Taming the Desert Locust
For the first time, an environmentally friendly weapon against desert locusts has been successfully tested under large-scale field conditions. During a field trial organized jointly by the plant protection authorities of Algeria and the U.N. Food and Agricultural Organization (FAO) near El Oued in eastern Algeria, the biopesticide, called Green Muscle®, was sprayed on more than 1,400 hectares of land infested by desert locust larvae. Locusts were clearly weakened and started moving slowly after four days and were then eaten by birds, lizards and ants. The new control method uses a natural fungus, called Metarhizium anisopliae, which infects locusts in such a way that they stop feeding and die in one to three weeks. "This successful large-scale test is a major breakthrough in the battle against locusts," said Niek van der Graaff, Chief of FAO's Plant Protection Service. "For the first time, the biopesticide Green Muscle® was shown to be effective against desert locust under realistic field conditions over a substantial area. While previous tests on the efficacy of Green Muscle® for desert locust control were only conducted in laboratories and on small plots of land, this trial now proves that the fungus can be successfully applied by professional plant protection teams over a large area. This shows that Green Muscle® is a realistic alternative to conventional pesticides," van der Graaff said.
The trial was conducted under optimal temperatures that favored the development of the fungus. More field testing under less favorable conditions is required to explore the potential and limitations of the product. Green Muscle® is a substance composed of the spores of the fungus Metarhizium anisopliae and a mixture of mineral and vegetable oils. The biopesticide is not toxic to humans and kills only locusts and grasshoppers and a very limited number of other insects. While most conventional pesticides kill locusts immediately, the fungus in Green Muscle® needs up to three weeks to grow within the body of the insect and finally kill it. The length of the incubation period depends on the environmental temperature; the fungus grows well between 15 and 35º C. In the northern African and Sahelian countries that are most affected by desert locust infestations, this temperature range prevails during parts of the winter and the rainy season when locusts breed.
There are other constraints. To protect food crops from imminent locust attacks by swarms, conventional pesticides are still required because they kill the locusts quickly. Green Muscle® cannot be applied on locust swarms. Green Muscle® is currently being produced commercially by only one company in South Africa with a limited production capacity, but efforts are being made to develop production in Senegal. The production of Green Muscle® is very costly when compared with chemical pesticides. However, a larger market could lower production costs significantly. Unlike conventional pesticides, the application of Green Muscle® requires minimum safety measures and less personal protection equipment. In the 2004-2005 locust upsurge, which affected up to 16 countries mainly in northwest Africa and the Sahel, about 12.8 million hectares of infestations were treated with pesticides. (FAO Press Release, 6/28/05).
