Abstract:
Spodoptera litura is a significant polyphagous pest in many countries, causing substantial failure
to numerous vegetable and field crops. The yellow fever mosquito, Aedes aegypti, is accountable
for dengue fever. It is there in more than 100 countries and threatens the health of just about 2.5
billion people. The application of synthetic insecticides in agricultural pest and mosquito control
plan has resulted huge damage to the ecosystem, insect pest resistance and adverse effects on
non-target organisms. Therefore, eco-friendly management tools against lepidopteran pest and
mosquito vectors are a primary concern. In this study, silver nanoparticles (AgNPs) were
synthesized by the leaf extracts of Pavetta indica. The AgNPs were illustrated by UV–vis
spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), and
transmission electron microscopy (TEM) analysis. P. indica - aqueous extract and AgNPs were
tested for their potential larvicidal activity against S. litura and A. aegypti. In addition, we
estimated the biological toxicity of aqueous extract of P. indica and green synthesized AgNPs on
non-target aquatic organisms, Gambusia affinis. The AgNPs was confirmed by the color of the
leaf extract which was altered from light yellow to light-brown within 3 h after the P. indica
extract was added to the AgNO3 solution. The pattern of AgNPs was confirmed through the
presence of an absorption peak at 466.5 nm. XRD patterns of AgNPs showed a high crystalline
nature. TEM analysis exhibited most of the AgNPs were roughly circular and spherical in shapes.
The leaf extract of P.indica exhibited a moderate toxic effect on S. litura after 24hr of exposure
(99.5 and 100% mortality was observed at 750 and 100 µg/mL of leaf extract and AgNPs,
respectively); Nevertheless, the utmost larval mortality was established in the AgNPs (LC50
=38.22 μg/mL). Under laboratory conditions, the AgNPs were greatly toxic against A. aegypti
with the LC50 value was 11.11 μg/mL and the negligible toxicity against G. affinis. On the whole,
the green synthesized AgNPs have potential to be employed as a promising candidate for the
control of agricultural pests and mosquitoes through eco-friendly and cost-effective approaches.
