Assessment of wheat ear insects in winter wheat varieties in central Germany

Abstract

Population densities of wheat ear insects infesting different winter wheat varieties (n = 50) were estimated during 2008 and 2009 seasons near Halle, central Germany. The research was aimed at identifying wheat varieties most resistant to wheat ear insect pests. Two methods were used to evaluate the degree of insect infestations in different wheat ear varieties. Wheat ears were dissected when kernels were in Zadoks stage 73 and examined using a binocular microscope to count the number of spikelets and infested kernels, and to identify the insect pests present. In addition, white water traps were placed on the soil underneath each variety to collect mature larvae of wheat blossom midges (WBMs) as an indicator of potential crop risk for the next year. There were significant differences in the number of thrips and WBM infesting wheat ears among varieties in both years. Thrips numbers were the highest in Akratos, Limes and Ritmo varieties in 2008 and in Michigan Amber, Elegant and Kontrast in 2009. Thrips were the lowest in Thuareg in 2008 and Robigus varieties in 2009. The results showed that the highest WBM infestation level was observed in Michigan Amber in both years. The lowest WBM infestations were found in Turkis, Cubus, Capo, Welford and Robigus in both years. The number of infested kernels was positively correlated with WBM among varieties. In the water traps, the highest numbers of WBM larvae were recorded in Saladin and Bussard in 2008 and Orlando, Julius and Glasgow varieties in 2009. The lowest values were recorded in Victo, Enorm, Robigus and Welford varieties in both years. The results provide a guide for selecting winter wheat varieties with resistance to these wheat ear pests.