10.22376/ijpbs.2019.10.1.p1-12 Volume 4 Issue 2 2013 (April - June) The present study was made an attempt to identify the larvicidal activity of the seagrass extracts. Four seagrass species and different plant extract (leaf and root) lessThan i greaterThan viz., Halophila ovalis lessThan /i greaterThan (AUOCAS025) lessThan i greaterThan , lessThan /i greaterThan lessThan i greaterThan Enhalus acorodies lessThan /i greaterThan (AUOCAS026) lessThan i greaterThan , Thalassia hemprichii lessThan /i greaterThan (AUOCAS027) and lessThan i greaterThan Halodule pinifolia lessThan /i greaterThan (AUOCAS028) were tested against lessThan i greaterThan A. aegypti lessThan /i greaterThan mosquito larvicidal activity. Batches of 25 early 4 lessThan sup greaterThan th lessThan /sup greaterThan instar larvae of lessThan i greaterThan A. aegypti lessThan /i greaterThan were transferred to 250ml enamel bowl containing 199ml of distilled water and 1ml of plant extracts (0.01mg-0.1mg). Each experiment was conducted with three replicated and a concurrent control group. A control group consisted of 1ml of DMSO and 199ml of distilled water only. The larvae were considered dead at the end of 24 hrs and the percentage of mortality was determined with the formulae with % of test mortality -% of control mortality/100-% of control mortality X100. The extract of lessThan i greaterThan H. ovalis lessThan /i greaterThan showed maximum larvicidal activity (LC lessThan sub greaterThan 50 lessThan /sub greaterThan value 0.067±0.007 μg.ml lessThan sup greaterThan -1 lessThan /sup greaterThan and LC lessThan sub greaterThan 90 lessThan /sub greaterThan value = 0.128±0.025 μg.ml lessThan sup greaterThan -1 lessThan /sup greaterThan ) followed by leaf extract of lessThan i greaterThan E. acorodies lessThan /i greaterThan (0.0852 ± 0.006 μg.ml lessThan sup greaterThan -1 lessThan /sup greaterThan and LC lessThan sub greaterThan 90 lessThan /sub greaterThan = 0.1369±0.036). Similarly no mortality was found in extracts of lessThan i greaterThan T. hemprichii lessThan /i greaterThan (leaf) lessThan i greaterThan H. pinifolia lessThan /i greaterThan (leaf) showed no mortality of 4 lessThan sup greaterThan th lessThan /sup greaterThan instar larvae of lessThan i greaterThan A. aegypti lessThan /i greaterThan . It is concluded from the present study that, the ethanolic extract of seagrass lessThan i greaterThan H.ovalis lessThan /i greaterThan possesses and they can be developed as lead compounds for mosquito control. M.SYED ALI S.RAVIKUMAR AND J. MARGARET BEULA Aedes aegypti, Dengue, Larvicidal, LC50, LC90 Mosquito control. 62-67