山蘇花葉芽線蟲在台灣之發生

文獻上記載Aphelenchoides fragariae（Ritzmema Bos, 1891）Christie, 1932可造成山蘇花葉斑病，然本省一直未發現此一病原線蟲及其引起之病害。民國89年在三峽地區山蘇花栽培園中，發現類似由線屬造成之葉斑病病徵，而後在嘉義、烏日及東部地區也陸續發現相同病情。從病葉分離病原線蟲，鏡檢後初步鑑定為葉芽線蟲Aphelenchoides spp.。本病原線蟲在直菌Alternaria citri上繁殖良好，生長溫度範圍為8-32°C，最適繁殖溫度則在20-28°C之間，低於4°C與高於36°C的情況下，線蟲則無法存活。病原性測定之結果發現，分離自草莓的葉芽線蟲A. besseyi無法感染山蘇花，而從山蘇花上分離得到之葉芽線蟲則可。殘存試驗顯示，添加山蘇花葉片的處理中，病原線蟲的存活情形明顯優於未添加者，在三個月後仍可分離到少量線蟲。以光學顯微鏡測量病原線蟲各部位的比例長度，與A. besseyi測量範圍上並無顯著差異。利用低溫場掃描式電子顯微鏡觀察病原線蟲之頭部型態（突起）、側區的側線數目（4條）與尾部分岔數目（3-4），確定為A. besseyi，而非文獻上記載引起山蘇花葉斑病之A. fragariae。寄主範圍測試結果顯示，本病原線蟲可以成功的感染水稻、草莓、非洲菫、秋石斛，卻無法感染百合、秋海棠，與文獻上所記載A. besseyi的寄主有些差異。其中值得注意的是，文獻記載A. fragariae於山蘇花上之寄生方式為內寄生，而本省感染草莓及水稻之A. besseyi在大部份之生活史中皆以外寄生方式危害植物，因此A. besseyi在本省能夠感染山蘇花不僅是一個新寄主之發現，其寄生行為之進化現象更具實質意義。本研究之結果初步朝演化的方向解釋其寄生行為的轉變，暫不將其歸類為一新的生物小種。

關鍵字

葉芽線蟲；山蘇花；形態鑑定；生理小種

並列摘要

Aphlenenchoides fragariae(Ritzema Bos, 1891) Christie, 1932, was reported to be a pathogenic species of nematode, causing the disease on fern, but it was not found in Taiwan. In 2000, a new disease on fern was first found in gardens at Chia-Yi and by isolation and identification, it was proven to be a disease caused by foliar nematode – Aphelenchoides spp. The nematode population was maintained by growing on Alternaria citri. The range of growth temperature for the nematode was 8 to 32°C, with the optimal temperature range of 20 to 28°C. Nematodes in diseased leaves on the ground could survive for three months. Results of morphological studies by scanning electron microscopy showed that the fern disease in Taiwan was caused by Aphelenchoides besseyi. The body dimension was similar among the three populations of A. besseyi collected from strawberry and fern plants in San-Shia and Chia-Yi, respectively. A. besseyi from fern plants was pathogenic on other hosts such as rice, strawberry, Africa violet and bailey, but it was non-pathogenic on lily and begonia. However, A. besseyi from strawberry was non-pathogenic on fern plants. Application of nematicides Oxamyl, Abamectin or Mocap was effective in reducing 10% of nematode population, but application of Phenamiphos was ineffective. This is the first report of the fern disease caused by A. besseyi in Taiwan. The occurrence of this disease in Taiwan might be the sign of adaptation during the nematode evolution process.

並列關鍵字

nematode ； fern ； identification ； biological race

國際替代計量

山蘇花葉芽線蟲在台灣之發生

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