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 of T. ni was found in cabbage (57.1%) followed by knol-khol (30.4%). Tropical Agricultural Research Vol. 25 (1): 120-126 (2013)
Highlights
Crucifers are cultivated over 4,155 ha across the country
Insecticide spraying has been the common practice among commercial farmers to manage cabbage caterpillar complex and ten different insecticides have been recommended by the Department of Agriculture, Sri Lanka (DOA, 2010)
Four species of leaf feeding caterpillars, Plutella xylostella, Crosidolomia pavonana, Trichoplusia ni, and Spodoptera litura were recorded in the cruciferous crops
Summary
Crucifers are cultivated over 4,155 ha across the country. Crucifer cultivation is associated with many different production limitations such as crop damage by insects, pathogens and weeds, less crop tolerance to the adverse weather and high input requirements (fertilizer, agrochemicals and irrigation). Cabbage feeding lepidopterans and their egg parasitoids many ecological and health problems are associated with insecticide applications. As a result of all these consequences, reduce use of insecticides has been proposed with the suggestion to implement integrated pest management (IPM) approach. Cabbage caterpillar complex can be potentially controlled by using egg, larval, and pupal parasitoids (Klass & Dirig , 1981). The major limitation of using larval and pupal parasitoids is that, the cabbage feeding caterpillars continue to attack the crop before they are being controlled. Use of egg parasitoids for controlling cabbage caterpillar is a better option as the pest is destroyed at egg stage before they start attacking the crop. In order to use the egg parasitoids efficiently, it is required to understand the interactions among host plants, pest species and the egg parasitoids
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
