Occurrence of winter wheat pests and their natural enemies on farms with different farming systems
1989
Sengonca, C. (Bonn Univ. (Germany, F.R.). Inst. fuer Pflanzenkrankheiten) | Brueggen, K.-U.
In 1986 and 1987, the influence of different farming systems on the occurrence of cereal pests and their natural enemies was investigated on winter wheat fields of a bio-dynamic farm, a conventional farm with livestock, and a conventional farm without livestock. No differences were observed for the spectrum of pests and their natural enemies on the differently managed fields. In both years, cereal leaf beetles and cereal aphids were the most numerous pests and their abundance correlated with the farming system. In conventionally managed fields the mean number of adult leaf beetles per sampling area was significantly higher than on the bio-dynamic fields. In 1987, the mean number of leaf beetles was: 79 (conventional with livestock), 68 (conventional without livestock), but only 22 on the bio-dynamic field. While in 1986, a low aphid infestation (three per tiller) was measured on all investigated fields, in 1987 there were 12 aphids per tiller in the conventional fields, but only six per tiller on the bio-dynamic field. The most important beneficial arthropods affecting the pest insects in the fields were the natural enemis of aphids, which economically are the most important pests in middle Europe. In 1987, a greater number of adult Coccinellidae and Syrphidae was detected on the field of the conventional farm without livestock as compared with the field of the farm with livestock and the field of the bio-dynamic farm. The most common Syrphidae was Episyrphus balteatus and about 60 per cent of all Coccinellidae were Propylea quatuordecimpunctata
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