Intra-specific genetic variation in Thrips tabaci
Toda S1, Murai T2, Morishita M3
1Department of Grape and Persimmon Research, National Institute of Fruit Tree Science, Higashihiroshima, Hiroshima 729-2494, Japan
2Faculty of Agriculture, Utsunomiya University, Utsunomiya Tochigi 321-8505, Japan
3Laboratory of Persimmon and Peach, Fruit Tree Experiment Station, Wakayama Research Center of Agriculture, Forestry and Fisheries, Kokawa Wakayama 649-6531, Japan
Correspondence: toda@affrc.go.jp
Thrips tabaci Lindeman is a widely-distributed pest insect that injures a wide range of crops. In Japan, it is known as a serious pest of Allium. However, this thrips has recently begun for the first time to infest other Japanese crops, such as persimmon and mandarin orange. It has been pointed out that there is genetic differentiation in T. tabaci (Brunner PC et al. 2004. Heredity 93: 364¨C370; Murai T and Toda S. 2002. In: Marullo R, Mound L, editors. Thrips and Tospoviruses: Proceedings of the 7th International Symposium on Thysanoptera, pp. 377¨C378. CSIRO and Universita degli studi Mediterranea di Reggio Calabria). To gain an understanding of the genetic background underlying this phenomenon, we investigated the genetic variation of this species. We collected 6 overseas and 11 Japanese local populations. DNA was extracted from individual female adults and a part of mitochondrial cytochrome oxidase gene subunit I (COI) was amplified. The nucleotide sequences were analyzed by direct sequencing and compared among populations. As a result, four different haplotypes were detected in Japanese populations. Two haplotypes of persimmon-feeding populations differed from the majority haplotype of other Japanese populations and were identical to that detected in overseas populations. However, it is not clear whether or not the persimmon-feeding population is from overseas. In this study, we also analyzed the COI sequence of 10 male adults from two overseas and one Japanese population. Although their sequences showed considerable variation, they formed an independent clade with several females. We presume that this clade consists of arrhenotokous strains and the others are thelytokous strains.
