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January 2001

Feature

 

Green Muscle: an environmentally friendly weapon against locust and grasshopper plagues

Locust After many years of collaborative research, scientists in Africa have come up with an environmentally friendly weapon that looks set to finally defeat locust and grasshopper plagues. The biopesticide, called Green Muscle, provides a safe, natural alternative to chemical insecticides in the fight against crop-destroying locusts and grasshoppers.

Swarms of locusts and grasshoppers have long plagued farmers in Africa and around the world. The first commercial quantities of Green Muscle were recently released in what is believed to be the largest aerial spraying of a biopesticide ever conducted in Africa. Early reports of the spraying in Niger indicate that the biopesticide provides complete control up to three times longer than do current chemical insecticides, making it less expensive for farmers to protect their crops from locusts and grasshoppers, as well as safer.

Scientists from the Nigeria-based International Institute of Tropical Agriculture (IITA), working with the Centre for Agriculture and Biosciences International (CABI) in the UK, developed the natural pesticide over a ten-year period as part of an international research consortium called LUBILOSA (LUtte BIologique contre les LOcustes et les SAuteriaux or Biological Control of Locusts and Grasshoppers).

The new control method uses a naturally occurring fungus, Metarhizium anisopliae, that is deadly to both locusts and grasshoppers but does not damage other insects, plants, animals, or people. When added to an oil-based carrier, the resulting dark green liquid can be sprayed by hand or from an aircraft. Once infected by the fungal preparation, locusts and grasshoppers die within 4–10 days. The fungus strain currently used by scientists is indigenous to Africa, but strains from various origins can be used. This makes localized formulations possible. Scientists foresee the fungal formulation as having widespread use beyond Africa in other countries where grasshoppers and locusts are problem pests.

Chemical insecticides kill beneficial small animals and insects, as well as pose dangers to local people. It is believed that the ongoing spraying of insecticides throughout Africa, including locations frequented by migratory birds, is also contributing to large decreases in the numbers of migratory flocks in Europe.

Teeth of the wind

Desert locusts periodically devastate crops across a large swath of Africa. An ancient problem, locusts’ destructive power was used to illustrate the wrath of God in the biblical description of the seven plagues of Egypt. In Arabic, the phrase for locusts is translated as “teeth of the wind.” They attack in hard-to-predict cycles about once every ten to 20 years, emerging when weather conditions in their breeding grounds around the Red Sea and on stopovers on their invasion routes are just right for them to multiply.

“Because of the immense size and range of the swarms, there is little that individual farmers can do when locusts strike,” says project leader Jürgen Langewald, an IITA entomologist and project leader of LUBILOSA. “It is up to governments and international organizations to take the lead in implementing strategies that incorporate the use of biological control.”

In modern times, desert locusts have swarmed over dozens of countries from Senegal in West Africa to as far east as India. The most recent invasion lasted from 1986 to 1989. One of the largest swarm clouds in the twentieth century, it covered about 1000 square kilometers and contained some 40 billion locusts. Experts estimate that the swarm consumed vegetation equivalent to the food needs of about 200 million people. And grasshoppers, close relatives of locusts, can cause even more damage over the long term, because of their permanent presence in and around farmers’ fields.

While no one can predict when locusts will strike again, Lukas Brader, entomologist and director general of IITA, believes Africa is overdue for its next invasion. “The question that government leaders and the heads of international organizations must ask,” he says, “is whether they are willing to put people and the environment at risk once again.” He notes that the stakes are far higher now than they were in the mid-1980s. Since that time, the number of people living in the affected areas has more than doubled. Moreover, additional applications of today’s less persistent chemicals will be needed, raising the cost. Brader believes that the next time locusts strike, the price might be as much as US$500 million. The cost of the 1986 locust invasion was estimated at about US$300 million.

“For these reasons, we are proposing to attack the locusts in their breeding grounds a method we have successfully tested,” says Langewald. As part of a preventative strategy, breeding areas mainly around the Red Sea would be treated each year with Green Muscle to catch young locusts before they are mature enough to fly and become a threat to farmers’ fields. According to Langewald, the cost of treating these areas would amount to US$15 million annually, a fraction of what would be required for an all-out effort using chemical spraying after the locusts have swarmed.

“While it is always easier to raise money and cut red tape after a crisis has occurred,” says Langewald, “a program based on prevention through biological control will better serve both people and the environment. To prevent the next invasion, international organizations, donors, non-governmental organizations and Africa’s national governments need to begin planning now.”

Green Muscle

The search for an alternative to the chemicals used to control locust and grasshopper infestations began in 1989 at CABI. The objective was to identify a natural enemy lethal only to locusts and grasshoppers. After studying more than 160 strains of fungi and other locust pathogens, CABI scientists identified the Metarhizium anisopliae strain currently used.

Large-scale testing of Green Muscle began in 1996 near Lake Chad, followed by on-farm trials conducted with organizations including CARE, AFRICARE, and local farmer associations. The formulation was approved by FAO in 1997. The commercial release of the biopesticide, conducted in August 2000, targeted a 2000-hectare area in Tahoua Province of Niger. Tahoua, an area of fertile agricultural valleys south of the Sahara desert, was devastated by locusts between 1986 and 1989 and again in 1992–93. The government of Niger, which is the first African government to integrate the new biopesticide into its pest control program, plans to introduce biopesticides to 300,000 hectares of agricultural land currently treated with chemicals.

Private companies are expressing interest in the new biopesticide. As these companies increase production, costs are expected to decline further. Biological Control Products of Durban, South Africa is the first company to receive a license to produce the biopesticide and is now starting mass production. Negotiations are currently under way with other manufacturers to produce it in the private sector.

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