Larvicidal activity of green synthesized silver nanoparticles using bark aqueous extract of Ficus racemosa against Culex quinquefasciatus and Culex gelidus.

Objective: To investigate the larvicidal activity of synthesized silver nanoparticles (Ag NPs) utilizing aqueous bark extract of Ficus racemosa (F. racemosa) was tested against fourth instar larvae of filariasis vector, Culex quinquefasciatus (Cx. quinquefasciatus) and japanese encephalitis vectors, Culex gelidus (Cx. gelidus).

Methods: The synthesized Ag NPs was characterized by UV-vis spectrum, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). The larvicidal activities were assessed for 24 h against the larvae of Cx. quinquefasciatus and Cx. gelidus with varying concentrations of aqueous bark extract of F. racemosa and synthesized Ag NPs. LC(50) and r(2) values were calculated.

Results: The maximum efficacy was observed in crude aqueous extract of F. racemosa against the larvae of Cx. quinquefasciatus and Cx. gelidus (LC(50)=67.72 and 63.70 mg/L; r(2)=0.995 and 0.985) and the synthesized Ag NPs (LC(50)=12.00 and 11.21 mg/L; r(2)=0.997 and 0.990), respectively. Synthesized Ag NPs showed the XRD peaks at 2 θ values of 27.61, 29.60, 35.48, 43.48 and 79.68 were identified as (210), (121), (220), (200) and (311) reflections, respectively. The FTIR spectra of Ag NPs exhibited prominent peaks at 3,425, 2,878, 1,627 and 1,382 in the region 500-3,000 cm(-1). The peaks correspond to the presence of a stretching vibration of (NH) C=O group. SEM analysis showed shape in cylindrical, uniform and rod with the average size of 250.60 nm.

Conclusions: The biosynthesis of silver nanoparticles using bark aqueous extract of F. racemosa and its larvicidal activity against the larvae of disease spreading vectors. The maximum larvicidal efficacy was observed in the synthesized Ag NPs.