DRDO-BU Center for Life Sciences, Bharathiar University, Coimbatore, 641 046 Tamil Nadu, India.
Parasitol Res. 2013 Feb;112(2):679-92. doi: 10.1007/s00436-012-3185-2. Epub 2012 Nov 29.
Mosquito-borne diseases with an economic impact create loss in commercial and labor outputs, particularly in countries with tropical and subtropical climates. Mosquito control is facing a threat because of the emergence of resistance to synthetic insecticides. Extracts from plants may be alternative sources of mosquito control agents because they constitute a rich source of bioactive compounds that are biodegradable into nontoxic products and potentially suitable for use to control mosquitoes. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, this study was undertaken to assess the adulticidal, repellent, and ovicidal potential of the crude hexane, ethyl acetate, benzene, aqueous, and methanol solvent extracts from the medicinal plants Andrographis paniculata, Cassia occidentalis, and Euphorbia hirta against the medically important mosquito vector, Anopheles stephensi (Diptera: Culicidae).The adult mortality was observed after 24 h of exposure. All extracts showed moderate adulticide effects; however, the highest adult mortality was found in methanol extract of A. paniculata followed by C. occidentalis and E. hirta against the adults of A. stephensi with LC(50) and LC(90) values of 210.30, 225.91, and 263.91 ppm and 527.31, 586.36, and 621.91 ppm, respectively. The results of the repellent activity of hexane, ethyl acetate, benzene, aqueous, and methanol extract of A. paniculata, C. occidentalis, and E. hirta plants at three different concentrations of 1.0, 3.0, and 6.0 mg/cm(2) were applied on skin of forearm in man and exposed against adult female mosquitoes. In this observation, these three plant crude extracts gave protection against mosquito bites without any allergic reaction to the test person, and also, the repellent activity is dependent on the strength of the plant extracts. Mean percent hatchability of the ovicidal activity was observed 48 h post-treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. Mortality of 100 % with methanol extract of A. paniculata exerted at 150 ppm and aqueous, methanol extract of C. occidentalis and E. hirta were exerted at 300 ppm. These results suggest that the leaf extracts of A. paniculata, C. occidentalis, and E. hirta have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi. Further detailed research is needed to identify the active ingredient in the extracts and implement the effective mosquito management program.
具有经济影响的蚊媒疾病会导致商业和劳动力产出的损失，尤其是在热带和亚热带气候的国家。由于对合成杀虫剂产生抗药性，蚊虫控制正面临威胁。植物提取物可能是蚊虫控制剂的替代来源，因为它们构成了生物活性化合物的丰富来源，这些化合物可生物降解为无毒产品，并且可能适合用于控制蚊子。植物源杀虫剂可能成为未来合适的替代生物防治技术。鉴于最近人们对开发植物源杀虫剂作为化学杀虫剂替代品的兴趣日益浓厚，因此进行了这项研究，以评估药用植物穿心莲、决明子和大戟的粗正己烷、乙酸乙酯、苯、水和甲醇溶剂提取物对医学上重要的蚊虫传播媒介按蚊（双翅目：库蚊科）的成虫致死、驱避和杀卵作用。暴露 24 小时后观察成虫死亡率。所有提取物均表现出中等程度的成虫致死效果；然而，穿心莲甲醇提取物对 A. stephensi 成虫的致死率最高，其次是决明子和大戟，LC50 和 LC90 值分别为 210.30、225.91 和 263.91 ppm 和 527.31、586.36 和 621.91 ppm。在人的前臂皮肤上涂抹三种不同浓度（1.0、3.0 和 6.0 mg/cm2）的穿心莲、决明子和大戟植物的正己烷、乙酸乙酯、苯、水和甲醇提取物的驱避活性的结果表明，这些三种植物粗提取物可防止蚊虫叮咬，而对试验者无任何过敏反应，并且驱避活性取决于植物提取物的强度。在处理后 48 小时观察到杀卵活性的平均孵化率。孵化率与提取物的浓度成反比，与卵的数量成正比。用 150 ppm 的穿心莲甲醇提取物和 300 ppm 的水、甲醇决明子和大戟提取物可使死亡率达到 100%。这些结果表明，穿心莲、决明子和大戟的叶提取物具有作为控制 A. stephensi 的理想生态友好方法的潜力。需要进一步进行详细研究以鉴定提取物中的有效成分，并实施有效的蚊虫管理计划。
