The Effect Of Nano-Pesticides On Cotton Leaf Worm, Spodoptera Littoralis (BOISD) Ghada Ahmed Antar Mohamed

Supervisor: Hussein Anis

Thesis (M.A.)—Nile University, Egypt, 2016.

"Includes bibliographical references"

Contents:
Introduction and Literature Review
1.1 Pests and pesticides
1.1.1 The Cotton leaf worm, Spodoptera littoralis (Boisd.)
1.1.2 Chlorpyrifos
1.1.2.1 Hazards of Chlorpyrifos
1.2 Nanopesticides
1.2.1 Nano-Silver
2.1.2.2 Properties, synthesis of silver nanoparticles and their dynamic in the Environment
Effect of AgNPs against plant pathogenic
AgNPs as an active ingredient for pest control
AgNPs associated with an organic active ingredient for pest control
1.3 Research approach
1.3.1 The aim of work
2.1.1 The objective
Chapter 2. Materials and Methods
2.1 Materials and chemical
2.2 Synthesis, Loading and Optimization of Silver Nanoparticles
2.2.1 Synthesis of the Nanosilver Core Particles:
2.2.1.1 PVP-AgNPs
1.1.2.1 Citrate-AgNPs
1.1.1 Synthesis of PVP-AgNPs and Citrate-AgNPs encapsulated CPM
2.2.3 Studying the effect of time and temperature on the nanocomposites plasmon band
2.3 Characterization of AgNPs, PVP-AgNPs@CPM, Citrate-AgNPs @CPM
2.3.1 Ultraviolet -Visible Absorption Spectroscopy
2.3.2 Transmission Electron Microscopy
2.3.3 Dynamic Light Scattering
2.3.4 Zeta Potential Analysis
2.3.5 Fourier Transform Infrared Spectroscopy
2.4 Bioassay
2.4.1 Rearing technique
2.4.2 Preparation of the test concentrations
2.4.3 Method of application
2.4.4 Data management and statistical analysis
Chapter 3. Results and Discussion
3.1 Synthesis, Optimization and Characterization of the Synthesized Nano-silver Core Particles and Nanopesticides
1.2.2 The PVP-AgNPs and PVP-AgNPs@CPM
3.1.2 Citrate-AgNPs and Citrate-AgNPs@CPM
3.1.3 Effect of Aging on the stability of synthesized AgNPs@CPM
3.1.3.1 PVP-AgNPs and PVP-AgNPs@CPM
1.2.1.1 Citrate-AgNPs and Citrate-AgNPs@CPM
3.1.4 Effect of temperature on the synthesized AgNPs@CPM
3.1.5 Dynamic Light Scattering
3.1.6 Zeta potential
3.1.7 FTIR spectroscopy
3.2 Bioassay
3.2.1 Susceptibility of S. littoralis larvae to AgNPs alone
1.1.1 Susceptibility of S. littoralis larvae to the treatments of CPM alone and the synthesized nanopesticides
3.2.2.1 Effect of tested pesticides on susceptibility of developmental stages of S. littoralis larvae
3.2.2.2 Effect of nanopesticides stability on the susceptibility of S. littoralis larvae
3.2.2.3 Effect of tested pesticides on cumulative mortality of S. littoralis larvae

Abstract:
The facile formulation of PVP and Citrate-coated silver nanoparticles encapsulation chlorpyrifos methyl (PVP-AgNPs@CPM) and (Citrate-AgNPs@CPM) was explored against 2nd and 4th instars of Spodoptera littoralis. The new proposed scheme was developed to enhance the lethal efficiency and minimize the adverse effects to environment in comparison to CPM alone. To best of our knowledge, this is the first study on efficiency of AgNPs encapsulated pesticide against crop pests. The formation of the synthesized AgNPs@CPM was investigated and characterized by using UV-Vis spectroscopy, TEM, DLS, Zeta potential and FTIR techniques. The effects of time and temperature on the synthesized nanopesticides were examined. In addition, the effect of AgNPs@CPM on susceptibility, developmental stages and cumulative mortality of S.littoralis larvae was also studied extensively. Our findings indicate that the synthesized AgNPs@ CPM was more efficient than CPM alone and bulk AgNPs. The highest potency of PVP-AgNPs@CPM and Citrate-AgNPs@CPM were recorded against 2nd larval instar ,at 48h post treatment (PT) of the 1st day post preparation (PP), and their LC50 values were 2.5 , 2.6 ppm (~ 3.8, 3.5 folds as toxic as CPM alone) ,respectively. Both nanopesticides showed enhanced solubility however, they were found to have tendency to aggregate with time. Studying the effect of aging on AgNPs@CPM stability and toxicity has revealed that Citrate-AgNPs@CPM was stable up to 6 weeks and show thermal stability while PVP-AgNPs@CPM was highly aggregated. The toxicity decreased by 1.5, 2.3 folds at 48h PT of 3rd PP, respectively. As aggregation affect Ag ion dissolution which is considered as one of main factors of AgNPs toxicity, we can conclude that, PVP-AgNPs@CPM showed higher efficiency and less persistent thus expected to be safer to ecosystem than Citrate-AgNPs@CPM.
Keywords: Nanopesticides,, Chlorpyrifos methyl, S. littoralis silver nanoparticles, Citrate-AgNPs@CPM , PVP-AgNPs@CPM, Pest control, Encapsulation.

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