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The present investigation was carried out to evaluate the larvicidal activity of 6 selected plants Alstonia scholaris L. (Apocynaceae), Derris indica Bennet (Fabaceae), Ocimum sanctum L. (Lamiaceae), Plumeria alba L. (Apocynaceae), Psidium guajsva L. (Myrtaceae) and Syzygium cumini (L.) Skeels. (Myrtaceae) against two mosquito species viz. Aedes albopictus Skuse and Cu/ex quinqufasciatus Say. Additional experiments to determine their bioactive potentials like lethality against the brine shrimp, Artemia salina L. nauplii, dose-mortality and repellency against the red flour beetle, Triblium castaneum (Hbst.) adults were also carried out. Isolation, purification and characterization of plant component(s) were also done to establish step-forward positive control measure(s) against two mosquito species from the pest control and pharmaceutical point of view.
Larvicidal activity
The Petroleum ether (Pet.E.), chloroform (CHC'3) and methanol (CH3OH) extracts of leaf, stem bark, stem wood and roots of D. indica, leaves of A. scholaris, P. albs, ps. guajava, S. cumini and whole plant of 0. sanctum was tested to evaluate the larvicidal potential against the two mosquito species Ae. a/bopictus and C. quinqufasciatus larvae through larvicidal activity. Against Ae. albopictus the extracts yielded significant results with dose levels ranged between 600 to 3.13ppm; and the observation of mortality was made after 6h of application and with 6h interval up to 30 hours. According to the intensity of activity the plants could be arranged in the following descending order: D. indica > P. alba > 0. sanctum > Ps. guajava > A. scholaris > S. cumini. Against C. quinquefasciatus the extracts yielded results with the same dose levels and observation intervals. According to the intensity of activity the plants could be arranged in the following descending order: D. indica > 0. sanctum >P. alba > A. scholaris > Ps. guajava > S. cumini.
Among the selected plants D. indica was found promisingly active and thus it was taken in to consideration for dose-mortality, repellency and brine shrimp lethality tests. |
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