Abstract: 【Aim】 The purpose of the paper is to determine the distribution of Bemisia tabaci biotypes and their infection status of tomato yellow leaf curl virus (TYLCV) in Xinjiang, northwestern China. 【Methods】 Mitochondrial cytochrome oxidase I (mtDNA COⅠ) gene sequences and two pairs of primers (TYLCVF/TYLCV-R and PA/PB) were utilized to identify biotypes of B. tabaci and to detect the status of carrying tomato yellow leaf curl virus (TYLCV). 【Results】 The results showed that samples collected from Shihezi city, Bole city, Yopurga county, Zepu county, Karghalik county, Shache county, Karakash county, Hotan city and Hotan county belong to the B biotype, and these samples showed 100% identity of the 720 bp COⅠ sequences examined with the references. Samples from Aksu city, Hami city, Shanshan county, Urumqi city, Karamay city and Yining city belong to the Q biotype, and their COⅠ sequence identities were 99.9%-100%. Both B biotype and Q biotype occurred in Turpan and Korla cities. TYLCV were detected in samples collected from Yining city, Urumqi city, Shanshan county, Hami county, Aksu city, Korla city, Shache county, Hotan county and Karakash county, and all these areas were in high risk of TYLCV occurrence except Shache county where TYLCV had already broken out in late 2011. 【Conclusion】 This study provides scientific basis for the control of Bemisia tabaci and the outbreak of TYLCV in Xinjiang.

Key words: Bemisia tabaci, biotype, mtDNA COⅠ gene, tomato yellow leaf curl virus, Xinjiang