Soil amendments suppress migratory pests and enhance yields.

Emerging migratory pests pose major challenges to farmers, yet management options remain limited beyond pesticide use. These migratory pests, such as locusts and other migratory grasshoppers, have high energy demands relative to their need for nitrogen and other nutrients. Laboratory and field-cage research has shown that feeding on high-nitrogen plants can suppress the growth, survival, and migration, because these insects struggle to meet energy requirements (carbohydrates and lipids) while contending with the costs of excess nitrogen intake. While soil amendments have been tested in field cages, their effect on migratory pest populations in open-air agroecosystems has not been examined. Here, working with 100 farmers, we present the first large-scale demonstration that soil amendments can reduce migratory pest abundance and improve crop yields under field conditions. Our open-air experiment reveals that even localized increases in plant nitrogen, at scales relevant to agricultural fields, can decrease plant palatability and abundance of leaf-chewing migratory insects in free-ranging populations. This study advances our understanding of the nutritional ecology of migratory herbivores and provides a promising addition to sustainable pest management strategies.