Abstract: To study the ecological regulation effects of species diversity in wheat fields on Sitobion avenae, field experiments were carried out in Langfang Experimental Station of Institute of Plant Protection, Chinese Academy of Agricultural Sciences from October，2007 to July，2008. The intercropping patterns of wheat and pea, by the proportions of planting row of pea and wheat in 2∶2, 2∶4, 2∶6 and 2∶8 (referred to as 2-2 intercropping, 2-4 intercropping, 2-6 intercropping and 2-8 intercropping, respectively), were plotted, and the field cultivar monoculture of wheat was planted as the control. Population dynamics of apterae and alatae S. avenae, population dynamics, species richness, diversity index and evenness of main natural enemies were systematically investigated and analyzed. The results showed that, compared with monoculture of wheat, the amount of S. avenae apterae per 100 plants (square-root transformed) in aphid peak period were very significantly lower in the intercropping treatments than in the control (P<0.01), and the cascade was as wheat monoculture (77.38) > 2-2 intercropping (68.62) > 2-4 intercropping (68.51) > 2-8 intercropping (65.19) > 2-6 intercropping (64.94). Although population dynamics of main natural enemies showed a similar trend with time, wheat-pea intercropping could preserve and augment natural enemies more than monoculture of wheat, and there were higher population densities of ladybeetles and aphid parasitoids, and higher species richness and diversity index of natural enemies, but lower evenness index in every intercropping field. It is so concluded that wheat-pea intercropping system can not only reduce the population of S. avenae, but also improve the stability and sustainability of controlling wheat pests by natural enemies.

Key words: Wheat, Sitobion avenae, natural enemies, species diversity, population dynamics, intercropping