Abstract:

For selecting suitable groundcover plants to attract natural enemies in pear orchards, 10 kinds of groundcover plants were investigated by sweep-net method before wheat harvest in Wei Shan-zhuang, Da Xing region, Beijing, China. The results showed that, in the pear orchard, 10 kinds of groundcover plants attracted 11 species of natural enemies, among which, aphid cocoon wasp and ladybird were two major groups. Among of groundcover plants, marigold (Tagetes erecta) attracted the most amount of natural enemy species (7 species), Monarda diclyma and white clover (Trifolium repens) were the sencond most to attract the species (6 species of each). Chenopodium album attracted aphid cocoon wasp at the most quantity (99.2% of total amount of natural enimies). Besides aphid cocoon wasp and ladybird, strawberry attracted Coccygomimus disparis as well. Alfalfa, perilla and Chenopodium album were the species that attracted the most total amount of natural enemies (4 individuals /m2 ). It was calculated reckoning that the groundcover plants of 6 m2 per pear tree could attract more than 10 individuls of natural enermies, in which the permissible pest threshold could reach to more than 0.2 invid./leaf. It was suggested that: selecting marigold, Monarda diclyma, white clover, perilla and strawberry as grundcover plants in pear orchard; utilizing Humulus japonicus, ruderal weed（each attracted 4 kinds of natural enemies）and Chenopodium album properly.