Muthukumaran Udaiyan, Govindarajan Marimuthu, Rajeswary Mohan
Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalainagar, 608 002, Tamil Nadu, India.
Parasitol Res. 2015 Mar;114(3):989-99. doi: 10.1007/s00436-014-4265-2. Epub 2014 Dec 30.
Mosquitoes transmit serious human diseases, causing millions of deaths every year. Mosquito control is to enhance the health and quality of life of county residents and visitors through the reduction of mosquito populations. Mosquito control is a serious concern in developing countries like India due to the lack of general awareness, development of resistance, and socioeconomic reasons. Today, nanotechnology is a promising research domain which has a wide ranging application in vector control programs. These are nontoxic, easily available at affordable prices, biodegradable, and show broad-spectrum target-specific activities against different species of vector mosquitoes. In the present study, larvicidal activity of aqueous leaf extract and silver nanoparticles (AgNPs) synthesized using C. asiatica plant leaves against late third instar larvae of Anopheles stephensi, Aedes aegypti, and Cx. quinquefasciatus. The range of varying concentrations of synthesized AgNPs (8, 16, 24, 32, and 40 μg/mL) and aqueous leaf extract (40, 80, 120, 160, and 200 μg/mL) were tested against the larvae of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus. The synthesized AgNPs from C. asiatica were highly toxic than crude leaf aqueous extract in three important vector mosquito species. The results were recorded from UV-Vis spectrum, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis (EDX). Considerable mortality was evident after the treatment of C. asiatica for all three important vector mosquitoes. The LC50 and LC90 values of C. asiatica aqueous leaf extract appeared to be effective against An. stephensi (LC50, 90.17 μg/mL; LC90, 165.18 μg/mL) followed by Ae. aegypti (LC50, 96.59 μg/mL; LC90, 173.83 μg/mL) and Cx. quinquefasciatus (LC50, 103.08 μg/mL; LC90, 183.16 μg/mL). Synthesized AgNPs against the vector mosquitoes of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus had the following LC50 and LC90 values: An. stephensi had LC50 and LC90 values of 17.95 and 33.03 μg/mL; Ae. aegypti had LC50 and LC90 values of 19.32 and 34.87 μg/mL; and Cx. quinquefasciatus had LC50 and LC90 values of 20.92 and 37.41 μg/mL. No mortality was observed in the control. These results suggest that the leaf aqueous extracts of C. asiatica and green synthesis of silver nanoparticles have the potential to be used as an ideal eco-friendly approach for the control of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus. This is the first report on the mosquito larvicidal activity of the plant extracts and synthesized AgNPs.
蚊子传播严重的人类疾病，每年导致数百万人死亡。蚊虫控制旨在通过减少蚊虫数量来提高县居民和游客的健康水平和生活质量。由于缺乏普遍认识、抗药性的产生以及社会经济原因，在印度等发展中国家，蚊虫控制是一个严重问题。如今，纳米技术是一个很有前景的研究领域，在病媒控制项目中有广泛应用。这些物质无毒、价格实惠且易于获取、可生物降解，并且对不同种类的病媒蚊子具有广谱的靶向特异性活性。在本研究中，用积雪草植物叶片合成的水提叶提取物和银纳米颗粒（AgNPs）对斯氏按蚊、埃及伊蚊和致倦库蚊的晚期三龄幼虫进行杀幼虫活性测试。测试了不同浓度范围的合成AgNPs（8、16、24、32和40μg/mL）和水提叶提取物（40、80、120、160和200μg/mL）对斯氏按蚊、埃及伊蚊和致倦库蚊幼虫的作用。从积雪草中合成的AgNPs对三种重要病媒蚊子的毒性比粗叶水提取物更高。通过紫外可见光谱、傅里叶变换红外光谱、扫描电子显微镜和能量色散X射线光谱分析（EDX）记录了结果。用积雪草处理后，对所有三种重要病媒蚊子都有明显的死亡率。积雪草水提叶提取物的LC50和LC90值对斯氏按蚊似乎有效（LC50，90.17μg/mL；LC90，165.18μg/mL），其次是埃及伊蚊（LC50，96.59μg/mL；LC90，173.83μg/mL）和致倦库蚊（LC50，103.08μg/mL；LC90，183.16μg/mL）。合成的AgNPs对斯氏按蚊、埃及伊蚊和致倦库蚊病媒蚊子的LC50和LC90值如下：斯氏按蚊的LC50和LC90值分别为17.95和33.03μg/mL；埃及伊蚊的LC50和LC90值分别为19.32和34.87μg/mL；致倦库蚊的LC50和LC90值分别为20.92和37.41μg/mL。对照组未观察到死亡情况。这些结果表明，积雪草的叶水提取物和银纳米颗粒的绿色合成有潜力作为控制斯氏按蚊、埃及伊蚊和致倦库蚊的理想生态友好方法。这是关于植物提取物和合成AgNPs蚊子杀幼虫活性的首次报告。
