1 ill., 1 table; 23 ref. Summaries (De, En)

Laboratory tests indicate that the cereal aphids Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi possessed higher nutritive value for the larvae of Aphidoletes aphidimyza than the green peach aphid Myzus persicae. Adult weight and egg production from larval reserve substances were significantly increased. The duration of larval and pupal stage and the rate of adult emergence were the same between the aphid species. Results of greenhouse experiments using an open rearing unit of A. aphidimyza on cereal aphids show that the predatory midge could reproduce in and disperse from the open rearing unit to successfully control populations of peach aphids on sweet pepper. In the midge treated greenhouses the aphid population densities remained at very low levels throughout the entire vegetation period. In the midge free greenhouses, however, population growth of the aphid increased very rapidly reaching peak population densities 4-5 weeks after aphid infestation. In two of the experiments midges were accidentally introduced into the midge free greenhouse. It became evident that the midge were able to suppress aphid populations effectively, even if the aphid density had reached a relatively high level. Cereal aphids are suggested as prey species for mass rearing of A. aphidimyza. The effectiveness of A. aphidimyza in suppressing aphid populations and the advantages of using open rearing unit in form of a 'cereal aphids- A. aphidimyza'-system for control greenhouse aphids are discussed

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