Evaluation of Neem (<i>Azadirachta indica</i>) Seed Extract Against Fall Armyworm, <i>Spodoptera frugiperda</i> (Lepidoptera: Noctuidae) in Maize Fields

Abstract

The increasing trends of damage to staple crops as well as the economic losses due to the fall armyworm (<i>Spodoptera frugiperda), </i>the notorious invasive insect pests prompted to devise effective pest management in colonized regions to ensure sustainable crop health. Deploying bioactive plant material is among the novel eco-friendly approaches to managing insect pests in maize agro-ecosystems. Therefore, the present study was conducted to determine the efficacy of neem seed extracts against S.<i>frugiperda</i> under field conditions at Babile, eastern Ethiopia. A total of 8 treatments, including 6 different neem seed extracts, Megathrin 0.5 L/ha, and un-sprayed (untreated) plots were set up in randomized complete block design with three replications to evaluate their efficacy against S.<i>frugiperda</i> in maize fields. Results showed that S.<i>frugiperda</i> infestation was significantly influenced by the treatments both at 32 days after sowing (DAS) and 39 DAS, however, a non-significant difference was observed at 25 DAS. Moreover, except for the number of rows per ear, all crop parameters were significantly influenced by the treatments. Notably, the treatments reduced S.<i>frugiperda</i> incidence and severity and achieved higher crop performance over untreated maize plants. Between 3.9% to 25.7% and 0.0% to 19.6%, reductions were recorded for S.<i>frugiperda</i> incidence at 32 DAS and 39 DAS, respectively, compared to untreated plants. Similarly, 22.7% to 47.7% and 33.8% to 46.2% reductions were observed for S.<i>frugiperda</i> severity at 32 DAS and 39 DAS, respectively. The highest grain yield (36.4 Qt/ha) was obtained from neem @ 75 gm/Lx3, which was followed by Megathrin 0.5 L/ha (31.9 Qt/ha), neem @ 62.5gm/Lx3 (31.6Qt/ha) and neem @ 75gm/Lx2 (31.2 Qt/ha), while significantly the lowest grain yield (21.8 Qt/ha) was obtained from untreated maize plants. Results indicated that the field application of neem seed extracts resulted in a significant reduction of S.<i>frugiperda</i> infestation and provided considerable yield advantages as compared to untreated plants. Hence, the promising efficacy of the locally available botanical insecticide could provide an opportunity to deploy it against S.<i>frugiperda</i> as an eco-friendly approach, although further study is needed to validate the findings of the present study across seasons and agroecologies.