- 學位論文
六種造林樹種植食作用及印度紫檀受 黯斑棕卷裙裳蛾危害之評估
Herbivory of Six Plantation Species and the Assessment of Damage on Pterocarpus indicus Willd. Caused by Plecoptera reflexa Guenée
摘要
本研究主要目的在了解台灣平地造林樹種之植食作用，以及一種裳蛾科昆蟲(Erebidae)黯斑棕卷裙裳蛾(Plecoptera reflexa Guenée)對於印度紫檀(Pterocarpus indicus Willd.)取食危害之評估，並了解植食程度對林木碳吸存效益之影響。試驗地位於屏東萬隆農場，屬熱帶氣候地區，本研究選擇六種平地造林樹種，包括印度紫檀、波斯皂莢(Cassia fistula L.)、水黃皮(Pongamia pinnata (L.) Pierre)、台灣櫸(Zelkova serrata (Thunb.) Makino)、無患子(Sapindus mukorossii Gaertner)及茄苳(Bischofia javanica Blume)。試驗從2012年11月開始至2013年12月為止，觀察植食作用之月變化；另於2013年4月至6月期間，於試驗地採集黯斑棕卷裙裳蛾各齡期幼蟲於生長箱中飼養，觀察量測幼蟲各階段發育日數及體重與幼蟲各齡期食葉量及食葉量百分比。本研究分析影響植食作用的葉部四種特性，包括：葉部氮濃度、碳氮比、全酚類化合物濃度及葉片硬度，發現於不同樹種間葉部四種特性皆有顯著差異，但僅有葉部全酚類化合物濃度及葉片硬度於不同月份間有顯著差異。本研究以葉面積損失比率量化植食作用之程度，發現葉面積損失比率在月份間及樹種間皆有顯著差異，於剛萌發幼葉時較低，隨葉片逐漸成熟而快速增加，主要集中於5-9月期間；各樹種葉面積損失比率年平均由高至低依次為印度紫檀(11.2%)、茄苳(7.6%)、波斯皂莢(6.7%)、水黃皮(4.9%)、台灣櫸(4.5%)及無患子(1.4%)。總合各樹種葉面積損失比率之月平均，求得屏東萬隆農場此六種樹種2013年之總植食程度年平均值為5.42%。由各樹種葉部特性與葉面積損失比率之相關性分析中發現，與各樹種受植食程度相關之葉部特性皆不相同，故不同樹種採取防禦策略不同，推測波斯皂莢所採取的防禦策略為機械防禦，印度紫檀、茄苳及台灣櫸所採取的防禦策略為化學防禦。依本試驗選定的葉部特性無法推測水黃皮與無患子為何種防禦方式。環境因子對植食作用之影響，在不同樹種間亦有差異，結果顯示：溫度與雨量為影響植食作用最重要的因子。本研究發現黯斑棕卷裙裳蛾可於一個月內完成一世代之生命周期，且於試驗地內族群數量龐大。黯斑棕卷裙裳蛾幼蟲體重於幼蟲期1-3齡時，成長緩慢，而於4-6齡時，快速成長，更於終齡時，大幅增加其體重。各齡期幼蟲之食葉量與體重成長趨勢相似，隨著齡期增長而逐漸增加食葉量比重，並於終齡時，大幅增加其食葉量，顯示終齡為黯斑棕卷裙裳蛾幼蟲危害印度紫檀的主要時期，未來應再持績監測並進一步對其生活史與寄主植物的研究，以期評估黯斑棕卷裙裳蛾對印度紫檀二氧化碳吸存量的長期影響。
並列摘要
In order to understand the effect of herbivory on plantation forest CO2 sequestration. The main purpose of this study is to explore the herbivory of six plantation species and to assess the feeding damage on Pterocarpus indicus Willd. caused by Plecoptera reflexa Guenée (Erebidae). The experiments started from November, 2012 to December, 2013. We selected six plantation tree species, including P. indicus, Cassia fistula L., Pongamia pinnata (L.) Pierre, Zelkova serrata (Thunb.) Makino, Sapindus mukorossii Gaertner and Bischofia javanica Blume to investigate the herbivory of tropical plantation species in Wan-Long Farm in Pingtung County. We also collected P. reflexa larvae and reared them in the growth chamber to observe the number of days and weight of larvae at various developmental stages, the gross leaf consumption and distribution of leaf consumption of each instar larva during the period from April to June, 2013. On the four leaf characteristics, including leaf nitrogen concentration, C: N ratio, total phenol concentration and leaf toughness, there were significant differences among species, but only total phenol concentration and leaf toughness were significantly different among months. The leaf area loss was used to evaluate the extent of herbivory. There were significant differences in leaf area loss among months and species. Leaf area loss occured mainly during the period from May to September. It was quite low during germination stage, and increased rapidly afterward. The annual average of leaf area loss was 11.2% for P. indicus, 7.6% for B. javanica, 6.7% for C. fistula, 4.9% for P. pinnata, 4.5% for Z. serrata and 1.4% for S. mukorossii. From six tree species, the leaf area loss averaged 5.42%. By the correlation analysis between leaf characteristics and leaf area loss, which indicated that the herbivory on each species was controlled by different leaf characteristics, and therefore different species chose different defensive strategies. Implying that C. fistula adopted mechanical defense, while P. indicus, B. javanica and Z. serrata adopted chemical defense. Whereas we could not speculate what defensive strategy for P. pinnata and S. mukorossii by this six leaf characteristics. Temperature and precipitation are two important environmental factors, their impact on each species is quite different. This study observed that P. reflexa could complete life cycle within a short period of time, and it had large number of population at experimental site. The weights of P. reflexa increase slowly during 1st-3rd instar, but grow rapidly during the 4th-6th instar. In particular, the weight of P. reflexa increase substantially at the end of larval stage. The trend of leaf consumption by P. reflexa increases proportionally with the increase of its weight. The larvae increase the proportion of leaf consumption with the elapse of instar, especially at the end of instar stage, which suggested that P. indicus was damaged mainly by the final instar larvae of P. reflexa. In the future, we should assess the effect of P. reflexa on the CO2 sequestration of P. indicus in long term. We should persist to monitor and continue the research of the life cycle and host plants of P. reflexa.