Organic management promotes natural pest control through enhanced plant resistance to insects

Lower insect pest populations found on long-term organic farms have largely been attributed to increased biodiversity and abundance of beneficial predators. However, potential induction of plant defenses has largely been ignored. This study aims to determine whether host plant resistance mediates decreased pest populations in organic systems, and to identify the underpinning mechanisms. We demonstrate that greater numbers of leafhoppers (Circulifer tenellus) settle on tomatoes (Solanum lycopersicum) grown using conventional management as compared to organic. Soil microbiome sequencing, chemical analysis, and transgenic approaches, coupled with multi-model inference, suggest that changes in leafhopper settling between organically and conventionally-grown tomatoes are dependent on salicylic acid accumulation in the plant, likely mediated by rhizosphere microbial communities. These results suggest that organically-managed soils and microbial communities may play an unappreciated role in reducing plant attractiveness to pests by increasing plant resistance.