Abstract：PCR-RFLP and sequencing of rDNA ITS regions of six geographic populations in genus Helicotylenchus were made. Four species, Helicotylenchus microcephalus, H. digonicus, H. dihystera, and H. pteracerus, were identified.Both the sequence length and digestion patterns were the same in the three populations of H. digonicus. The digestion patterns varied in different four specices, which was identified as H. microcephalus, H. digonicus, H. dihystera and H. pteracerus, respectively based on the morphological method. The combination of six enzymes, AluⅠ, AvaⅠ, HaeⅢ, HinfⅠ, MspⅠ and RsaⅠ, could be used effectively to identify and classify this four Helicotylenchus species. This is the first report about the molecular data of the nematode genus in China.
