Anti-cockroach Activities of Biosynthesized Silver Nanoparticles using Petiveria alliacea Extracts

Background This study was conducted with a view to biosynthesize silver nanoparticle (AgNPs) using the root (PaR) and leaf (PaL) extracts of Petiveria alliacea and evaluation of their activities against cockroach which is a major household insect pest. Methods The biosynthesized AgNPs were characterized by UV-Vis spectrophotometry, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). PaR-AgNPs and PaL-AgNPs were tested at three different concentrations (1, 5, 10% v/v) using two mode of applications (fumigant and contact toxicity) at different hours of exposure. Results The peak absorbance of the AgNPs occurred at the wavelengths of 426 and 442 nm for PaL-AgNPs and PaR-AgNPs respectively with the brownish colloidal solutions. FITR peaks indicated the presence of alkenes (= C-H-), esters (C = O), amides (N-H), and aliphatic amines (C-N) in the samples, while the TEM and EDX analyses showed the presence of silver in the AgNPs colloidal solution with the spherical nanoparticles ranging from 5.95–76.19 nm in size. Both AgNPs exhibited insecticidal action against adult cockroach, with the fumigant application exerting killing faster than the contact application. While 80–90% mortality of cockroach was observed through fumigant, the contact application resulted to 40–50% mortality after three hours of exposure at 10% v/v. These show that the effectiveness of the bio-fabricated AgNPs formulations depended on the concentrations, hours of exposure, and mode of application. Conclusion Therefore, silver nanoparticles based insecticides can be incorporated into the pest management program of household pests especially cockroach.