環太平洋地區蔥薊馬(Thysanoptera, Thripidae, Thrips tabaci Lindeman)之遺傳變異

Thrips tabaci Lindeman with different characteristics of body color and number of setae are commonly found in imported agricultural products. It is a cosmopolitan pest, and is considered to contain three morphospecies. In this study, both genes of the nuclear internal transcribed spacer 2 (ITS2) region and mitochondrial cytochrome oxidase subunit I (COI) of onion thrips collected from the Pacific Rim area are used in the genetic diversity analysis. For the Pacific Rim countries the greatest difference in COI sequences, more than 2%, is found in the New Zealand population. Two major haplotype groups were found in the statistical parsimony analysis. One is the haplotype from the coastline of the Americas including the USA, Peru, and Mexico, and the other is from west Pacific countries including China, Japan, and Taiwan. The compilation of sequences in this study and those from the genbank indicate that the greatest variability of COI genes is found in the European population, where three distinct phylogenetic lineages can be found. Lineage A constitutes most of the individuals from Europe, those from lineage C definitely come from Europe, and those from the Pacific Rim mostly fall in lineage B which is a cosmopolitan group. For the ITS sequences, the greatest difference, up to 16%, is found in the population of the United Kingdom. The statistical parsimony network suggests that there is a close affinity in haplotypes among the populations of England, New Zealand, and Japan. Genetic analyses of both genes indicate that T. tabaci in Taiwan constitutes only one of the different populations in the world. Thus, the introduction of foreign T. tabaci populations should be prevented to try and reduce their hybridization with local population, which may result in serious economic damage.