Dataset DOI: 10.5061/dryad.8gtht773f

Description of the data and file structure

These data sets contain the data collected in a three year (2020-2022) field study across three research farms in Maryland, United States. In the study, 2 insecticide treatments (a neonicotinoid seed treatment and an in-furrow pyrethroid treatment) were compared to an untreated control in Bt and non-Bt field corn. The treatments were each replicated three times in each corn hybrid in a Latin-square design. In the early season we sampled seedling stand, slug activity-abundance, slug injury to seedlings, predator (adult carabid and other) activity-abundance on a species level, and predation on sentinel prey. We also collected yield data. The associated codes analyze the relationships between slug activity-abundance and injury/plant stand and the relationship between slug injury and yield. They also contain analysis of insecticide treatment impacts to slugs, slug injury, predators, and predation.

In addition to the field study, we also conducted a laboratory study to test whether the native pest slug Deroceras laeve detects and avoids chemical cues from predatory carabids that occur in corn fields. For this, we made full-body extracts of Chlaenius tricolor and Poecilus chalcites (native predators) as well as Amara aenea and Zophobas morio (for non-predatory controls) and used laboratory-raised slugs in bioassays to assess responses. Data and codes for this study are also included.

Files and variables

File: 01_plot_plan.tif

Description: This image shows the basic plot plan and arrangement of treatments used throughout this study. Treatments are laid out in a Latin square design, with 3 replications of each of the three treatments.

File: 02_trap_placement.jpg

Description: This image shows the arrangement of traps and sentinel prey cages in each replicate plot. Differently-sized and shaded circles indicate the 4 sentinel prey cages, 2 slug pitfall shelter traps, and 2 predator pitfall traps.

File: 03_arena_design.tif

Description: This image shows a schematic of the bioassay arena used to test for slug responses to beetle chemical cues.

File: carabid_community.xlsx

Description: This data set contains the activity abundances of carabids collected during the studied, with most individuals identified to genus and species.

We sampled beetles following planting with two pitfall traps per replicate plot. Traps were filled 1/4 with antifreeze, covered with a slanted plastic lid, and checked and refilled weekly for three weeks in almost all years and location. All arthropods were collected and stored in 70% EtOH, and soil, slugs, earthworms, and antifreeze removed. These arthropod samples were sorted, with centipedes, staphylinids, beetle larvae, and spiders counted. Carabid beetles (and beetles that looked like carabids) were counted and pinned for ID. All IDs were done by Scott McCluen.

Variables

• year -- Sampling year (2020-2022).
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• date -- Date the traps were collected (they were deployed 7 days prior) in month/day/year format. In 2020 there were 3 dates for Beltsville and Keedysville, and 2 dates for Queenstown. In 2021 and 2022 there were 3 for each location.
• week -- The week after planting the sampling was done.
• sampling_week -- Which of the 2 or 3 sampling weeks this sample is from.
• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• trap -- There were two traps per replicate treatment. 1 is closer to rep 1, 2 is closer to rep 3.
• family -- Insect family of each specimen.
• species -- The genus and species when possible in "genus.species" format determined by Scott McCluen.
• sp_code -- 2 letter code indicating species. Numbers added to the end as needed for species with two letters that are already used by another species.
• tribe -- The tribe for each species as determined by bugguide.net.
• genus -- The genus of the beetle.
• trophic_id -- Feeding guild of each species as determined by published literature (see the manuscript's supporting information).
• count -- The number of the beetles of this genus.species from the sample.

File: MS_bioassays.xlsx

Description: This data set contains the data from slug bioassays. In these bioassays, slugs (Derocera laeve) were placed within the brightly-lit central compartment of an arena with two dark shelters on either side, and given the choice to enter a shelter. The threshold of each shelter was given control or treatments to serve as a chemical cue to the slug and elicit responses in shelter choice. 12 bioassay arenas were in use on each date, with 3 replicates of the 4 beetle treatments, or 12 blanks for the blanks data set. Bioassays lasted 1 hour. New slugs were used each time.

Variables (beetle cue data)

• date -- The date on which the bioassay was performed (the bioassays were conducted across 6 dates in September and October 2023) in month/day/year format.
• rep -- Temporal replicate number, corresponding with the date of the bioassay (1-6)
• arena -- Number assigned to each arena (1-12).
• treatment -- Which beetle cue treatment was being tested (ct = Chlaenius tricolor, pc = Poecilus chalcites, am = Amara aenea, and zm = Zophobas morio).
• side -- Which side of the arena contained the beetle cue (left or right).
• choice_1 -- Which treatment side of the arena was entered first (c = control, t = treatment, and na = slug did not enter a side).
• ch_1_side -- Which side of the arena was entered first (left, right, or na = slug did not enter a side).
• choice_2 -- Which treatment side of the arena the slug occupied at the end of 60 minutes (c = control, t = treatment, and na = slug did not enter a side).
• ch_2_side -- Which side of the arena the slug occupied at the end of 60 minutes (left, right, or na = slug did not enter a side).
• time_out -- The ten minute period where the slug entered an arena side (0 = 0-10 minutes, 10 = 10-20 minutes, 20 = 20-30 minutes, 30 = 30-40 minutes, 40 = 40-50 minutes, 50 = 50-60 minutes, 60 = no choice made).
• reemerged -- Indicates if the slug reemerged after entering an arena side (yes, no, or na = slug did not enter a side).

Variables (blanks data)

• date -- The date on which the bioassay was performed (the bioassays were conducted across 6 dates in December 2023) in month/day/year format.
• rep -- Temporal replicate number, corresponding with the date of the bioassay (1-6)
• arena -- Number assigned to each arena (1-12).
• choice_1 -- Which side of the arena was entered first (l = left, r = right, or na = slug did not enter a side).
• choice_2 -- Which side of the arena was occupied at the end of the bioassay (l = left, r = right, or na = slug did not enter a side).
• time_out -- The number of minutes until an arena side was entered.
• reemerged-- Indicates if the slug reemerged after entering an arena side (yes, no, or na = slug did not enter a side).
• time_window -- The ten minute period where the slug entered an arena side (0 = 0-10 minutes, 10 = 10-20 minutes, 20 = 20-30 minutes, 30 = 30-40 minutes, 40 = 40-50 minutes, 50 = 50-60 minutes, 60 = no choice made).

File: pitfall_predators.xlsx

Description: This data set contains the activity-abundance of predators caught in pitfall traps that were not adult carabid beetles (i.e. staphylinids, centipedes, predatory beetle larvae, and spiders).

We sampled predators following planting with two pitfall traps per replicate plot. Traps were filled 1/4 with antifreeze, covered with a slanted plastic lid, and checked and refilled weekly. All arthropods were collected and stored in 70% EtOH, and soil, slugs, earthworms, and antifreeze removed. These arthropod samples were sorted, with different types of potential predators counted. Carabid beetles (and beetles that looked like carabids) were counted and pinned for ID.

Variables

• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• year -- Sampling year (2020-2022).
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• week -- The week number of sampling, counted from planting
• sample_date -- Date the traps were collected (they were deployed 7 days prior) in month/day/year format
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• trap -- There were two traps per replicate treatment. 1 is closer to rep 1, 2 is closer to rep 3.
• staph_adults -- The number of staphylinid adults in the sample.
• opiliones -- The number of opilionids in the sample.
• spiders -- The number of spiders in the sample.
• beetle_larvae -- The number of predatory beetle larvae (carabids, staphylinids, and lampyrids) in the sample.
• chilopods -- The number of chilopods in the sample.

File: seedling_damage.xlsx

Description: This data set contains stand counts (healthy plants), stunted plant counts, and counts of plants injured by a range of pest types as well as physiological and deer-injured plant counts. 

Foliar samples were taken by visually sampling stand count and damage to seedlings (3 subsamples per plot, located between rows 6+7, 12+13, and 18+19, spaced in the front, middle, and back of plots to make a diagonal line across the plot. Each subsample contained 50 feet of row and was measured by laying a 25 foot measuring tape between two rows, or measuring 25 feet with a measuring wheel, and sampling the seedlings on either side.

Stand count was taken by counting the seedlings on either side of the tape. Stunted plants were counted the same way. Stunted plants were less than half the size of most of the seedlings.

Foliar pest damage was counted by visually assessing seedlings. Only damage greater that 0.25 cm^2 was recorded. Soil damage was recorded when seedlings showed characteristic symptoms of below-ground feeding. Plants were excavated, and if conclusive evidence of white grub or wireworm feeding was found, those pests were recorded. Physiological damage refers to evidence of poor emergence ("buggy whipping"). Only the one type of damage, whichever one caused the most extensive damage, was recorded per plant. One type of pest damage very rarely subsumed other.

Variables

• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• year -- Sampling year (2020-2022).
• date -- Date on which the sampling took place in month/day/year format.
• dap -- The number of days after planting on which sampling took place.
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• growth_stage -- The phenological stage of the corn seedlings at sampling, according to the number of collared leaves.
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• ss -- The subsample number. There were 3 subsamples per replicate plot, each assessing the seedlings withing 50 feet of row.
• stand -- The number of healthy plants in the subsample.
• stunted -- The number of stunted plants in the subsample.
• soil_pest -- The number of plants in the subsample with signs of soil pest damage, but without identifying characteristics allowing it to be attributed to a specific pest.
• grub -- The number of plants in the subsample with signs of grub damage, or with soil pest damage and grubs found during excavation.
• wireworm -- The number of plants in the subsample with signs of wireworm damage, or with soil pest damage and wireworms found during excavation.
• cutworm -- The number of plants in the subsample with cutworm damage.
• armyworm -- The number of plants in the subsample with armyworm damage.
• flea beetle -- The number of plants in the subsample with flea beetle damage.
• slug -- The number of plants in the subsample with slug damage.
• stinkbug -- The number of plants in the subsample with stinkbug damage.
• non-ID chewing -- The number of plants in the subsample with chewing damage that could not be identified.
• physiological -- The number of plants in the subsample with physiological damage (e.g. emergence issues like buggy whipping).
• deer -- The number of plants in the subsample with deer damage.

File: sentinel_prey.xlsx

Description: Sentinel prey data from live waxmoth larvae deployed overnight in replicate plots during the seedling stage.

Cards were assembled by taping 5 waxworm larvae to an index card, ventral side down. Sentinel prey data were collected by deploying sentinel prey cards in plots overnight and then counting the number of missing and damaged larvae per card the following morning. 4 cards per plot were placed in wire cages per plot. Sentinel prey cages were placed between rows 9 + 10 and 15 + 16 at Beltsville and Queenstown. At Keedysville, we put them between rows 8 + 9 and 14 + 15 to avoid the marking rows where the soil was disturbed. We placed the cards between 1:55-6:00 PM the day before (usually around 3:00 PM), and collected them between 7:30-10:30 AM the following day.

We counted the number of missing larvae and the number of larvae with feeding damage, while taking notes of leaking (but not visibly wounded) larvae, and the cards where ants were primarily responsible for the damage. At Keedysville on 5/28/21 there were a significant number of spiders feeding on the larvae but not necessarily causing visible damage. These were photographed and recorded, and the larvae were counted as damaged.

Variables

• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• year -- Sampling year (2020-2022).
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• week -- The week number of sampling, counted from planting.
• dap -- The number of days after planting that sampling took place.
• date -- The sampling date in day/month/year format.
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• cage -- The cage where the card was placed-- numbered 1-4 moving further from the front (rep 1 end) of the plot (see plot plan and trap location figures).
• missing -- The number of larvae missing.
• damaged -- The number of larvae visibly damaged, including both ant and other feeding.
• damaged_leaking -- The number of larvae visibly damaged as well as the number presumed to be damaged (not just missing) due to stains on the card.
• ant_damaged -- The number of larvae with signs of ant feeding.
• predator_damaged -- Damaged and leaking counts minus the number of ant damaged larvae.

File: slug_counts.xlsx

Description: Slug counts taken from pitfall shingle slug traps once a week in the mornings. "data" tab contains complete data, "data_one_date" tab contains data from the week closest to seedling sampling, "data_two_dates" contains data from the 2 weeks closest to seedling sampling, and "data_three_dates" contains data from the 3 weeks closest to seedling sampling.

Variables

• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• year -- Sampling year (2020-2022).
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• week -- The week number of sampling, counted from planting.
• dap -- The number of days after planting that sampling took place.
• date -- The sampling date in day/month/year format.
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• subsample -- Which slug trap (there were 2 per replicate) the sample came from. 1 is closer to rep 1 while 2 is closer to rep 3.
• slugs_na -- The number of slugs counted under the shingle foot print, including in the cup. Only non-flooded and non-animal-disturbed counts included. Flooded and animal-disturbed traps are treated as missing data.
• slugs_f_d -- The number of slugs counted under the shingle foot print, including in the cup. Flooded and animal-disturbed counts are included in cases where the trap was not submerged with standing water.

File: slug_damage_area.xlsx

Description: The area of seedlings injured by slugs when injury was present, for up to 25 plants per replicate plot.

In 2021 and 2022 slug damage area was measured at the same time as slug damage incidence during seedling sampling. Any seedling that was classified as slug damaged (up to 25 per subsample) had its damage area measured with a transparent piece of plastic with a 1 cm^{2 grid drawn on it. Only non-cotyledon leaves were measured for damage. Only seedlings with at least 0.25 cm}2 were counted as damaged. It's worth noting that slug damage on corn tends to be streaky, so damage had to be mentally added up.

Variables

• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• year -- Sampling year (2021 or 2022).
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• growth_stage -- The phenological stage of the corn seedlings at sampling, according to the number of collared leaves.
• dap -- The number of days after planting that sampling took place.
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• ss -- The subsample number. There were 3 subsamples per replicate plot, each assessing the seedlings withing 50 feet of row.
• plant -- The identifier for the plant sampled. There were up to 25 plants per subsample from which we measured slug damage area.
• slug_area -- The area of slug damage per seedling in cm^2.

File: yield.xlsx

Description: Yield collected at maturity. Harvest took place differently at different farms in different years.

2020: At Queenstown, plots were harvested on Oct 5th, offloaded to a truck, which was then weighed in lbs. 4 cup samples were removed from the hopper to analyze for moisture, and we analyzed the moisture from 1 sample from each bag, unless a sample was more than 2% different from a preceeding sample, in which case we took 3 samples and recorded the mean. At Keedysville, plots were harvested on Oct 9th, offloaded onto a truck and weighed in lbs. Single samples were taken for moisture analysis. Beltsville was harvested on Oct 22nd, and weight and moisture were measured by the combine.

2021: At Queenstown, plots were harvested on September 21st and followed the same procedure from 2020. At Keedysville, plots were harvested on Oct 7th, offloaded into a weigh wagon and weighed in pounds. 4 cup samples were removed and one moisture test was done on each (the Keedysville moisture reader takes a very large amount of corn). At Beltsville, plots were harvested on Oct 8th and weighed with a weigh wagon. Samples were removed for moisture, and one measurement was made per sample.

2022 At Queenstown, plots were harvested individually on Septermber 22nd and 23rd, and followed the same procedure from 2020. At Keedysville, plots were harvested on October 18th, following the same procedure as in 2021. There was a harvest mistake at Keedysville that meant we have no yield data for Poncho rep 1 in the Bt. At Beltsville, plots were harvested on October 28th and weighed with a weigh wagon. Samples were removed for moisture, and two were taken except where the first 2 differed by more than 0.3, in which case a third sample was taken. Then averages were taken.

Corrected yield weight per plot was calculated by multiplying the raw weight by 1 minus the percent moisture (to calculate the dry weight) and then dividing by .85 (15% moisture). This weight was then divided by 56 (lbs/bushel of corn), to give bushels per plot. We used this web page to do these calculations. https://www.agry.purdue.edu/ext/corn/news/timeless/WaterShrink.html#:~:text=If%20the%20desired%20ending%20grain,ending%20percent%20dry%20matter%20content.

At all farms, the length of plots were measure in feet and inches, and the two sides averaged (with a measuring tape in 2020 and measuring wheel in 2021 and 2022). Then, we multiplied the average of the two sides by 60ft, the width of the plot. In two cases at Keedysville in 2022 plots where harvested incorrectly (Poncho rep 3 and Control rep 1 of the Bt), so the plot size is smaller. The area of the plot was divided by 43,560ft to calculate the acerage of each plot.

The number of bushels per plot was divided by the number of acres per plot to give the bushels/acre per plot.

Variables

• year -- Sampling year (2020-2022).
• location -- Location where the sampling took place (Queenstown, Beltsville, or Keedysville Maryland).
• corn -- The corn hybrid planted, either Bt (LC1196 VT2P DoublePro, Local Seed in 2020 or P1197YHR, Pioneer in 2021 and 2022) or nonBt (P1197LR, Pioneer all years).
• rep -- The column of the Latin square plot design. Each rep contains one plot of each of three treatments.
• treatment -- Treatment applied in the plot. Capture (in-furrow pyrethroid, bifenthrin, 13.6 fl oz/acre), Poncho (NST, clothianidin, .25 mg/seed), or Control (no NST or pyrethroid applied).
• bushels per acre -- The number of bushels for a plot divided by the number of acres of the plot.
• kg per hectare -- Bushels per acre multiplied by 62.77.

Code/software

All analysis was performed using Base R version 4.5.2/ R Studio version 2026.01.1.

File: Cramer_slug_biocontrol_analysis.Rproj

This file contains all of the code required to load packages and run scripts. In order to reproduce this project:

1) Download this R project

2) If needed, download all excel files into the Raw data folder

3) If needed, download all markdown files into the Annotated code folderFile: 01_packages_to_install.Rmd

4) Using the Knit dropdown for each markdown file, set the Knit Directory to Project Directory

5) Run the code in the "01_Packages_to_install" markdown

You should now be able to run all of the markdowns in any order to reproduce the analysis performed for this study.

File: 01_Packages_to_install.Rmd

This markdown file contains code to install the packages needed to run the analyses in the subsequent markdowns. It also includes comments with a brief description of what each package will be used for. 

File: 02_Slug_counts.Rmd

This markdown file contains the code used to clean and prepare, explore, analyze, and summarize slug count data. Preparation includes taking means weekly slug counts across different numbers of sampling weeks, as well as pooling slug injury across subsamples (adding injured plant counts across subsamples to give total counts per replicate plot). Slug counts and slug injury are correlated to determine which counts are most relevant to injury. Based off of these explorations, slug counts in the 2 weeks closest to seedling sampling are used. Exploration includes visualizing slug counts with histograms and boxplots. Treatment effects on slug counts are tested using generalized linear mixed models. Means and standard errors are generated.

File: 03_Slug_injury_slug_aa.Rmd

This markdown file contains the code used to clean, prepare, explore, analyze, and create plots of the relationship between slug counts and slug injured seedlings. Preparation includes calculating mean weekly slug counts across the two closest sampling weeks, as well as pooling slug injury across subsamples (adding injured plant counts across subsamples to give total counts per replicate plot). The relationships between these variables are explored visually, as well as with linear and generalized linear mixed models. The relationship is analyzed by generalized linear mixed model. Figures are generated based using the percent of injured plants and model-predicted confidence intervals.

File: 04_Stand_aa.Rmd

This markdown file contains the code used to clean, prepare, explore, analyze, and create plots of the relationship between slug counts and establishment (the percent of seeds planted that were seedlings at V2-V4). Preparation includes calculating mean weekly slug counts across different numbers of sampling weeks, pooling stand counts across subsamples (adding numbers of plants across subsamples to give total counts per replicate plot) and calculating the establishment percentage, and calculating the total percent of insect injured plants across subsamples to use as a covariate. The relationships between these variables are explored visually, as well as with linear mixed models. The relationship is analyzed by linear mixed model. Figures are generated using model-predicted confidence intervals.

File: 05_Yield_slug_injury.Rmd

This markdown file contains the code used to clean, prepare, explore, analyze, and create plots of the relationship between slug injured seedlings and yield. Preparation includes pooling slug injury across subsamples (adding injured plant counts across subsamples to give total counts per replicate plot) and calculating the total percent of insect injured plants across subsamples to use as a covariate. The relationships between percentages of injury and yield are explored visually, as well as with linear mixed models. The relationship is analyzed by linear mixed model. Figures are generated using model-predicted confidence intervals.

File: 06_Seedling_slug_damage.Rmd

This markdown file contains the code used to clean and prepare, explore, analyze, and summarize slug injury data. Preparation includes pooling slug injury across subsamples (adding injured plant counts across subsamples to give total counts per replicate plot). Exploration includes visualizing slug injury with histograms and boxplots. Treatment effects on slug injury counts are tested using generalized linear mixed models. Means and standard errors are generated.

File: 07_Pitfall_predators.Rmd

This markdown file contains the code used to clean and prepare, explore, analyze, and summarize counts of predators caught in pitfall traps that were not adult carabid beetles. Preparation includes pooling counts across sampling weeks and taking the mean counts within replicate plot to give the mean early season count per trap. Exploration includes visualizing predator counts with histograms and boxplots. Treatment effects on predator counts are tested using generalized linear mixed models. Means and standard errors are generated.

File: 08_Beetle_community.Rmd

This markdown file contains the code used to clean and prepare, explore, analyze, and summarize various aspects of the carabid community, including distance-based redundancy analysis to test effects on the community over all, and univariate analysis of diversity metrics and counts of all carabids, large predatory carabids, and specific taxa. Preparation includes pooling counts across sampling weeks and taking the mean counts within replicate plot to give the mean early season count of each species per trap. Exploration includes visualizing predator counts with histograms and boxplots. Treatment effects on the community overall are tested with distance-based redundancy analysis, and a figure is generated from this analysis. Effects on diversity metrics are tested with linear mixed models, and counts are tested using generalized linear mixed models. Means and standard errors are generated.

File: 09_Sentinel_prey.Rmd

This markdown file contains the code used to clean and prepare, explore, analyze, and summarize sentinel prey data. Preparation includes pooling data across subsamples (adding injured prey counts across subsamples to give a total percent of damage per replicate plot). Exploration includes visualizing sentinel prey predation with histograms and boxplots. Treatment effects on the percent of sentinel prey with signs of predation are tested using generalized linear mixed models. Means and standard errors are generated.

File: 10_Slug_bioassay.Rmd

This markdown file contains the code used to prepare, analyze, and summarize slug bioassay data. Preparation includes calculating the number of slugs choosing each side (treatment or control or left versus right) of the arena. Difference from random choice is analyzed by exact binomial test. Time spent choosing and likelihood of choosing are also analyses by linear mixed model and generalized linear mixed model respectively. Means and standard errors are generated.

Access information

Other publicly accessible locations of the data:

• There are no other publicly accessible locations of the data

Data was derived from the following sources:

• The data were not derived from additional sources.