الفهرس 
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Abstract
The present study aimed to prepare SiO2-, ZnO- and CuO-NPs and to evaluate their efficiency against adults of the German cockroaches.
The obtained results can be summarized as follows:
1-Synthesis and characterization of Nano particles:
The SiO2-, ZnO- and CuO-NPs were prepared and the formation of Nanoparticles was demonstrated using UV-Vis spectroscopy and the formed Nanoparticles were characterized by TEM, DLS and ZP.
UV-Vis absorption spectrum of the formed NPs recorded absorption peaks as 350 nm for SiO2-NPs, 368 nm for ZnO-NPs and 668 nm for CuO-NPs.
As shown from TEM, SiO2-NPs had a spherical shape and were well dispersed in a polymer matrix; the particle size range was 5.16-14.72 nm. ZnO-NPs with polymorphic structure and well dispersed; the particle size range was 10.04-39.7 nm. CuO-NPs had a spherical shape with some clusters and the particle size range was 26.50-52.56 nm.
As indicated from DLS, the average particle diameter of synthesized NPs was 129.4 nm for SiO2-NPs, 165.5 nm for ZnO-NPs and 177.1 nm CuO-NPs.
As shown from ZP, The ZP values of synthesized NPs were -37.87 mV for SiO2-NPs, 9.02 mV for ZnO-NPs and -47.74 mV for CuO-NPs. These values mean that, the prepared NPs were stable and cauld be kept away from further aggregation.
2-Insecticidal activity:
Silica, Zinc and Copper, powders and NPs were evaluated for their insecticidal activity against adult German cockroach by contact and feeding methods after 3, 5 and 7 days of treatment.
2.1- Comparative relative efficiency of the tested compounds by contact and feeding methods.
The relative efficacies of the tested NPs by contact method compared with that of the metal powders as reference materials indicated that, SiO2-, ZnO- and CuO-NPs were about 8.44, 13.77 and 13.44 times more effective than the metal powders at the same concentrations. While the relative efficacies of the tested NPs by feeding method compared with that of the metal powders as reference materials indicated that SiO2-, ZnO- and CuO-NPs were about 1.89, 3.02 and 3.1times more effective than the metal powders at the same concentrations.
It was concluded that the adults German cockroach were more susceptible to SiO2-NPs than ZnO- and CuO-NPs. Based on L.C50 values, the feeding method was more effective in controlling cockroaches than the contact method.
2.2- Effects of the tested Nanoparticles on adult weights of the German cockroach.
The results revealed that, the weights of treated adults with tested NPs were decreased after 3 days of treatment by contact and feeding methods. SiO2-NPs induced more significant reduction in weights of treated adults followed by ZnO- and CuO-NPs.
2.3- Adherence of tested NPs to the German cockroach adults:
Scanning Electron Microscopy photographs showed the differences in the distribution of tested NPs on antennae, legs, wings, thorax and abdomen of the treated adults compared with untreated control. SiO2-NPs were more densely coated the cuticle of treated adults than ZnO-NPs and CuO-NPs leaded to some abrasion of the cuticle of treated adults and losing some of scales on insect’s legs. The strong attachment of SiO2-NPs on the cuticle of adults may be due to their small size and large surface area of particles compared to other NPs.
2.4- Stability of the synthesized NanoParticles:
The efficiency of the synthesized NPs after four months of synthesis was evaluated. Results showed that SiO2-NPs at 80 mg caused 100% mortality by contact and feeding methods. While the recorded mortality caused by ZnO-NPs were slightly decreased to 90 and 98% by contact and feeding methods, respectively compared to 92 and 100% at zero time.
Copper Oxide Nanoparticles were less stable than SiO2- and ZnO-NPs. The recorded mortalities were 66.67 and 76% compared with 86 and 100% at zero time by contact and feeding methods, respectively.
3-Biochemical studies:
The biochemical activity of SiO2-, ZnO- and CuO- NPs on adults of the German cockroaches by contact and feeding methods was investigated after 48 hrs of treatment. Results indicated that all of the tested NPs induced a significant reduction in the mean total protein and carbohydrates of treated adults as well as the activity of AchE, while the activity of LDH was increased compared with untreated control.