Abstract

Objective: To synthesize silver nanoparticles by using Azadirachta indica (A. indica) and Elephantopus scaber (E. scaber) leaf extract as reducing and stabilizing agent and to check the efficacy of silver nanoparticles towards mortality of mosquito larval and pupal stages of Culex quinquefasciatus (Cx. quinquefasciatus). Methods: The silver nanoparticles were synthesized using A. indica and E. scaber leaf extract. The synthesized nanomaterials were characterized using UV-vis spectrophotometer, Fourier transform infrared spectroscopy, transmission electron microscopy and fluorescent microscopy. Finally, the synthesized nanoparticles were applied on fourth instar larval and pupal stages of Cx. quinquefasciatus larvae and pupae and mortality was counted for 48 h. Dead larval bodies were electron dispersive X-ray studied to see whether silver has entered into the body or not. Pupal hatching under the influence of these nanoparticles were also studied. Results: Silver nanoparticles were synthesized from A. indica and E. scaber leaf which were stable. Mortality results highlighted that LC50 and LC90 of A. indica and E. scaber induced silver nanoparticle are 1.64, 4.32 mg/L and 1.43, 4.32 mg/L respectively during 48 h of incubation. EDX study of dead larval body showed a clear signature of silver in their body which suppose to be the main cause of their mortality. Pupal hatching is also hampered by the sublethal doses. Conclusions: A. indica and E. scaber may be good source as reducing agent of stable silver nanoparticles. Green synthesized silver nanoparticles may be a good eco-friendly alternative to control mosquito larvae and pupae of Cx. quinquefasciatus.

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