Chemical compounds and insecticidal effects of three medicinal plant essential oils on Sitophilus oryzae L

Due to the raising concerns about chemical and synthetic pesticides hazards on the environment and the human health, there is a trend to using botanical and natural pesticides increased. To this end, Salvia officinalis L., Lavandula angustifolia Mill and Nepeta pogonsperma Jamzad & Assadi as the potential plants for pest control can be used. The present study was conducted to identify chemical composition, fumigant toxicity and repellence activities of the essential oils from these plants against Sitophilus oryzae L. Dried aerial parts of the plant were subjected to hydro-distillation using a modified Clevenger-type apparatus. The composition of the essential oil was analyzed by gas chromatography and mass spectrophotometry (GC/MS). The experiments were conducted using a complete randomized design with 5 replications at laboratory conditions (28±1 ˚C, 70±5 % R.H. and 12:12 h dark:light). The major components of S. officinalis, L. angustifolia and N. pogonosperma were Thujone (37.29%) and 1,8-cineol (41.3 and 34.86%), respectively. All the tested plants showed insecticidal activity against S. oryzae. The LC50 values of essential oils for S. officinalis, N. pogonsperma and L. angustifolia, were estimated 148.19, 150.49 and 156.72 µl/l air against S. oryzae, respectively. The results showed that the essential oil of N. pogonosperma strongly repelled S. oryzae (86.5%) compared with the essential oils from S. officinalis and L. angustifolia (67 and 61.5%, respectively).