Larvicidal activities of citrus hystrix (kaffir lime) leaf extract against aedes albopictus / Nik Mohamed Adzfar Mohamed Resli

Aedes mosquitoes are widespread, and mosquito control efforts are essential to prevent outbreaks of many arboviruses such as dengue, zika and chikungunya. At present, chemical insecticides are often utilised for this purpose, which can cause long term environmental effects and the evolution of resistance if not controlled. This study was conducted to determine the efficacy of Citrus hystrix (kaffir lime) leaf extract act as a natural alternative larvicide to substitute the use of chemicals. The method of extraction used was maceration digestion. It is a modified form of maceration which involves drying, crushing, soaking with gentle heat and removal of solvent to obtain a pure crude extract. A total 25 larvae were used to test against five (5) different concentrations (50, 40, 30, 20 and 10 ppm) of Citrus hystrix for 24 - 48 hrs and evaluated in terms of mortality rates. Experimental tests were conducted in triplicate and analysed using probit analysis and analysis of variance (ANOVA). Three types of control were used in tandem namely positive (11 mg abate), negative (distilled water) and quality control (10% (v/v) solvent) to ensure the reliability of the test results. Findings revealed 100% effectiveness at 50 ppm. LC₅₀and LC₉₀ were determined at 20.87 ppm and 35.27 ppm, respectively. Results indicate that Citrus hystrix leaf extracts have great potential to replace the use of chemicals as a larvicidal agent as it only requires a low concentration to kill more than 90% of the larvae. The concentration needed is much lower compared to other plants for the same purpose. Further studies are required to elucidate the bioactive compound responsible for the larval death.