Population genetics and the origin of new invasive biotype Q of Bemisia tabaci (Hemiptera: Aleyrodidae) in Taiwan
Date Issued
2009
Date
2009
Author(s)
Chiang, Yi-Hsien
Abstract
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.
Subjects
pest
invasive species
poinsettia
COI sequence
microsatellite markers
phylogeography
Type
thesis
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