應用台灣本土病原真菌防治入侵之小花蔓澤蘭之探討

Abstract

小花蔓澤蘭(Mikania micrantha)為菊科，多年生藤蔓類雜草，原產於中南美洲，1970年代被引入台灣作為綠色植被，但由於其強勁生長勢、高繁殖力又富於攀爬，導致小花蔓澤蘭纏勒之農林作物被遮蔽，無法行光合作用而枯死，對本地之農林生態系造成嚴重危害。台灣目前之防治方法主要為人工物理伐除或化學性殺草劑之施用；此外，在生物防治，如利用植食性昆蟲:蔓澤蘭綿蚜(Aleurodaphis mikaniae)、大麗燈蛾(Aglaomorpha histrio formosana )及香澤蘭癭實蠅(Cecidochares connexa)亦被探討其用於生物防治之可行性。另外，印度、台灣、南大洋洲巴布亞新幾內亞(Papua New Guinea)，由原產地引進銹病菌天敵(Puccinia spegazzinii)，進行古典生物防治(classic biocontrol)。台灣於2007年自英國CABI(Commonwealth Agricultural Bureau International)引進Puccinia spegazzinii，測試其寄主專一性後即施放此銹病真菌性天敵，至今銹病菌已於野地存活並建立族群，並侵染中南部九縣市之小花蔓澤蘭，其有效性追蹤仍在進行中。另一方面，為進行綜合防治，擬利用本地之真菌性天敵協力加乘作用，以進行淹沒式生物防治(inundative biocontrol)，遂進行調查、分離、鑑定本地可寄生於小花蔓澤蘭之真菌性天敵，依柯霍式準則 (Koch’s postulates) 於實驗室、溫室進行病原性以及寄主專一性檢測。目前研究顯示所分離數株小花蔓澤蘭之病原真菌，如Alternaria tenuissima、Cercospora coniogrammes、Phoma multirostrata及Lasiodiplodia pseudotheobromae等對小花蔓澤蘭具病原性，若進一步證實其具寄主專一性，則將探討此本土寄生性真菌其生理特性、劑型最佳化，以供生物防治使用。

Mikania micrantha, an invasive weed originated from the southern America, was initially introduced into Taiwan around 1970 as cover vegetation. However, due to the highly competitive colonization capacity and entangling capability, M. micrantha would prevent the photosynthesis of the invaded agro-forest crops, leading to host death and severe deterioration of the eco-balance. In the past, physical slash or chemical herbicides were the major control measures used to control the invasive weed in Taiwan. In other aspects, the potential of several Mikania specific feeding-insects, such as mikania thrip ( Aleurodaphis mikaniae)、lamp moth (Aglaomorpha histrio formosana) and gall fly(Cecidochares connexa), have been investigated for biocontrol in Malaysia and Taiwan. In addition, more recently, Mikania parasitic rust Puccinia spegazzinii has been introduced from UK, CABI(Commonwealth Agricultural Bureau International) into India, Papua New Guinea and Taiwan for classic biocontrol since 2005 thereafter. Currently, the population of the rust released in Taiwan has been established and infected the Mikania weed in nine counties in central and southern Taiwan. The biocontrol efficacy of the rust P. spegazzinii in Taiwan is under surveillance and monitering. Attempt to integrate the control of Mikania weed by local fungal pathogens, by an inundative biocontrol method to enhance the biocontrol efficacy, we conducted survey, isolation and characterization of the native fungal pathogens by traditional morphological characteristics and molaculer markers. Furthermore, via Koch’s postulates, we proved the pathogenicity of several obtained fungal pathogens, ie. Alternaria tenuissima, Cercospora coniogrammes, Phoma multirostrat aand Lasiodiplodia pseudotheobromae by a detached leaf inoculation method and seedling inoculation in laboratory or in greenhouse. The host specificity of these fungal pathogens torward Mikania weed will be tested and formulation will be further optimized for field application to control the invasive weed.