Intercropping of wheat and walnut reduce populations of <i>Chromaphis juglandicola</i>

Intensive agriculture is associated with a great decline in biodiversity and biocontrol of pests. Intercropping potentially promotes natural enemy's abundance and species biodiversity and enhance pest biocontrol. We monitored the population dynamic of Chromaphis juglandicola (Kaltenbach) (Hemiptera: Aphididae) and tested the effect of intercropping conventionally managed winter wheat with walnut on the abundance of C. juglandicola and its predators (including ladybeetles, lacewings, hoverflies, and spiders), and the diversity, evenness, and dominant concentration of predators on walnut. The density of C. juglandicola in walnut trees was peaked in mid-July. It, but not its predators, was significantly reduced in walnut-wheat plots, but the species diversity and evenness of predators declined, and the dominant concentration increased. Intercropping benefited C. juglandicola control by reducing their density in walnut. Overall, the increasing of plant diversity in intercropping system of wheat with walnut enhance the aphid C. juglandicola biocontrol, which can reduce the reliance on pesticide in walnut and result in a walnut producing agroecosystem that is more nature-inclusive and healthy for human and the ecosystem.