Evaluation of some phenolic extracts against aphids (Aphis craccivora) Koch under laboratory conditions

Local farmers worldwide have complained in recent years that insect pests have become resistant to the majority of insecticides, owing to pesticide abuse. In addition, highly poisonous and harmful substances may cause health and environmental dangers. Friendly alternatives such as plant extracts are the main targets as substituents to synthetic pesticides. The present study aimed to extract total phenols from some plants and evaluate their efficacy on aphids, Aphis craccivora, under laboratory conditions. Four methanolic plant extracts from Punica granatum, Lantana camara, Portulaca oleracea and Ziziphus jujuba, containing phenolic components were evaluated against A. craccivora through: slide dipping, spraying, and leaf dipping techniques. Generally, positive relationships between the concentrations of the tested phenolic extracts and their mortality percentages were noticed in the case of slide dipping and spraying techniques. Conversely, no biological efficacy was found using the leaf dipping technique. The descending order of effectiveness of the tested extracts depending on their EC50 values was 0.017, 0.321, 1.142 and 16.114 ppm for Z. jujuba, P. oleraceae P. granatum and L. comara, respectively, in the case of the slide dipping technique. In contrast, P. granatum, L. camara, P. oleraceae and Z. jujuba had EC50 values of 0.0023, 0.017, 0.321 and 2.3409 ppm, respectively, in the case of the spraying technique. Additionally, a direct proportion was found between mortality percentages and treatment period for plant extracts under study with both techniques. After formulation and completion of additional essential field research, phenols isolated from the plants under study could be employed to combat A. craccivora.