Larvicidal effects of biofabricated iron nanoparticles made from the aqueous extracts of Eupatorium adenophorum and Artocarpus hirsutus, with their effect on the predatory efficiency of mosquito fish

The present study investigated the larvicidal effect of bio-synthesized iron nanoparticles (FeNPs) using two tropical plant species, Artocarpus hirsutus and Eupatorium adenophorum against Culex quinquefasciatus mosquito larvae. The synthesized nanoparticles, AH-FeNP and EA-FeNP were characterized by UV–vis spectroscopy, XRD analysis, AFM, HR-TEM, and EDX. Preliminary phytochemical studies and FTIR confirmed the presence of secondary metabolites with hydroxyl, amine, and carbonyl as reducing/ capping agents. Results of the characterization indicated that the plant-mediated Fe-NPs have the size of 29–36 nm and had high crystalline nature. As synthesized nanoparticles have shown considerable larvicidal activity against C. quinquefasciatus with LC₅₀ and LC₉₀ values of 3.316 mg/L and 6.558 mg/L for AH-FeNP, 3.296 mg/L and 7.529 mg/L for EA-FeNP respectively. Furthermore, the result revealed that both FeNPs have distinct concentration-dependent larval mortality. They were toxic at higher concentrations (35 mg/L) and showed 76.66 % mortality of mosquito larvae for AH-FeNP and 73 % for EA-FeNP. The in-situ experiment with both FeNPs and their effect on the mosquito fish Gambusia affinis have shown an improved efficiency of predation and the fishes have no ill effects after being susceptible to both FeNPs for a week. Overall, the result depicts that both AH-FeNP and EA-FeNP have mosquito larvicidal activity especially against larvae of C. quinquefasciatus and the in-vitro exposure study showed that they are less toxic to fishes like G.affinis. The present work also suggests bioaugmented iron nanoparticles can be contemplated as a futuristic, efficacious and environmentally safe pesticide.