USDA-Agricultural Research Service, Application Technology Research Unit, Horticultural Insects Research Laboratory, 1680 Madison Ave., Wooster, OH 44691, USA.
J Econ Entomol. 2013 Feb;106(1):159-67. doi: 10.1603/ec12319.
Larvae of scarab beetles (Coleoptera: Scarabaeidae) are important contaminant and root-herbivore pests of ornamental crops. To develop alternatives to conventional insecticides, 24 plant-based essential oils were tested for their acute toxicity against third instars of the Japanese beetle Popillia japonica Newman, European chafer Rhizotrogus majalis (Razoumowsky), oriental beetle Anomala orientalis (Waterhouse), and northern masked chafer Cyclocephala borealis Arrow. Diluted solutions were topically applied to the thorax, which allowed for calculating LD50 and LD90 values associated with 1 d after treatment. A wide range in acute toxicity was observed across all four scarab species. Of the 24 oils tested, allyl isothiocyanate, cinnamon leaf, clove, garlic, and red thyme oils exhibited toxicity to all four species. Allyl isothiocyanate was the most toxic oil tested against the European chafer, and among the most toxic against the Japanese beetle, oriental beetle, and northern masked chafer. Red thyme was also comparatively toxic to the Japanese beetle, oriental beetle, European chafer, and northern masked chafer. Interspecific variability in susceptibility to the essential oils was documented, with 12, 11, 8, and 6 of the 24 essential oils being toxic to the oriental beetle, Japanese beetle, European chafer, and northern masked chafer, respectively. Analysis of the active oils by gas chromatography-mass spectrometry revealed a diverse array of compounds, mostly consisting of mono- and sesquiterpenes. These results will aid in identifying active oils and their constituents for optimizing the development of plant essential oil mixtures for use against scarab larvae.
金龟子幼虫（鞘翅目：金龟子科）是观赏作物重要的污染和根食性害虫。为了开发替代传统杀虫剂的方法，对 24 种植物源精油进行了测试，以评估其对日本丽金龟（Popillia japonica Newman）、欧洲鳃金龟（Rhizotrogus majalis（Razoumowsky））、东方鳃金龟（Anomala orientalis（Waterhouse））和北方假面鳃金龟（Cyclocephala borealis Arrow）三龄幼虫的急性毒性。将稀释的溶液局部施用于胸部，可计算出处理后 1 天与 LD50 和 LD90 值相关的数值。在所有四种鳃金龟中，观察到急性毒性存在广泛差异。在所测试的 24 种油中，丙烯基异硫氰酸酯、肉桂叶、丁香、大蒜和红百里香油对所有四种物种均具有毒性。丙烯基异硫氰酸酯是对欧洲鳃金龟测试的最有毒油，也是对日本丽金龟、东方鳃金龟和北方假面鳃金龟最有毒的油之一。红百里香对日本丽金龟、东方鳃金龟、欧洲鳃金龟和北方假面鳃金龟也具有相当毒性。记录了对精油的种间易感性的变异性，在 24 种精油中有 12、11、8 和 6 种对东方鳃金龟、日本丽金龟、欧洲鳃金龟和北方假面鳃金龟具有毒性。通过气相色谱-质谱分析对活性油的分析揭示了一系列不同的化合物，主要由单萜和倍半萜组成。这些结果将有助于确定活性油及其成分，以优化植物精油混合物的开发，用于防治鳃金龟幼虫。
