Anti-larvicidal Activity of Silver Nanoparticles Synthesized from Sargassum polycystum Against Mosquito Vectors

Mosquitoes act as vectors of pathogens and parasites that cause dreadful diseases (malaria, dengue, chikungunya, yellow fever, lymphatic filariasis and Japanese encephalitis) in human beings. Synthetic chemical insecticides cause undesirable consequences in human beings and thus affect the ecosystem. Marine source based nanosynthesis has been reported as cheap and cost effective alternative for mosquito management. We have developed an ecofriendly protocol for the synthesis of nanoparticles using seaweed extract. The synthesized nanoparticles were characterized using UV-visible spectroscopy, FTIR, SEM, EDAX and XRD. We found that the extract treated at 60 degrees C was found to be more effective in synthesizing the nanoparticles. SEM analysis revealed that the Sp-AgNPs were predominantly cubical in shape and size ranges from 20 to 88nm. The three strong diffraction peaks were observed by XRD analysis and it confirmed the crystalline nature of silver nanoparticles. Synthesized Sp-AgNPs were tested against four mosquitoes larvaes (An. stephensi, Ae. aegypti, Cx. quinquefasciatus and Cx. tritaeniorhynchus) and their mortality was examined. We found that Ae. aegypti has shown higher mortality rate of about 80% and 90% after 48h and 72h of treatment with Sp-AgNPs and moderately toxic against Cx. quinquefasciatus larvae and it has shown maximum of 80% mortality rate at 72h of treatment. The mosquito larvae An. stephensi and Cx. tritaeniorhynchus has shown less response compared to others tested. So we believe that, fabricated Sp-AgNPs will be the promising eco-friendly tool to control Ae. aegypti and Cx. quinquefasciatus vectors.