Larvicidal Potential of Plant Extracts (Piper Nigrum and Illicium Verum) Against Aedes Aegypti

Seow, Ka Jun (2019) Larvicidal Potential of Plant Extracts (Piper Nigrum and Illicium Verum) Against Aedes Aegypti. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Being the major vector of various life-threatening diseases such as dengue haemorrhagic fever and dengue shock syndrome, Aedes aegypti has gained concerns and efforts are taken to control the population and to overcome development of resistance to chemical insecticides. Botanical extracts could be a safer and effective alternative to conventional insecticides as conventional insecticides pose side effects to the environment and also human. In this study, the extracts of Piper nigrum and Illicium verum using three different solvents: ethanol, ethyl acetate, and petroleum ether were evaluated against late third to early forth instar larvae of Aedes aegypti. The plants were extracted through two different approaches, Soxhlet extraction and maceration (cold extraction) with three different solvents. Four different concentrations of extracts, 50 ppm, 25 ppm, 10 ppm and 1 ppm, were tested against Ae. aegypti larvae for 96 hours under room temperature with a photoperiod of 12h light and 12h dark (12L:12D). The larval mortality after each 24 hours was observed. The chemical composition in the plant extracts were analysed using gas chromatography-mass spectrometry. The extraction yields of both Soxhlet and maceration methods for P. nigrum and I. verum showed no significant difference. Nevertheless, choice of solvents for Soxhlet and maceration extraction in P. nigrum did affect the extraction yield. Results from the larvicidal bioassay showed that overall I. verum in petroleum ether exhibited the best larvicidal effect (LC50= 0.839 ppm, LC90= 15.063 ppm) followed by P. nigrum in petroleum ether (LC50= 1.144 ppm, LC90= 9.481 ppm) maceration extraction. For Soxhlet extraction, ethyl acetate extract of P. nigrum has the lowest LC50 value of 4.458 ppm, and LC90 value of 19.751 ppm, compared to petroleum ether extract of I. verum (LC50= 5.621 ppm, LC90= 17.337 ppm). GCMS analysis indicated the presence of the active compounds in P. nigrum extracts such as pinene, limonene, caryophyllene, and piperine, while estragole, limonene, estragole were found in I. verum extracts. The potential bioactive compound for larvicidal activity in P. nigrum may be piperine due to its low LC50 value against Ae. aegypti, while in I. verum, estragole and limonene could be the active phytochemicals that caused larval mortality.