| Summary: | 碩士 === 國立中興大學 === 昆蟲學系 === 93 === The objective of this study is to investigate interactions between plants, phytopathogens, and herbivores. Tomato (Lycopersicon esculentum) was used as the test plant, and tomato mosaic virus (ToMV) and corn earworm (Helicoverpa armigera) were used as phytopathogen and herbivore, respectively. This study focused primarily on the performance of corn earworm which was reared on the tomato leaf that had been infected with ToMV or attacked by corn earworms. The performance parameters, such as feeding preference, oviposition preference, growth rates, consumption rates, and food processing efficiencies, were compared between treatments. The result shows that corn earworm had decreased adult weight, efficiency of conversion of ingested food (ECI), and efficiency of conversion of digest food (ECD) reared on tomato plants inoculated with ToMV. However, no difference was found in the feeding and oviposition preference trial. In contrast, tomato plants which damaged by corn earworm would deter the later corn earworms’ feeding and oviposition. Corn earworm’s approximate digestibility (AD), total consumption (TC), relative growth rate (RGR), and relative consumption rate (RCR) were decreased. In addition, the development duration (DUR) was prolonged in this assay. Furthermore, after attacked by ToMV and corn earworm, plant chemistry was analyzed at different time intervals. Results revealed that ToMV infection and corn earworm injury can increase host plant’s peroxidase and polyphenol oxidase activity, respectively. Besides, both ToMV and corn earworm would alter host plants’ soluble and non-soluble carbohydrate concentrations. Based on the chemical analysis results, we found that corn earworm’s performance may be affected by host plant chemistry. Overall, insect injury has stronger effect on plant chemistry and corn earworm’s performance than virus infection.
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