Mind your neighbors: Intra-varietal interactions drive the influence of crop genotypic diversity on herbivore populations

Crop fields will soon face new challenges under climate change. Changes in temperature and precipitation patterns in some regions will likely lead to an increased threat of drought. In addition, climate change will likely lead to pest outbreaks in some areas. These abiotic and biotic stressors together will jeopardize crop production and food security. A promising tactic to manage these stressors and maintain crop productivity is to increase crop intraspecific (i.e. genotypic) diversity. Evidence from both agricultural and natural systems has demonstrated that intraspecific plant diversity can influence arthropods, increase plant productivity, and increase system stability. We increased genotypic diversity and intraspecific plant-plant interactions within a wheat model system by increasing variety diversity. Our low diversity treatments consisted of monocultures of a single variety, while high diversity treatments contained all possible three-variety mixtures chosen from a pool of five varieties. We performed greenhouse experiments using the bird cherry-oat aphid (Rhopalosiphum padi) to determine the influence of genotypic diversity and water stress on pests and plant productivity. Thus far, our results appear to indicate that genotypically diverse variety mixtures hold potential to diminish the influence of climate change by improving pest management, plant productivity and ecosystem resilience. Our results also build upon a growing body of evidence demonstrating the ecological importance of intraspecific diversity.