Abstract The peanut beetle, Ulomoides dermestoides Fairmaire (Coleoptera: Tenebrionidae), is a worldwide pest of stored grains. This study evaluated the toxicity and repellency of lemongrass (Cymbopogon citratus) essential oil and its components (citral and geranyl acetate) against U. dermestoides adults. Lethal doses (LD50 and LD90), survival rate, respiration rate, and repellent activity were determined. The major components of lemongrass essential oil were neral (24.6%), citral (18.7%), geranyl acetate (12.4%), geranial (12.3%), and limonene (7.5%). Lemongrass essential oil (LD50 = 5.17 μg insect−1), citral (LD50 = 4.17 μg insect−1), and geranyl acetate (LD50 = 7.21 μg insect−1) caused high contact toxicity in U. dermestoides adults. The survival rate was 99% in control insects, decreasing to 65.7% in insects exposed to the LD50 of lemongrass essential oil, 41.3% in insects treated with geranyl acetate, and 28.5% in those treated with citral. Insects exposed to lemongrass essential oil, geranyl acetate, or citral showed low respiration rates, reduced locomotor activity, and avoidance responses to treated surfaces. These findings demonstrate that lemongrass essential oil and its terpenoid components exhibit insecticidal and repellent activity against U. dermestoides, suggesting their potential for controlling this stored grain pest.

中文翻译：

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Cymbopogon citratus (Poaceae) 精油及其萜类化合物（柠檬醛和醋酸香叶酯）对 Ulomoides dermestoides 的杀虫和驱虫活性

摘要 花生甲虫 Ulomoides dermestoides Fairmaire（鞘翅目：Tenebrionidae）是一种世界性的贮藏害虫。本研究评估了柠檬草（Cymbopogon citratus）精油及其成分（柠檬醛和醋酸香叶酯）对 U. dermestoides 成虫的毒性和排斥性。测定了致死剂量（LD50 和 LD90）、存活率、呼吸率和驱虫活性。柠檬草精油的主要成分是神经元 (24.6%)、柠檬醛 (18.7%)、醋酸香叶酯 (12.4%)、香叶醛 (12.3%) 和柠檬烯 (7.5%)。柠檬草精油（LD50 = 5.17 μg 昆虫-1）、柠檬醛（LD50 = 4.17 μg 昆虫-1）和醋酸香叶酯（LD50 = 7.21 μg 昆虫-1）在 U. dermestoides 成虫中引起高接触毒性。对照昆虫的存活率为 99%，下降到 65。暴露于柠檬草精油 LD50 的昆虫中为 7%，在用醋酸香叶酯处理的昆虫中为 41.3%，在用柠檬醛处理的昆虫中为 28.5%。暴露于柠檬草精油、醋酸香叶酯或柠檬醛的昆虫表现出低呼吸率、减少的运动活动以及对处理过的表面的回避反应。这些发现表明，柠檬草精油及其萜类成分对 U. dermestoides 具有杀虫和驱虫活性，表明它们具有控制这种储藏谷物害虫的潜力。