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Updated On: Monday, 22 April 2019

Biological weapon against fall armyworm found in Africa

[LAGOS] Scientists have identified a biological weapon that could help fight the scourge of fall armyworm, a devastating pest that experts say threatens the food security of about 200 million people in Africa.

According to the UN’s Food and Agriculture Organization (FAO), fall armyworm has already spread across Sub-Saharan Africa since its detection in the region in 2016, affecting millions of hectares of maize and sorghum crops. The biological weapon, known as Telenomus remus, is an egg parasitoid — an insect that completes its larval development within the body of another insect leading to the death of its host. It is already being used to tackle fall armyworm in the Americas, experts say.

“We hope that by using this parasitoid or other biological control agents, the quantity of synthetic insecticides used against fall armyworm will diminish.”

Marc Kenis, CABI

Now an international team of researchers have used DNA analysis and morphological observations to confirm the presence of T. remus in Benin, Cote d’Ivoire, Kenya, Niger and South Africa, according to a study published in the journal Insects last week (29 March). “T. remus is a vital tool that can fight against the fall armyworm, a pest that has the ability to cause yield losses of up to 20.6 million tonnes per annum in 12 of Africa’s maize-producing countries,” says Marc Kenis, lead author of the study and head of risk analysis at the Centre for Agriculture and Bioscience International (CABI, the parent organisation of SciDev.Net). Kenis tells SciDev.Net that the main control method currently used is broad-spectrum insecticides, which has serious economic, environmental and health consequences. Fall Army Worm
The fall armyworm. Copyright: CABI
The use of natural enemies to control a pest, an approach called biological control, is environmentally more sustainable and has no negative effect on human health. “Many teams in Africa are looking for natural enemies of fall armyworm in several African countries. Of particular interest are parasitoids,” says Kenis. “Our discovery showed that the parasitoid is already in West, East and Southern Africa and can readily be used as a biological control agent.” Kenis cautions, however, that biological control agents do not fully eradicate pests. “They just lower their populations and impact below a tolerance threshold,” he says. “We hope that by using this parasitoid or other biological control agents, the quantity of synthetic insecticides used against fall armyworm will diminish.” The team of scientists say surveys should now be carried out throughout Africa to assess the distribution and impact of Telenomus remus on the continent. The main challenge will be to develop a production method specific to the African context that will be economically viable for farmers, Kenis adds. He believes African policymakers should facilitate the use of T. remus as a biological control agent by allowing it to be registered. Tony Wemton, director of Wemton Agricultural Development and Advisory Services in Nigeria, tells SciDev.Net that Nigerian farmers have been using insecticides to tackle fall armyworm, which can cause great harm to farmers and end users of their products. “With this new biological weapon that can fight against fall armyworm, African governments can help local farmers by making funds available through grants or subsidies so that they can have access to it,” Wemton says. This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.

References

Marc Kenis and others Telenomus remus, a candidate parasitoid for the biological control of Spodoptera frugiperda in Africa, is already present on the continent (Insects, 29 March 2019) Wikimedia commons/Sam Droege [Public domain]

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