Physiological evaluation and yield of cucumber infected by whitefly (Bemisia tabaci) under effect by six medicinal plant extracts

Plant-derived extracts and essential oils may function as environmentally friendly non-persistent bio-pesticides that are safe for humans as well as other animals. In this study, we investigated the effects of six endemic plant extracts as well as commercial insecticides against Bemisia tabaci and some physiological responses in cucumber as the host plant at field conditions. The plant extracts and Stamipride as chemical pesticide were sprayed on the plants at 250, 500 and 1000 ppm concentrations. All extracts led to the reduced number of adults as compared with control, among which the greatest impact on the control of this pest was recorded for the extract of Oliveria decombens. Application of all extracts especially at concentrations of 500 and 1000 ppm significantly increased the number of first and second grade fruits. The content of potassium significantly increased and the content of calcium decreased by increasing the concentration of extracts from 250 to 1000 ppm. Results showed that application of extracts and pesticide, especially at high concentrations, imposed negative effects on plant and significantly increased the antioxidant activity in cucumber leaves. In general, all extracts used, especially the extract of Oliveria decombens at a low concentration(250 ppm)was extremely efficient in controlling the adult population of Bemisia tabaci without adverse effects on host plants compared with the commercial insecticide.