Evaluation of Neem Leaf Extract As A Substitute For Chemical Insecticides In The Control of Fall Armyworm (Spodoptera frugiperda) And Yield of Maize In Umudike Abia State, Nigeria

Abstract

Field experiments were conducted to compare the effectiveness of a botanical insecticide (Neem aqueous leaf extract) and chemical  insecticides (cypermethrin, dimethoate and chlorpyrifos) in the control of fall armyworm (Spodoptera frugiperda) and yield of maize. The aim of the study was to assess the effect of botanical insecticide (Neem leaf aqueous extract) (NLAE) and the chemical insecticides (cypermethrin, dimethoate and chlorpyrifos) on the population of S. frugiperda larvae, ascertain level of maize leaf damage as well as yield of maize in relation to different insecticidal treatments. The maize variety used in the experiment was OBA SUPER 2 (yellow seeded). The experiment was laid out in an RCDB with four replications. Seeds were sown on ridges spaced 1m apart and 50cm between stands at 2 seeds per stand and later thinned down to one healthy plant 10 days after planting (DAP) in 5m² plots. Application of insecticide started at 21 days after sowing (DAS) and continued at fortnightly interval. Data were collected on the number of larvae of S. frugiperda, damaged and undamaged plants and grain yield of maize. All data were subjected to analysis of variance (ANOVA) and separation of mean done using Duncan’s New Multiple Range Test (DNMRT). During both years, it was found that the insecticides (botanical and chemical) significantly (P<0.05) reduced the larvae populations when compared with the control, with neem aqueous leaf extract (NLAE) being the most effective. The study found that the insecticides significantly increased the yield of the crop when compared with the control. Seed yield reductions of 38.0 % and 23.0 % were recorded in the control when compared with neem leaf extract treated plots in 2017 and 2018 trials, respectively. This suggests that neem leaf extract could be used as substitute in the control of fall armyworm for increased yield of maize.