EFFECTS OF SELECTED BOTANICAL OILS FOR THE CONTROL OF COPEA POD BORER (MARUCA VITRATA) AND PERFORMANCE OF COWPEA UNDER SCREENHOUSE CONDITIONS IN MINNA, NIGER STATE, NIGERIA

Abstract

This study evaluated the biopesticidal efficacy of neem oil (Azadirachta indica), jatropha oil (Jatropha curcas), and castor oil (Ricinus communis), applied singly, binary and ternary combinations, for managing cowpea pod borer infestation and cowpea performance in a screenhouse. A Completely Randomized Design (CRD) with nine treatments replicated three times was used. Treatments included neem oil (3 ml/L), jatropha oil (2 ml/L), castor oil (1 ml/L), three binary combinations, one ternary combination, cypermethrin (standard), and a control. Data on pest damage, growth and yield parameters were analysed using ANOVA, with means separated by Duncan's Multiple Range Test (DMRT) at p ≤ 0.05. Results revealed a significant difference among the treatments for pest damage and most growth parameters. The result further indicated that, castor oil (1 ml/L) was the most effective treatment, recording the lowest plant infestation score (2.00), flower infestation score (1.67), and pod damage (18.3%), as well as the tallest plants (155.47 cm at 6 WAS) 100-seed weight (10.80 g). Neem oil (3 ml/L) also provided reliable pest suppression. The ternary combination recorded pest damage levels which were not statistically significant from the control and also produced the lowest grain yield (0.03 kg/pot).  Yield components showed no significant differences. The absence of significant differences may partly reflect the restricted rooting volume under pot conditions, although this possibility was not directly investigated. Single-oil applications, especially Castor oil at 1 ml/L showed potential as a botanical alternative for managing cowpea pod borer under screenhouse conditions. Based on the result of this study, combining multiple botanical oils at the tested concentrations is not recommended.