臺灣地區新入侵煙草粉蝨 Q 型生物小種族群遺傳結構與入侵源之研究

Abstract

煙草粉蝨 (Bemisia tabaci) 被列為世界百大入侵生物種之一，造成農業和經濟上嚴重的危害。目前世界上共訂名超過 26 型生物小種。最近研究指出 Q 型生物小種近年來隨著聖誕紅迅速的擴散至世界各地。入侵臺灣的 Q 型生物小種於 2006 年 2 月，首度於臺南的亞洲蔬菜研究發展中心發現。在 791 筆臺灣地區的採集資料中，僅在 7 個聖誕紅的溫室內發現到 Q 型生物小種，推測目前還是屬於入侵的初期。本研究探討入侵來源具有重要的意義，可做為檢疫工作上的依據，加強檢測由特定管道所進口的花卉，預防 Q 型生物小種的再次入侵。親緣地理學之研究，利用粒線體 COI 序列做為遺傳標記，探討煙草粉蝨的 Q 型生物小種，在世界各地的遺傳差異及擴散途徑。建構最小跨度網狀圖，發現 Q-related 型生物小種起源於中、西非洲，而 Q 型生物小種起源於歐洲和亞洲交界處，並以自然擴散的方式進入歐洲，而入侵世界各地的 Q 型生物小種源自於歐洲，推測是藉由人類貿易行為擴散。利用 12 個微衛星基因座 (microsatellite loci)，研究煙草粉蝨 Q 型生物小種族群的遺傳結構和親緣關係，發現臺灣地區的 Q 型生物小種族群可能來自兩次以上的入侵。桃園復興的族群呈現獨特的遺傳結構，顯示溫室內的族群來自一個單一的入侵源。根據隔離分化模式的分析，臺灣地區其他溫室內各族群基因交流頻繁，推測是隨著種苗交換，而在各個溫室之間擴散，使遺傳分化差異小。因此防治策略上，要加強歐洲進口花卉的檢疫，亦要注意種苗交換的問題，防止 Q 型生物小種在臺灣地區的溫室之間迅速擴散。

The sweetpotato whitefly, Bemisia tabaci, is among the top 100 invasive pests in the world. This species causes serious agricultural damages in many countries. More than 26 biotypes have been detected worldwide. Recently, biotype Q was reported as a new invasive pest globally which has spread throughout the world with the trade of poinsettia (Euphorbia pulcherimma). In 2006, biotype Q was first recorded at the World Vegetable Center in Tainan, Taiwan. After wards, 791 samples were collected in Taiwan. Biotype Q was found in 7 poinsettia greenhouses, but not in the field. I hypothesized that it is in the early stages of invasion. Determining the origin of this invasion is important for importing quarantine. This study provides information for eradication program, and further introductions and reinvasions will hopefully be avoided by applying intensive quarantine regulations on possible invasion routes. Using mitochondrial cytochrome oxidase I (COI) sequences as a molecular marker to study phylogeography, I explored genetic differences and dispersal patterns of B. tabaci biotype Q in the world by reconstructing a minimum spanning network. The origin of biotype Q-related biotypes was in Central and West Africa. However, the origin of biotype Q was somewhere between Europe and Asia, and then it spread into Europe by natural dispersal. Recent invasion events in the world of biotype Q were from Europe. This suggests that it spread by human trade. Moreover, I applied 12 microsatellite loci by means of multiplex polymerase chain reaction (PCR) to investigate phylogenetic relationships and the population structure of B. tabaci biotype Q populations. Results suggest that there were at least 2 invasions of Taiwan. The genetic structure of the Fusing population (Taoyuan County, northwestern Taiwan) possesses molecular characteristics, suggesting that the population initiated from an independent invasion. Furthermore, great gene flow and slight genetic differentiation among populations in Taiwan were shown by violating the isolation by distance expectation. The migration of individuals between greenhouses may be caused by the movement of poinsettias between greenhouses and other human activities. The program of pest management should prescribe the plantlet trade regulation to avoid further dispersal of B. tabaci Q biotype among greenhouses in Taiwan.