Repellency Effect of Some Biochemical Extracts of Castor Bean Leaf on Two Sap-Sucking Insect Pests

Abstract

Two castor bean landraces; Grey Small Seeded Landrace (GSSL) and Red Medium Seeded Landrace (RMSL) were detected during this work using seed external features and molecular analysis by ISSRs technique. Leaves of the GSSL were heavy infested with the castor bean whitefly, Trialeurodes ricini, while the RMSL leaves were not infested at all with this whitefly. Main four biochemical groups; phenols, terpenoids, alkaloids, and tannins were analyzed in the two landrace leaves. Analysis results indicated highly significant differences between the two landraces in phenols, terpenoids, and tannins while no differences were detected in alkaloids. Repellency effect of phenols, terpenoids, and tannins extracted from whitefly-resistant castor bean landrace leaf (RMSL) on two sap-sucking insects; T. ricini and the striped mealybug, Ferrisia virgata was determined. Results indicated that the three extracts have repellency effect on T. ricini with PR of 69.3, 58.3, and 17.7% for phenols, terpenoids, and tannins; respectively. Also, terpenoids only showed repellency effect on F. virgate with PR 57% and phenols showed low repellency effect. While tannins showed attractiveness effect on F. virgate, so it could be used in traps for this mealybug pest. These results suggested that the three biochemical extracts from castor bean had a repellent and/or attractant effect on T. ricini and F. virgata and could be used as effective and environmentally sustainable bio-insecticides for controlling the two sap-sucking pests.