Validating Indigenous Farmers’ Practice in the Management of the Fall Armyworm Spodoptera frugiperda (J. E. Smith) in Maize Cropping Systems in Africa

Abstract

Before the invasion of the fall armyworm (FAW)Spodoptera frugiperdainto Africa, small-holder farmers had been using indigenous practices such as applying fish soup to plants to managestemborer pests. Although farmers have since begun adapting this practice against FAW, no attempthas been made to scientifically evaluate this practice. Therefore, we assessed the efficacy of applyingfish soup to maize plants that were artificially infested with FAW under semi-field conditions. Ourresults showed that foliar damage is inversely correlated with the concentration of a fish soup andsugar solution, with the highest (100%) concentration resulting in the lowest foliar damage and thehighest plant recovery. The FAW foliar damage results for maize plants treated with 100%, 50%, 10%fish soup and sugar, and distilled water were 46.3±5.6, 51.1±5.0, 71.6±5.2, and 99.4±0.4%,respectively, whereas plant recovery results from the same treatments were 35.2±3.7, 31.1±5.4,20.0±4.6, and 0.0±0.0%, respectively. A concentration of fish soup and sugar solution of at least25.9% was required to achieve the lowest foliar damage of 17.8% and peak plant recovery of 73.6%.Fish soup and sugar solutions attracted a wide range of insects, including potential natural enemies(predators and parasitoids) of FAW, in a dose-dependent manner. Maize plants treated with fish soupand sugar showed higher chlorophyll content and better growth than the control did. Proximateand chemical analysis showed that fish soup contains essential plant growth nutrients (e.g., nitrogen,phosphorus, and calcium). Through GC-MS analyses, we identified 76 volatile organic compounds infish soup, of which 16 have been reported as insect attractants, highlighting their potential ecologicalsignificance. Therefore, the indigenous pest management practices for FAW, such as the use of fishsoup, deserve particular attention. These practices could contribute to food security and improve thelivelihoods of vulnerable communities. Further field validation studies, economic analyses, productdevelopment, and optimisation are therefore required to optimise the use of fish soup based onfish waste.