Temporal variation of chemical profiles and insecticidal properties of Cinnamomum glanduliferum (Wall.) Nees leaf essential oil

Abstract

Chinese traditional medicine has been faced with pest attacks in storage units for decades thus causing grave waste of resource and misfortunes. Essential oils are rich in different organs of Cinnamomum glanduliferum (Wall.) Nees which often exploited for insecticidal purpose. Contact toxicity and repellency rate of essential oils, derived from C. glanduliferum leaves monthly from 2021 to 2022, were investigated targeting storage pests Tribolium castaneum and Liposcelis bostrychophila for the first time. Gas chromatography-mass spectrometry (GC/MS) and principal component analysis (PCA) revealed L-camphor, cineole, nerolidol, linalool and caryophyllene were the main components. Dominant ingredients showed seasonal difference, as L-camphor was presented in majority of oils from September to November 2021 (72.60%−84.01%) but cineole was abundant in 2202–2208 specimens (66.58%−78.75%). It was confirmed by partial correlation analysis that the content of L-camphor positively related to average temperature but showed inverse relationship with month precipitation. Moreover, there was a significant positive correlation (p <0.01) between cineole percentage and month precipitation. The most powerful contact effect against T. castaneum and L. bostrychophila, was both found in L2109, indicating a low LD50/LC50 value (12.13 μg/adult and 104.67 μg/cm2 respectively). Winter time (December and January) had best repellent performance against two insect species with relative correlations higher than 0.5. The work intends to optimize ideal collection period of C. glanduliferum leaves by insecticidal properties, and also explore the relationship between climate and oil feature compounds, relieving the stress of pesticide dilemma and promoting further exploitation of bio-pesticides.