Onion thrips, Thrips tabaci Lindeman, is a broadly distributed pest that attacks a wide range of crops. To investigate the intra-specific morphometric variation and the genetic diversity of this species in Iran, four populations from tobacco and 18 populations from onion were studied in 17 Iranian provinces. Morphological analysis using principal component and canonical discriminant analyses indicated that the populations on tobacco were strikingly different from those collected on onion. DNA sequence data for the COI gene was obtained for all populations along with a further 21 population sequences retrieved from GenBank database. Maximum parsimony analyses revealed the distinct clades of T. tabaci on tobacco in addition to onion with the exception of one population collected from tobacco in Golestan province. The results were identical for maximum likelihood and neighbor-joining analyses. Both molecular and morphometric analyses show heterogenecity of T. tabaci populations representing at least two different biotypes on tobacco and onion.

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