Determination of the effects of plant extracts on cabbage aphid [Brevicoryne brassicae L. (Hemiptera: Aphididae)]

The cabbage aphid [Brevicoryne brassicae (Hemiptera: Aphididae)] causes significant losses in the production areas of cruciferous plants, especially cabbages, and other cultivated plants belonging to the Brassicaceae family. Considering the biology of the pest, population density, and damage potential, combating this pest has become particularly important in recent years. While chemical control is often preferred against cabbage aphids, synthetic chemical-based active substances are generally used. Due to the adverse effects of chemical control practices on nature and living organisms, the exploration of alternative control methods has gained importance in recent years. Plant extracts, one of these alternative methods, stand out due to their low negative impact on the environment, partial effects on non-target organisms, and low risk of resistance. In this study, plant extracts were obtained from Hypericum perforatum, Lavandula angustifolia, Origanum onites, Mentha piperita, Rosmarinus officinalis and Laurus nobilis plants using two different solvents, namely hot water and cold water. Extracts at concentrations of 5%, 15%, 20%, and 25% were applied to adult individuals of the pest in the study. The effects of these extracts on B. brassicae adult individuals were examined through spraying and residual methods. Although there was no significant difference observed among the different solvents, extracts made with hot water were considered to be relatively more effective. Direct spraying on live organisms is anticipated to be more successful. It is thought that, in the future, these plant extracts used in this study could be tested not only in laboratory conditions but also in field conditions, potentially serving as an alternative control method for B. brassicae.