Environmental context and herbivore traits mediate the strength of associational effects in a meta-analysis of crop diversity

1. Crop diversification offers a promising solution to meet expanding global food demands while maintaining ecosystem services. Diversification strategies that employ mixed planting to reduce pest damage (e.g., intercropping), termed \"associational effects” (AE) in the ecological literature, can decrease (associational resistance) or increase (associational susceptibility) herbivore abundance on a focal plant. While application of AE to agroecosystems typically reduces pest abundance, the range of outcomes varies widely.
2. We conducted a meta-analysis using 272 estimates of insect herbivore abundance on crops neighbored by a conspecific or heterospecific from 44 studies undertaken on six continents. We focus on four agricultural crops well-represented from sites across the globe to test hypotheses related to understanding how herbivore traits (diet breadth, feeding guild, origin), plant traits (crop type, phylogenetic distance to neighbor), and environmental context (climate, experimen..., Data for this meta-analysis were collected by extracting data from published primary research articles. No new data were collected for this study. Methods for the literature search, screening of papers, extration of response variables, moderators, and effect sizes are described in detail in the associated paper and supplemental materials., Data were processed for analysis using R. The R scripts for processing the data are made available here.