Augmenting plant diversity within a farm field can promote pest regulation and can reduce the need for external inputs. Biodiversity-mediated benefits to ecosystem function are highly context-dependent because herbivorous arthropods and their predators’ response is dependent on taxon-specific interactions at multiple scales. The identity, community composition, and spatial relationships of the plants within polycultures are known to influence insect abundance and diversity, but experiments investigating the links between local diversification practices, insect pests, and their natural enemies are far fewer. I investigated how incorporating plant diversity affects pest regulation in three agricultural production systems. I conducted these experiments to further our knowledge of the ecological interactions and mechanisms mediating the benefits of these practices and to further their adaptation to the northeastern United States. Chapter 1 explores the effect of varietal and intrafamilial species diversity on yellow dwarf viruses, aphid populations, and yield in wheat and barley mixtures. This experiment revealed that aphid preferences led to decreased virus pressure in the wheat varietal mixture, and that aphid attraction to barley did not lower species mixture yields. Chapter 2 investigates how legume intercrop species identity, the induction of maize defenses by fall armyworm larvae, and egg mass height on maize plants influence predation rates in maize-legume intercrops. Larval induction did not increase overall predation rates, but instead made predation rates more even across upper and lower egg masses on induced maize plants. In Chapter 3, I assess the impact of incorporating cover crops and eliminating insecticide seed treatments on seedcorn maggot pressure at commercial dairy farms along a gradient of landscape composition. The use of these local sustainable management practices did not impact seedcorn maggot damage or yield overall, and landscape composition affected all local practices equally. As the percentage of agriculture in the landscape surrounding a farm increased, seedcorn maggot pressure decreased. These chapters demonstrate the importance of understanding how arthropod pest and predator species respond to plant varietal diversity and species diversity across different spatial and landscape contexts. They also support the implementation of moderate, practical diversification by demonstrating the feasibility of cover crops and insecticide reduction.