Fungal pesticide saves crops from locusts

The red locust: A small creature with a big appetite Copyright: Wikimedia Commons

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[DAR ES SALAAM] Crops in East and Southern Africa have been saved from devastation by the first large-scale use of a biopesticide made of fungal spores.

Locust swarms lay waste to crops, with just a small part of a swarm — around a tonne of locusts — eating the same amount of food in one day as around 2,500 people, according to the UN Food and Agriculture Organization (FAO).

The FAO feared that infestations of red locusts would turn into a full-scale invasion, endangering the food security of millions. But spraying the biopesticide, Green Muscle, in Tanzania appears to have contained the outbreak.

Green Muscle consists of spores of the fungus Metarhizium anisopliae suspended in mineral oils. The fungi grow in the locust, producing a toxin and weakening them, making them easy prey for birds and lizards.

Most infected locusts die within 1–3 weeks, depending on the temperature and humidity. The pesticide has an 80 per cent mortality rate.

The spraying campaign, organised by the FAO and the International Locust Control Organization for Central and Southern Africa, started on 21 May in Tanzania. Around 10,000 hectares have been sprayed so far. 

The FAO will spend US$2 million deploying the pesticide in Tanzania, Malawi and Mozambique over the next few months.

A senior FAO locust expert, Christian Pantenius, told SciDev.Net that African countries should embrace the technology, which costs just US$17 per hectare.

Green Muscle kills only locusts and grasshoppers, unlike chemical pesticides, which can harm a wide range of organisms. Even the birds and lizards that eat the treated locusts suffer no side effects, says Pantenius.

Since its commercial release in 2000, Green Muscle has been tried in Madagascar, Niger, Senegal and Sudan, but this is its first large-scale application.

However, the time lag from spraying to the locusts dying — and the fact that the fungus survives for weeks — means that Green Muscle is more appropriate for prevention than controlling outbreaks, says Pantenius.

Baldwyn Torto of the International Centre of Insect Physiology and Ecology in Kenya, told SciDev.Net that Senegal and South Africa are ready to produce Green Muscle.