South African scientist finds fungus that kills armyworm
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- Letodi Luki Mathulwe, an entomologist with South Africa's agriculture department in KwaZulu-Natal, noticed armyworm caterpillars in Kikuyu grass fields were being killed by a white fungal growth while insects in neighbouring areas were thriving.
- Mathulwe's team collected samples and tested them at their Pietermaritzburg laboratory, with the resulting peer-reviewed paper confirming the fungus's lethal effect on Spodoptera exempta.
- Chemical treatments currently exist only for young armyworm caterpillars, and none have proven effective against mature populations — the gap the fungus discovery could fill.
- African armyworm outbreaks have inflicted severe agricultural losses, including a 2017 event estimated to have wiped out up to 40% of Zambia's maize production.
- Armyworm infestations also release a chemical in grass that sickens cattle, compounding the strain on farmers already dealing with food-price inflation — 736% in Zimbabwe and 35% in Malawi in 2024.
- Mathulwe said more testing is required before the fungus can be developed into a product for farmers, but it could one day remove the panic that sets in when armyworms appear in grazing fields.
Why it matters: The armyworm destroys up to 40% of maize in bad outbreak years and sickens livestock through a toxin it leaves in grass, with no current chemical fix for mature caterpillars. A naturally occurring fungus that works against mature populations gives east and southern African farmers — already battered by hyperinflation in Zimbabwe (736%) and Malawi (35%) — a potential biological control tool that targets the pest's most destructive life stage.
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