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Tanzania flexes its Green Muscle

The fungus-based 'mycopesticide', can be applied to large areas through aerial spraying (© FAO/Christian Pantenius)
The fungus-based 'mycopesticide', can be applied to large areas through aerial spraying
© FAO/Christian Pantenius

Effective even in the searing temperatures of the Sahel, a biopesticide containing fungal spores has recently been used to successfully avert a locust plague in East Africa, which could have destroyed the food crops of millions.

Although the biopesticide, Green MuscleTM, has already been trialled in a number of African countries, it is the first time that it has been used on such a large-scale. Funded by the FAO and the UN's Central Emergency Response Fund, the successful operation offers "a model for combating other transboundary pests that are threatening the region," says Modibo Traoré, assistant director-general of FAO.

During the aerial spraying campaign, organised by FAO and the International Locust Control Organization for Central and Southern Africa, the biopesticide was used to target adult red locusts (Nomadracis septemfasciata) across the wetlands of the Iku-Katavi National Park of Tanzania. Ten thousand hectares had been treated by the end of July 2009, two months after the start of the campaign. FAO will spend US$2 million to continue the campaign into Malawi and Mozambique over the coming months.

Dedicated research

Developed over a decade of collaboration by the LUBILOSA* programme, Green MuscleTM is highly selective in attacking locusts and grasshoppers, with no adverse effects observed on non-target organisms. However, more than 160 strains of fungi and other locust pathogens had to be studied before CABI scientists identified the fungus Metarhizium anisopliae var acridum, which is used in Green MuscleTM. The product consists of spores of the fungus suspended in a mixture of mineral oils.

An adult locust eats its own body weight (about 2g) in vegetation each day (© FAO/G.Tortoli)
An adult locust eats its own body weight (about 2g) in vegetation each day
© FAO/G.Tortoli

According to Dr Dave Moore of CABI, who helped develop the mycopesticide, the development of a fungus-based pest control agent for locusts dispelled early reservations in the scientific community. "Most biological pesticides have a limited shelf-life," he says. "However through persistent experimentation during the germination, drying and packaging stages, the LUBILOSA programme was able to produce large numbers of viable M. anisopliae spores, and a packaged product with a shelf life of 18 months at 30°C. Under refrigeration, Green MuscleTM lasts up to five years."

The fungus is now produced in commercial quantities in Senegal and South Africa. It is grown on rice, with its microscopic spores collected by harvesting machines that evolved through many variations, culminating in an industrial-scale version now in use in Africa.

An effective alternative

Green MuscleTM is not only more environmentally benign than chemical alternatives but is also more effective and persistent. Spores exposed to sunlight are killed within eight hours, but spores shaded or hidden in plant crevices can survive for several weeks. In trials, chemical insecticides were found to kill insects very rapidly, but within a few days pest numbers were rising again. Insect numbers in areas treated with Green MuscleTM only began to drop after 7-10 days, but they continued to fall and remained low long after the insect numbers in the chemically-treated areas had returned to control levels.

In one day a swarm of 50 million desert locusts can devour crops that would have been a day's food for over 180,000 people (© FAO/Giampiero Diana)
In one day a swarm of 50 million desert locusts can devour crops that would have been a day's food for over 180,000 people
© FAO/Giampiero Diana

In Tanzania, Green MuscleTM was used to kill adult locusts, but Moore suggests that preventative spraying of the insects in their younger 'hopper' stage is more effective. The speed at which the fungal infection spreads through the insect is primarily determined by temperature. Infected locusts tend to sun themselves, raising their body temperature and slowing fungal spread. As a result, a level of infection which might kill the insect in five days in the laboratory can take ten days or more in the field. For farmers whose crops or fodder plants are being eaten by adult insects, such a long period from spray to death might be unacceptable. It is recommended, therefore, that the pesticide be used proactively to treat breeding sites, rather than reactively to control outbreaks. This could be done most effectively by establishing community-based early warning systems. Organising these, with the involvement of wildlife rangers and farmers, is one of the next challenges for locust control.

Dr Moore is philosophical, however, about how long widespread adoption may take. "At the beginning, developing a fungal-based control for locusts seemed a huge problem," he says, "but that was easy compared with the difficulties of getting uptake and use." Several countries, including Madagascar, Niger and Sudan, have already trialled the product in smaller areas, and Yemen has expressed an interest in mycopesticides more generally, because of fears that chemical products are responsible for the collapse in bee colonies. Moore is hopeful that with commercial production of Green MuscleTM now underway in Senegal and South Africa, the success of the first large-scale application will be a turning point.

* LUBILOSA - Lutte Biologique contre les Locustes et les Sauteriaux - a collaborative programme led by CABI, with the International Institute of Tropical Agriculture (IITA), Cotonou, Benin, and the Département de Formation en Protection des Végétaux, Niamey, Niger.

Date published: September 2009

 

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