author(s)
Trymore Kamunhukamwe, Jean K Nzuma, Antony Maodzeka, Chido G Gandawa, Nakai Matongera, Leonard Madzingaidzo and Leonard Muturiki

abstract
Fall Armyworm (FAW), Spodoptera frugiperda, is prevalent in Zimbabwe, causing significant damage to maize and yield losses. Three synthetic insecticides (Nemesis, Ecoterex and Lamda-cyhalothrin) belonging to different chemical groups and neem bio-pesticide (Neem Leaf Extract) were tested for their efficacy against FAW under laboratory and field conditions. The aim of the study was to assess the effect of neem bio-pesticide and synthetic insecticides on the population of FAW larvae, level of leaf damage and maize grain yield in comparison with untreated control plants. In laboratory experiment, neem bio-pesticide and the three synthetic insecticides resulted in significantly higher FAW larval mortality (p < 0.05) at 24, 48 and 72 hours after application of treatments as compared with the untreated plants. Neem bio-pesticide and the synthetic insecticides caused highest percentage of larval mortality (> 90%) at 72 hours after treatment application. In the field, both bio-pesticide and synthetic insecticides resulted in significantly higher efficacy (p < 0.05) against fall armyworm larvae, reduced the level of leaf damage and increased maize grain yield as compared to the untreated control plants. The untreated maize plants were found to be extensively damaged by FAW as compared to those treated with insecticides and neem bio-pesticide. The highest efficacy was recorded on plants treated with Nemesis, followed by Neem Leaf Extract, Ecoterex and lastly Lamda-cyhalothrin, respectively. The neem bio-pesticide and synthetic insecticides which were used in this study showed high efficacy against FAW larvae and can be recommended to be used as components for integrated pest management (IPM) plans for FAW under smallholder farmer conditions in Zimbabwe and the rest of Africa.