Abstract:
The present research is aimed to investigate the susceptibility of Cx. quinquefasciatus larvae (2nd and 4th
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 (R2
>0.90). LC50 values of extract for 2nd and 4th instar larvae were 451.8 and 599.6 ppm, respectively. The LC90 values of extract for 2nd and 4th instar larvae were 2519.6 and 3017.7 ppm, respectively. The LC50 and LC90 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 KDT50 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 KDT50 value at highest concentration (0.13 mg/cm2 ) was 94.4 minutes and at lowest concentration (0.017 mg/cm2 ) was 178.9
minutes. KDT90 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/cm2) caused 60±8.2% mortality.
