Evaluation of Toxic Properties of Cotyledon Powders and Oils of Sandbox, Hura crepitans L. against Sitophilus zeamais Motschulsky (coleoptera: curculionidae)

Hura crepitans cotyledons were extracted in the laboratory with n-hexane. The powder and oil extracts were assessed at the temperature of 28±2°C and relative humidity of 75±5% for their insecticidal activity against Sitophilus zeamais infesting maize grains, using mortality, ovicidal, and adult emergence effect as indices. The long term protectant ability of the powder and the oil was also investigated. Results obtained showed that powder and oil of H. crepitans were toxic on S. zeamais. The powder showed 100% mortality with dosage of 0.8 g by day 8 of exposure, while the oil showed 100% mortality with concentration of 1.5 and 2.0% by day 4 and 8 of exposure. The powder and oil extract drastically reduced oviposition and totally prevented adult emergence at higher powder dosages and oil concentrations. Both the powder and oil drastically reduced infestation and subsequent damage in treated grains. No damage was recorded in maize grains treated with 1.5 and 2.0% powder and 1.0, 1.5 and 2.0% oil of H. crepitans. The results obtained from this study showed that cotyledons powder and extract from H. crepitans are effective in controlling S. zeamais infesting maize grains in the store and could serve as alternative to chemical insecticides.