Insecticidal Activity of an Under-utilized Tropical Plant Seed oil, Hura crepitans L. on Cowpea Seed Beetle, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)
AJAYI O. E and ADEDIRE C. O.
ABSTRACT: The insecticidal activity of Hura crepitans L (Sand box) oil was assessed by assaying its effect on mortality of adult Callosobruchus maculatus F, seed
germination and protection of treated cowpea seeds from bruchid infestation and damage, Bioassays were carried out at six rates of 0, 0,1, 0,5, 1, 1.5, and 2% v/w
which correspond to 0, 1, 5, 10, 15 and 20ml/kg cowpea seeds respectively, Results show that Sandbox seed oil has contact toxic effect on adult C maculatus with 40% bruchid mortality at the lowest oil treatment of 0.1 % at 1 day after treatment and 100% mortality at 15 and 2% oil treatment at 1-day post-treatment period, The lowest oil treatment of 0.1% gave 97.50% bruchid mortality at 4 days after application compared to 11.25% mortality in the solvent-treated control. Sub-lethal doses of oil namely, 0.25%, 0.50% and 1.0% (v/w cowpea seeds) gave
100% protection from bruchid infestation over a period of 12 weeks, The Sandbox seed oil gave 100% inhibition of seed germination at all the concentrations evaluated, The study has revealed that sandbox oil is a potent bio-insecticide for protecting cowpea seeds from C maculatus infestation and damage, However, seeds meant for planting should not be treated with the oil.