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In 1993–1997 the occurrence of cabbage aphid (Brevicoryne brassicae L.) and predators from Cecidomyiidae, Coccinellidae and Chrysopidae was observed on the nine different late cabbage vegetables; Savoy cabbage cv. ‘Vertus’, white cabbage cv. ‘Amager’, red cabbage cv. ‘Langendijker’, brussel sprouts cv. ‘Maczuga’, cauliflower cv. ‘Pionier’, blue kohlrabi cv. ‘Masłowa’, white kohlrabi cv. ‘Delikates’, kale cv. ‘Zielony Kędzierzawy’ and broccoli cv. ‘Piast’. Among the examined predators only the cecidomyiid – Aphidoletes aphidimyza Rond. (Cecidomyiidae) played an important role in reducing the number of cabbage aphids. The cruciferous species had no impact on the density of A. aphidimyza population, and females laying eggs. The size of aphid colonies on cabbage leaves played the most important role.
In1993–1997 the occurrence of predatory syrphids inthe cabbage aphid (Brevicoryne brassicae L.) colonies was observed on the nine different cabbage vegetables: savoy cabbage cv. Vertus, white cabbage cv. Amager, red cabbage cv. Langendijker, brussels sprout cv. Maczuga, cauliflower cv. Pionier, blue kohlrabi cv. Masłowa, white kohlrabi cv. Delikates, kale cv. Zielony Kędzierzawy and broccoli cv. Piast. The number of aphids as well as amount of aphidophagous Syrphidae feeding in their colonies on the different cabbage vegetables were compared. The species compositionwas also estimated. Eight species of Syrphidae were collected: Episyrphus balteatus (Deg.), Sphaerophoria scripta (L.), S. rueppelli (Wied.) S. menthastri (L.), Metasyrphus corollae (Fabr.), Scaeva pyrastri (L.), Syrphus vitripennis (Meig.), Paragus quadrifasciatus (Meig.). In the all years of observation the dominant species were E. balteatus (Deg.), S. scripta (L.) and S. rueppelli (Wied.). The highest number of syrphid larvae were collected from cabbage aphid colonies on the white and savoy cabbage.
In 1993–1997 the occurrence of Lepidoptera pests: Pieris rapae L., Pieris brassicae L., Mamestra brassicae L., and Plusia gamma L. were observed on the nine different late cabbage vegetables; Savoy cabbage cv. Vertus, white cabbage cv. Amager, red cabbage cv. Langendijker, brussel sprouts cv. Maczuga, cauliflower cv. Pionier, blue kohlrabi cv. Masłowa, white kohlrabi cv. Delikates, kale cv. Zielony Kędzierzawy and broccoli cv. Piast. The field observations showed that butterflies differentiated among host-species for oviposition. The butterfly females of all species preferred for oviposition the brussel sprouts and deposited a substantially larger number of eggs on leaves of them. Plant species with green leaves were more preferred than the red leaf ones.
In 1993–1995 from the cabbage aphid colonies, fed on nine different varieties of Brassica oleracea L. syrphid larvae and pupae were collected. The remaining emerged adults of Syrphidae were classified to eight species. The parasitization varied within the years of observation and oscillated from 14,4% to 46,4%. Four parasitic Hymenoptera: Diplazon laetatorius (F.), Diplazon sp., Pachyneuron grande (Thoms.), and Syrphophagus aeruginosus (Dalm.) were reared. The parasitoids identified belong to the following three families Ichneumonidae, Pteromalidae, and Encyrtidae. The largest group of reared parasitoids belonged to the family Ichneumonidae of which the most frequent was Diplazon laetatorius (F.). It occurred in each year of observations. The parasitization by D. laetatorius reached 21,7%.
In 1993–1997, 990 pupae of diamondback moth (Plutella xylostella L.) were collected from nine different varieties of Brasica oleracea L., grown on experimental farm near Kraków. Only 234 moths (23.6%) were recovered from the cocoons. The most important factor reducing the population of DBM was parasitization (65.1%). It varied between the years of observation and oscillated from 60% to 90.3%. Sixhundred and fourty four specimens of parasitic wasps belonging to 11 species from families: Ichneumonidae (5 species), Braconidae (3 species), Pteromalidae (2 species) and Eulophidae (1 species) were reared out. In each year of observations the most abundant species among DBM parasitoids was Diadegma fenestralis Holmgr. as it constituted 71.4% of all of the wasps reared. In the years 1994 and 1996 with low abundance of diamondback moth, D. fenestralis was the only species parasitizing 66.7% and 89.5% of the pest larvae
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