Abstract: The feeding experiment with different sorts of Brassica vegetable crops showed that Plutella xylostella larva preferred the seedlings of Chinese cabbage (Brassica campestris L.), radish (Raphanus sativus L.) and caixin (Brassica campestris L.) to those of rape (Brassica napus L.) and cabbage (Brassica olereacea L.), with a selection proportion of 93.33% and 6.67% between Chinese cabbage and rape, and of 16.67% and 83.33% between cabbage and caixin. On the whole, the feeding preference of P. xylostella larva was less related to the contents of soluble glucide and starch in the vegetables, but had a definite negative correlation to the content ratio of these compounds. The P. xylostella larva fed with Chinese cabbage and caixin grew better than that fed with rape and cabbage, and the feeding amount and body weight of per larva were 0.583～0.637 cm² and 2.07～2.18 mg, respectively. The larva preferred damaged vegetable seedlings, too.

Key words: rhizosphere, bulk soil, microelement, vegetation, hilly-gully region of Loess Plateau