Green and facile biosynthesis of silver nanocomposites using the aqueous extract of Rubus ellipticus leaves: Toxicity and oviposition deterrent activity against Zika virus, malaria and filariasis mosquito vectors

- Rubus ellipticus-synthesized Ag nanoparticles were studied by UV-vis spectroscopy, XRD, FTIR, SEM, EDX and TEM
- Potent ovicidal, larvicidal and adulticidal activity was reported on Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus
- Relatively lower toxicity was found on three non-target natural enemies, LC50 ranged from 896 to 2261 μg/mL
- Ag nanoparticles showed high oviposition deterrent activity on the three mosquito species

Botanical-based nanosynthesis has been recently reported as a cheap alternative for mosquito management. In this study, we investigated the synthesis of silver nanoparticles (AgNPs) using the leaf extract of Rubus ellipticus and AgNPs were characterized using UV-vis spectroscopy, XRD, FTIR, SEM, TEM and EDX analyses. The toxicity of R. ellipticus leaf extract and AgNPs was evaluated against eggs, larvae and adults of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. Compared to the leaf aqueous extract, biosynthesized AgNPs showed higher toxicity against the mosquito larvae with LC50 values of 12.50, 13.83 and 15.09 μg/mL, respectively. AgNPs exerted zero hatchability at 60, 75 and 90 μg/mL on A. stephensi, A. aegypti, and C. quinquefasciatus, respectively. Concentrations of 12-60 μg/mL reduced egg laying by gravid females from 72.28 to 91.48%. Maximum adulticidal efficacy was observed for AgNPs, with LD50 values were 21.10, 23.04 and 25.06 μg/mL, respectively. AgNPs were found safer to non-target organisms Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 values ranging from 896 to 2261 μg/mL. Overall, R. ellipticus-fabricated AgNPs acted as effective toxic agents and ovideterrents against three important mosquitoes species, with little harmful effects on non-target aquatic species.

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