Lavandula angustifolia Mill. Essential Oil Exhibits Distinct Insecticidal Activities Against Pea Leaf Weevil Adults on Faba Bean under Laboratory and Growth Chamber Conditions

The pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae, PLW), is a significant insect pest of pea (Pisum sativum L.) and faba bean (Vicia faba L.), and it is responsible for serious economic damages. The current study aims to investigate the insecticidal activities of seven essential oil species on S. lineatus adults in the laboratory as well as the most effective ones under growth chamber conditions. Out of the tested essential oils, Lavandula angustifolia Mill. and Mentha arvensis L. oils showed substantial insecticidal activity against S. lineatus adults (100%) by contact activity at a concentration of 1.5% after 1 and 3 h of application, respectively, with an estimated LC50 of 0.224 and 0.320% at 72 h after treatment, respectively. L. angustifolia essential oil also resulted in a significant mortality rate of 70% by ingestion activity, with an LC50 of 1.340% at 48 h after application under laboratory condition. The growth chamber bioassays confirmed these significant effects, displaying a mortality rate of 70% at 96 h after application at 1.5%. The gas chromatography–mass spectrometry analysis showed that linalool acetate (32.91%) and linalool (26.69%) dominated the L. angustifolia essential oil composition. These findings highlighted that L. angustifolia essential oils are promising agents for the development of biopesticide formulation for the control of S. lineatus, as a safe and ecofriendly alternative compared to chemical insecticides.