Each year, mosquito-borne diseases infect nearly 700 million people, resulting more than one million deaths. In this study, we proposed a Metarhizium anisopliae-based method of green synthesis of silver nanoparticles to control the rural malaria vector Anopheles culicifacies. Silver nanoparticles were characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction. In acute toxicity experiments, larvae (I–IV instar) and pupae of A. culicifacies were exposed to M. anisopliae-synthesized silver nanoparticles (15, 30, 45, 60, and 75 ppm). LC50 of silver nanoparticles was 32.8 ppm (I), 39.8 ppm (II), 45.9 ppm (III), 51.9 (IV), and 60.0 ppm (pupa). Lower dosages of myco-synthesized silver nanoparticles have detrimental effects on larval and pupal development of A. culicifacies. EI50 was 14.9 ppm. Overall, this research highlighted that myco-synthesized silver nanoparticles can be proposed as effective tools for eco-friendly control of the rural malaria vector A. culicifacies

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Furthermore, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. In this research, silver nanoparticles (AgNP) were synthesized using the aqueous extract of the seaweed Sargassum muticum. The production of AgNP was confirmed by surface plasmon resonance band illustrated in UV-vis spectrophotometry. AgNP were characterized by FTIR, SEM, EDX, and XRD analyses. AgNP were mostly spherical in shape, crystalline in nature, with face-centered cubic geometry, and mean size was 43-79 nm. Toxicity of AgNP was assessed against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. In laboratory, AgNP were highly toxic against larvae and pupae of the three mosquito species. Maximum efficacy was observed against A. stephensi larvae, with LC50 ranging from 16.156 ppm (larva I) to 28.881 ppm (pupa). In the field, a single treatment with AgNP (10 × LC50) in water storage reservoirs was effective against the three mosquito vectors, allowing complete elimination of larval populations after 72 h. In ovicidal experiments, egg hatchability was reduced by 100% after treatment with 30 ppm of AgNP. Ovideterrence assays highlighted that 10 ppm of AgNP reduced oviposition rates of more than 70% in A. aegypti, A. stephensi, and C. quinquefasciatus (OAI = -0.61, -0.63, and -0.58, respectively). Antibacterial properties of AgNP were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. AgNP tested at 50 ppm evoked growth inhibition zones larger than 5 mm in all tested bacteria. Overall, the chance to use S. muticum-synthesized AgNP for control of mosquito vectors seems promising since they are effective at low doses and may constitute an advantageous alternative to build newer and safer mosquito control tools. This is the first report about ovicidal activity of metal nanoparticles against mosquito vectors.

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