Control of field insect pests of mung bean (<i>Vigna radiata</i> L. Wilczek) using some plant extracts in Umudike, Nigeria

Abstract

Field trials were conducted at Umudike, Nigeria, during the 2015 and 2016 cropping seasons to determine the efficacy of plant extracts from seven plant species against field insect pests of mung bean, Vigna radiata L. Wilczek. The extracts tested were obtained from scent leaf (Ocimum gratissimum), neem leaf (Azadirachta indica), bitter leaf (Vernonia amygdalina), garlic (Allium sativum), turmeric (Curcuma longa), plantain (Musa paradisiaca) peel and Negro pepper (Xylopia aethiopica). Karate (Lambda-cyhalothrin EC) at 50 mL was introduced as a check in the trials. The experimental design was a randomised complete block design (RCBD) with three replicates. Data were collected weekly on the insect population densities, yield and yield components. The results indicated that all the treatments were effective against mung bean insect pests (Aphis craccivora [aphid], Bemisia tabaci [whitefly], Amrasca biguttula biguttula [jassid] and Zonocerus variegatus[grasshopper]). There was a significant (p ≤ 0.05) reduction in the population of insects on the plots treated with plant extracts and karate in 2015 and 2016 cropping seasons. The population densities of grasshoppers in 2015 and whitefly in 2016 were significantly lower in the treated plots compared with the control plots. Azadirachta indica and C. longa extracts recorded the highest seed yield of 50.00 kg/ha and 42.33 kg/ha in 2015 and 2016, respectively. No significant differences were observed between the plant extracts and karate, which recorded significantly higher yields when compared with the control (23.30 kg/ha). All the plant extracts used exhibited insecticidal activity against the insect pests of mung bean. It is, therefore, recommended that these plant extracts can be used for the control of mung bean insect pests to achieve sustainable production, food security and quality.