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Data and analyses from: Herbivory and time since flowering shape floral rewards and pollinator-pathogen interactions

Citation

Aguirre, Luis A.; Davis, Julie K.; Stevenson, Philip C.; Adler, Lynn S. (2020), Data and analyses from: Herbivory and time since flowering shape floral rewards and pollinator-pathogen interactions, Dryad, Dataset, https://doi.org/10.5061/dryad.bk3j9kd8m

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 floral phenology. Our results emphasize the role of herbivores in shaping pollen chemistry, with consequences for interactions between pollinators and their pathogens.

Usage Notes

File descriptions and variable explanations are all contained in the file metadata.txt. All R scripts will call the appropriate data file from user's directory. 

Contents:

  1. metadata.txt
  2. pollen.bioassays.R
  3. pollen.bioassay.csv
  4. nectar.bioassays.R
  5. nectar.bioassay.csv
  6. alk.conc.tweedie.R
  7. pollen.jdate.simple.csv
  8. binomial.csv

Funding

PGAV Destinations Pollinator Research Grant

IMSD/NEAGEP First-Year Pre-Doctoral Fellowship, Award: NIH 25 GM099649

Lotta M. Crabtree Fellowship

National Science Foundation Graduate Research Fellowship, Award: NSF 1451512 ; 1938059

National Science Foundation and Austrian Science Fund GROW Program, Award: NSF 1938059 ; FWF GRW 7-B

Torrey Plant Biology Fellowship

National Institutes of Health, Award: R01 GM1220 62-01

PGAV Destinations Pollinator Research Grant

IMSD/NEAGEP First-Year Pre-Doctoral Fellowship, Award: NIH 25 GM099649

Lotta M. Crabtree Fellowship

National Science Foundation and Austrian Science Fund GROW Program, Award: NSF 1938059 ; FWF GRW 7-B

Torrey Plant Biology Fellowship