Larvicidal activity of extracts from different parts of Neem (Azadirachta indica) against Aedes Aegypti mosquitoes’ larvae

Abstract

Dengue is one of the major health problem in many countries. The genus Aedes in which Aedes aegypti (Family: Culicidae) mosquito belongs to, is the major vector of dengue fever disease. Search for larvicidal active compound(s) is one of the several attempts to find effective and affordable ways to control this mosquito. The aim of this study is to investigate the toxic effect of different solvent (acetone, chloroform, ethanol) extracts from different parts (bark, leaf, root, and seed) of Neem, genus Azadirachta of Azadirachta indica (Family: Meliaceae) against A. aegypti larvae. For the larvicidal bioassay, four concentrations (50, 100, 500, and 1000 ppm) of plant crude extracts were prepared; 1 mL of dimethyl sulfoxide (DMSO) was used to solubilize the extracts in water. In each solution was inserted 10 larvae (second and third instar). A set of control using 2.0% DMSO and untreated sets of larvae in (tap) water were also run for comparison. Data were evaluated and the LC50 and LC90 values were read. The larvicidal activities of the crude extracts were varied and the LC50 and LC90 values ranges from 50 to 837.5 ppm and 94 to 950 ppm, respectively. Assays showed that leaf acetone and root chloroform extracts were more toxic against larvae and causes 100% mortality at concentration of 1000 ppm in 24 h. Whereas, the rest extracts achieved 100% mortality at 1000 ppm in 48 h. Bioactive phytochemical classes, such as alkaloids and sesquiterpene lactones were screened by TLC; and the results obtained were negative for alkaloids and positive for sesquiterpene lactones. Therefore, the results obtained in this study shows the potential of the crude extracts of A. indica againstA. aegypti larvae; and this may warrant further research to determine the bioactive compound(s). Key words: Neem (Azadirachta indica), crude extract, larvicidal activity, Aedesaegypti, larvae.