GC-MS analysis of insecticidal essential oil of flowering aerial parts of Saussurea nivea Turcz

Essential oil of S. nivea flowering aerial parts was obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry (GC-MS). A total of 43 components of the essential oil of S. nivea were identified. The principal compounds in the essential oil were (+)-limonene (15.46%), caryophyllene oxide (7.62%), linalool (7.20%), α-pinene (6.43%), β-pinene (5.66%) and spathulenol (5.02%) followed by β-eudesmoll (4.64%) and eudesma-4,11-dien-2-ol (3.76%). The essential oil of S. nivea exhibited strong contact toxicity against S. zeamais with an LD50 value of 10.56？μg/adult. The essential oil also possessed fumigant toxicity against S. zeamais with an LC50 value of 8.89？mg/L.The study indicates that the essential oil of S. nivea flowering aerial parts has a potential for development into a natural insecticide/fumigant for control of insects in stored grains.The maize weevil (Sitophilus zeamais Motschulsky) is one of the major pests of stored grains and grain products in the tropics and subtropics [1]. Infestations not only cause significant losses due to the consumption of grains; they also result in elevated temperature and moisture conditions that lead to an accelerated growth of molds, including toxigenic species [2]. Currently, control of stored product insects relies heavily on the use of synthetic insecticides and fumigants, which has led to problems such as disturbance of the environment, increasing application costs, pest resurgence, pest resistance to pesticides and lethal effects on non-target organisms in addition to direct toxicity to the users [3]. Thus, there is a considerable interest in developing natural products that are relatively less damaging to mammalian health and the environment than existing conventional pesticides, as alternatives to non-selective synthetic pesticides to control the pests of medical and economic importance [4,5]. In recent years, various workers have been concentrating their efforts on the search for natural products