Efficacy of selected environmentally friendly management options  against the fall armyworm spodoptera frugiperda (Lepidoptera:  Noctuidae) and their cost-effectiveness on maize zea mays in Burundi

Mpawenimana, A.; Kahuthia-Gathu, R.; Mwangi, M.; Agbodzavu, K.M.; Abang, A.F.; Lamboni, Y.; Hitimana, C.; Kantungeko, D.; Mutuo, P.; Fiaboe, K.K.M.

Efficacy of selected environmentally friendly management options against the fall armyworm spodoptera frugiperda (Lepidoptera: Noctuidae) and their cost-effectiveness on maize zea mays in Burundi

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Descripción

Fall armyworm, Spodoptera frugiperda Smith, is the major cause of maize yield losses in Africa, and insecticides used to control it are often ineffective, costly, and harmful. The study evaluated the efficacy and cost-effectiveness of selected low toxicity synthetic insecticides, bio insecticides, botanicals and intercropping systems. Experiments were carried out during the rainy and dry seasons of 2022 and data were collected on five key parameters: damage severity, incidence, larval abun dance, yield, and economic effectiveness. Emamectin benzoate 050WG, chlorantraniliprole (50 g/L) + lambda-cyhalothrin (100 g/L), and Bacillus thuringiensis effectively reduced damage severity, incidence, and larval abundance. Azadirachta indica aqueous leaf extract reduced damage severity and incidence in Mparambo during the dry season compared to the control. Intercropping maize with soybean consistently reduced the infestation compared to other intercropping systems and control. It had the lowest damage incidence, severity, and larval abundance except in Mparambo during the rainy season and Mugerero during the dry season. None of the treatments, either insecticides or intercropping, significantly increased the yield, except for the treatment with no fertilizers in Mugerero during the rainy season, which recorded a significantly lower yield. Therefore, high damage incidence accompanied by low damage severity and low larval density (< 1 larva per plant) did not result in yield loss. The maize + soybean intercropping system produced the highest net benefit among the evaluated treatments, except in Mparambo during the dry season. Overall, the results emphasize the importance of considering both agronomic effectiveness and economic returns when recommending pest management strategies.