Seasonal Population Dynamics and Harmfulness of Wheat Thrips in Agrocenoses of Grain Crops

Abstract

The purpose of the study was to identify forage plants and specialized entomophages of wheat thrips in agrocenoses of winter and spring grain crops cultivated in the Samara region. The highest number of adult pests was noted in winter wheat crops (2365.0 ind./100 strokes), the lowest in winter barley crops (565.0 ind./100 strokes). Egg laying by wheat thrip females occurred on all grain crops. Larvae of wheat thrips were noted in the ears of winter and spring wheat, triticale, and winter barley, with the exception of spring barley. During the research, two specialized entomophages were identified: striped thrips and predatory thrips. During the research years, the largest numbers of predatory thrips were noted in winter wheat crops in the earing phase (90 ind./100 strokes) and in spring wheat and spring barley crops in the booting phase—75 ind./100 strokes and 40 ind./100 strokes, respectively. The damage to winter wheat grain by wheat thrips varied from 55.3% to 69.2% and was higher than the damage to spring wheat grain (38.5–64%). With a certain ratio of specialized entomophages and wheat thrips, it is possible to refuse the use of insecticides in the cultivation of grain crops.