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العنوان
Effect of gamma irradiation and nano-formulations of some plant extracts on the cotton leaf worm, spodoptera littoralis /
المؤلف
Salama, Marwa Salah Mohammed.
هيئة الاعداد
باحث / Marwa Salah Mohammed Salama
مشرف / Abd El-Wahab Abd El-Maksoud Ibrahim
مناقش / Nehad Mohamed El- Barkey
مناقش / Magdia Abd El -Rhman Hazaa
الموضوع
Entomology.
تاريخ النشر
2021.
عدد الصفحات
274 p. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
علم الطفيليات
تاريخ الإجازة
5/8/2021
مكان الإجازة
جامعة بنها - كلية العلوم - علم الحشرات
الفهرس
Only 14 pages are availabe for public view

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Abstract

English Summary
The present study was carried out to investigate the toxic and biological effects of some plant extracts (Silybum marianum, Borago officinalis, Moringa oleifera, Azadirachta indica and Bougainvillea glabra) on the cotton leaf worm Spodoptera littoralis. Moreover, the present study exhibited a novel green method for synthesizing and stabilizing spherical shaped silver nanoparticles (Ag NPs) using these tested plant extracts. Aqueous dispersion of highly stable silver nanoparticles were synthesized using gamma radiations with S. marianum and B. officinalis plant extracts as reducing and stabilizing agent. All the synthesized Ag NPs were characterized then evaluated against the 3rd instar larvae of S. littoralis. Additionally, the morphogenetic effect and histological changes in the mid gut tissues by the synthesized Ag NPs were demonstrated.
The obtained results can be summarized as follows:
Ι. Effect of some plant extracts on the 3rd instar larvae of the cotton leaf worm, S. littoralis
1.1. Susceptibility of S. littoralis larvae to the tested plant extracts
The efficiency of the tested plant extracts (S. marianum, B. officinalis, M. oleifera, A. indica and B. glabra) were evaluated as stomic posions against the 3rd instar larvae of S. littoralis. Larvae were exposed to serial concentrations of (12500, 25000, 50000 and 100000 ppm) of each extract.
The results revealed that larval mortality increased with increasing the plant extract concentration and the time after treatment. The highest mortality percentage occurred mainly by S. marianum extract. The toxicity values of the tested plant extracts based on (LC50) were arranged in descending order as follows: S. marianum < Borago officinalis < Azadirachta indica< Moringa oleifera < Bougainvillea glabra.
1.2. Biological activity of the tested plant extracts against the 3rd instar larvae of S. littoralis
The biological effects of the tested plant extracts (LC50) on the 3rd instar larvae of S. littoralis can be summerized as follows:
Only S. marianum extract significantly increased the percentage of pupal mortality as compared with the untreated group. The average of larval pupal period was significantly elongated by all tested plant extracts except M. oleifera. There was a significant reduction in the pupation percent of larvae survived after all plant extracts treatment. The percentage of survival was significantly reduced at all tested plant extracts treatments. Only S. marianum extract significantly reduced the percentage of adult emergence.
The results indicated that no significant difference among the sex ratio of all treatments and the control group was observed. The sex ratio seemed to be skewed to male side in all treated insects. The adult longevity of both males and females resulted from larvae treated with all tested plant extracts was decreased compared with the control treatment. Moreover, a significant decrease in fecundity and egg-hatchability percent was induced by all tested plant extracts.
IΙ. Biosynthesis and characterization of silver nanoparticles
Synthesis of silver nanoparticles (Ag NPs) was carried out using the previous tested plant extracts which act as reducing, stabilizing and capping agents. Aqueous solutions of AgNO3 were reduced by the tested plant extracts for the formation Ag NPs. The biosynthesized Ag NPs were characterized by surface plasmon absorbance. Transmission electron microscopy (TEM) and the dynamic light scattering (DSL) measurements certified the size and the size distribution of the produced Ag NPs; XRD analysis confirmed that the formed silver nanoparticles were completely free from impurities and having a crystalline nature. The scanning electron microscope (SEM) showed that the produced silver nanoparticles were slightly agglomerated, having irregular and spherical shapes. Further investigations were carried out by Fourier Transform Infrared Spectroscopy (FTIR); data indicated abounding of Ag NPs with the tested plant extracts and provided evidence for the presence of possible biomolecules responsible for reducing and capping agent which helps in increasing the stability of the synthesized Ag NPs. All the tested plant extracts had an important role in the reduction of silver nanoparticles. Additionally, highly stable Ag NPs were synthesized using gamma radiations with S. marianum and B. officinalis plant extracts as capping and stabilizing agent. The size of the produced Ag NPs can be changed by controlling the radiation dose and the mixing method of AgNO3 solution with S. marianum and B. officinalis plant extracts (in situ and ex situ irradiation process). DLS and TEM measurements indicated that the size of the synthesized Ag NPs depend on the dose and the irradiation process. The irradiation process was carried out at doses ranged from 10 to 50 kGy; in case of in situ irradiation process the best dose for high reduction of silver ions into nanoparticles with smaller size was 40 kGy at a dose rate of 1.132 kGy/h and when the radiation dose increased to 50 kGy, the reduction of silver ions was decreased, while in case of ex situ irradiation process the best dose was 10 kGy and the size of the produced Ag NPs increased by increasing the radiation dose to 40 kGy. At the radiation dose 50 kGy, the formation of Ag NPs was suppressed.
ΙΙΙ. Biological activity of the synthesized Ag NPs using some plant extracts against the 3rd instar larvae of S. littoralis
The obtained results showed that all the biosynthesized Ag NPs demonstrated a significant increase in the larval mortality percentage by increasing the concentration and the time after treatment. Furthermore, it seems that the toxicity of the tested Ag NPs greatly depends on their particle size, i.e. the small size of nanoparticles induced higher mortality. A significant increase in the pupal mortality percentage was recorded by LC50 of all synthesized Ag NPs except B .glabra Ag NPs compared with the untreated group. The average of larval pupal period was significantly elongated by all tested Ag NPs except B .glabra Ag NPs compared with the control group. There was a significant reduction in the pupation percent at all synthesized Ag NPs compared with that resulted from the untreated larvae. The recorded data showed a significant reduction in the percentage of adult emergence at all synthesized Ag NPs except B. glabra Ag NPs. Moreover, the survival percentage was significantly diminished compared with the control group. The percentage of malformation among the resulted pupae was significantly increased with all synthesized Ag NPs compared with the control group. Meanwhile, there was no significant difference in adult deformity between all treatments and the control group. The sex ratio was not affected by all the tested Ag NPs compared with the control group and the sex ratio among the progeny seemed to be skewed to male side. It was observed that the number of deposited eggs per mated female as well as the egg hatchability percentages were significantly decreased among the different mating combinations through all synthesized Ag NPs compared with the control group. The adult longevity of mated males and females in P1 resulted from larvae treated with LC50 of all synthesized Ag NPs was significantly decreased among the mating combinations compared with the control treatment.
ΙV. Biological activity of S. marianum and B. officinalis Ag NPs prepared under gamma radiations effect against the 3rd instar larvae of S. littoralis
The larval mortality percentage was significantly increased by increasing the concentrations of S. marianum and B. officinalis Ag NPs prepared under gamma radiations effect (40 kGy) as well as the time after treatments compared with the control group. Both S. marianum and B. officinalis Ag NPs (LC50 value) accomplished a significant increase in pupal mortality percentages and elongated the average of larval-pupal period as compared to the control treatment. Furthermore, there was a significant reduction in the percentages of pupation, emergence and survival at both treatments compared with the control group. The percentage of malformations among the resulted pupae and adults were significantly increased at both treatments compared with the control group. No significant difference was found among the sex ratio of insects treated with both Ag NPs in comparison with the control group. The obtained data deliberated that the average number of eggs, egg hatchability percent and the average number of spermatophores per mated females were significantly declined among the different mating combinations at both treatments compared with the control group. Additionally, the adult longevity of both mated and unmated males and females in P1 in case of larvae treated with both Ag NPs was significantly reduced among the different mating combinations at both treatments compared with the control group.
V. Morphogenetic effects:-
The LC50 of all synthesized Ag NPs tested against the 3rd instar larvae of S. littoralis induced some morphogenetic effects such as larval, pupal and adult’s deformities. The exposure to Ag NPs causes demelanization of larval cuticle. As a result, larvae appeared partially or totally bleached due to the lack of melanin pigments. Moreover, all malformed pupae failed to transform to adult stage, also the malformed adults were unable to develop normally and died.
VΙ. Histological studies
The treatment with S. marianum extract, S. marianum Ag NPs and S. marianum Ag NPs prepared under gamma radiations effect induced ultrastructure abnormalities in the larval mid gut of S. littoralis in which vacuolation in the cytoplasm of the epithelial cells was appeared, detachment of the epithelial cells from the basement membrane in some areas, but it was still intact in other in case of treatment with S. marianum extract. In case of treatment with S. marianum Ag NPs, destruction of the epithelial cells and their boundaries, degeneration in the epithelial cell organelles were observed. Severe damage was occurred by the treatment with S. marianum Ag NPs prepared under gamma radiations effect in which some cells were scattered between the epithelial cells and the peritrophic membrane, the mitochonderia appeared swelling with complete cohesion of the cristae, the nucleus of the epithelial cells appeared containing degenerated nucleolus in addition to destroyed nuclear envelop and the chromatin material was degenerated. Moreover, the microvilli became shorter, underwent fragmentation, a decrease in their number and size was apparent, degenerated and disintegrated into the gut lumen and prominent gaps were seen among them in case of all treatments.