Evaluation of Larvicidal Activity of Extracts Against Larvae.

<b>Background and Objective:</b> The resistance of <i>Aedes aegypti</i> larvae against temephos become an obstacle in controlling the arboviral vector. This condition triggered researchers to investigate the larvicidal activity of phytochemical compounds that are effective, safe, biodegradable and eco-friendly from various medicinal plants. This study evaluated the larvicidal activity of <i>Kaempferia galanga</i> extracts against <i>Ae. aegypti</i> larvae. <b>Materials and Methods:</b> Four solvents with different polarities, namely ethanol, ethyl acetate, n-hexane and water were used in the sequential extraction. The final larvicidal bioassay test of the four extract types was designed in five replicates of five concentration ranges, namely 1.0, 8.75, 17.5, 35.0 and 70.0 ppm. A total of 20 3rd instar larvae of <i>Ae. aegypti</i> were contacted with each replicate in a plastic cup. Larval mortality and effective concentration of larvicide were calculated and determined after 24 and 48 hrs of exposure. <b>Results:</b> The average range of larval mortality according to the concentration of larvicide extracts of ethanol, ethyl acetate, n-hexane and water was 40-91, 2-36, 7-83 and 44-86% after 24 hrs and 88-100, 11-84, 12-99 and 77-100% after 48 hrs of exposure. The data yielded LC₅₀ for 24 and 48 hrs of exposure at 1,563 and 0.061 ppm, 206,739 and 7,623 ppm, 47,579 and 38,063 ppm and 1.33 and 0.300 ppm, respectively. <b>Conclusion:</b> The polar extract of <i>K. galanga</i> showed high effectiveness so it is necessary to design the right formulation for field application, potency stability and active period of this larvicide residue.