Efficacy of Bitter Kola (Garcinia kolea) Oil in the Management of Callosobruchus maculatus (F.) Infestation in Two Cowpea (Vigna unguiculata (L.) Walp) Varieties in Maiduguri, Nigeria

Abstract

The study efficacy of Bitter Kola (Garcinia kolea) oil in controlling Callosobruchus maculatus infestation in two cowpea (Vigna unguiculata) varieties. The experiment was conducted using five Bitter Kola oil concentrations (0.0, 1.0, 2.0, 3.0, and 4.0 ml/50g of cowpea grains) under laboratory conditions to assess their effects on adult mortality, progeny production, and grain damage and weight loss after 40 days of treatment. The results showed that adult mortality increased significantly (P<0.05) with increasing Bitter Kola oil concentration, with the 4.0 ml/50g dose yielding the highest mortality of 9.25% was obtained in Borno Brown and 9.75% in Local White) after four days of treatment. Similarly, progeny emergence were significantly reduced with increasing oil concentration. The control treatment (0.0 ml/50g) had the highest progeny production (340.50% and 359.75% for Borno Brown and Local White, respectively) and weight loss (39.35% and 41.45%), while the 4.0 ml/50g treatment recorded the lowest values (20.93% and 24.15%). The findings indicate that Bitter Kola oil is a potent bio-insecticide against C. maculatus, providing effective protection of cowpea grains during storage. The 4. 0 ml/50g dose rate is recommended for use, as it produced the best results. Further studies are encouraged to investigate the mode of action, formulation, and effectiveness of the plant product under different storage conditions.