在傳統農業中殺蟲劑及殺菌劑被廣泛且高度的使用於防治病蟲害，這些化學合成物質雖顯著提升了農業生產，但同時亦對環境保護造成嚴重的衝擊。相關研究報告指出，在plant growth-promoting rhizobacteria (PGPR)這些不具致病性的根圈細菌處理下，不僅植株之生長表現獲得促進，此外，亦能夠間接誘導植物之防禦反應。透過PGPR誘導出之系統性抗性對地上部的害蟲可能具有防治的效果，進而提升植物之適存度。本實驗之目的為探討Bacillus mycoides之CHT2401、CHT2402和CHR001三菌株對植物生長表現之影響，並進一步探討以不同處理之植物餵食斜紋夜蛾及桃蚜所造成之影響。此實驗所使用之植物為甘藍與青椒，分別將其栽植於以Bacullus mycoides處理過之土壤中，五週後記錄其乾重以比較植株的生長表現。在昆蟲生長發育方面，將斜紋夜蛾及桃蚜限制於植株之葉片上，待其取食一段時間後，記錄斜紋夜蛾之相對生長速率與桃蚜若蚜之發育時間及最終族群之大小。同時將取食前後之處理葉片進行化學防禦物質polypphenol oxidase (PPO)及peroxidase (POD)活性分析。試驗結果指出，經Bacillus mycoides處理過之植株與控制組相較之下顯著擁有較高的生物量和葉面積。然而，取食處理過之植株的斜紋夜蛾並未與控制組有顯著差異；相反的，取食處理過之甘藍的桃蚜，其最終建立出的族群大小顯著較控制組來的大。由於化學防禦物質分析結果沒有顯著差異，故推測兩種昆蟲之表現應是受植株營養差異影響，但尚須針對營養物質作進一步研究。儘管試驗結果並未符合預期，但Bacillus mycoides對於促進植物生長的效果仍有相當的價值存在，未來可針對操作處理進行調整，以期達到害蟲防治之效果。無論這些有益微生物是扮演生物性肥料亦或是生物性殺蟲劑的角色，其在永續農業上皆有相當的發展潛力存在。

In the conventional agriculture system, high applications of pesticides and fungicides were used widely in order to obtain yields as much as possible. Nowadays, the serious pollutions caused by these synthetic chemicals motivated scientists to find other solutions. Based on previous studies, plant growth-promoting rhizobacteria (PGPR) had potential to be the alternatives. These non-pathogenic microbes not only enhance plant growth but may also indirectly trigger the defensive responses of plants. Through the induced systemic resistance (ISR), pests aboveground may be affected negatively and the better fitness of plants is promised. In this study, the effects of three strains of Bacillus mycoides, CHT2401, CHT2402, and CHR001, on plant growth promoting were evaluated. Additionally, the performance of tobacco cutworm (Spodoptera litura) and green peach aphid (Myzus persicae) fed on treated plants were assessed as well. Cabbage and sweet pepper were first sowed in the soil contained each strain, and the dry weight of plants were recorded 5 weeks later. As for insect performance, both cutworms and aphids were restrained on the specific leaves, after two days, the relative growth rate (RGR), nymph development time and final population size of each treatment were recorded, respectively. In the same time, leaves before feeding and leaves after feeding were collected to analyze enzymes activity such as polyphenol oxidase (PPO) and peroxidase (POD). Results demonstrated that plants under bacterial treatments had significant higher biomass and leaf area than those of the control treatment. However, insects fed on bacteria-treated plants did not show any negative effects. In contrast, the bigger population size was built when cabbage was inoculated with B. mycoides. Since there had no significant PPO or POD activity induced, it is assumed that the responses of insect to plant could be influenced by nutrition-related factors. Although these result did not meet the prediction in the beginning, the function of promoting plant growth of these three strains were still valuable. Possibly, with different operating practices, more promising results could be obtained. No matter these beneficial microbes act as biofertilizers or pesticides or both, they should play a significant role in the sustainable agriculture system for sure.

Abstract i
Contents iii
Contents of tables v
Contents of figures vi
Introduction 1
Materials and methods 6
1. Plant culture 6
2. Insect rearing 6
2.1. Green peach aphid 6
2.2. Tobacco cutworm 7
3. Bacterial strains and preparation of bacterial treatments 7
3.1. The source of bacterial strains 7
3.2. Preparation of bacterial suspension and broth 7
4. Effects of Bacillus mycoides on plant growth 8
5. Effects of Bacillus mycoides treated plants on insect performance and
preference 9
5.1. Effects on tobacco cutworm 9
5.2. Effects on green peach aphid 10
6. Chemical analysis 11
6.1. Analysis of protein content 11
6.2. Activity of polyphenol oxidase (PPO) 12
6.3. Activity of peroxidase (POD) 12
7. Statistical analysis 12
Results 14
1. Effects of Bacillus mycoides on plant growth 14
1.1. Plants treated with bacterial strains by seed coating 14
1.2. Plants treated with bacterial strains by soil mixture 14
2. Effects of Bacillus mycoides treated plants on insect performance
and preference 15
2.1. Effects on tobacco cutworm performance 15
2.2. Effects on tobacco cutworm preference 15
2.3. Effects on aphid performance 15
2.4. Effects on aphid preference 16
3. Chemical analysis 16
3.1. Before insect feeding 16
3.2. After insect feeding 16
Discussions 18
Conclusions and future prospects 22
References 23
Table 1. Illustration of 9 different treatments used in this study 28
Table 2. Illustration of the leaves sources of the chemical analysis 29
Figure 1. The design of the preference test of cutworm 30
Figure 2. The cabbage feeding area of 4th instar tobacco cutworms 31
Figure 3. The dry weight of plants under different ST treatments by seed Coating 32
Figure 4. The dry weight of plants under different SM treatments by seed coating 33
Figure 5. The dry weight of plants under different ST treatments by soil mixture 34
Figure 6. Plants treated with different SM treatments by soil mixture 35
Figure 7. The dry weight of plants under different SM treatments by soil mixture 36
Figure 8. The leaf area of plants under different SM treatments by soil mixture 37
Figure 9. The RGR of tobacco cutworm larva when feeding on treated plants 38
Figure 10. The feeding area of 4th instar tobacco cutworms when fed on treated cabbage for two days 39
Figure 11. The responded number of cutworms to differently treated leaves without additional suspension spray 40
Figure 12. The responded number of cutworms to differently treated leaves with additional suspension spray 41
Figure 13. The development time of aphids from 4-day-old nymph to 1-day-old adult when feeding on treated cabbage 42
Figure 14. Effects of different treatments of cabbage on population size of aphids, 5 days after the first birth 43
Figure 15. The responded number of aphids to differently treated leaves without additional suspension spray 44
Figure 16. The responded number of aphids to differently treated leaves with additional suspension spray 45
Figure 17. Polyphenol oxidase activity of cabbage when plants were 4-week-old without insect feeding 46
Figure 18. Peroxidase activity of cabbage when plants were 4-week-old without insect feeding 47
Figure 19. Polyphenol oxidase activity of cabbage when plants were 4-week-old and 4-week-old but treated with cutworm feeding 48
Figure 20. Polyphenol oxidase activity of cabbage when plants were 4-week-old and treated with cutworm feeding 49
Figure 21. Peroxidase activity of cabbage when plants were 4-week-old and 4-week-old but treated with aphid feeding 50
Figure 22. Peroxidase activity of cabbage when plants were 4-week-old and treated with aphid feeding 51

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