New research announced by scientists at the Centre for Agriculture and Biosciences International (CABI) confirms that the recently introduced crop-destroying armyworm caterpillar is now spreading rapidly across mainland Africa. 

They said the pest could spread to tropical Asia and the Mediterranean in the next few years, becoming a major threat to agricultural trade worldwide.

Fall armyworm is native to North and South America and can devastate maize production, the staple food crop that is essential for food security in large areas of Africa. It destroys young plants, attacking their growing points and burrowing into the cobs.

It has not previously been established outside of the Americas. In the past year, it was found in parts of West Africa for the first time and now a CABI-led investigation has confirmed it to be present in Ghana. It can be expected to spread to the limits of suitable African habitat within a few years. 

Plant doctors working in CABI’s Plantwise plant clinics, which work to help farmers lose less of what they grow, have found evidence of two species of fall armyworm in Ghana for the first time.

This has been confirmed by DNA analysis undertaken at CABI’s molecular laboratory in the U.K. In Africa, researchers are working to understand how it got there, how it spreads, and how farmers can control it in an environmentally friendly way.

“We are now able to confirm that the fall armyworm is spreading very rapidly outside the Americas, and it can be expected to spread to the limits of suitable African habitat within just a few years," CABI chief scientist Dr. Matthew Cock said.

"It likely travelled to Africa as adults or egg masses on direct commercial flights and has since been spread within Africa by its own strong flight ability and carried as a contaminant on crop produce."

Known as the fall armyworm because it migrates into temperate North America in Autumn (fall), this pest has long been a problem throughout tropical America, damaging vital crops.

It mostly affects maize (corn) but it has been recorded eating more than 100 different plant species, causing major damage to economically important cultivated grass crops such as maize, rice, sorghum and sugarcane as well as other crops including cabbage, beet, peanut, soybean, alfalfa, onion, cotton, pasture grasses, millet, tomato, potato and cotton.

Detections in South Africa

According to a release by South Africa's Department of Agriculture, Forestry and Fisheries (DAFF) on Feb. 6, results of a diagnostic report confirmed that the pest was positively identified from samples collected in the Limpopo and Gauteng Provinces. 

Farmer organization Agri SA said "little is known on how this pest entered Southern Africa."

The group said it wished to alert farmers that the application of chemicals must be carried out in consultation with chemical representatives, adding that DAFF has also started with a process of emergency registration of an agricultural chemical to be applied against this pest.

"Although this pest attacks mostly maize plants, it may occasionally attack cotton, wheat, sorghum, soybeans, potatoes and groundnuts," it said.  

"It is therefore also important to scout these crops for damage and the presence of the invasive species. Since this pest is basically foreign to Africa, very little is known on its long-term effects.

"It may become a migratory pest similarly to the African Army Worm and may migrate in large numbers from one area to another causing great damage."

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