Yellow rocket, Barbarea vulgaris (R. Br.) variety arcuata, was evaluated as a trap crop for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in cabbage, Brassica oleracea L. variety capitata, in 2003, the numbers of P. xylostella larvae found in Þeld plots of cabbage alone were 5.2Ð11.3 times higher than those on cabbage plants in plots that included cabbage and several rows of yellow rocket. In an outdoor experiment in screenhouses, P. xylostella oviposition on cabbage

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... compared among six treatments that varied in the percentage of yellow rocket in relation to cabbage (0, 4, 8, 16, 24, and 32% of the plants were yellow rocket). Results indicated that the percentage of eggs laid on cabbage decreased as the percentage of yellow rocket in the treatment increased, but this decrease was not signiÞcant beyond 20% of the plants being yellow rocket. In 2004, the numbers of P. xylostella larvae in Þeld plots of cabbage alone were 1.6 Ð2.4 and 1.7Ð2.8 times higher than numbers in treatments with 10 and 20% trap crop, respectively. Sticky trap and sweep net captures of P. xylostella adults indicated that within-Þeld dispersal was reduced by the presence of yellow rocket and aggregation occurred around yellow rocket plants. Our study suggests that using yellow rocket as a trap crop may reduce P. xylostella infestations in cabbage Þelds, and this possibility is discussed in the context of general crop and insect pest management practices in crucifers.