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Blumea balsamifera (L.) DC. (Asteraceae), also known as sambong, is a perennial herb used in China for medicinal purposes. The essential oil (EO) of B. balsamifera was extracted by hydrodistillation. Thirty chemical components of the EO were analyzed by gas chromatography-mass spectrometry (GC-MS) and GC, accounting for 88.0% (w/w) of the total oil. The EO of B. balsamifera was mainly composed of monoterpenes and sesquiterpenes, in which borneol (23.3%), β-caryophyllene (20.9%) and camphor (11.8%) were the major components. The insecticidal activities of the EO and its three main compounds against Tribolium castaneum, Lasioderma serricorne and Sitophilus oryzae were evaluated. The results of bioassays displayed that the EO of B. balsamifera did not have fumigant toxicity to the three target insects, but exhibited significant contact activity against L. serricorne (LD50 = 12.4 μg/adult) and S. oryzae (LD50 = 44.4 μg/adult). Meanwhile, the EO showed a notable repellent effect on T. castaneum at all testing concentrations and a general repellent effect on S. oryzae at high concentrations (78.63 nL/cm2). β-Caryophyllene showed the best performance in the contact toxicity bioassays against the three insects. The results indicated that B. balsamifera has the potential to be used as a source of botanical insecticides for the control of stored-product insects.

Volatile secondary metabolites of plants interact with environments heavily. In this work, characteristic components of Michelia yunnanensis essential oils (EOs) were isolated, purified and identified by column chromatography, GC-MS and NMR. Leaves of M. yunnanensis were collected monthly and extracted for EOs to investigate chemical and insecticidal activity variations as well as potential influencing environments. Different organs were employed to reveal distribution strategies of characteristic components. Results of insecticidal activities showed that all EOs samples exerted stronger contact activity to Lasioderma serricorne, but repellent effect was more efficient on Tribolium castaneum. One oxygenated sesquiterpene was isolated from EOs, basically it could be confirmed as (+)-cyclocolorenone (1). It exerted contact toxicity to L. serricorne (LD50 = 28.8 µg/adult). Chemical analysis showed that M. yunnanensis leaves in reproductive period would produce and accumulate more 1 than in vegetative period. Moreover, reproductive organs (flowers and fruits) contained more 1 than vegetative organs (leaves and twigs). Partial correlation analysis indicated that temperature-related elements positively correlated with the relative content of 1. [ABSTRACT FROM AUTHOR]