Omnia Abdullah Shehata Hassanein Elkraly,  <br/><br/>
The diversity and impact of bacterial endosymbionts in some agricultural pests / 
 تنوع وتأثير البكتيريا التكافلية الداخلية على بعض الآفات الزراعية 
by Omnia Abdullah Shehata Hassanein Elkraly ; Supervisors Prof.Tahany Abd Elrahman, Prof. Sherif Mohamed Elnagdy, Prof. Hassan Mohamed El-Saadany, Prof. Mona Abdelrahman Elerian Awad. 
 - 72 pages :   illustrations ;  25 cm. +   CD. 
<br/><br/>Thesis (Ph.D)-Cairo University, 2024. 
<br/><br/>Bibliography: pages 69-72. 
<br/><br/> The United Nations Sustainable Development Goals and Egypt Vision 2030 underscore the necessity for sustainable agricultural practices and reduced pesticide use, highlighting the need for environmentally friendly alternatives. Therefore, examining the diversity and impact of insect endosymbionts is essential. This study demonstrates that endosymbiotic bacteria play a crucial role in the physiology and behavior of host insects and have potential applications in sustainable pest management, biotechnology, and eco-friendly bioremediation.<br/>These issues are discussed in detail across three chapters as follows:<br/><br/>Chapter One: First Report of Spiroplasma and Rickettsia in Red Palm Weevil (Rhynchophorus ferrugineus) in Egypt<br/>This chapter examines the facultative endosymbionts associated with sexual reproduction, specifically Spiroplasma, Rickettsia, and Wolbachia, in RPW populations from six locations in Egypt. A phylogenetic analysis of RPW from Egypt was performed to determine the haplotype using the COXI gene. Although Wolbachia is commonly found in arthropods, it was not detected in any RPW samples. This study is the first to report the coexistence of Spiroplasma and Rickettsia in RPW from Egypt. The findings suggest that Spiroplasma is a facultative endosymbiont, while Rickettsia may be a recent introduction or coexists with Spiroplasma. Additionally, the RPW individuals showed a strong genetic link to Saudi Arabian haplotypes, indicating that the infection may have originated there and spread to Egypt, possibly through the internal movement of infected date palms.<br/><br/>Chapter Two: Impact of Gut Microbiota in Red Palm Weevil (Rhynchophorus ferrugineus): Implications for Pest Management, Pesticide Resistance, and Thermal Stress Tolerance<br/>This chapter explores the gut microbiota of RPW, identifying eight bacterial species across three phyla and assessing their impact on host metabolism, pesticide resistance, and thermal stress tolerance. The gut bacteria showed stability across life stages and significantly contributed to the production of metabolic enzymes, including cellulase, xylanase, pectinase, amylase, and lipolytic enzymes, with Bacillus subtilis playing a key role in larval metabolism. Additionally, these bacteria demonstrated the ability to degrade various pesticide families, with Arthrobacter sp. effectively degrading chlorpyrifos. The study highlights the importance of gut bacteria in host fitness and adaptation to thermal stress. These findings suggest that gut bacteria could be leveraged in environmentally friendly pest management strategies, although further research is needed to explore their practical applications in IPM programs. Combining bactericidal compounds with insecticides to target symbiotic gut bacteria and utilizing bacterial isolates for pesticide bioremediation are potential strategies. Mass-rearing initiatives could also benefit from incorporating gut bacteria, and endosymbionts should be considered in ecological models of climate change.<br/><br/>Chapter Three: Influence of Gut Microbiota on Metabolism and Pesticide Degradation in Black Cutworm (Agrotis ipsilon)<br/>The United Nations Sustainable Development Goals and Egypt Vision 2030 underscore the necessity for sustainable agricultural practices and reduced pesticide use, highlighting the need for environmentally friendly alternatives. Therefore, examining the diversity and impact of insect endosymbionts is essential. This study demonstrates that endosymbiotic bacteria play a crucial role in the physiology and behavior of host insects and have potential applications in sustainable pest management, biotechnology, and eco-friendly bioremediation.<br/>These issues are discussed in detail across three chapters as follows:<br/>This chapter examines the facultative endosymbionts associated with sexual reproduction, specifically Spiroplasma, Rickettsia, and Wolbachia, in RPW populations from six locations in Egypt. A phylogenetic analysis of RPW from Egypt was performed to determine the haplotype using the COXI gene. Although Wolbachia is commonly found in arthropods, it was not detected in any RPW samples. This study is the first to report the coexistence of Spiroplasma and Rickettsia in RPW from Egypt. The findings suggest that Spiroplasma is a facultative endosymbiont, while Rickettsia may be a recent introduction or coexists with Spiroplasma. Additionally, the RPW individuals showed a strong genetic link to Saudi Arabian haplotypes, indicating that the infection may have originated there and spread to Egypt, possibly through the internal movement of infected date palms.<br/>This chapter explores the gut microbiota of RPW, identifying eight bacterial species across three phyla and assessing their impact on host metabolism, pesticide resistance, and thermal stress tolerance. The gut bacteria showed stability across life stages and significantly contributed to the production of metabolic enzymes, including cellulase, xylanase, pectinase, amylase, and lipolytic enzymes, with Bacillus subtilis playing a key role in larval metabolism. Additionally, these bacteria demonstrated the ability to degrade various pesticide families, with Arthrobacter sp. effectively degrading chlorpyrifos. The study highlights the importance of gut bacteria in host fitness and adaptation to thermal stress. These findings suggest that gut bacteria could be leveraged in environmentally friendly pest management strategies, although further research is needed to explore their practical applications in IPM programs. Combining bactericidal compounds with insecticides to target symbiotic gut bacteria and utilizing bacterial isolates for pesticide bioremediation are potential strategies. Mass-rearing initiatives could also benefit from incorporating gut bacteria, and endosymbionts should be considered in ecological models of climate change.<br/>This chapter demonstrates the potential of gut bacteria in BCW for sustainable pest management and biotechnological applications. Gut bacteria in BCW larvae from Ismailia produce lipolytic and proteolytic enzymes and can degrade various polysaccharides, including cellulose, xylan, pectin, and starch. Variations in gut microbiota composition significantly impact BCW metabolism. The bacteria also exhibit pesticide degradation capabilities, suggesting a role in pesticide resistance. Brachybacterium conglomeratum and Glutamicibacter sp. were examined for their effects on metabolism and chlorpyrifos degradation, both individually and in consortia. The study found that bacterial consortia are more effective than individual isolates in breaking down polysaccharides, emphasizing the need to avoid antagonistic interactions within consortia. Although Wolbachia, Spiroplasma, and Rickettsia were absent in BCW, the findings underscore the potential of gut bacteria for IPM and bioremediation. Future research should focus on combining pesticides with bactericidal substances to eradicate gut endosymbionts and on using gut microbes for large-scale insect production and environmental management.  تناولت رسالة الدكتوراه التى قامت بها الطالبة تنوع وأهمية البكتريا التكافلية الداخلية في مكافحة الآفات الزراعية، حيث تلعب هذه البكتيريا دورا محوريا في مكافحة الآفات بطريقة مستدامة وصديقة للبيئة، وأثبتت قدرتها على تحلل المبيدات الحشرية وتحسين مقاومة الآفات للإجهاد الحراري بالآضافة إلى أهميتها في تحسين الهضم. وأحسب أن نتائج الرسالة سوف تضيف الجديد في هذا المجال كما ان الطالبة قد بذلت الجهد الوفير للوصول إلى النتائج. هذه الرسالة متكاملة مكونة من ثلاث فصول تمت كتابتها ومناقشتها بشكل متكامل وموضوعيز ولقد أجادت الطالبة في المناقشة العلنية، إضافة إلى نشر نتائج الرسالة في ثلاثة أبحاث في مجلات علمية متخصصة ومرموقة ذات معامل تأثير عالي.  <br/>أجرت الطالبة هذه الرسالة بهدف دراسة تنوع وتأثير التعايش الداخلي للبكتيريا التكافلية مع الآفات الزراعية وأوضحت النتائج أهمية كبيرة لهذه البكتيريا في العمليات الأيضية وسلوك الحشرات المضيفة، وهذا بلإضافة إلى استخداماتها المحتملة في مكافحة الآفات واستصلاح البيئة الملوثة بالمبيدات وذلك بطرق التكنولوجيا الحيوية والصديقة للبيئة. بناءاً علي ما تقدم فقد حققت هذه الرسالة الهدف المنشود منها، واستوفت الأبحاث المقدمة متطلبات درجة الدكتوراه. <br/>أثبتت الدراسات التى قامت بها الباحثة القدرة الموجودة للبكتريا المتعايشة داخل الحشرات على تحليل المبيدات الحشرية وبالتالي يمكن لهذه البكتيريا ان تكون مفيدة لتطوير استراتيجيات المعالجة البيولوجية للمبيدات صديقة للبيئة المستخدمة في برامج الإدارة المتكاملة للآفات. كتبت الرسالة بلغة علمية سليمة وخططت تجاربها بطريقة سلسة ونفذت بدقة وعلى أساس علمي سليم واستخدمت الطرق العلمية الكفوءة والحديثة وكل هذا أدى إلى نتائج سليمة ومؤكدة ومؤيدة بالعديد من المراجع الحديثة وتم نشرها في مجلات علمية مرموقة ذات معامل تأثير عالي.  
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<br/><br/><br/>Text in English and abstract in Arabic & English. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Agricultural pests<br/>الآفات الزراعية
<br/><br/><label>Subjects--Index Terms: </label>Agrotis ipsilon  Black cutworm,  Cellulose Degradation  Coexistence  Date palm  Endosymbiotic bacteria  Gut bacteria  Insecticide degradation  Metabolism 
<br/><br/><label>Dewey Class. No.: </label>632.7