Bioactivities of 3-Butylidenephthalide and n-Butylbenzene from the Essential Oil of Ligusticum jeholense against Stored-product Insects

The essential oil extracted from roots and rhizomes of Ligusticum jeholense Nakai et Kitagawa was investigated for its chemical composition by GC-MS analysis, and evaluated for its contact toxicity and repellency against Tribolium castaneum and Lasioderma serricorne, along with some of its individual components. The essential oil was rich in aromatics (65.34%) with low molecular weight. Major components included sedanolide (33.95%), 3-butylidenephthalide (18.76%), spathulenol (8.90%) and myristicin (6.76%). The results of bioassays indicated that the essential oil of L. jeholense and 3-butylidenephthalide possessed significant repellent activities against T. castaneum at 2 and 4 h post-exposure. Meanwhile, 3-butylidenephthalide had potent contact toxicity against L. serricorne (LD50 = 13.64 µg/adult). The minor component n-butylbenzene in the oil was highly toxic to T. castaneum (LD50 = 23.99 µg/adult) and L. serricorne (LD50 = 7.86 µg/adult) in contact assays, but failed to repel these beetles at all testing concentrations. Spathulenol and myristicin exerted good insecticidal and repellent effects on the two target insects. This work suggests that the essential oil of L. jeholense has promising potential for development as natural insecticide or repellent to control pest damage in warehouses.