Target Enzymes of Origanum majorana and Rosmarinus officinalis Essential Oils in Black Cutworm ( Agrotis ipsilon ): In Vitro and In Silico Studies.

In this study, in vitro and in silico approaches were employed to assess the toxicity of marjoram ( Origanum majorana ) and rosemary ( Rosmarinus officinalis ) essential oils (EOs) to A. ipsilon larvae. The study determined the activities of ATPases in the larvae after treatment with the LC 20 and LC 70 of each EO. α-esterase and glutathione-S-transferase (GST) activities were also determined after treatment with LC 10 and LC 30 of each EO. Furthermore, molecular docking was employed to determine the binding affinity of terpinene-4-ol and α-pinene, the major constituents of O. majorana , and R. officinalis EOs, respectively, compared to the co-crystallized ligand of α-esterase, diethyl hydrogen phosphate (DPF). Toxicity assays revealed that O. majorana EO was more toxic than R. officinalis EO to the A. ipsilon larvae at 96 h post-treatment. However, the LC 20 and LC 70 of the latter significantly inhibited the activity of the Na + -K + pump at almost all intervals. The same concentrations significantly inhibited the Mg 2+ /Ca 2+ -ATPase and Ca 2+ pump at 96 h post-treatment. In contrast, O. majorana EO showed a variable effect on the Na+-K+ pump across different time intervals. On the other hand, LC 10 and LC 30 of both EOs showed varied effects on α-esterase and GST over time. Molecular docking revealed energy scores of -4.51 and -4.29 kcal/mol for terpinene-4-ol and α-pinene, respectively, compared to a score of -4.67 for PDF. Our study demonstrated the toxicity of the tested EOs to A. ipsilon , suggesting their potential efficacy as insecticides.