Data from: Off-target drift of the herbicide dicamba disrupts plant-pollinator interactions via novel pathways

Baucom, Regina 1 ; Iriart, Veronica2; Soble, Anah1; Armstrong, Matthew R.1; Ashman, Tia-Lynn2

Published Jan 28, 2025 on Dryad. https://doi.org/10.5061/dryad.fttdz093r

Data files

Jan 28, 2025 version files 1.57 MB

DicambaMasterDatasheet2021.csv

132.92 KB
Pollinator_2021_reformat.csv

1.43 MB
README.md
6.56 KB

Abstract

While herbicide use in agriculture is expected to have many effects on surrounding weed communities, it is largely unknown how plant exposure to sublethal doses of herbicide may subsequently impact plant-pollinator interactions. We tested the hypothesis that sublethal herbicide exposure indirectly alters plant-pollinator interactions through changes in plant traits, and specifically through alterations in floral display.

Using a common garden experiment, we exposed 11 weed species to the herbicide dicamba and examined the potential for changes in pollinator abundance and patterns of pollinator visitation as well as alterations to plant traits.

We found variation among plant species in the extent of damage from dicamba drift, and variation in size, flowering time, and flower displays, with some plant species showing negative impacts and others showing little effect. Pollinator frequencies were reduced in dicamba-exposed plots, and pollinator visits were reduced for some weed species yet not others. Structural equation modeling revealed that the relationship between flower display and pollinator visits was disrupted in the presence of dicamba.

Our study provides the most comprehensive picture to date of the impacts of herbicide drift on plant-pollinator interactions, with findings that highlight an underappreciated role of services supplied by weedy communities.

README: Off-target drift of the herbicide dicamba disrupts plant-pollinator interactions via novel pathways

Regina S Baucom1, Veronica Iriart, Anah Soble, Matthew R. Armstrong, and Tia-Lynn Ashman

https://doi.org/10.5061/dryad.5x69p8ddt

Description of the data and file structure

Key for headers in "DicambaMasterDatasheet2021.csv" and "Pollinator_2021_reformat.csv"

Data collected from a common garden field experiment conducted with eleven weed species and the herbicide dicamba. Note that NA filled in cells of either datasheet indicates data not present or is not relevant.

Files and variables

File: DicambaMasterDatasheet2021.csv

Description: Plant growth and damage data

Variables

column label description

ID Individual plant id
num.label: front side of the tags on the plants in the field-- every plot is numbered 1-66. All except plot 11 have 13 columns and 6 rows, the counting is left to right top to bottom Plot 11 has 6 rows and 11 columns
ind.label: back side of the tags on all plants in the field-- species name, plot number (1-11), biorep number (1-6)
SPP: Four letter species code
species2: Full scientific name
Plot: plot number 1-11
PlantingDay: date that seed was planted--for plants seeded on 5-21 this was in the greenhouse, all other days in the field
greenhouseorfield: planted in greenhouse and then transplanted or initially planted seed in the field.
germ.day: data first seen, usually happened around 6-18 when germination began to be recorded. this is in julian days
trans.day: date transplanted if the plant was transplanted. anything with planting day on may 22 was from the greenhouse, all others from a different place in the field
trans: 1 means a transplant from greenhouse and 0 means planted as seed
Survival7/20: 1 if plant is present by 7/13, 0 if absent, assumed dead or never germinated
datefirstflower date flowers first seen in the field to be open in Julians
TRT: control, drift, or full spray
prespray.initials: Initials of person who took pre-spray data
prespraydate: The date the pre-spray measure was taken
pre.spray.leafcount: total number of leaves counted immediately prior to dicamba treatment. This includes deformed or withering leaves, so long as they are still attached to the plant.
pre.spray.leafsize: largest dimension of the biggest leaf measured immediately prior to dicamba treatment. Units are centimeters taken with a ruler.
pre.spray.height: tip of the longest stem to the ground in cm
presprayNotes: relevent notes collected on that day
postspray.48hr.initials: Initials of the person who took postspray data
postspray.48hr.date: Date postspray data was taken
postspray.48hrleafcount: count of total attached leaves at 2 days post spray
postspray.48hrdamagedleaves: count of leaves expressing dicamba damage (curling, yellowing) 2 days post spray
postspray.48hrNotes: Notes from postspray measurement
Notes_7/29: mammalian herbivory in plot 4
Notes_8/6: mammalian herbivory in plot8
post.spray.3wkleafcount: total number of leaves counted 3 weeks post dicamba treatment. This includes deformed or withering leaves, so long as they are still attached to the plant.
post.spray3wkdamagedleaves: count of leaves expressing dicamba damage (curling, yellowing) 3 weeks post spray
post.spray.3wkleafsize: largest dimension of the biggest leaf measured 3 weeks post dicamba treatment. Units are centimeters taken with a ruler.
post.spray.3wkheight: tip of the longest stem to the ground in cm
postspray.3wknotes: notes taken at the 3 week post spray collection time
herbivory.photo.initials: initials of person who collected herbivory photos
deformed: 1 or 0 for if new leaves appear deformed while taking herbivory photos
Notes8/17: notes taken during herbivory photos
Notes9/29: herbivory damage in plots 7 and 10
Seedcount: count of seeds collected throughout the season but estimated, and should not be used. Other datasheet has comprehesive seed counts
Observed6/30: survival taken during germination
Notes6/30: notes taken during germination
Observed7/5: survival taken during germination
Notes7/5: notes taken during germination
Observed7/9: survival taken during germination
OpenFlowerCumulative_2timesaweek: flower count taken 2 times a week for 11 weeks added up
OpenFlowerCumulativeTotal: flower count taken 2 times a week for 11 weeks plus the first 5 rounds of pollinator observation flower counts to add up all total flower counts with extra between 8/19 and 9/1
Herbivory7/5: herbivory noted during germination

NA's in this datasheet indicates lack of relevancy (ie in notes columns) or a missing plant (ie columns recording vegetative traits)

File: Pollinator_2021_reformat.csv

Description: Pollinator obs data

column name description

ID: Plot_IndID, plot number and individual plant id
Round_Number: 1-12 of round of observation
Date: observation date
Plot: plot ID
TRT: the level of dicamba treatment, control vs dicamba
Weather: weather description, added descriptor for being shaded by trees not present in 2019
StartTime: start of visitation observation
EndTime: end of visitation obervation
VisitationTime: Length of observation in minutes
Location: number in plot, "vicinity" means a pollinator was observed during the abundance count within the plot area not at a specific plant
Target.Nontarget: T=target species, background=volunteer
Species: plant species
Target.Nontarget: identified target plants (those we planted) vs volunteers
NumFlowersOpen: number of open flowers
Abundance: pollinator was present in plot at entrance, a snapshot
Approach: when a pollinator comes close to a flower without visiting
Visit: a foraging visit by a pollinator
notes: notes on pollinator visit/approach counts

Note that in Approach/Visit columns, pollinator id's are the following: HB=Honeybee, SB=Sweat bee, TB=True bug, YJ = Yellow jacket, HF=Hover fly, BB = Bumblebee
NA's in this datasheet indicates lack of relevancy since the presence of data indicates a visit or approach by a specific pollinator

Code/software

We used the program R (version 4.2.1) to conduct all statistical analyses. Scripts DicambaPollination1-15-25.Rmd, DicambaFieldAnalysis1-15-25.Rmd, and SEM.Rmd accompany this work and provide code for analysis of pollinator abundance and visitation, plant traits, and structural equation modeling linking plant traits and pollinator visits.