Pesticidal Effects Of Gmelina arborea (Roxb) Powders On Beans Weevil ( Callosobruchus maculatus ) At Vom

ABSTRACT Cowpea (Vigna unguiculata (L.) Walp. is one of the most nutritious grain legumes where it is valuable as a source of dietary protein yet most of the yields are lost as a result of infestation by pest especially Callosobruchus maculatus. cowpea weevil which is one of the most prevalent and a major destructive insect pest of stored legumes. Controlling of the pest by use of synthetic pesticides is raising serious concern on the environmental safety and consumer health hazards. This study was aimed at determining the pesticidal efficacy of Gmelina arborea stem bark and leaf powder on C. maculatus. The experiment was laid in a Completely Randomized Design (CRD) with three application rates (10g/200g grains, 10g/200g grains and 5+5g/200g cowpea grain) of the botanicals (leaf and stem bark powders and combination of leaf stem bark powders respectively) replicated three times was used in the assessment. The parameters and data collected in the experiment are; percentage of weevil mortality, Grain damaged, Number of Exit holes, newly emerged weevil, percentage of weight damaged. All data generated were statistically analyzed. The results of this study demonstrated the active potentials of these G. arborea plant parts as plant-derived pesticides against cowpea weevil. The effect of treated plant parts on percentage mortality rate showed significant difference (P < 0.05) over the untreated (control) as mixed leaf and stem bark powders recorded the highest mortality rate (85.00%). The leaf (51.70%) and stem bark (43.30%) powders also showed higher effect (51.70%) respectively while the lowest mortality rate was observed in the control (21.67%). The untreated (control) gave the highest number of newly emerged weevils (2.33) whereas the lowest (5.33) was found in Gmelina leaf + stem bark powders Gmelina leaf + stem bark powders attained the highest beans damage (11.00) while the lowest (9.67) was recorded in Gmelina leaf powders. The exit holes made by the weevils at the end of the experiment amongst G. arborea plant parts were highest (9.33) in Gmelina stem bark powders whereas lowest was recorded on Gmelina leaf + stem bark powders (5.33). Leaf + Stem bark powders was the most effective throughout the experiment followed by the leaf and stem bark powders respectively. In view of these findings G. arborea leaf and stem bark powders have a strong bioactivity and is effective against C. maculatus. Therefore, since these plant parts have no any adverse effects on the grains and safe to the environment, they are recommended for future usage in storage grains to control of C. maculatus.