The aromatic plant essential oils and their hormetic effect on Rhyzopertha dominica (Coleoptera: Bostrichidae)

Essential oils (EOs) are increasingly recognized as eco-friendly alternatives to synthetic pesticides due to their biodegradability and reduced risks to non-target species. This study investigates the bioactivity of 30 EOs on Rhyzopertha dominica, a major pest of stored grains, with a focus on their repellency and attractiveness across varying concentrations. The area preference method (APM) was used to evaluate EO bioactivity at concentrations ranging from 0.00064 to 0.064 μL cm−2. The results revealed strong repellent or attractive activity for certain EOs, while others exhibited concentration-dependent dual effects, acting as attractants at lower concentrations and repellents at higher ones. In addition, the bioactivity shown in the APM by nine selected EOs was compared to that obtained by testing the same EOs through a two-choice behavioral bioassay (TCB) at corresponding concentrations. At a 2 % EO concentration, the TCB results indicated significant repellent activity (p < 0.05) for lemon verbena, palo santo, matico, pumin, cinnamon, and anise, which exhibited the strongest effects. In contrast, nutmeg demonstrated significant attractive properties (p < 0.05). Black pepper and mandarin EOs displayed trends toward repellency and attractiveness, respectively. Both methods confirmed the bioactivity of the EOs against R. dominica. These results underscore the concentration-dependent hormetic effects of EOs on R. dominica and highlight the importance of precise optimization in pest management strategies for their application.