Green synthesis of metal nanoparticles using leaf extracts of Mammea americana L. (Calophyllaceae) and its efficacy against vector mosquito larvae and non-target organisms

Mosquito vectors pose a significant threat to human society due to their high morbidity rate. In this study, the effectiveness of green-synthesized silver nanoparticles (AgNPs) and copper oxide nanoparticles (CuONPs), derived from Mammea americana L. leaf extracts, was assessed against the 3rd instar larvae of three vector mosquitoes, namely Culex quinquefasciatus, Culex vishnui, and Aedes albopictus. Furthermore, the study characterizes the synthesized nanoparticles through various spectroscopic techniques. Synthesized AgNPs and CuONPs from the M. americana leaves were mostly quasi spherical and oval-shaped, having Surface Plasmon Resonance (SPR) bands at the peaks of 420 nm and 290 nm. When exposed to 0.1, 0.5, 1, 1.5, and 2 ppm of metal nanoparticles, the larvicidal activity of silver nanoparticles was found to be superior to that of copper oxide nanoparticles. The lowest LC50 values for larvicidal and pupicidal activities were calculated as 0.17 ppm and 14.13 ppm against 3rd instar larvae of Cx. quinquefasciatus and pupae of Cx. vishnui, respectively. After 72 h of exposure, both MNPs had no impact on the non-targeted organisms. Both MNPs (AgNPs and CuONPs) exposed larvae showed significant reduction in essential esterase enzymes, specifically acetylcholinesterase, α- and β-carboxyl esterase, and GST enzymes compared to the untreated larvae. The overall findings of this research demonstrated that the AgNPs and CuONPs synthesized from M. americana leaf extracts can act as efficient and eco-friendly natural mosquitocidal agents.