Influence of different rotations on population development of cereal aphids and associated predators in winter wheat
1992
Henze, M. (Bonn Univ. (Germany). Inst. fuer Pflanzenkrankheiten) | Sengonca, C.
The influence of several four leveled crop rotations including different rates of cereals on the coverage level through weeds, the population dynamic and cereal aphids, and their predators as well as the crop yield was studied in winter wheat in 1989 and 1990. The coverage level through weeds was a little higher in a crop rotation with organic fertilization and a low cereal portion (crop rotation C: sugar beets - winter wheat - maize -maize) than in a crop rotation with a larger portion of creal crops (crop rotation A: sugar beets - oats - winter wheat -winter barley). The cereal aphids Sitobion avenae (F.), Metopolophium dirhodum (Wlk.) and Rhopalosiphum padi (L.) occurred in both years and S. avenae was the most encountered of all species. The obtained results indicated that the crop rotation affected the population dynamic of the cereal aphids in winter wheat. The highest number of aphids was observed in winter wheat of crop rotation A in 1990. On the other hand, the lowest number of aphids was found in crop rotation C, being more infested with weeds. It could be shown, that the most abundant predators in all crop rotations were Coccinellidae, especially Coccinella septempunctata (L.), followed by Syrphidae and Chrysopidae. The number of predators which were collected with sweep nets during June and July were lower in 1989 than in 1990. Significantly more predators were observed in winter wheat of crop rotation C (17 individuals) than in winter wheat of rotation A (9.5 individuals) in 1990. In both years the wheat yield in crop rotation C (65.3 dt/ha and 72.6 dt/ha) was higher than in rotation A (56.8 dt/ha and 66.4 dt/ha)
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