Lippia gracilis Schauer, Verbenaceae, is a plant popularly known as "Alecrim-da-Chapada" or “Alecrim-de-Serrote", characteristic of the savanna areas in North and Northeast Brazil. Its essential oil has been tested for pest control due to its bioactive potential. In this work, the chemical composition was analyzed and the insecticidal effect of the pinene/cineol/limonene chemotype leaf oil of L. gracilis, from Chapada das Mesas, Maranhao State, was tested against the armyworms Spodoptera frugiperda (Lepidoptera: Noctuidae). GC and GC-MS analysis identified α-pinene (24.5%), 1,8-cineole (16.2%), β-pinene (11.9%) and limonene (9.6%) as the main constituents of the oil, which presented a yield of 4.3%. For the insecticidal activity, the topical and surface contact tests were carried out with ten-days armyworm’s larvae (third instar), in different concentrations of oil and α-pinene, its main constituent. For the oil, the acute topical toxicity (LD50) was 0.09 μL/insect, and the contact surface toxicity (LC50) was 1.55 μL/cm2, while for α-pinene these values were (LD50) 0.28 μL/insect and (LC50) 2.50 μL/cm2, respectively. Thus, the oil was more active than α-pinene showing that the insecticide effect is due to the synergistic action of the mixture of its constituents. The results lead to the conclusion that the essential oil is promising as a sustainable tool in the management of S. frugiperda.

中文翻译：

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Lippia gracilis 精油化学型，蒎烯-桉树脑-柠檬烯对草地贪夜蛾（鳞翅目：夜蛾科）的毒性

在不同浓度的油和α-蒎烯中，其主要成分。对于油，急性局部毒性 (LD50) 为 0.09 μL/昆虫，接触表面毒性 (LC50) 为 1.55 μL/cm2，而对于 α-蒎烯，这些值为 (LD50) 0.28 μL/昆虫和 (LC50)分别为 2.50 μL/cm2。因此，该油比 α-蒎烯更具活性，表明杀虫效果是由于其成分混合物的协同作用。结果得出的结论是，精油有望成为管理草地贪夜蛾的可持续工具。因此，该油比 α-蒎烯更具活性，表明杀虫效果是由于其成分混合物的协同作用。结果得出的结论是，精油有望成为管理草地贪夜蛾的可持续工具。因此，该油比 α-蒎烯更具活性，表明杀虫效果是由于其成分混合物的协同作用。结果得出的结论是，精油有望成为管理草地贪夜蛾的可持续工具。