Scientists collaborating with farmers in Senegal have demonstrated that enriching soil with nitrogen reduces damage from the Senegalese grasshopper and doubles millet harvests. This approach makes crops less attractive to the pests by altering their nutritional content. The findings, tested on real farms, offer a sustainable tool for managing migratory insects.
Locust swarms pose a persistent threat to global agriculture, capable of devastating crops over vast areas equivalent to major cities like New York or Phoenix. Arianne Cease, who leads Arizona State University's Global Locust Initiative, has spent over 15 years studying these insects and ways to mitigate their impact. Her team's latest research, published in Scientific Reports in 2026, reveals a simple soil-based strategy that curbs outbreaks.
The study focused on the Senegalese grasshopper, which frequently damages crops in smaller groups rather than forming massive swarms. Partnering with communities that had previously collaborated on smaller projects, researchers worked with 100 farmers across two Senegalese villages. Each farmer planted two millet plots: one treated with nitrogen fertilizer and one untreated.
Results showed clear benefits in the treated plots. They hosted fewer grasshoppers, exhibited less leaf damage, and yielded twice as much millet at harvest. Measurements taken three times during the growing season confirmed the reductions, with no increase in other pests.
Cease explained the mechanism: nutrient-poor soils produce plants high in carbohydrates but low in protein, creating a 'donut diet' ideal for locusts' energy needs during migration. Nitrogen enrichment shifts this balance, increasing protein and reducing carbs, which hinders the insects' ability to thrive.
"This breakthrough represents an important step forward in the sustainable management of migratory pests, offering a community-based tool that expands the available treatment options," Cease said.
Lead author Mamour Touré of Université Gaston Berger in Saint-Louis, Senegal, highlighted the practical value: "The results are of major importance to the scientific community and also to Senegalese farmers. The study gave them a better understanding of grasshoppers and locusts, as well as a practical way to control them at the local level."
While the trial used fertilizer, ongoing efforts emphasize compost for long-term sustainability. USAID funding ended in early 2025, yet farmers have adopted composting independently, abandoning the practice of burning crop residues. Touré noted: "Farmers unanimously stated that they no longer burn crop residues after land clearing, but instead practice composting to fertilize their fields, thereby helping to reduce grasshopper infestations."
The team now seeks funding to extend this method to other locust-affected regions. For the United States, which lacks native locusts but faces grasshopper pests like the 'Dirty Dozen' species, the research holds relevance. Cease warned of potential expansion from the Central American locust, predicting Texas could become suitable habitat in 10 to 15 years.
