The efficacy of scent leaf (Ocimum grattissimum) in controlling cowpea pod borer (Maruca vitrata) In Owerri, Nigeria

Abstract

This experiment was conducted at the Teaching and Research Farm of Faculty of Agriculture and Veterinary Medicine, Imo State University, Owerri,  Nigeria, between May-August, 2018. It investigated the efficacy of Ocimum gratissimum against cowpea pod borer, Maruca vitrata. Four rates of liquid  extracts were used, 0, 50, 100, and 150 mls as treatments using randomized complete block design. Proximate analysis on Ocimum gratissimum revealed  percentage nutritional contents of ash 14.58%, moisture 82.22%, fibre 9.37% and protein 3.16%. Phytochemical analysis revealed phytate, 12.45g, tannin,  15.43g, sapogenin 11.64g, anthocyanidines 0.27g, and quinine 11.09g. Mineral compositions were Sodium 0.321mg/100g, potassium 0.355mg/100g,  calcium 0.0144mg/100g, Magnesium 1.85mg/100g and cadmium 0.187/100g. Heavy metals include zinc, 0.250mg/100g, cadmium 0.00mg/100g,  chromium 0.00mg/100g, Fe 0.381mg/100g, Nickel 0.291mg/100g and manganese 0.492mg/100g. Infrared compounds were alcohol 3344.5, aldehyde  2719, carboxylic acid 2995.5, alkenes 2804.4, isocyanate 2804.4. Data were collected on number of insects observed after application, number of plants  infested, number of leaves damaged, and number of pods per plot and yield weight. Further results showed that treatments reduced number of insects,  number of plants infested, number of leaves damaged, 2, 3, 4 WAP and these were significantlydifferent P≤0.05. Number of pods and yield weight were  significantly P≤0.05 different over the control. In this study, Ocimum gratissimum reduced the number of insect pest attack (Maruca vitrata) on cowpea and  these actions were due to the anti-nutritional constituents contained in the extract.