Short communication. Insecticidal activity of different extracts of Rhamnus dispermus (Rhamnaceae) against peach trunk aphid, Pterochloroides persicae (Homoptera: Lachnidae)

Bark of Rhamnus dispermus Ehrenb (Rhamnaceae) was collected from Ash-Shoubak, Jordan, and extracted with hexane, chloroform, acetone and ethanol, respectively. The aim of this study was to test the insecticidal activity of these extracts against the peach trunk aphid (PTA), Pterochloroides persicae (Homoptera: Lachnidae), since it has been shown that Rhamnus spp. may contain compounds that can act as botanical pesticides. Three concentrations (100, 1000, and 10,000 ppm) of each dry extract were obtained by dissolving the dry extract in 0.01% solution of dimethyl sulfoxide (DMSO). Results showed that, at the highest concentration (10,000 ppm), all the extracts caused mortality in the PTA adults after 24 h of exposure. Both the acetone and ethanol extracts showed higher mortality (69 and 71%, respectively) than the hexane and chloroform extracts (40 and 56%, respectively) after 72 h of exposure at the highest concentration. In comparison, the synthetic control, Imidacloprid, killed 93% of the PTA adults. Nevertheless, extracts from R. dispermus provided valuable mortality rates for the PTA and can be used as botanical insecticides as part of the integrated pest management programs of this insect pest. Additional key words: anthraquinones, botanical insecticide, flavonoids, IPM.