煙草粉蝨 (半翅目：粉蝨科) 體內番茄捲葉病毒之偵測及其內共生菌之分子變異

Abstract

煙草粉蝨 (Bemisia tabaci (Gennadius)) 是一種泛世界性分佈的農業害蟲，由於其寄主植物範圍廣泛，因此具有多種生物型，並且被認為是一個種群 (species complex) 。在台灣地區，煙草粉蝨有B、An 及 Nauru 三種生物小種。煙草粉蝨透過取食植物汁液、分泌蜜露污染植物和傳播植物病毒危害宿主植物，在台灣地區尤其以台灣番茄捲葉病毒 (Tomato leaf curl Taiwan virus, ToLCTWV) 造成番茄作物的損失最為嚴重。本研究全面採集台灣地區番茄作物上的煙草粉蝨，利用聚合酶連鎖反應自煙草粉蝨偵測 ToLCTWV，並利用專一性引子區別生物小種，結果顯示番茄田間煙草粉蝨98.97% 為B生物小種，偵測出帶有 ToLCTWV 的均為 B 生物小種。利用分子標示進行 ToLCTWV 親緣關係與親緣地理學之研究。遺傳距離分析結果，ToLCTWV 分為台灣東部與西部兩個品系，西部品系內遺傳差異小，東部品系內差異較大。於實驗室進行保毒實驗，試驗結果顯示，B 和 Nauru 生物小種對於 ToLCTWV 的保毒能力相當，而 An 生物小種於取食 ToLCTWV 第十天之後，即無法在其體內偵測到病毒的 DNA。針對煙草粉蝨傳病毒相關內共生菌的研究，本研究自 Nauru 及 B 生物小種增幅得內共生菌 groEL 基因序列，兩者序列相似度為73%。此外，分析多種生物小種主內共生菌 16S rDNA 的結果顯示，煙草粉蝨內共生菌16S rDNA，可能與生物小種及地理分佈有關。

Bemisia tabaci (Gennadius) is a globally distributed insect pest in the field. It has a wide range of host plants and is thought to be a species complex with many biotypes. In Taiwan, biotypes B, An, and Nauru have been recorded. The economic impacts of this insect pest consist of its damage to host plant health by sucking plant juices, its pollution of plants by secreting honeydew, and its transmission of plant viruses. The most serious damage caused by B. tabaci is its transmission of Tomato leaf curl Taiwan virus (ToLCTWV) to tomato plants in Taiwan. In this research, we collected B. tabaci from many tomato fields in Taiwan, and detected the ToLCTWV from B. tabaci by polymerase chain reaction (PCR). At the same time, specific primer sets were used to identify the biotypes of B. tabaci. In this research, 98.97% of the examined B. tabaci specimens were biotype B, and all of viruliferous B. tabaci specimens with the ToLCTWV were biotype B. Moreover, we studied the phylogeny and phylogeography using molecular markers. The results showed that the ToLCTWV can be separated into western and eastern Taiwan “variants”. Genetic distance analysis revealed that the variants of western Taiwan are closely related. On the contrary, genetic distances among variants of eastern Taiwan were more variable. Furthermore, we studied the retention possibility of the ToLCTWV among B. tabaci biotypes, and found that both the B and Nauru biotypes can maintain the ToLCTWV. In contrast, retention of the ToLCTWV by biotype An was weak after 10 days of infection. In the study of symbionts of B. tabaci, we found that sequence similarity of the protective gene against virus particles was 73% between biotypes Nauru and B. Furthermore, phylogenetic analysis of 16S rDNA showed that the primary symbionts were consistently grouped with B. tabaci biotypes and the geographic distribution.