Stabilization and characterization of Phyllanthus acidus L. leaf synthesized metal nanoparticles and their comparative efficacy as larvicides against three vector mosquitoes

Abstract

The recurring global outbreaks of mosquito-borne diseases and the lack of vaccines, and preventive therapeutic approaches to combat diseases coupled with insecticide resistance, eventually emphasize the necessity of developing biological system-focused mosquito control strategies. In the present study, aqueous leaf extract from the Phyllanthus acidus L. plant was used to synthesize the metal nanoparticles (MNPs) such as silver, copper oxide, iron oxide, and zinc oxide, characterization has been carried out and their efficacies were also tested against the early 3rd instar larvae of the major mosquito vectors. According to analytical characterization, the silver (Ag), copper (CuO), iron (FeO), and zinc (ZnO) NPs had face-centered cubic crystallites with average sizes of 50, 52.33, 40.56, and 79.45nm, respectively. The agglomerated and clustered surface shape of MNPs was confirmed by FE-SEM analysis, and EDX tests were used to determine the fundamental composition of each particle. When exposed to 1, 5, 10, 15, and 20 ppm of metal nanoparticles, the larvicidal activity of silver nanoparticles was found to be superior to that of other nanoparticles demonstrating efficacy in the following order: silver > iron > copper > zinc against the larvae of filarial vector Culex quinquefasciatus, Japanese encephalitis vector Culex vishnui and dengue vector Aedes albopictus. After 72 h of exposure, the AgNPs had very little detrimental impact on the non-targeted organisms (Chironomus sp. larvae), causing 3.33 % of deaths. The exposure of MNPs to control larval body homogenates resulted in a considerable decrease in the key esterase enzymes, namely acetylcholinesterase, α-and β-carboxyl esterase, and GST enzymes. According to the present results, MNPs made from P. acidus leaf extracts have a strong enough negative effect to reduce the prevalence of vector mosquitoes.