STUDIES ON PEST COMMUNITIES ON EARS OF WINTER-WHEAT (TRITICUM-AESTIVUM L)

The change in communities of pests on the ears of winter wheat was studied in five growth stages from DC 51 to 85. Despite low severity due to less favourable weather the mean number of arthropodes from various species ranged from a minimum of 2.7 (DC 51) to 12.5 (DC 75) per ear. With a sample size of 150 ears per growth stage 15 to 107 different combinations of species (communities) could be detected. In the milky stage (DC 75) communities of four and five and in the dough stage (DC 85) of four species were most frequent. Significant relationships could be found for some communities in certain stages, which, however, changed with the development of the ear. Many communities appeared to be chancy and rather dependent on weather. Diseases (Septoria tritici, Puccinia striiformis) were less expressed on ears during this study. The influence of diseases on the stem basis and on root on the communities on the ears is discussed.