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 off.racemosa and synthesized Ag NPs.LC50 and r2 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(LC50=67.72 and 63.70 mg/L;r2=0.995 and 0.985) and the synthesized Ag NPs(LC50=12.00 and 11.21 mg/L;r2=0.997 and 0.990).respectively.Synthesized Ag NPs showed the XRD peaks at 2θvalues 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.

Larvicidal and adulticidal potential of medicinal plant extracts from south India against vectors

Objective:To determine the larvicidal and adulticidal activities of hexane,ethyl acetate and methanol extracts of Momordica charantia（M.charantia）,Moringa oleifera（M.oleifera）,Ocimum gratissimum（O.gratissimum）,Ocimum tenuiflorum（0.tenuiflorum）,Punica granalum（P. granatum） and Tribulus terrestris（T.terrestris） against Culex gelidus（Cx.gelidus） and Culex quinquefasciatus（Cx.quinquefasciatus）.Methods:Bioassay test was carried out by WHO method for determination of larvicidal and adulticidal activity against mosquitoes.Results:All plant extracts showed moderate larvicidal and adulticidal activities,however the effective larval mortality was found in the leaf ethyl acetate and methanol extract of O.gratissimum and bark methanol extract of M.oleifera against Cx.gelidus with LC50 values of 39.31.66.28,and 21.83μg/mL respectively,and methanol extract of 0.gratissimum,0.tenuiflorum and P.granatum against Cx.quinquefasciatus with LC50 values of 38.47.24.90 and 67.20μg/mL,respectively.The adult exposed for 1 h and mortality was recorded at 24 h recovery period.Above 90%- mortality was found in the ethyl acetate and methanol extract of all experimental plants at the concentrations of 500μg/mL.Conclusions:The present results suggest that the medicinal plant extracts provided an excellent potential for controlling Cx.gelidus and Cx.quinquefasciatus.