Campus Centro-Oeste Dona Lindu, Universidade Federal de São João del Rei, Av. Sebastião Gonçalves Coelho, 400 - Chanadour, Divinópolis, MG,, CEP 35501-296, Brazil.
Departamento de Biologia, Universidade Estadual Paulista Júlio de Mesquita Filho, Instituto de Biociências de Rio Claro, Av. 24 A, 1515 - Jardim Vila Bela, Rio Claro, SP, 13506-900, Brazil.
Environ Sci Pollut Res Int. 2018 Nov;25(31):31718-31726. doi: 10.1007/s11356-018-3149-x. Epub 2018 Sep 12.
The control of mosquitoes by means of chemical insecticides has been a problem, mainly due to the possibility of resistance developed by insects to xenobiotics. For this reason, demand for botanical insecticides has increased. In this sense, the present work aims to verify the susceptibility and morphological and biochemical alterations of Culex quinquefasciatus larvae after exposure to essential oil (EO) of leaves of Baccharis dracunculifolia. To observe the larvicidal action, larvae were exposed to EO at concentrations of 25, 50, 100, and 200 mg/L, until their emergence to adults. The control group was exposed to deionized water and dimethyl sulfoxide. Morphological analyses were also carried out using hematoxylin and eosin, mercury bromophenol blue, Nile blue, and periodic acid Schiff. Biochemical analyses of total glucose, triacylglyceride (TAG), protein, and acetylcholinesterase levels were performed. The phytochemical analysis of the EO showed (E)-nerolidol as the major compound (30.62%). Larvae susceptibility results showed a LC of 34.45 mg/L for EO. Morphological analysis showed that there were histological changes in midgut. For biochemical analyses, the glucose level in the larvae exposed to EO for 24 h decreased significantly, unlike the TAG levels, which increased. The total protein level of the larvae also increased after exposure for 24 h, and acetylcholinesterase levels decreased significantly. Taking all our data into account, we can conclude that EO causes destabilization in larva, leading to histological changes, metabolic deregulation and, consequently, their death.
通过化学杀虫剂来控制蚊子一直是一个问题，主要是由于昆虫对异生物产生抗性的可能性。出于这个原因，对植物性杀虫剂的需求增加了。从这个意义上说，目前的工作旨在验证巴西苦荬菜叶精油（EO）暴露后致倦库蚊幼虫的敏感性以及形态和生化变化。为了观察幼虫的杀幼虫作用，将幼虫暴露于浓度为 25、50、100 和 200 mg/L 的 EO 中，直到它们变成成虫。对照组暴露于去离子水和二甲基亚砜中。还使用苏木精和曙红、汞溴酚蓝、尼罗蓝和过碘酸希夫进行形态分析。进行了总葡萄糖、三酰基甘油（TAG）、蛋白质和乙酰胆碱酯酶水平的生化分析。EO 的植物化学分析显示（E）-橙花叔醇是主要化合物（30.62%）。幼虫敏感性结果显示 EO 的 LC 为 34.45 mg/L。形态分析表明，中肠存在组织学变化。对于生化分析，暴露于 EO 24 小时的幼虫的葡萄糖水平显著降低，而 TAG 水平增加。暴露 24 小时后，幼虫的总蛋白水平也增加，乙酰胆碱酯酶水平显著降低。考虑到我们所有的数据，我们可以得出结论，EO 导致幼虫不稳定，导致组织学变化、代谢失调，从而导致它们死亡。
