In vitro bio-control of malarial and filarial vectors using crude extract and isolated fractions of medicinal herbs (Spilanthes spp.) and characterization of the larvicidal compounds
2013
Pandey, V. | Sarma, G. | Shankar, V. | Agrawal, V.
Bioefficacy of the three Spilanthes spp. were evaluated using their crude flower head extracts against malaria (An. Stephensi Liston, An. Culicifacies species C) and filarial (Cx. Quinquefasciatus Say) mosquito vectors. Cent per mortality were achieved against the last III/early IVth instar larvae of all the three mosquito spp. within 24 h of exposure period. Of the three plant spp., S. acmella proved to be the most effective in inducing complete lethality at minimum doses, the respective LC50 and LC90 values being 4.57 and 7.83 ppm (An. Stephensi), 0.87 and 1.92 ppm (An. Culicifacies) and 3.11 and 8.89 ppm (Cx. Quinquefasciatus). This was followed by S. calva and S. paniculata extracts, respectively. Larvicidal compounds were isolated from flower heads of micropropagated Spilanthes spp. plants in a bioassay guided fractionation and isolation process. TLC of the crude extract sample was carried out using different solvent systems, viz., hexane-ethyl acetate, hexane-acetone, chloroform-acetone and chloroform-methanol, of which hexane-ethyl acetate showed maximum resolution.
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