Environmental Biotechnology Division, School of Bio Sciences and Technology, VIT University, Vellore, Tamil Nadu, India.
Parasitol Res. 2011 Jun;108(6):1447-55. doi: 10.1007/s00436-010-2193-3. Epub 2010 Dec 10.
The purpose of the present study was to assess the effect of crude extracts of marine actinobacteria on larvicidal, repellent, and ovicidal activities against Culex tritaeniorhynchus and Culex gelidus (Diptera: Culicidae). The early fourth instar larvae of C. tritaeniorhynchus and C. gelidus, reared in the laboratory, were used for larvicidal, ovicidal, and repellent assay with crude extracts of actinobacteria. Saccharomonospora spp. (LK-1), Streptomyces roseiscleroticus (LK-2), and Streptomyces gedanensis (LK-3) were identified as potential biocide producers. Based on the antimicrobial activity, three strains were chosen for larvicidal activity. The marine actinobacterial extracts showed moderate to high larvicidal effects after 24 h of exposure at 1,000 ppm and the highest larval mortality was found in extract of LK-3 (LC(50) = 108.08 ppm and LC(90) = 609.15 ppm) against the larvae of C. gelidus and (LC(50) = 146.24 ppm and LC(90) = 762.69 ppm) against the larvae of C. tritaeniorhynchus. Complete protections for 240 min were found in crude extract of LK-2 and LK-3 at 1,000 ppm, against mosquito bites of C. tritaeniorhynchus and C. gelidus, respectively. After 24-h treatment, mean percent hatchability of the ovicidal activity was observed. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. Crude extracts of LK-1 and LK-3 showed no hatchability at 1,000 ppm against C. tritaeniorhynchus and C. gelidus, respectively. This is an ideal ecofriendly approach for the control of Japanese encephalitis vectors, C. tritaeniorhynchus and C. gelidus.
本研究旨在评估海洋放线菌粗提物对三带喙库蚊和致倦库蚊幼虫的杀幼虫、驱避和杀卵活性的影响。使用实验室饲养的三带喙库蚊和致倦库蚊的早期第四龄幼虫进行了放线菌粗提物的杀幼虫、杀卵和驱避活性测定。发现 Saccharomonospora spp.（LK-1）、玫瑰色链霉菌（LK-2）和格氏链霉菌（LK-3）是潜在的杀生物剂产生菌。基于抗菌活性，选择了三种菌株进行杀幼虫活性测定。海洋放线菌提取物在 1000 ppm 暴露 24 小时后表现出中等至高的杀幼虫效果，在 LK-3 提取物中发现最高的幼虫死亡率（LC50=108.08 ppm，LC90=609.15 ppm）对致倦库蚊幼虫和（LC50=146.24 ppm，LC90=762.69 ppm）对三带喙库蚊幼虫。在 1000 ppm 时，LK-2 和 LK-3 的粗提取物对三带喙库蚊和致倦库蚊的蚊咬均提供了 240 分钟的完全保护。处理 24 小时后，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，与卵成正比。LK-1 和 LK-3 的粗提取物在 1000 ppm 时对三带喙库蚊和致倦库蚊均无孵化能力。这是控制日本脑炎传播媒介三带喙库蚊和致倦库蚊的一种理想的环保方法。
