New research in Agronomy reveals that during a recent upsurge of locusts in the Horn of Africa, the use of traditional insecticides harmed local bird and honeybee populations. But Somalia selected a treatment option that can control swarms while protecting human health and wildlife. The results suggest a path toward sustainable locust management.
The U.N. Food and Agriculture Organization (FAO) describes the Desert Locust as “the most destructive migratory pest in the world.” In a single day, their mobile swarms can consume the same amount of food as 35,000 people, threatening both food security and agricultural producers’ livelihoods.
The research paper focuses on Ethiopia and Somalia, which recently experienced the most extreme infestation of locusts in 25 years according to the World Bank, and Kenya, which saw the worst outbreak in more than 70 years. In these countries “the massive invasions of [the Desert Locust] overwhelmed existing control capabilities,” the authors state.
As swarms surged, Ethiopia and Kenya responded with the application of insecticides classified as organophosphates and pyrethroids. While these control agents can successfully kill off locusts rapidly at scale, past upsurges in Western Africa have shown re-invasions are possible within weeks.
These chemicals are also known groundwater pollutants and soil contaminants. The authors note that during the recent locust invasion, limited monitoring of the environmental impact of insecticide application occurred. But, they add, it is safe to assume “negative environmental side effects” that “were widespread but remained largely unreported.”
The paper estimates that spraying of these chemicals led to the mortality of “thousands” of birds and the displacement of tens of thousands. And in Ethiopia—one of the top ten natural honey producing countries in the world, according to research from Injibara University—honey production declined by as much as 75 percent. This is due to honeybee deaths, a reduction in honeybee lifespan, and delayed development caused by the insecticide treatment.
“The fight with highly toxic pesticides against the devastating outbreak of desert locust in years 2019 to 2022 created very high costs for people and the environment,” Alexander Müller, Founder and Managing Director of TMG – Think Tank for Sustainability tells Food Tank. A co-author of the paper, Müller continues: “The revenue loss for the honey producers can be estimated around US$500 million. An initial True Cost Analysis of the loss of environmental services (pollination) is 15 times higher! And the question arises how much biodiversity, and especially insects, has been destroyed with this action.”
In contrast, Somalia’s response to the locust swarms included the bio-insecticide known as Metarhizium acridum with promising outcomes. Treatment resulted in the disintegration of swarms within days and “more importantly,” the authors state, the locusts lost their appetite. Thoroughly tested, M. acridum also “protects the environment and human health” unlike organophosphates, according to the researchers.
To make the treatment of M. acridum even more effective, however, the paper recommends combining the response with another intervention: predator birds.
While a bird’s consumption of locusts can vary by season or geography, they can slash locust populations by as much as 50 percent in 17 days. Though promising on its own, the application of M. acridum can actually reduce locust populations further. Locusts affected by the bio-insecticide tend to move to the top of crops to bask in the sun. And once locusts are exposed, birds can more easily locate them, further reducing swarm sizes.
The authors find that the use of M. acridum, either alone or in combination with predator birds, is most effective as an early means of control.
“We need an innovative early warning system and better early action to make the fight against locusts and other pests and diseases more efficient and less dangerous for people and the environment,” Müller tells Food Tank. “[The Intergovernmental Panel on Climate Change] has warned us that climate change will make such outbreaks more frequent and will change the spread of the risks.”
And if utilized correctly, the authors conclude, the paper’s recommended approach can manage locusts “before they develop to threaten crops, pastures, and ultimately livelihoods.”
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Photo Courtesy of Nicolas Lindsay, Unsplash