Sarita Kumar, Aarti Sharma and Radhika Warikoo
The antagonistic impacts of chemical toxicants-based intrusion measures for the control of mosquitoes have received extensive public apprehension because of numerous problems; including insecticide resistance, revival of pests, environmental contamination, lethal effects on humans and other non-target organisms. These complications have reasoned the requirement to explore and formulate the alternative plant-based strategies possessing eco-safety, bio-degradability and non-toxicity to nontarget organisms. Spikenard plant, Nardostachys jatamansi also known as the healing oil is grown in Northern India and China. Though earlier used as perfume and for healing purposes, it is not widely used today. In the current study, the efficacy of the roots of spikenard plant, Nardostachys jatamansi were explored against larvae of dengue vector, Aedes aegypti. The roots were separately extracted in two solvents; hexane and petroleum ether; which were then assessed against early fourth instars of Aedes aegypti as per procedure recommended by WHO. The larvae dead and in the moribund state were scored after 24 h of exposure and data was analysed statistically to calculate LC values. Both extracts proved to possess excellent larvicidal potential. The bioassays with hexane roots extracts resulted in LC50 and LC90 value of 140.64 and 302.54 ppm, respectively after 24 h of exposure, while the extracts prepared from petroleum ether showed LC50 and LC90 value of 84.50 and 214.12 ppm, respectively. The petroleum ether root extract exhibited 1.7–fold more larvicidal potential as compared to hexane root extract. The treated larvae that remained alive formed larvalpupal intermediates establishing the delayed toxic effects of the extracts. Further investigations are required to assess the impact of extracts on non-target organisms and explore the suitability of its use in the fields.
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