Phytochemical Analysis and Efficacy Of Rosemary (Rosmarinus Officinalis) and Mint (Mentha Spicata) Extracts Against Fall Armyworm (Spodoptera Frugiperda) on Baby Corn (Zea Mays)

Abstract

Fall armyworm (Spodoptera frugiperda, J.E. Smith) is a pest with devasting effects on maize. A laboratory biassay was conducted to analyse the phytochemicals and determine the efficacy of M. spicata and R. officinalis extracts on FAW. Treatments were laid out in a Completely Randomized Design (CRD) with 3 replications. The factors included solvent [Methanol (Me), dichloromethane (DCM), distilled water (Di)] and the plant species (M. spicata and R. officinalis). Coragen SC 200 (Co) and Distilled water (Di) were the positive and negative controls, respectively. FAW rearing, plant extract preparation and phytochemical screening were done using standard procedure. Data collection and analysis was done using standard procedures. The extract yield was highest for R. officinalis regardless of the solvent used. Me-R. officinalis and Di-M. spicata extracts yielded the highest. Saponins, glycosides, alkaloid, flavonoids and tannins. Flavonoid contents were 7.9036 mg/mL and 6.0073 ± 0.6117 mg/mL in methanolic extract of M. spicata and R. officinalis, respectively. M. spicatha and R. officinalis extracts caused 100% mortality to 3rd instar larvae. Based on the findings, both M. spicata and R. officinalis have several secondary metabolites that confer insecticidal activity of the plants against FAW, hence should be evaluated under field conditions.