Larvicidal activity of four selected Malaysian medicinal plant extracts against Aedes albopictus
Zaridah MZ., Mohd Kamal N.H., Ihsan Safwan K., Muhammad Danial CR., Azman M., Nurul Aina A.S.

In this study, the larvicidal activity of four medicinal plant extracts was studied in the range of 2.5 to 20 mg/ml in a laboratory bioassay against the early 4th instar larva of Aedes albopictus. Mortality data were subjected to determine the lethal concentration (LC50) to kill 50 percent of the treated larva for each species. The leaves of Mitragyna speciosa Korth (M. speciosa) and Senna alata Linn (S. alata), the root of Eurycoma longifolia Jack (E. longifolia), and the fruit of Morinda citrifolia Linn (M.citrifolia) were collected and extracted. For the bioassay test, 10 larva were taken and added into 6 well plates containing 1 ml of water and 1 ml of the samples with a final concentration of 2.5 mg/ml, 5 mg/ml 10 mg/ml, and 20 mg/ml. The positive control was polysorbate 80. The percentage of mortality was reported. The results showed that the aqueous extracts of M. speciosa, S. alata, E. longifolia, and M. citrifolia have low larvicidal activity with different capabilities. Extracts of S. alata, M. citrifolia, and E.longifolia can kill larva at concentrations of 20 mg/ml and 10 mg/ml. However, M.speciosa can only cause larval death at high concentrations. There were no IC50 detected in all samples. All samples were only killed in the range of 0.3 to 1 larva within 24hours and most larva were paralyzed. The aqueous extracts of M. speciosa, S. alata, E. longifolia, and M. citrifolia showed low larvicidal activity. The order of herb toxicity for larva from very toxic to less toxic is M. citrifolia > S. alata >E. longifolia > M. speciosa. 

Keywords: Antilarval, Mitragyna speciosa, Senna alata, Eurycoma longifolia, Morinda citrifolia