Larvicidal, pupicidal and adulticidal activities of non-polar solvent extract of Cymbopogon nardus [Linn.] whole plant against a mosquito, Culex quinquefasciatus [Say.]

ABSTRACT

The present research is aimed to investigate the susceptibility of Cx. quinquefasciatus larvae [2[nd] and 4[th] instars], pupae and adults during exposure to various concentrations of C. nardus n-hexane extract. Increase in mortality of larvae and pupae was observed with increase in concentration of the extract solution [R[2]>0.90]. LC[50] values of extract for 2[nd] and 4[th] instar larvae were 451.8 and 599.6 ppm, respectively. The LC[90] values of extract for 2[nd] and 4[th] instar larvae were 2519.6 and 3017.7 ppm, respectively. The LC[50] and LC[90] values of extract during pupicidal activity were 1307.7 and 2257.9 ppm, respectively. During CDC bottle bioassay, mosquito adult knockdown was observed after exposure to various concentrations [0.15% to 1.25%] of C. nardus n-hexane extract. The KDT[50] values at highest [1.25 %] and lowest [0.15%] concentrations were 100.9 and 184.2 minutes, respectively. After 24 hours exposure period, the highest extract concentration [1.25%] caused 62.5+/-6.5% mortality. During filter paper impregnation bioassay, the KDT[50] value at highest concentration [0.13 mg/cm[2]] was 94.4 minutes and at lowest concentration [0.017 mg/cm[2]] was 178.9 minutes. KDT[90] values at these concentrations were 176.7 and 290.1 minutes, respectively. After 24 hours of recovery period, the filter papers impregnated with highest extract concentration [0.13mg/cm[2]] caused 60+/-8.2% mortality