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Abstract

This study was conducted to examine the host preference by adult crucifer feeding insects and their egg parasitoids in relation to crops of family Cruciferaceae. Radish (Raphanus sativus L.), cabbage (Brassica oleracea L. var. captata), mustard (B. juncea L.) and knol-khol (B. oleracea var,.Gongylodes) crops were cultivated at the University Experimental Station at Dodangolla, Sri Lanka in 5 m x 5 m plots, separated by 5 m wide non-crop natural vegetation. Crops were established on different planting dates in order to get synchronized vegetation. Eggs of crucifer feeding caterpillars were collected at weekly intervals from 10% of plants in each plot. Collected eggs were incubated separately until the emergence of adult parasitoid or the host caterpillar. Plutella xylostella, Crosidolomia pavonana, Trichoplusia ni, and Spodoptera litura were recorded as pest caterpillars. Their oviposition preference significantly varied with the host crop. The total egg parasitism of Trichogramma species significantly varied with the crops. The highest parasitism ofT. ni was found in cabbage (57.1%) followed by knol-khol (30.4%).

Keywords: Oviposition, parasitism, Plutella, Trichogramma, Trichoplusia