Formulation of clitoria ternatea leaves-mediated silver nanoparticles to control aedes aegypti larvae

Abstract

Introduction: Global rise in the Aedes-borne diseases and harmful effects of synthetic insecticides has diverted research to explore secondary metabolites in plants as mosquito control agent in the form of nanoparticles. Current study investigated Clitoria ternatea-mediated nanoparticles against Aedes aegypti. Methods: The aqueous and hexane leaf extracts of C. ternatea were assayed against Ae. aegypti early fourth instars. The extract-mediated silver nanocomposites (AgNCs) were synthesized after optimizing the volume and concentration of silver nitrate solution. The synthesis was tracked by the colour change of reaction mixture from pale yellow to dark brown followed by monitoring with UV-Visible spectroscopy and Dynamic Light Scattering. Results: The biosynthesis of 3 mM, 4 mM and 5 mM AgNCs was traced at 438, 401 and 407 nm, respectively. The average particle size distribution ranged from 34.62 to 60.64 nm and polydispersity index was 0.6-0.7. The 24 h larval exposure with aqueous and hexane leaf extracts demonstrated respective LC50 values of 53.057 and 42.179 mg/L, which decreased significantly on larvicidal assay with NCs. The 5mM AgNCs showed the maximum efficiency with LC50 of 10.317 mg/L after 24 h. Scanning and transmission electron microscopy images demonstrated a spherical, poly-dispersed structure with diameter in the 1-27 nm range. The assays against non-targets; Moina and Cyclops ascertained the eco-safety of NCs. Conclusion: The study demonstrated the C. ternatea leaf extract as possible effective mosquito nano-larvicide, alternate to traditional insecticides. Field studies, which could not be held due to the current pandemic, would further ascertain the possible use of these NCs against Aedes larvae.