| 中文摘要 | 第5-7页 |
| Abstract | 第7-8页 |
| Abbreviations | 第12-17页 |
| CHAPTER I Literature Review | 第17-34页 |
| 1.1 Cotton bollworm (Helicoverpa armigera), the challenging pest | 第17-25页 |
| 1.1.1 Distribution and pest status of H. armigera | 第17-18页 |
| 1.1.2 Biology of H. armigera | 第18-23页 |
| 1.1.3 Management tactics of H. armigera | 第23-25页 |
| 1.2 Origin and function of Bacillus thuringiensis insecticidal crystal proteins | 第25-29页 |
| 1.2.1 Discovery of B. thuringiensis | 第25页 |
| 1.2.2 Mode of action of Bt | 第25-26页 |
| 1.2.3 Bt applications in agriculture | 第26-27页 |
| 1.2.4 Evolution of resistance to Bt Cry toxin in H. armigera | 第27-29页 |
| 1.3 Role of gut microbial communities in insects | 第29-31页 |
| 1.3.1 Bacterial community composition in larval gut of H. armigera | 第30-31页 |
| 1.4 Effect of antibiotics on insect gut microflora in the pathogenicity of Bt | 第31-33页 |
| 1.4.1 Role of antibiotics in microbial community composition | 第31-32页 |
| 1.4.2 Influence of antibiotics on pathogenicity of Bt | 第32-33页 |
| 1.5 Objectives | 第33-34页 |
| CHAPTER II Biological activity of Cry1Ac protoxin against H. armigera strains | 第34-40页 |
| 2.1 Introduction | 第34页 |
| 2.2 Materials and methods | 第34-35页 |
| 2.2.1 Insect strains and Cry1Ac toxin | 第34-35页 |
| 2.2.2 Bioassays of variation in susceptibility of H. armigera strains to Cry1Ac | 第35页 |
| 2.2.2 Statistical analysis | 第35页 |
| 2.3 Results | 第35-38页 |
| 2.3.1 Intrinsic toxicity of Cry1Ac protoxin to larvae of different H. armigera strains | 第35-38页 |
| 2.4 Discussion | 第38-40页 |
| CHAPTER III Effect of antibiotics on midgut microorganisms in different H. armigera strains | 第40-45页 |
| 3.1 Introduction | 第40页 |
| 3.2 Materials and methods | 第40-41页 |
| 3.2.1 Effect of antibiotics on midgut microflora in different H. armigera strains | 第40-41页 |
| 3.2.2 Statistical analysis | 第41页 |
| 3.3 Results | 第41-43页 |
| 3.3.1 Effect of antibiotics on midgut microorganisms in different H. armigera strains | 第41-43页 |
| 3.4 Discussion | 第43-45页 |
| CHAPTER IV Effect of different antibiotics on toxicity of Cry1Ac in three H. armigera strains | 第45-52页 |
| 4.1 Introduction | 第45页 |
| 4.2 Materials and methods | 第45-46页 |
| 4.2.1 Effect of different antibiotics on toxicity of Cry1Ac in three H. armigera strains | 第45-46页 |
| 4.2.2 Statistical analysis | 第46页 |
| 4.3 Results | 第46-50页 |
| 4.3.1 Evaluation of different antibiotics on toxicity of Cry1Ac towards larval mortality of H.armigera | 第46-48页 |
| 4.3.2 Evaluation of different antibiotics on toxicity of Cry1Ac towards larval growth weight ofH. armigera strains | 第48-50页 |
| 4.4 Discussion | 第50-52页 |
| CHAPTER V Effect of different concentrations of antibiotic cocktail on toxicity of Cry1Ac towardsthree H. armigera strains | 第52-59页 |
| 5.1 Introduction | 第52页 |
| 5.2 Materials and methods | 第52-53页 |
| 5.2.1 Effect of different concentrations of antibiotic cocktail on toxicity of Cry1Ac towardsthree H. armigera strains | 第52页 |
| 5.2.2 Statistical analysis | 第52-53页 |
| 5.3 Results | 第53-57页 |
| 5.3.1 Effect of different concentrations of antibiotic cocktail on insecticidal toxicity of Cry1Acagainst H. armigera | 第53-55页 |
| 5.3.2 Effect of different concentrations of antibiotic on biological activity of Cry1Ac in larvalweight against H. armigera | 第55-57页 |
| 5.4 Discussion | 第57-59页 |
| CHAPTER VI Effect of antibiotics on midgut bacterial composition of H. armigera strains due totoxicity of Cry1Ac | 第59-92页 |
| 6.1 Introduction | 第59-60页 |
| 6.2 Materials and methods | 第60-63页 |
| 6.2.1 Effect of antibiotic on midgut bacterial composition of H. armigera strains due to toxicityof Cry1Ac | 第60页 |
| 6.2.2 Larval midgut dissection | 第60-61页 |
| 6.2.3 DNA extraction | 第61页 |
| 6.2.4 PCR amplification and MiSeq sequencing of 16S rRNA genes | 第61-62页 |
| 6.2.5 Sequence analysis | 第62页 |
| 6.2.6 Statistical analysis | 第62-63页 |
| 6.3 Results | 第63-87页 |
| 6.3.1 Bacterial community composition associated with larval midgut of third instar H.armigera populations | 第63-66页 |
| 6.3.2 Bacterial community composition associated with larval midgut of H. armigera strainsacross different samples | 第66-72页 |
| 6.3.3 Effect of antibiotics on bacterial community composition of 96S due to Cry1Ac | 第72-75页 |
| 6.3.4 Effect of antibiotics on bacterial community composition of BtR due to Cry1Ac | 第75-79页 |
| 6.3.5 Effect of antibiotics on bacterial community composition of FS due to Cry1Ac | 第79-84页 |
| 6.3.6 Comparison in diversity of gut microflora due to antibiotics and Cry1Ac among H.armigera strains | 第84-87页 |
| 6.4 Discussion | 第87-92页 |
| Chapter VII Summary | 第92-95页 |
| References | 第95-113页 |
| Acknowledgments | 第113-115页 |
| Author Biography | 第115-116页 |
| Appendix | 第116-121页 |
