Validating indigenous farmers’ practice in the management of the fall armyworm Spodoptera frugiperda (J. E. Smith) in maize cropping systems in Africa

Abstract

Abstract Before the invasion of the fall armyworm (FAW) Spodoptera frugiperda into Africa, smallholder farmers had been using indigenous practices such as applying fish soup onto plants to manage stemborer pests. Although farmers have since begun adapting this practice against FAW, no attempt had been made to evaluate the practice scientifically. Therefore, we assessed the efficacy of applying fish soup to maize plants that were artificially infested with FAW under semi-field conditions. Our results showed that foliar damage is inversely correlated with the concentration of a fish soup + sugar solution, with the highest (100%) concentration resulting in the lowest foliar damage and the highest plant recovery. A concentration of fish soup + sugar solution of at least 25.9% was required to achieve the lowest foliar damage of 17.8% and peak plant recovery of 73.6%. Fish soup + 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 soup + sugar showed higher chlorophyll content and better growth than the control did. Proximate and 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 in fish soup, of which 16 have been reported as insect attractants, highlighting their potential ecological significance. Therefore, the indigenous pest management practices for FAW, such as the use of fish soup, deserve particular attention. These practices could contribute to food security and improved livelihoods of vulnerable communities. Further field validation studies, economic analyses, product development and optimisation are required.