Fungus kills African armyworm, offering hope to farmers

A naturally occurring soil fungus can kill the African armyworm, a devastating crop pest, raising hopes for a new control method for farmers in east and southern Africa.

South African scientist Letodi Luki Mathulwe made the discovery in April 2025 during an outbreak that reached KwaZulu-Natal.

Farmers in the region rely on crops like maize and sorghum and on Kikuyu grass for livestock grazing. Armyworm caterpillars not only consume staple crops but also release a chemical that can sicken cattle, threatening food security and livelihoods.

The fungus fills a critical gap: while chemicals control early-stage caterpillars, nothing effectively kills mature populations. Mathulwe’s finding could reduce the panic that outbreaks cause.

Mathulwe, an entomologist with the agriculture department, collected samples from Kikuyu grass fields in KwaZulu-Natal where dead caterpillars were enveloped in a white substance. She confirmed the fungus’s role in her Pietermaritzburg laboratory. Her team’s findings appear in a peer-reviewed research paper.

A previous outbreak in 2017 destroyed up to 40% of Zambia’s maize production. An outbreak in 2025 strained economies in Zimbabwe, where inflation hit 736% in 2024, and Malawi, where it reached 35% in 2024.

The African armyworm, Spodoptera exempta, is most damaging as a caterpillar but becomes highly mobile as a moth, allowing populations to spread rapidly.

Mathulwe says more testing is needed to turn the fungus into a product for farmers. She believes it could eventually eliminate the fear the insect creates, protecting both crops and livestock when the next outbreak occurs.