Division of Entomology, Department of Zoology, School of Life Sciences, Bharathiar University, Coimbatore, 641 046, Tamil Nadu, India.
Parasitol Res. 2012 Sep;111(3):997-1006. doi: 10.1007/s00436-012-2924-8. Epub 2012 May 6.
Vector control is a critical requirement in epidemic disease situations, as is an urgent need to develop new and improved mosquito control methods that are economical and effective yet safe for nontarget organisms and the environment. Mosquitoes transmit serious human diseases, causing millions of deaths every year. Use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of synthesized natural products for vector control have been a priority in this area. In the present study, activity of silver nanoparticles (AgNPs) synthesized using Euphorbia hirta (E. hirta) plant leaf extract against malarial vector Anopheles stephensi (A. stephensi) was determined. Range of concentrations of synthesized AgNPs (3.125, 6.25, 12.5, 25, and 50 ppm) and methanol crude extract (50, 100, 150, 200, and 250 ppm) were tested against larvae of A. stephensi. The synthesized AgNPs from E. hirta were highly toxic than methanolic crude extract against malarial vector, A. stephensi. The synthesized AgNPs were characterized by UV-vis spectrum, scanning electron microscopy (SEM), and X-ray diffraction. SEM analyses of the synthesized showed that AgNPs, measuring 30-60 nm in size, were clearly distinguishable. The synthesized AgNPs showed larvicidal effects after 24 h of exposure; however, the highest larval mortality was found in the synthesized AgNPs against the first to fourth instar larvae and pupae of values LC(50) (10.14, 16.82, 21.51, and 27.89 ppm, respectively), LC(90) (31.98, 50.38, 60.09, and 69.94 ppm, respectively), and the LC(50) and LC(90) values of pupae of 34.52 and 79.76 ppm, respectively. Methanol extract exhibited the larval toxicity against the first to fourth instar larvae and pupae of values LC(50) (121.51, 145.40, 169.11, and 197.40 ppm, respectively), LC(90) (236.44, 293.75, 331.42, and 371.34 ppm, respectively), and the LC(50) and LC(90) values of pupae of 219.15 and 396.70 ppm, respectively. No mortality was observed in the control. These results suggest that synthesized silver nanoparticles are a rapid, eco-friendly, and single-step approach; the AgNPs formed can be potential mosquito larvicidal agents.
病媒控制是传染病情况下的关键要求，因此迫切需要开发新的和改进的蚊虫控制方法，这些方法既经济有效，又对非目标生物和环境安全。蚊子传播严重的人类疾病，每年导致数百万人死亡。使用合成杀虫剂来控制病媒蚊子会导致生理抗性和环境的不利影响，除了高运营成本。合成天然产物的杀虫剂一直是该领域的优先事项。在本研究中，使用大戟（Euphorbia hirta）植物叶提取物合成的银纳米粒子（AgNPs）对疟疾病媒按蚊（Anopheles stephensi）的活性进行了测定。合成 AgNPs（3.125、6.25、12.5、25 和 50 ppm）和甲醇粗提物（50、100、150、200 和 250 ppm）的浓度范围进行了测试，以对抗按蚊幼虫。大戟合成的 AgNPs 比甲醇粗提取物对疟疾病媒按蚊的毒性更高。用紫外可见光谱、扫描电子显微镜（SEM）和 X 射线衍射对合成 AgNPs 进行了表征。合成 AgNPs 的 SEM 分析表明，AgNPs 大小为 30-60nm，可明显区分。合成 AgNPs 在暴露 24 小时后表现出杀幼虫作用，但在第一至第四龄幼虫和蛹的 LC（50）值（分别为 10.14、16.82、21.51 和 27.89 ppm）、LC（90）值（分别为 31.98、50.38、60.09 和 69.94 ppm）和 LC（50）和 LC（90）值分别为 34.52 和 79.76 ppm）中，合成 AgNPs 表现出最高的幼虫死亡率。甲醇提取物对第一至第四龄幼虫和蛹的幼虫毒性表现为 LC（50）值（分别为 121.51、145.40、169.11 和 197.40 ppm）、LC（90）值（分别为 236.44、293.75、331.42 和 371.34 ppm）和 LC（50）和 LC（90）值分别为 219.15 和 396.70 ppm）。对照中没有观察到死亡。这些结果表明，合成银纳米粒子是一种快速、环保、单一的方法；形成的 AgNPs 可能是潜在的蚊虫杀幼虫剂。
