Distribution and Host Range of Cuscuta in Taiwan, Kinmen and Matsu, with Special Reference to Host Preference of C. Japonica Var. Formosana

Abstract

菟絲子屬(Cuscuta)在台灣地區有記錄5個分類群，包括菟絲子(C. australis)、平原菟絲子(C. campestris)、中國菟絲子(C. chinensis)、台灣菟絲子(C. japonica var. formosana)及日本菟絲子(C. japonica var. japonica)。本研究調查菟絲子屬植物在台灣（含離島）及金馬地區的分布及寄主範圍，並進行台灣菟絲子的寄主喜好性觀測。菟絲子自1972年後迄今未在台灣地區再發現；平原菟絲子分布最廣，寄主多達265種；中國菟絲子寄主有36種；台灣菟絲子是台灣特有變種，寄主有182種；日本菟絲子寄主有48種。菟絲子屬的寄主包括蕨類、裸子植物、雙子葉植物及單子葉植物，也包括寄生植物本身，顯示在台灣的菟絲子屬植物對寄主沒有專一性。本研究觀測台灣菟絲子寄主喜好性，證實是有喜好性的。就斷莖寄生試驗結果，台灣菟絲子對寄主青葉楠(Machilus zuihoensis var. mushaensis)形成的吸器數遠多於對馬利筋(Asclepias curassavica)形成的吸器數，也顯示台灣菟絲子是有喜好性的。野外針對台灣菟絲子寄生14種寄主植物進行喜好性觀測，顯示對個別物種如：光果龍葵(Solamum, americanum)及通條樹(Stachyurus, himalaicus)有特別喜好。

There are five taxa of Cuscuta in Taiwan, namely C. australis, C. campestris, C. chinensis, C. japonica var. formosana, and C. Japonica var. japonica, respectively. Of these, C. australis has not been collected since 1972. Distribution and host range of Cuscuta were investigated in Taiwan, Kinmem and Matsu. The host preference of C. japonica var. formosana as also studied. Based on 6-year data from Taiwan, Kinmen and Matsu, we found that C. campestris was widely distributed and had infested 265 species of vascular plants C. chinensis had infested 36 species C. japonica var. formosana had infested 182 species and C. japonica var. japonica had infested 48 host species. Cuscuta showed no host specialization. Its host range included ferns, gymnosperms, dicots, monocots and itself. Based on our survey, Cuscuta japonica var. formosana showed host preference. The number of haustoria of C. japonica var. formosana on Machilus zuihoensis var. mushaensis as more than that on Asclepias curassavica. Observation of the host preference of C. Japonica var. formosana for 14 host species showed that the parasite as most likely to attack Solanum americanum and Stachyurus himalaicus.