Biosynthesis of Silver Nanoparticles From Sargassum Muticum Extract and Its Compatibility With Trichoderma Harzianum for Controlling the Tomato Leaf Miner, Tuta Absoluta

A worldwide destructive pest that has an impact on tomato output is the tomato leaf miner, Tuta absoluta. Biosynthesized nanoparticles and entomopathogenic fungi (EFs) are widely recognized for their ability to regulate the development and emergence of this insect pest. The goal of the current investigation was to synthesize, characterize, and evaluate the bio-fabricated silver nanoparticles from the brown alga, Sargassum muticum extract either singly or combined with the locally entomopathogenic fungus (EF), Trichoderma harzianum against T. absoluta. A color change was detected by visual examination of the surface plasmonic band of the biosynthesized AgNPs capped with S. muticum extract, which peaked at 407 nm using UV-Vis spectroscopy. Transmission electron microscopy (TEM) revealed that the AgNPs had a spherical, oval, and hexagonal shape with a nanoscale size of 11 nm. Analysis of fourier transform infrared (FTIR) spectroscopy revealed that multiple molecules were bonded to AgNPs via CH2, C=O, and C=C groups. The zeta potential of prepared silver nanoparticle is -20.6 mV. Energy-dispersive X-ray spectroscopy (EDX) analysis indicate the presence of Ag, C, O2, k, Cl, S, Si, Mg, and Na substances, and Ag was the main element, accounting for approximately 9.08% of mass, as evidenced by an intense signal at 2.983 KeV. The isolated fungus was molecularly identified as T. harzianum T1. The major constituent of the fungal filtrate was 6,8-dibromo-2-(3-pyridyl)-4-phenyl-quinazoline (70.31%). The results showed an overall good insecticidal activity (39.0-92.0% mortality) of the compounds tested when applying individually for three days, with a higher mortality on larvae over pupae. The S. muticum-AgNPs was compatible with conidial suspension or filtrate of T. harzianum T1 with larval mortality percentage of 96.0 or 85.2% 72 h-post treatments. The data collected suggest that these compounds, especially when nanoformulated combined with fungal conidia, could be effectively applied to T. absoluta integrated pest management strategies.