Vol. 1, Issue 6 (2016)
Larvicidal activity of Silver Nanoparticle synthezed by the leaf extracts of Azadirachta indica against Culex quinquefasciatus (Say) (Diptera : Culicidae)
Author(s): Subashini K, Jeyasankar A, Ramesh N, Sivakami R
Abstract: In the present investigation the larvicidal activity of Silver nanoparticle synthezed by the leaf extracts of Azadirachta indica against Culex quinquefasciatus was attempted in the laboratory conditions. The result of the present study indicated that the larval mortality of C. quinquefasciatus was high in 0.05% (500 ppm) and the lowest mortality was recorded in 0.01% (100 ppm). The LC90 and regression equation were 0.062, Y=40.914+11.388 X. The 95% lower and upper confidence limit of LC50, LC90 (LCL-UCL) were (0.022 – 0.043) and (0.048-0.105) ppm respectively. The chi –square value 0.001 was significant at p<0.05 level (Chi: Pearson Goodness of Fit test 19.437 Df 4 P 0.001). The percentage of adult emergence inhibition were 22.0±1.8%, 35.5±2.5%, 48.0±3.0%, 68.0±3.4% and 90.0±2.2% at different concentration viz., 25.0ppm, 50.0ppm, 75.0ppm, 100.0ppm and 125.0ppm against the larvae of C. quinquefasciatus. The LC50 value was 515.11 ppm and the LC90 value was 954.24 ppm. The regression equation was Y=11.15+0.416X. The 95% lower and upper confidence limit of LC50, LC90 (LCL-UCL) were (470.22-625.20) and (880.11-1252.15) ppm respectively. The chi –square value 0.04.35 was significant at p<0.05 level. The result revealed that the A. indica leaf extract was safe for non-target organisms as no adverse effects or mortality was recorded. This shows that the extract if used in the field where these organisms co-inhabit with the mosquito larvae will only kill the larvae and not harm other organisms.