Chemical insecticides have many harmful effects, including as foodborne residues and environmental contaminants, as well as side effects on natural enemies and serious risks for human health. The use of plant-derived essential oils (EOs) as effective bio-agents has become an essential component of integrated pest management. In this study, the contact toxicity, deterrent, and repellent activities were evaluated for essential oils obtained from Mentha piperita, Mentha longifolia, Salvia officinalis, and Salvia rosmarinus, grown at high altitudes in the Taif region, KSA, on Aphis punicae. Furthermore, the toxicity of these EOs against the predator Coccinella undecimpunctata was estimated. A total of 17, 14, 16, and 26 compounds were identified in the EOs of M. piperita, M. longifolia, S. officinalis, and S. rosmarinus, respectively. They showed a variation in the major compounds: M. piperita (Carvone, 61.16%), M. longifolia (Pulegone, 48.6%), S. officinalis (Eucalyptol, 33.52%), and S. rosmarinus (α-pinene, 36.65%). A contact toxicity test on A. punicae imago and C. undecimpunctata larvae showed that LC50 were approximately four-fold greater for all tested EOs towards aphids compared to towards the predator, while the two species of Salvia sp. were more effective than the other two species of Mentha sp. The LC50 values on A. punicae ranged from 1.57 to 2.97 µg/mL, while on C. undecimpunctata larvae, they ranged from 5.96 to 10.33 µg/mL. Furthermore, the EOs of two species of Salvia sp. showed excellent repellence and deterrence against A. punicae. In conclusion, the tested EOs, especially those from Salvia sp., have been shown to be promising natural aphicides, repellent, and deterrent against A. punicae, and they are safe for important insect predators.
Keywords: Lamiaceae family; aphids; aromatic plants; biological control; essential oils; insect predators.