Abstract
Thrips tabaci Lindeman is an extensively distributed pest insect that injures a wide range of crops. To investigate the intra-specific genetic diversity of this species, we analyzed an 810 bp region of the mitochondrial cytochrome oxidase gene subunit I (COI). Eight populations from six foreign countries and 18 Japanese populations were tested, and 17 different haplotypes were identified. Apparent differences were found between arrhenotokous and thelytokous strains in their COI sequences. A phylogenetic tree of the COI gene shows two distinct groups. We assume that these two groups correspond respectively to the arrhenotokous strain and the thelytokous strain. Japanese thelytokous types consisted of five haplotypes. Two haplotypes were identified from problematic populations in terms of the greater amount of damage they caused and the development of insecticide resistance. Both haplotypes were also found overseas, suggesting that some strains from overseas may have caused the above-mentioned problems in Japan.
