Abstract

In this work, we investigated the bioactivities of the essential oil (EO) extracted from the Rhododendron thymifolium and its principal germacrone against Lasioderma serricorne and Tribolium castaneum. The EO was obtained by steam distillation. Germacrone was obtained by cryogenic crystallization. The bioactivity of EO and germacrone was tested via contact and repellent activity assays. The results showed that EO and germacrone possessed contact and repellent activities against two species of insects. EO exhibited obvious contact activity against the L. serricorn adults, larvae and T. castaneum larvae with LD₅₀ values of 29.15 µg/adult, 42.73 µg/larva, 19.65 µg/larva respectively. Germacrone exhibited excellent contact activity against the L. serricorne adults, larvae and the T. castaneum larvae with LD₅₀ values of 17.18 µg/adult, 20.94 µg/larva, 20.93 µg/larva respectively. And at the highest testing concentrations (78.63 and 15.73 nL/cm²), the repellent activity of EO and germacrone on two target insects was comparable to that of the positive control (DEET) after 30 h exposure. In especially, in the treatment of the 120 h after the repellent activity of EO and germacrone against T.castaneum adults and larvae were still very significant and showed the same level percentage repellency as DEET. Meanwhile, germacrone exhibited inhibition of acetylcholinesterase activity with IC₅₀ values of 3%. The results indicated that the EO of R. thymifolium and germacrone had the potential to be developed as natural insecticides and repellents for the control of T. castaneum and L. serricorne.

摘要

在这项工作中，我们调查了从杜鹃花胸腺叶提取的香精油（EO）的生物活性及其主要抗生殖器灵藻（Lasioderma serricorne和Tribolium castaneum）的生物活性。通过蒸汽蒸馏获得EO。通过低温结晶获得草酮。通过接触和驱避活性测定法测试了EO和胚芽酮的生物活性。结果表明，EO和胚芽酮具有对两种昆虫的接触和驱避活性。EO对LD ₅₀的L. serricorn成虫，幼虫和T. castaneum幼虫表现出明显的接触活性。成人分别为29.15 µg /幼虫，42.73 µg /幼虫，19.65 µg /幼虫。Germacrone对Serricorne的成年幼虫，幼虫和T. castaneum幼虫表现出极好的接触活性，其LD ₅₀值分别为成人17.18 µg，幼虫20.94 µg /幼虫，20.93 µg /幼虫。并且在最高测试浓度（78.63和15.73 nL / cm ²）下，暴露30 h后，EO和胚芽酮对两种目标昆虫的驱避活性与阳性对照（DEET）相当。特别是在EO和杀菌粉对T.castaneum的驱避活性后的120小时内成虫和幼虫仍然非常重要，并显示出与DEET相同水平的驱虫百分率。同时，胚芽酮显示出对乙酰胆碱酯酶活性的抑制，IC ₅₀值为3％。结果表明，R的EO 。百里香和杀菌素具有潜在的潜力，可作为天然杀虫剂和驱虫剂来控制锥栗和丝线莲。