| Summary: | 碩士 === 國立中興大學 === 森林學系 === 89 === The main purpose of this study is to investigate the chemical compositions varied in different felling seasons, ages and positions of Moso and Thorny bamboos in relation to insect pest.
The extractives and starch contents of 3-year-old Moso and Thorny bamboos varied with different felling seasons. The tendency of the change was apparently in accordance with the metabolism of these two bamboo species. In different harvesting seasons, the lignin, holocellulose and pentosan contents in bamboos didn''t change too much. During the months of high-extractive-content, the bamboo had relatively higher starch content. Higher starch contents in bamboo are attractive to bamboo borers. The starch content in old bamboo is higher than that of the young one. But the extractives were not truly in the same tendency. Extractives in young Thorny bamboo were higher than those in the old, but in Moso, it might be on contrary.
The variations of extractives and starch contents in various positions of bamboo culm were more complex. During the months of high extractive and starch content, the bottom and middle portion of bamboos would be higher than the top. If during the period of low extractive and starch content, there are no too much difference among these three portions.
Dinoderus minutus (Fabricius) and Lyctus brunneus (Stephens) were the two most common bamboo pests in Taiwan. The tendency of the pest damage to bamboo was markedly affected by its felling season. During the period of February to April and July to August, Thorny bamboo is easily attacked by the insect pests, but for Moso bamboo it was October through March. These damage situations were closely related to the extractives and starch contents during felling seasons, especially the starch content. The severe pests are usually found in the bamboo of high starch content. It is important to choose suitable felling season in order to reduce the pest damage in the future.
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