Aphid flight and change in abundance of winter wheat pests

Composition, dominance and change in population density of species flying over and feeding on winter wheat fields was studied between 1982 and 1998 at Mosonmagyaróvár. There were 29 aphid species among flying insects. The ones imposing risk to winter wheat were as follows: Diuraphis noxia Kurdj., Metopolophium dirhodum Walk., Rho‐palosiphum padi L., Schizaphis graminum Rond., Sitobion avenae Fabr. Number of flying individuals changed year by year, depending principally on climatic factors (temperature, relative humidity, and rainfall). Flight was continuous from late April to harvest. In the average of 17 years flight peak was observed in June.

Establishment of the firsts alate individuals of aphids with holocyclic development can be expected from the second decade of April. As a result of the continuous reproduction, the peak in number of individuals was observed in the second decade of June. During the six years between 1993 and 1998 this value was 17.18 aphids/ plant. Every year there were deviations from the average data, e.g., in 1994 aphid number per plant was 33.61. These pests appeared on the ears in the first decade of June, their number was continuously increasing due to drying of leaves.

During the six years when detailed data were recorded, Rh. padi L. was the dominant species three times (1994: 70.4%; 1995: 82.6%; 1996: 87.9%), M. dirhodum Walk. took this role two times (1993: 67.1%; 1997: 84.8%) and S. avenae Fabr. only once (1998: 53%).

Considering seventeen years’ data, it is necessary to produce resistant varieties and/or seed dressing, or insecticide treatment to control the first alates.