Chemicals help West Africa’s efforts to control cotton pest

Without taking a break to wipe away the perspiration on their foreheads, labourers in northern Ivory Coast gathered cotton by the handful. The crop was rescued through the intensified application of additional insecticides after a recent pest, the Indian cotton jassid or Amrasca biguttula insect, caused unprecedented damage throughout West and Central Africa in the previous season.

The unexpected emergence of the insect in the 2022-23 season injected a toxin into the plants, resulting in a nearly 25% year-on-year decline in production. Some countries experienced more than a 50% loss in their projected harvest. Issouf Kabe Coulibaly, a farmer in the Ivorian department of Korhogo, vividly recounted the devastation, as he and fellow farmers struggled to sustain their families, accumulating debts due to the losses incurred.

This crisis underscored the region’s susceptibility to invasive species and its dependence on chemical solutions, which research indicates may not provide a sustainable, long-term safeguard for a crop vital to millions and a crucial foreign currency earner for economically strained governments across the region, from Benin to Burkina Faso.

To counteract the threat posed by the tiny grasshopper-like insects, the use of swiftly tested and approved new pesticides proved effective this year. The U.S. Department of Agriculture (USDA) projected a 22% rebound in production, reaching 4.9 million 480-pound bales in the 2023-24 season across West and Central Africa’s ten cotton-growing nations.

By late November, the fields around Korhogo were abundant with cotton bolls, and workers diligently harvested the frosted-looking white puffs. Farmers expressed relief that the implemented solutions appeared successful, preventing a recurrence of the previous year’s cotton shortage.

In response to the jassid crisis, cotton producers recognized the need for urgent action. The unprecedented scale of the issue prompted collaboration among experts from the PR-PICA cotton production program, who identified and recommended three new pesticides for farmers in the region to use during the sowing season in May.

Although there was initial hesitancy among some farmers, fearing potential risks, the success of the new chemical approach became evident during the harvest. Farmers like Issouf Kabe Coulibaly, who had reduced their planting area due to concerns, saw their fears unfounded as workers efficiently harvested ample quantities of cotton, signaling the effectiveness of the new chemical regimen.

Despite the successful rebound in production, researchers caution that this recovery might be short-lived. They emphasize the importance of developing pest-resistant cotton varieties, expanding monitoring systems, researching alternative bio-controls, and addressing jassids at different stages of their life cycle to establish sustainable, long-term solutions.

While insecticides have proven effective in the short term, experts warn that relying solely on this approach perpetuates a vicious cycle, as resistance is likely to develop over time. The economic argument for investing in sustainable tools is clear, as biological invasions have cost Africa up to $79 billion between 1970 and 2020.

Entomologists attribute the influx of new invasives to weak border controls and changing climate conditions, which can alter a species’ range or facilitate its spread. Genetic tests indicate that the new jassid in West Africa originated from Asia, emphasizing the need for comprehensive strategies to address the complex challenges posed by invasive species.

Some farmers, like septuagenarian Navaga Tuo in Korhogo, express reservations about the overreliance on chemical solutions. While encouraged by his neighbors’ successful harvests, Tuo remains cautious about using more chemical sprays and emphasizes the importance of finding sustainable solutions to eliminate jassids, recognizing agriculture as their primary livelihood.