the effects of dosage or compound combinations. We used the generalist pollinator Bombus impatiens and its obligate gut par-asite Crithidia bombi to study the effects of nectar chemistry on host-parasite interactions. In two experiments we tested (1) whether the secondary compounds thymol and nicotine act synergistically to reduce parasitism, and (2) whether dietary thymol concentration affects parasite resistance. In both experiments, uninfected Bombus impatiens were inocu-lated with Crithidia and then fed particular diet treatments for 7 days, after which infection levels were assessed. In the synergism experiment, thymol and nicotine alone and in com-bination did not significantly affect parasite load or host mortality. However, the thymol-nico-tine combination treatment reduced log-transformed parasite counts by 30 % relative to the control group (P = 0.08). For the experiment in which we manipulated thymol concentration
Dan S Ray - One of the best experts on this subject based on the ideXlab platform.
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presence of multiple mrna cycling sequence element binding proteins in Crithidia fasciculata
Journal of Biological Chemistry, 2003Co-Authors: Bidyottam Mittra, Jane C. Hines, Krishna Murari Sinha, Dan S RayAbstract:A consensus sequence present in the 5'- or 3'-untranslated regions of several Crithidia fasciculata messenger RNAs encoding proteins involved in DNA metabolism has been shown to be necessary for the periodic accumulation of these mRNAs during the cell cycle. A protein complex termed cycling sequence-binding protein (CSBP) has two subunits, CSBPA and CSBPB, and binds the consensus sequence with high specificity. The binding activity of CSBP was shown to vary during the cell cycle in parallel with the levels of putative target mRNAs. Although disruption of the CSBPA gene resulted in loss of both CSBPA and CSBPB, the putative target message levels still continued to vary during the cell cycle. The presence of an additional and distinct binding activity was revealed in these CSBPA null mutant cells. This activity, termed CSBP II, was also expressed in wild-type Crithidia cells. CSBP II has higher binding specificity for the cycling sequence element than the earlier described CSBP complex. Three polypeptides associated with purified CSBP II show specific binding to the cycling sequence. These proteins may represent a family of sequence-specific RNA-binding proteins involved in post-transcriptional regulation.
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expression and cellular localization of trypanosoma cruzi type ii dna topoisomerase
Molecular and Biochemical Parasitology, 1998Co-Authors: Stenio Perdigao Fragoso, Jane C. Hines, Dan S Ray, Denise Mattei, Samuel GoldenbergAbstract:Topoisomerases are enzymes that participate in many cellular functions involving topological manipulation of DNA strands. There are two types of topoisomerases in the cell: (a) type I topoisomerases; and (b) type II topoisomerases (topo II). Previously we have cloned and sequenced the gene encoding Trypanosoma cruzi topo II (TcTOP2). This study group has raised an antiserum against recombinant type II DNA topoisomerase (TctopoII) to study the expression of this gene during T. cruzi differentiation and to determine the cellular location of the enzyme. Western blot analysis showed that T. cruzi TctopoII is expressed in the replicative epimastigotes but not in the infective and non-replicative trypomastigotes. However, slot blot analysis of RNAs extracted from epimastigotes and metacyclic trypomastigotes showed that the mRNA encoding the enzyme is present in both developmental stages of the parasite. Confocal laser microscopy using the antiserum raised against recombinant TctopoII showed that the enzyme is located exclusively in the nucleus of the parasite. Similar results were obtained by immunofluorescence analysis of Crithidia fasciculata. However, monoclonal antisera against the corresponding enzyme extracted from C. fasciculata recognizes a kinetoplast protein in both T. cruzi and Crithidia
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molecular cloning and expression of the gene encoding the kinetoplast associated type ii dna topoisomerase of Crithidia fasciculata
Molecular and Biochemical Parasitology, 1992Co-Authors: Sally G Pasion, Jane C. Hines, Ruedi Aebersold, Dan S RayAbstract:A type II DNA topoisomerase, topoIImt, was shown previously to be associated with the kinetoplast DNA of the trypanosomatid Crithidia fasciculata. The gene encoding this kinetoplast-associated topoisomerase has been cloned by immunological screening of a Crithidia genomic expression library with monoclonal antibodies raised against the purified enzyme. The gene CfaTOP2 is a single copy gene and is expressed as a 4.8-kb polyadenylated transcript. The nucleotide sequence of CfaTOP2 has been determined and encodes a predicted polypeptide of 1239 amino acids with a molecular mass of 138 445. The identification of the cloned gene is supported by immunoblot analysis of the β-galactosidase-CfaTOP2 fusion protein expressed in Escherichia coli and by analysis of tryptic peptide sequences derived from purified topoIImt. CfaTOP2 shares significant homology with nuclear type II DNA topoisomerases of other eukaryotes suggesting that in Crithidia both nuclear and mitochondrial forms of topoisomerase II are encoded by the same gene.
Jane C. Hines - One of the best experts on this subject based on the ideXlab platform.
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Mitochondrial DNA ligase in Crithidia fasciculata
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Krishna Murari Sinha, Jane C. Hines, Nicholas DowneyAbstract:Kinetoplast DNA (kDNA), the form of mitochondrial DNA in trypanosomatids, consists of thousands of interlocked circular DNAs organized into a compact disk structure. A type II DNA topoisomerase, a DNA polymerase β, and a structure-specific endonuclease have been localized to antipodal sites flanking the kDNA disk along with nascent DNA minicircles. We have cloned a gene (LIG k) encoding a mitochondrial DNA ligase in the trypanosomatid Crithidia fasciculata, and we show that an epitope-tagged form of the ligase colocalizes with the other replication proteins at the antipodal sites and also at the two faces of the kDNA disk. DNA LIG k becomes adenylated in reactions with ATP, and the adenylate moiety is removed by incubation with pyrophosphate or nicked DNA. The ligase interacts physically with the β polymerase and is proposed to be involved in the repair of gaps in the newly synthesized minicircles. In yeast and mammals, a single gene encodes both nuclear and mitochondrial forms of DNA ligase. The LIG K protein sequence has low similarity to mitochondrial DNA ligases in other eukaryotes and is distinct from the C. fasciculata nuclear DNA ligase (LIG I).
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presence of multiple mrna cycling sequence element binding proteins in Crithidia fasciculata
Journal of Biological Chemistry, 2003Co-Authors: Bidyottam Mittra, Jane C. Hines, Krishna Murari Sinha, Dan S RayAbstract:A consensus sequence present in the 5'- or 3'-untranslated regions of several Crithidia fasciculata messenger RNAs encoding proteins involved in DNA metabolism has been shown to be necessary for the periodic accumulation of these mRNAs during the cell cycle. A protein complex termed cycling sequence-binding protein (CSBP) has two subunits, CSBPA and CSBPB, and binds the consensus sequence with high specificity. The binding activity of CSBP was shown to vary during the cell cycle in parallel with the levels of putative target mRNAs. Although disruption of the CSBPA gene resulted in loss of both CSBPA and CSBPB, the putative target message levels still continued to vary during the cell cycle. The presence of an additional and distinct binding activity was revealed in these CSBPA null mutant cells. This activity, termed CSBP II, was also expressed in wild-type Crithidia cells. CSBP II has higher binding specificity for the cycling sequence element than the earlier described CSBP complex. Three polypeptides associated with purified CSBP II show specific binding to the cycling sequence. These proteins may represent a family of sequence-specific RNA-binding proteins involved in post-transcriptional regulation.
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expression and cellular localization of trypanosoma cruzi type ii dna topoisomerase
Molecular and Biochemical Parasitology, 1998Co-Authors: Stenio Perdigao Fragoso, Jane C. Hines, Dan S Ray, Denise Mattei, Samuel GoldenbergAbstract:Topoisomerases are enzymes that participate in many cellular functions involving topological manipulation of DNA strands. There are two types of topoisomerases in the cell: (a) type I topoisomerases; and (b) type II topoisomerases (topo II). Previously we have cloned and sequenced the gene encoding Trypanosoma cruzi topo II (TcTOP2). This study group has raised an antiserum against recombinant type II DNA topoisomerase (TctopoII) to study the expression of this gene during T. cruzi differentiation and to determine the cellular location of the enzyme. Western blot analysis showed that T. cruzi TctopoII is expressed in the replicative epimastigotes but not in the infective and non-replicative trypomastigotes. However, slot blot analysis of RNAs extracted from epimastigotes and metacyclic trypomastigotes showed that the mRNA encoding the enzyme is present in both developmental stages of the parasite. Confocal laser microscopy using the antiserum raised against recombinant TctopoII showed that the enzyme is located exclusively in the nucleus of the parasite. Similar results were obtained by immunofluorescence analysis of Crithidia fasciculata. However, monoclonal antisera against the corresponding enzyme extracted from C. fasciculata recognizes a kinetoplast protein in both T. cruzi and Crithidia
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molecular cloning and expression of the gene encoding the kinetoplast associated type ii dna topoisomerase of Crithidia fasciculata
Molecular and Biochemical Parasitology, 1992Co-Authors: Sally G Pasion, Jane C. Hines, Ruedi Aebersold, Dan S RayAbstract:A type II DNA topoisomerase, topoIImt, was shown previously to be associated with the kinetoplast DNA of the trypanosomatid Crithidia fasciculata. The gene encoding this kinetoplast-associated topoisomerase has been cloned by immunological screening of a Crithidia genomic expression library with monoclonal antibodies raised against the purified enzyme. The gene CfaTOP2 is a single copy gene and is expressed as a 4.8-kb polyadenylated transcript. The nucleotide sequence of CfaTOP2 has been determined and encodes a predicted polypeptide of 1239 amino acids with a molecular mass of 138 445. The identification of the cloned gene is supported by immunoblot analysis of the β-galactosidase-CfaTOP2 fusion protein expressed in Escherichia coli and by analysis of tryptic peptide sequences derived from purified topoIImt. CfaTOP2 shares significant homology with nuclear type II DNA topoisomerases of other eukaryotes suggesting that in Crithidia both nuclear and mitochondrial forms of topoisomerase II are encoded by the same gene.
Adler, Lynn S - One of the best experts on this subject based on the ideXlab platform.
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Herbivory and time since flowering shape floral rewards and pollinator-pathogen interactions
'Springer Science and Business Media LLC', 2020Co-Authors: Aguirre, Luis A., Stevenson, Philip C., Davis, Julie K., Adler, Lynn SAbstract: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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Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen
ScholarWorks@UMass Amherst, 2019Co-Authors: Locascio, George M., Irwin, Rebecca E, Aguirre, Luis A., Adler, Lynn SAbstract:Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) of Bombus impatiens previously, but the breadth of this effect was unknown. We tested whether pollen from nine H. annuus cultivars, four wild H. annuus populations, H. petiolarus, H. argophyllus and two Solidago spp., reduced Crithidia in B. impatiens compared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. All Helianthus and Solidago pollen reduced Crithidia by 20–40-fold compared to buckwheat pollen, and all but three taxa reduced Crithidia compared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduce Crithidia infection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease
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From plant fungi to bee parasites: mycorrhizae and soil nutrients shape floral chemistry and bee pathogens
'Wiley', 2019Co-Authors: Stevenson, Philip C., Aguirre, Luis A., Davis, Julie K., Barber, Nicholas A., Adler, Lynn SAbstract:Bee populations have experienced declines in recent years, due in part to increased disease incidence. Multiple factors influence bee-pathogen interactions, including nectar and pollen quality and secondary metabolites. However, we lack an understanding of how plant interactions with their environment shape bee diet quality. We examined how plant interactions with the belowground environment alter floral rewards and, in turn, bee-pathogen interactions. Soil-dwelling mycorrhizal fungi are considered plant mutualists, although the outcome of the relationship depends on environmental conditions such as nutrients. In a 2x2 factorial design, we asked whether mycorrhizal fungi and nutrients affect concentrations of nectar and pollen alkaloids (anabasine and nicotine) previously shown to reduce infection by the gut pathogen Crithidia in the native bumblebee Bombus impatiens. To ask how plant interactions affect this common bee pathogen, we fed pollen and nectar from our treatment plants, and from a wildflower pollen control with artificial nectar, to bees infected with Crithidia. Mycorrhizal fungi and fertilizer both influenced flowering phenology and floral chemistry. While we found no anabasine or nicotine in nectar, high fertilizer increased anabasine and nicotine in pollen. AMF decreased nicotine concentrations, but the reduction due to AMF was stronger in high than low-nutrient conditions. AMF and nutrients also had interactive effects on bee pathogens via changes in nectar and pollen. High fertilizer reduced Crithidia cell counts relative to low fertilizer in AMF plants, but increased Crithidia in non-AMF plants. These results did not correspond with effects of fertilizer and AMF on pollen alkaloid concentrations, suggesting that other components of pollen or nectar were affected by treatments and shaped pathogen counts. Our results indicate that soil biotic and abiotic environment can alter bee-pathogen interactions via changes in floral rewards, and underscore the importance of integrative studies to predict disease dynamics and ecological outcomes
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Data for: Possible synergistic effects of thymol and nicotine against Crithidia bombi parasitism in bumble bees
2018Co-Authors: Biller, Olivia M, Adler, Lynn S, Irwin, Rebecca E, Mcallister Caitlin, Palmer-young, Evan CAbstract:Data and R scripts for analysis of nicotine-thymol synergy experiment and thymol dose experiment evaluating effects of nectar secondary metabolite treatments on Crithidia bombi parasite load and mortality in the bumble bee Bombus impatiens.
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Effects of short-term exposure to naturally occurring thymol concentrations on transmission of a bumble bee parasite
'Wiley', 2018Co-Authors: Rothchild, Kristina W., Adler, Lynn S, Irwin, Rebecca E, Sadd, Ben M., Stevenson, Philip C., Palmer-young, Evan CAbstract:Background: Plants produce antimicrobial phytochemicals that can reduce growth and infectivity of parasites in animals. Pollinator parasites are transmitted between hosts that forage on shared flowers. Floral transmission directly exposes parasites to phytochemicals on floral surfaces and in nectar, both at flowers and, post-ingestion, in the crop. This exposure could directly affect parasite transmission to new hosts. Approach: We combined nectar chemical analyses with field and cell culture experiments to test effects of the floral phytochemical thymol on transmission potential of the trypanosomatid gut parasite Crithidia in Bombus impatiens. First, we measured thymol concentrations in Thymus vulgaris nectar. Second, we tested how addition of thymol to floral nectaries affected parasite transmission to foraging bees. Third, we used cell cultures to determine direct, dose-dependent effects of short term thymol exposure on subsequent in vitro parasite growth. Results: We found 26.1 ppm thymol in Thymus vulgaris nectar, 5-fold higher than previously documented in this species. However, addition of thymol to flowers of parasite-inoculated inflorescences of four plant species did not affect acquisition of Crithidia infection during a foraging bout. Cell culture experiments showed that thymol concentrations needed to reduce subsequent Crithidia growth by 50% (120 ppm) were 4.6-fold higher than the highest detected nectar concentration. Conclusions: Although thymol exposure can influence Crithidia viability, Crithidia are robust to the duration and magnitude of exposure encountered during floral foraging under natural conditions. Our experiments suggest that any effects of thymol alone on Crithidia-host infection dynamics probably reflect indirect, possibly host-mediated, effects of chronic thymol ingestion