الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Plant-mediated green synthesis is a cutting-edge and expanding resource in the seeking for more environmentally friendly processes. The efficacy of nanoparticle biosynthesis is very promising, and it inspires many research groups around the world to use new methods to manage vectors and pests.
In this study, silver nanoparticles (AgNPs) were synthesized using Artemisia herba-alba plant extract and was tested against an important pest, Spodoptera littoralis larvae. To confirm the physical characterization of AgNPs formation, ultraviolet-visible spectrophotometry, Transmission electron microscopy, X-ray diffraction analyses, particle size and zeta potential analysis, and Fourier transform infrared spectroscopy were used. The particles appeared as spherical particles with sizes ranging from 9.68 to 36.7 nm and a charge of -32.0 mV. XRD analysis showed four obvious peaks corresponding to 111, 200, 220, and 311, which were more intense than the other planes.
Feeding and contact application methods were used to evaluate the larvicidal activity of green synthesized AgNPs against S. littoralis larvae. LC50 and LC90 values of synthesized AgNPs were calculated and varied greatly according to the application method. After 5 days of treatment, the calculated LC50 of applied AgNPs by feeding application was 74.569 ml/ml (soln./ H2O), whereas contact application recorded an LC50 of 27.47 ml/ml (soln./ H2O) after 30 h of treatment. Biochemical alterations and extended effect that followed the applications were investigated. Feeding normal larvae with Ar-AgNPs for five consecutive days or exposing it to LC25 or LC50 of the same compound through contact for 30h produced a significant elevation in both SOD and AChE activity. It is merit noting that, the contact treatment has higher effect than feeding application.
The larval and pupal mortality after treated with LC50 of Ar-AgNPs through feeding or contact were increased compared with control larvae. The pupation rate was reduced in all treatments compared to the control treatment. The percentage of adult emergence significantly decreased to 63.64% in case of feeding compared to 94.83% in the control. Moreover, treatment through contact with LC50 caused a significant reduction in the adult emergence percentage as it recorded 41.67% %, and the highest adult malformation. The treatment with Ar-AgNPs through both feeding and contact application methods caused a significant increase in the larval, pre-pupale and pupal period compared with control, while the adult duration had no significant decreased compared with control duration.
Morphological abnormalities were detected through all stages. Histopathological signs of AgNPs treatment were detected as the destruction of the cuticle layer, disintegration of gut epithelia, and gonad deformation. Our results proved the success of green synthetized NPs application against S. littoralis larvae, which may open new avenues in pest control.