Biosystematics of the cecidomyiid forming polymorphic galls on the leaves of Litsea acuminata (Bl.) Kurata

造癭昆蟲與植物長期交互作用下，常發展對其寄主植物、植物組織之專一性，而其引發之蟲癭形態亦常與造癭物種之身分對應，因此有許多研究指出，蟲癭形態可視為造癭昆蟲表型之延伸或判斷造癭物種之依據。於台灣產長葉木薑子葉片曾記錄杯狀及傘狀蟲癭，但於野外調查發現，除上述所提兩種形態之外，尚存在一系列中間型形態，此類變異極大之蟲癭是否為單一造癭物種引發? 引發蟲癭形態變異之機制為何? 則有待釐清。本研究以引發杯狀蟲癭之癭蚋(cup-shaped gall midge，本文以CGM代稱)及引發傘狀蟲癭之癭蚋 (umbrella-shaped gall midge，本文以UGM代稱)做為材料，以分類鑑定、生物學調查及蟲癭形態學比較，檢驗蟲癭形態是否反應造癭物種遺傳特性或其他生物及非生物特性。於分類鑑定方面，結合形態特徵及分子證據，顯示幼蟲胸骨、蛹頭角、雄性生殖器等特徵均相似，且兩類癭蚋之COI遺傳距離差異不超過1.6%，確立為單一物種，並處理為一新種。於生物學方面，兩類癭蚋之生活史並無一致的現象，推論與蟲癭多型性之成因無關；於寄生蜂調查方面，雖然寄生蜂物種及數量受到樣區不同而有差異，但仍可發現UGM之寄生比率(40%以上)高於CGM (20%~40%)；於地理分布調查顯示，CGM遍布台灣全島，而UGM僅分布於台灣中部；於蟲癭形態發育顯示，杯狀蟲癭(6月)發育時間較傘狀蟲癭(8月)早；於植物體分布顯示，兩類蟲癭大部分(88%)分布於葉片背面，於不同年生枝條之著生比率則隨樣區而有所不同，顯示蟲癭於植物體分布狀況與蟲癭形態無直接關連；於蟲癭形態發育時期(10~11月)之溫溼度記錄顯示，杯狀蟲癭均產於日均溫(13.75℃及14.74℃)及日平均溼度 (83.35%及84.42%)較低之環境，而傘狀蟲癭則產於日均溫 (16.74℃及17.58℃)及平均溼度(91.77%及95.77%)較高之環境。綜合結果顯示 (1) 由分子分析、寄生比率、蟲癭形態及地理分布顯示此種癭蚋於各樣區具有分化的趨勢，且各樣區之分化可反應於(三種杯狀及兩種傘狀)蟲癭形態上。此外，由分子資料推測，僅分布於台灣中部且寄生率高之傘狀蟲癭為較原始的蟲癭型式，而於全台分布且寄生率較低的杯狀蟲癭為衍生之蟲癭型式。(2) 寄生比率、兩類蟲癭發育時間、溫濕度記錄及海拔分布等資料均顯示與蟲癭多型性有相關性，並進一步推測溫度、溼度或是溫濕度聯合效應可能為影響蟲癭多型性之重要因子。(3) 蟲癭形態雖可作為造癭物種之判斷依據，但仍需對該造癭物種所引發之蟲癭形態變異有所瞭解，以避免產生誤判造癭物種之結果。The specificity of the host species, plant organ, and morphology of gall inducing insect are the consequences of long term interactions between gall inducing insects and their host plant. Previous studies have suggested that gall morphology could be regarded as the extensions of phenotypes of galling species, and henthforth use as an indication for identifying gallers. The cup-shaped and umbrella-shaped galls on Litsea acminata in Taiwan have been recorded in previous studies. However, there are a series of intermediate forms exist besides cup-shaped and umbrella-shaped galls in our field research. Are these different types of galls induced by a single species? What kind of mechanisms could cause the variation of gall morphology? In this study, cup-shaped gall midge (CGM) and umbrella-shaped gall midge (UGM) were collected for the study of their taxonomy, comparative biology and gall morphology to test whether gall shape reveal the genetic bases of gall inducers and to understand its relationship with other biological and non-biological factors. In the taxonomic study, morphological traits showed that the larval sterna spatuala, pupal apical horn, and male genitalia of CGM and UGM were similar. Besides, the COI distance variation of CGM and UGM was less than 1.6%. It indicates that CGM and UGM are the same species. It is described as a new species here. In the biological studies, life history within and among populations of CGM and UGM varied which suggests that life history were not associate with gall polymorphism. The parasitism ratio of UGM (more than 40%) were higher than CGM (20~30%), even the parasitoid species number and abundance were affected by environmental factors at different sampling areas. In geographical distribution, CGM distributed all over Taiwan wheras UGM could be only found in central Taiwan. The gall developmental time of CGM (June) was earlier than UGM (August) and they both mainly grew on the lower surface of leaves (about 88%). Examination of galls developed on branches of different years showed that it didn't relate to the gall types. The recording of temperature and humidity during the growth phase of galls, October and November, reveals that cup-shaped galls located at the place with lower average temperature (13.75℃and 14.74℃) and humidity (83.35% and 84.42%), while umbrella-shaped galls were located at the place where both average temperature (average 16.74℃and 17.58℃) and humidity (91.77% and 95.77%) were higher. In summarize, (1) The results of molecular analysis, parasitic rate, gall morphology, and geographical distribution, indicate that the gall midge diversifies among different populations of the same species, and the diversification reflects on the morphological variation of each gall type. Besides, the umbrella-shaped gall which distributed only in central Taiwan and with higher rate of parasitism might be the primitive type, and the cup-shaped gall which widely distributed in Taiwan and with lower rate of parasitism would be derived type. (2) The data of parasitism, gall developmental time, altitude, temperature and humidity were related to the gall polymorphism and further inference could be made that temperature, humidity, or hygrothermal effects are important factors affecting gall polymorphism. (3) the overall results suggest that gall morphology may provide a basis for determining species of gall inducers but it is important to understand the variation of gall morphology to avoid misidentification of galling species.目次（含頁碼） 中文摘要...................................................i 英文摘要.................................................ii 目次......................................................iv 表次.......................................................v 圖次......................................................vi 前言.......................................................1 往昔研究...................................................2 一、 造癭昆蟲與蟲癭...................................2 二、 蟲癭多型性概述...................................4 三、 癭蚋分類學.......................................5 四、 癭蚋生態及生物學.................................6 五、 長葉木薑子及其葉片蟲癭研究.......................9 材料與方法..............................................11 研究材料.................................................11 研究方法.................................................12 一、 癭蚋分類處理....................................12 二、 癭蚋生物學調查..................................15 三、 蟲癭形態學記錄......................................16 結果......................................................17 一、 癭蚋分類處理....................................17 二、 癭蚋生物學調查..................................20 三、 蟲癭形態學記錄..................................26 討論......................................................29 一、 CGM及UGM之COI遺傳距離與分子親緣關係探討.......29 二、 蟲癭形態與癭蚋生物學探討........................35 (一) 蟲癭形態與癭蚋生活史之探討..........................35 (二) 蟲癭形態與癭蚋致死因子之探討.......................35 (三) 蟲癭形態與地理分布之探討.......................37 (四) 蟲癭形態與蟲癭發育時間之探討.......................38 (五) 蟲癭形態與蟲癭於植物體分布之探討.............38 三、 多型性蟲癭綜合探討..............................38 參考文獻..................................................40 表........................................................47 圖........................................................57 附錄......................................................7