Insecticidal, fungicidal, phytotoxic activity and chemical composition of Lavandula dentata essential oil

Abstract

Pest control in agriculture is generally carried out through the application of synthetic insecticides causing deterioration of the health and environment. Essential oils (EOs) extracted from plants are seen as alternatives to synthetic pesticides. This study aimed at determining the insecticidal, fungicidal, phytotoxic activity and composition of the EO from leaves and green stems of Lavandula dentata (Lamiaceae). EO chemical composition was determined/identified by gas chromatography mass spectrometry. The insecticidal, fungicidal, phytotoxic activity of the EO was evaluated at different concentrations. The main components of EO were eucalyptol (34.33%), fenchone (17.78%), and camphor (15.75%). EO showed good insecticidal activity on the three pest insects evaluated. LC50 values against Sitophilus zeamais (Coleoptera: Curculionidae) and Tribolium castaneum (Coleoptera: Tenebrionidae) were 26.9 and 11.3 μl/l air (assay without food) and 42.7 and 29.3 μl/l air (assay with food), respectively, while for Epicauta atomaria (Coleoptera: Meloidae), LC50 was 26.9 μl/l air (assay without food). Moreover, EO had good fungicidal activity against Cercospora kikuchii, Cercospora sojina, and Septoria glycines (Capnodiales: Mycosphaerellaceae) plant pathogenic fungi, with ID (diameter of the inhibition zone of fungal growth) median values of 34.00, 29.50 and 22.00 mm at a concentration of 5 μl/disc, respectively. Finally, EO exhibited a strong phytotoxic activity against Lactuca sativa (Asteraceae) model plant inhibiting 100% of the radicle growth at a concentration of 25.0 μl/ml. In conclusion, L. dentata EO could be considered as a good biopesticide for future integrated pest management programs.