This document contains all data and R statistical software code needed to reproduce the analyses presented in the manuscript:

Woolfolk, S., G. Matthews, and Q. D. Read. 2024. Comparison of infestation rates of fall armyworm (Lepidoptera: Noctuidae) neonates for maize resistance screening. Journal of Insect Science. (Citation to be updated)

Summary

The data included here come from an experiment to assess a technique for measuring resistance of maize to fall armyworm. An economically important global maize pest, fall armyworm (FAW, Spodoptera frugiperda), causes damage mainly to the above-ground parts of maize plants, primarily the whorl tissues. One of our research unit missions is to identify and develop maize germplasm with resistance to FAW. One method to measure resistance in maize to FAW is visual rating of leaf-feeding damage after infestation with neonates into the whorl. The data presented here are from a replicated experiment crossing eleven maize lines (four susceptible and seven resistant) with five FAW infestation rates; the experiment was repeated in two consecutive years. The measured response was leaf feeding damage on a categorical scale.

The statistical model presented here is a cumulative logistic mixed model. It treats the response variable (leaf damage rating) as an ordered categorical response. We include a random effect to account for the split-plot design, and include three-way interactions between fixed effects of genotype, treatment, and year. We present means for each genotype and treatment based on the underlying modeled probabilities of each category (weighted averages of the modeled probabilities).

Files

• FAW_combinedyears.csv: All experimental data, with the following columns:
• • Year: Year of data collection (2023 or 2024)
  • Row: Numeric identifier of row
  • Rep: Numeric identifier of replicate block
  • Entry: Numeric identifier of genotype
  • Pedigree: Text identifier of genotype
  • Treatment: Number of neonates per whorl (10, 20, 30, 40, 50)
  • Plant: Numeric identifier of individual plant within row
  • Rating: Categorical leaf-feeding damage rating (scale of 0-9)
• FAW_analysis.Rmd: RMarkdown notebook with all R statistical code to reproduce analyses
• FAW_analysis.html: HTML rendered output of Rmd notebook