Fabrication of green nanoinsecticides from agri-waste of corn silk and its larvicidal and antibiofilm properties

Abstract

The corn silk (CS) is composed of the thread-like stigmas of female inflorescences of Zea mays L. and represents an important waste material from maize crop production that can be recycled in further applications. In this research, the CS was used for the bio-fabrication of Ag nanoparticles (AgNPs) that were evaluated against (I-V) larval instars and pupae of the mosquito vector Aedes aegypti. CS-AgNPs were characterized by UV-Vis spectroscopy, TEM, EDAX, XRD, FTIR, DLS, and zeta potential analysis. Z. mays extract analyzed by gas chromatography mass spectrometry reveals 14 compounds. The larvicidal effectiveness of CS-fabricated AgNPs was 2.35 μg·mL-1 (I Instar) to 6.24 μg·mL-1 (pupae). The field application in water storage reservoirs of both CS extracts and CS-AgNPs (10 × LC50) led to a 68-69% reduction in larval density after 72 h post-Treatment. Ecotoxicological impact of CS-fabricated AgNPs was evaluated on the predatory efficacy of Poecilia reticulata on all the larval instars and pupae of Ae. aegypti. Finally, CS-AgNPs were tested to elucidate its anti-biofilm attributes. The CS-AgNPs at 125 μg·mL-1 showed a biofilm inhibition of 90% on S. aureus and 79% on S. epidermidis. These results support the use of CS-AgNPs for futuristic green alternative to mosquito vector management.