Organic compost belowground and floral diversity aboveground interactively shape natural enemies in urban gardens

Plant diversity aboveground can exert top-down pressure on herbivores by attracting predatory insects, while organic soil amendments rich in beneficial microbes can limit herbivores from the bottom up by enhancing plant defensive chemistry. Aboveground and belowground forces always operate simultaneously to shape herbivore pressure, but understanding how they interact is a longstanding and persistent challenge. Here, we examine how organic composts mediate effects of plant diversity across trophic levels, using zucchini plants (Cucurbita pepo) as a study system. Over two field seasons, we manipulated vermicompost treatments in 18 experiments in school gardens that varied in surrounding plant and floral resource diversity, and measured responses of insect herbivores and their natural enemies.  Vermicompost strengthened a positive relationship between flower richness and foliar-feeding omnivores, suggesting that robust reservoirs of omnivores at flower-rich sites mounted stronger response..., Experimental treatments
In August 2021 and May 2022, experiments were established at nine school garden sites in Athens, GA, USA (Appendix Table S1). In 2022, three of the original school garden sites were dropped from the study due to teacher turnover and other factors beyond our control, and were replaced by three new sites. Therefore, experiments were repeated in six sites across both years, with a total of 12 unique sites across the two-year study. Within each year, all sites were separated by a minimum distance of 0.8 km (Appendix Figure S1).
Each site consisted of two adjacent raised garden beds (1.2 m × 2.4 m), with eight zucchini seedlings placed 0.6 m apart in two rows. One bed at each site was randomly selected for vermicompost treatments while the other served as a control. Four sites had pre-existing garden beds, while new beds were established at the remaining five sites. New beds were filled with organic raised bed planting mix (Kellogg Garden Organics, Carson, CA). In 202..., , # Organic compost belowground and floral diversity aboveground interactively shape natural enemies in urban gardens

This dataset includes results from experimental manipulations of vermicompost treatments made to zucchini plants in 18 experiments performed over two years in urban school gardens. On each zucchini plant, we counted herbivorous pest insects, foliar-feeding omnivorous insects, and predatory arthropods. It also includes observational field surveys of floral resource richness (estimated at the family level) from the surrounding environment at each site.

## Description of the Data and file structure

Missing data/Blank cells (when samples were lost or damaged) are noted as \"n/a\" throughout the data set.

This spreadsheet contains four sheets:

Sheet 1 (annual.means.without.outliers) contains annual mean estimates of floral resources, insects, and soils from each site, pooled across all sample dates for each experiment. This sheet excludes outlier insect counts from three pla...