Evaluating the resistance of nine wheat cultivars to the sunn pest, Eurygaster integriceps Put., in the field conditions in Naghadeh, west Azarbaijan

The sunn pest, Eurygaster integriceps Put. is the most important pest of wheat in Iran that can considerably reduce its quality and quantity yield. Identification and deployment of resistant cultivars is an effective integrated pest management (IPM) strategy of this pest. Field experiments were conducted to evaluate the resistance of nine wheat cultivars to this pest in 2014. To study the level of resistance of cultivars, the infested and non-infested plots were isolated and arranged based on a randomized complete block design in field. The plants of infested plots were infested naturally. Non-infested plots controlled with chemical method. Grain yield, thousand grains weight and the weight of fifty sunn pest damaged grain in infested plots was determined and compared to non-infested plots for each cultivar. Also, density of fourth and fifth instars nymphs and percent of sunn pest damaged grains per nymph were determined in infested plots for each cultivar. Significant differences were observed for all studied traits (P≤0.01). The comparison of means showed that the cultivars Zarrin and Saysionese with means of 0.35±0.03 and 0.38±0.01%, respectively, had the least grain yield loss in comparing with non-infested wheats. Significant positive correltion was observed between grain yield decrease and percent of sunn pest damaged grains (P≤0.01).