Mosquitocidal activities of malaysian plants

ZARIDAH, M. Z., NOR AZAH, M. A. & ROHANI, A. 2006. Mosquitocidal activities of Malaysian plants. Extracts from about 30 species of plants in Malaysia were tested for their ability to kill the larvae or to repel or knock down the adults of Aedes aegypti, the vector mosquito for dengue and dengue hemorrhagic fever. Observation of mortality was made after 24 hours of exposure to the plant extract/essential oil to obtain the median lethal concentration (LC 50 ) of the plant extract/essential oil tested. In repellency and knockdown effects of adult mosquitoes, median effective concentration (EC 50 ) was obtained after each test. The three best extracts for killing larvae were the essential oils of Zanthoxylum acanthopodium stem, Aquilaria malaccensis wood and Pelargonium citrosum plant. For repelling adult mosquitoes, the most effective was the leaf essential oil of Cymbopogon nardus, followed by that of A. malaccensis. Knock-down ability was best with mosquito coils made from the seed kernel of Azadirachta indica, followed by the leaf of C. nardus and the wood of Fernandoa adenophylla. Keywords: Larvicidal, adulticidal, knock-down effect, repellency effect ZARIDAH, M. Z., NOR AZAH, M. A. & ROHANI, A. 2006. Aktiviti antinyamuk tumbuh-tumbuhan Malaysia. Ekstrak daripada 30 spesies tumbuhan Malaysia diuji keupayaannya membunuh larva atau menghalau atau memengsankan nyamuk dewasa Aedes aegypti iaitu vektor demam denggi dan demam denggi berdarah. Pemerhatian untuk kematian dilakukan 24 jam selepas pendedahan nyamuk kepada ekstrak tumbuhan atau minyak pati bagi memperoleh kepekatan maut median (LC 50 ) ekstrak tumbuhan atau minyak pati yang diuji. Dalam kesan menghalau dan kesan memengsankan nyamuk, kepekatan berkesan median (EC 50 ) diperoleh. Tiga ekstrak terbaik bagi membunuh larva ialah minyak pati daripada batang Zanthoxylum acanthopodium, kayu Aquilaria malaccensis dan tumbuhan Pelargonium citrosum. Minyak pati daripada daun Cymbopogon nardus paling berkesan untuk menghalau nyamuk, diikuti oleh A. malaccensis. Keupayaan memengsankan nyamuk paling baik dengan lingkaran nyamuk yang diperbuat daripada isirong biji Azadirachta indica, diikuti oleh daun C. nardus dan kayu Fernandoa adenophylla