الفهرس 
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Abstract
The Egyptian cotton leafworm, Spodoptera littoralis (Boisduval), is considered one of the economically important insect pests in Egypt and worldwide. Larvae of S. littoralis cause considerable destruction as they feed on leaves, fruiting points, flower buds, and occasionally on bolls. As a result, many control strategies were applied to manage the damage of this pest. Using conventional synthetic insecticides has been a traditional strategy for controlling the Egyptian cotton leafworm. However, the extensive use of these chemical compounds gave rise to many disadvantages, resistance, resurgence, and residues. Finding alternatives to conventional chemical insecticides is challenging for researchers in this context.
Nowadays, there is a trend to use nanotechnology tools in agricultural practices as they balance minimal and maximum pest control, safe concentration, and reduce the cost of pest control. Applying nanotechnology in agriculture assures the objective of clean, safe, and environmentally favorable nanomaterials using biocompatible and nontoxic solvents, biodegradable and biocompatible natural matrices, and energy-efficient and sustainable processes.
Accordingly, the present study aimed to avoid the environmental hazards of extensive amounts of synthetic pesticides. Moreover, the present work studied the possibility of developing a much more effective control method of insecticide in a nano form, which may also lead to decreasing the price of insect pest management programs.
A commercial emamectin benzoate, AgNPs (as a carrier), and nanoform of the tested emamectin benzoate compound were investigated against the 4th instar larvae of the cotton leafworm, S. littoralis for their efficacy under laboratory conditions.
The results showed that the nanoform of EMB+AgNP was the most toxic compound against the 4th instar larvae, as detected from the low value of LC50. Followed by EMB and AgNPs. All tested compounds show instant larval mortality. Results also showed that treatment of 4th instar larvae with LC50 of tested formulae varied effect on some biological parameters. The mean larval duration, pupal duration, pupation percentage, adult emergence rate, female fecundity, and egg fertility were significantly reduced. In addition, results revealed that treatment with sublethal concentrations of tested formulae showed a significant decline in some detoxifying enzymes as an immunological response to treatment. Results showed that the total hemocyte counts were significantly reduced due to treatment.
Moreover, the histopathological changes in the midgut tissues of late 6th instar larvae treated as 4th instar larvae support the obtained biochemical changes results. In addition, results showed the Vg expression showed a non-significant decline due to treatment with EMB compared to control, which indicated a down-regulation in the Vg gene. On the other hand, results showed up-regulation in the Vg expression compared to control due to treatment with AgNPs and EMB+AgNPs. The change in the Vg expression showed a non-significant increase in AgNPs, but it was significantly increased in EMB+AgNPs treatment.