Recent research indicates that intraspecific diversity can influence primary productivity and community resilience against biotic and abiotic stress, but the mechanisms by which plant genotypic diversity mitigates stress remain largely unresolved. We used greenhouse studies with wheat and aphids to determine whether the genotypic diversity of a plant’s neighborhood influences performance and fitness of herbivores on a focal plant and if drought changes the effects of neighborhood diversity. We used a pool of varieties that we had previously screened for herbivore and drought resistance to create “minimally diverse” and “more diverse” neighborhood surrounding a focal plant, which we infested with aphids.
Results/Conclusions
Summarized across all varieties we tested, plant–plant interactions in diverse neighborhoods reduced aphid performance and generated associational resistance, although effects on aphids depended on variety identity. In diverse mixtures, drought stress greatly diminished the genotypic diversity-driven reduction in aphid per- formance. Our results suggest inter-varietal interactions in genotypic mixtures can affect herbivore performance in the absence of herbivore movement and that abiotic stress may diminish any effects. Accounting for how neighborhood diversity influences resistance of an individual plant to herbivores will help aid development of mixtures of varieties for managing insect pests and clarify the role of plant genotypic diversity in ecosystems.