Yadav R, Tikar S N, Sharma A K, Tyagi V, Sukumaran D, Jain A K, Veer V
Vector Management Division, Defence Research and Development Establishment, Gwalior, India.
J Vector Borne Dis. 2015 Mar;52(1):88-94.
BACKGROUND & OBJECTIVES: Screening of crude extracts of plants facilitates the establishment of highly effective extract for mosquito control. This practice should be preferred before in depth study of plant extracts rather than spending much efforts and energy in detailed examinations for practically ineffective extracts. In this study, leaf powders of four weed plants were used for the quick screening of effective plant extract as larvicide against III instar larvae of Aedes albopictus Skuse. At the same time, effect of different seasons on the larvicidal efficacy of plants and selection of proper solvents for further investigation were also studied.
Leaves of Vernonia cinerea, Prosopis juliflora, Hyptis suaveolens and Malvastrum coromandelianum plants were collected in summer, winter and rainy seasons from Madhya Pradesh region (India). To assess the larvicidal efficacy the suspensions of leaf powders in different solvents (isopropanol, methanol, acetone, dimethylsulfoxide and water) were used for larvicidal bioassay. The mortality counts were made after 24 h and the LC50 and LC90 values were calculated.
Results showed that leaf powder of V. cinerea in acetone collected during summer showed highest efficacy with LC50 value of 0.22 g/l and LC90 of 0.96 g/l followed by methanolic solution of P. juliflora with LC50 of 0.44 g/l and LC90 value as 1.85 g/l. Amongst all solvents, leaf powder in acetone; while among seasons, summer collected plant materials were found to be more effective larvicides as compared to others.
INTERPRETATION & CONCLUSION: Summer and winter collected leaves of V. cinerea and P. juliflora dissolved in the solvents of medium polarity range showed significant larval toxicity and thus suggests a detailed study on these plants as potential larval control agents.
对植物粗提物进行筛选有助于确定高效的灭蚊提取物。在对植物提取物进行深入研究之前，应优先采用这种方法，而不是在对实际无效的提取物进行详细检测时花费大量精力。在本研究中，使用四种杂草植物的叶粉快速筛选对白纹伊蚊（Aedes albopictus Skuse）三龄幼虫有效的杀幼虫植物提取物。同时，还研究了不同季节对植物杀幼虫效果的影响以及选择合适的溶剂用于进一步研究。
在夏季、冬季和雨季从印度中央邦地区采集灰叶斑鸠菊（Vernonia cinerea）、牧豆树（Prosopis juliflora）、香彩雀（Hyptis suaveolens）和野葵（Malvastrum coromandelianum）的叶子。为评估杀幼虫效果，将叶粉在不同溶剂（异丙醇、甲醇、丙酮、二甲基亚砜和水）中的悬浮液用于杀幼虫生物测定。24小时后进行死亡计数，并计算半数致死浓度（LC50）和90%致死浓度（LC90）值。
结果表明，夏季采集的灰叶斑鸠菊叶粉在丙酮中的效果最佳，LC50值为0.22克/升，LC90为0.96克/升，其次是牧豆树的甲醇溶液，LC50为0.44克/升，LC90值为1.85克/升。在所有溶剂中，叶粉在丙酮中的效果最佳；而在各个季节中，夏季采集的植物材料作为杀幼虫剂比其他季节采集的更有效。
夏季和冬季采集的灰叶斑鸠菊和牧豆树叶子溶解在中等极性范围内的溶剂中显示出显著的幼虫毒性，因此建议对这些植物作为潜在的幼虫控制剂进行详细研究。
