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 (Wall.) Nees which often exploited for insecticidal purpose. Contact toxicity and repellency rate of essential oils, derived from leaves monthly from 2021 to 2022, were investigated targeting storage pests and for the first time. Gas chromatography-mass spectrometry (GC/MS) and principal component analysis (PCA) revealed -camphor, cineole, nerolidol, linalool and caryophyllene were the main components. Dominant ingredients showed seasonal difference, as -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 -camphor positively related to average temperature but showed inverse relationship with month precipitation. Moreover, there was a significant positive correlation ( <0.01) between cineole percentage and month precipitation. The most powerful contact effect against and , was both found in L2109, indicating a low LD/LC value (12.13 μg/adult and 104.67 μg/cm 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 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.

中文翻译：

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肉桂叶精油的化学特征和杀虫特性的时间变化

几十年来，中药材储存单位一直面临虫害侵袭，造成严重的资源浪费和灾难。精油富含（Wall.）Nees 的不同器官，这些器官经常被用于杀虫目的。首次针对 2021 年至 2022 年每月从叶子中提取的精油的接触毒性和驱避率进行了针对仓储害虫的调查。气相色谱-质谱（GC/MS）和主成分分析（PCA）显示樟脑、桉树脑、橙花叔醇、芳樟醇和石竹烯是主要成分。主要成分表现出季节性差异，2021年9月至11月的大多数油中都含有樟脑（72.60%−84.01%），但2202年至2208年的标本中桉树脑含量丰富（66.58%−78.75%）。偏相关分析证实，樟脑含量与平均气温呈正相关，与月降水量呈负相关。此外，桉树脑含量与月降水量呈显着正相关（<0.01）。对 和 的最强接触效应均在 L2109 中发现，表明 LD/LC 值较低（分别为 12.13 μg/成人和 104.67 μg/cm）。冬季（12月和1月）对两种昆虫的驱避效果最好，相对相关性均高于0.5。旨在通过杀虫特性优化叶片的理想采集期，并探讨气候与油脂特征化合物的关系，缓解农药困境的压力，促进生物农药的进一步开发利用。