Chemical composition and toxicity of the essential oil ofCayratia japonicaagainst two grain storage insects

During our screening program for new agrochemicals from Chinese medicinal herbs, essential oil of Cayratia japonica aerial parts was found to possess strong insecticidal activities against Sitophilus zeamais and Tribolium castaneum. A total of 37 components of the essential oil were identified by gas chromatography (GC) and GC–mass spectrometry (GC–MS). Linalool (19.4%), trans-α-ionene (11.4%), α-terpineol (7.9%), dihydroactinolide (7.8%) and geranial (5.8%) were the main components of the essential oil. The essential oil exhibited strong fumigant toxicity against S. zeamais and T. castaneum adults with LC50 values of 10.05 and 15.67 mg/L air, respectively. Cayratia japonica essential oil also possessed contact toxicity against S. zeamais and T. castaneum adults with LD50 values of 32.06 and 44.49 mg/adult, respectively. The essential oil C. japonica may have potential to be developed as a new natural fumigant/insecticide for the control of stored-product insects.