Awojide Shola Hezekiah, Lajide Labunmi and Owolabi Bodunde Joseph
Keywords: Essential oil, insect pest, mortality, toxicity, fumigative, contact and component
Abstract: Insect pests are major constraints on crop production, the use of synthetic insecticides as a control against this pest has resulted in environmental concerns. The insecticidal activities of the essential oil of Piper umbellatum were investigated in the laboratory against bean weevil (Callosbruchus maculatus) and rice weevil (Sitophilus oryzae). The essential oil from P. umbellatum was extracted by steam distillation and graded into different concentrations, 1, 2, 2.5, 3, 4, 5, 7.5, 10 ml/l. The chemical component of the oil was analyzed by GC-MS. The toxicity of each dose was evaluated against bean weevil (C. maculatus) and rice weevil (S. oryzae) at different exposure time. The essential oil was toxic to both insects, toxicity of the essential oil was dose and time dependent (P<0.05). Essential oil of P. umbellatum induces higher toxicity in bean weevil than in rice weevil in all assay conducted. Analysis by GC-MS revealed the presence of 37 components in the essential oil, the major component are aromadendrene (13.74%), caryophyllene (10.44%), linalool (8.55%) and ?- bisabolene (8.06%). Based on present study results, it is suggested that the plant is suitable for possible use as insect pest control
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