TOXICITY AND ANTI-FEEDING EFFECTS OF WALNUT (JUGLANCEREGIA L.) EXTRACT ON SITOPHILUS ORYZA L. (COLEOPTERA: CURCULIONIDAE)

摘要

The rice weevil, Si/ophilus oryzae (L.) (Cole-optcra: Curculionidac) is one of the most destructive insects of stored grain pest in Iran and many parts of the world. Using plant extracts such as walnut extract as an alternative stored pest control strategy has no irreparable consequences on the environment, human health and livestock products. In this study, we evaluated the contact, fumigant and antifeedant activities of Juglans regia leaf extract to control of S. oryzae. The contact toxicity showed that the highest concentration of walnut extract (0.1 g/ml) was the most effective concentration (66.66 %) at different days after treatment. The LC50 value was calculated equal to 0.012 (0.002-0.481) g/ml. The results of fumigant toxicity of walnut extract during different days showed that the mortality was dependent upon the concentration so tliat the highest amount of mortality was observed in the 0.1(g/ml) concentrations on the 7Ul, 10th and 14th days after treatment with 43.33%, 56.66% and 76.66%, respectively. The antifeedant toxicity revealed that weight of rice kernels was decreasing with the increasing of walnut extract concentration and weight loss was slightly increased from 0.1 (g/ml) to 0.00001(g/ml) concentrations. Oiir results imply that the leaf extracts of J. regia can be introduced as an effective insecticide against S. oryza.