Abstract
To discriminate between arrhenotokous and thelytokous forms of the onion thrips (Thrips tabaci), we developed a simple molecular diagnostic method that uses PCR-RFLP of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Digestion of 490-bp COI amplicons with EcoO109I provided reproductive form-specific RFLP patterns. Using this method, we surveyed the frequencies of the two reproductive forms in 9 Welsh onion fields in Tottori Prefecture. Arrhenotoky dominated in the western area, although 100% of individuals were thelytokous in the eastern area. The COI haplotype of the arrhenotokous individuals was haplotype 1 or 2, which has not previously been found in Japan.
