Screening of the susceptibility of newly released genotypes of potato to thrips infestation under field conditions in northwest Iran

• The density of Thrips tabaci adults and larvae and its damage index were compared between the seven potato genotypes.
• Mean relative growth rate (MRGR) and crop yield were compared in thrips-infested and control plants under field conditions.
• The population levels of thrips adults and larvae were lowest on the cultivar Savalan.
• The mean damage index was lowest on Savalan.
• In thrips-infested plants, the lowest percentage of MRGR loss and the lowest percentage of yield reduction were observed on Savalan.

Use of host plant resistance is an essential component of integrated management of Thrips tabaci Lindeman. The present research was designed to screen five commercial cultivars of potato, namely Agria, Kondor, Morene, Diamant and Savalan, and two breeding lines 397082-2 and Khavaran for their susceptibility to thrips infestation and for their mean relative plant growth rate (MRGR) and crop yield in an experimental field (not frected with insecticides) and a control field (chlorpyrifos frected) in the Ardabil region of Iran in 2011 and 2012. Thrips populations were assessed by visual inspection on potato leaves. At harvest time, the percentage of leaf area damaged by thrips infestation was assessed on leaves of the tested genotypes. All adults of phytophagous thrips collected in the experimental field were T. tabaci. In both years the mean numbers of thrips adults and larvae were lowest on Savalan cultivar among the tested genotypes. The mean damage index was also lowest on Savalan in both years and the MRGR and the mean yield were greatest in Savalan in the control field. Moreover, in thrips-infested plants, the lowest percentage of MRGR loss and the lowest percentage of yield reduction were observed in Savalan (3.7% and 5.8%, respectively). Of the genotypes tested, Savalan is the most resistant host and has potential for use in the sustainable management of T. tabaci on potato.