Larvicidal activity of some selected medicinal plant extracts against the vector of filariasis
The present study assessed the role of larvicidal activities of hexane, ethyl acetate and methanol dried leaf and bark extracts of Ocimum gratissimum, Gleditsia triacanthos, Eucalyptus sglobulus and Azadirachta aindica against the fourth instar larvae of filariasis vector, Culex quinquefasciatus mosquito (Diptera: Culicidae). Larvicidal activities of four medicinal plant extracts were studied in the range of 4.69 to 1000 mg/l in the laboratory bioassays against early 4th instar larvae of Culex quinquefasciatus. The mortality data were subjected to probit analysis to determine the lethal concentrations (LC50 and LC90) to kill 50 and 90 per cent of the treated larvae of the respective species. All plant extracts showed moderate effects after 24 h of exposure; however, the highest toxic effect of leaf methanol extract of Ocimum gratissimum, bark ethyl acetate extract of Eucalyptus globulus, methanol extract of Azadirachta indicia and methanol bark extract of Gleditsia triacanthos against the larvae of Culex quinquefasciatus with LC50=43.00, 41.02, 40.12 and 20.36 mg/l; LC90=278.32, 218.72, 215.01 and 86.29 mg/l respectively. The result of ﬁndings shows that leaf and bark extract of G. tricantha, A .indica, O. gratissimum and E .globulus can be developed as ecofriendly larvicides.