Green fabricated silver nanoparticles as a new eco-friendly insecticide for controlling stored cowpea bug Callosobruchus maculatus (Coleoptera: Bruchidae)

The stored cowpea bug Callosobruchus maculates F. (Coleoptera: Bruchidae) is a significant pest. The present study involves the synthesis of silver nanoparticles (AgNPs) with the assistance of Cissus quadrangularis stem and their efficacy in controlling C. maculatus, a species of beetle belonging to the family Bruchidae. The confirmation of nanoparticle formation was achieved via UV-visible spectroscopy, while the physical and chemical properties were analysed through the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Zetasizer measurement of the average particle size of AgNPs synthesized using C. quadrangularis stem extract. The morphology of the nanoparticles was predominantly spherical and elliptical, and their range size was determined from 9.23 nm to 19.23 nm through analysis of the TEM images. Aggregates and clusters of particles are generated. The efficacy of C. quadrangularis stem water extract, silver nitrate (AgNO3), and synthesized AgNPs as insecticides against C. maculates was evaluated. The evaluation of the pesticidal effect was conducted through the implementation of antifeedant and filter paper -impregnated methodologies. The study revealed that the efficacy of C. quadrangularis silver nanoparticles (Cq-AgNPs) surpassed that of C. quadrangularis aqueous extract. The aqueous extract exhibited an LC50 value of 5.22 mg/L, while the synthesized Cq-AgNPs demonstrated an LC50 value of 1.87 mg/L. The antifeedant method was utilized to determine the LC50 readings of the aqueous extract, and synthesized Cq-AgNPs, which were found to be 4.01 mg/L, and 1.51 mg/L, respectively. These results suggest that Ag nanoparticles synthesized by C. quadrangularis may be useful in protecting stored grain pests against C. maculates.