Community dynamics of wheat aphid natural enemies in wheat-oilseed rape or wheat-garlic intercropping fields

The dynamics of wheat aphid natural enemy community in different intercropping patterns (wheat-oilseed rape intercropping, wheat-garlic intercropping and monoculture) were investigated with biodiversity measures including species richness (S), dominance (D), Shannon's Index (H′), and evenness (E). It was showed that the species richness of natural enemies in wheat-oilseed rape intercropping pattern was almost higher than those of the other two patterns during the investigation period. However, the other two patterns were similar in the whole stage of investigation. The dominant species of natural enemies among the three planting patterns were different at the beginning of investigation, but in the mid-and late-stage were Aphidius avenae. During investigation, diversity index of natural enemies in wheat-oilseed rape intercropping pattern was the highest. After May 8, the dominance of A. avenae in wheat-oilseed rape intercropping pattern was the lowest with significant difference compared with the other two patterns, and the index of evenness was the highest. It is concluded that in wheat-oilseed rape intercropping pattern, with higher species richness and higher stability community of natural enemies, it could control wheat aphid infection especially in early wheat filling stage, and there was no obvious effect of wheat-garlic intercropping on community structure and dynamics of wheat aphid natural enemies.