Occurrence dynamics of pest and natural enemy populations on spring maize intercropped with leguminous green manure crops

In order to develop better cropping practices for the control of corn pests, we sought to determine the occurrence dynamics of pest and natural enemy populations on spring maize intercropped with leguminous green manure crops. In 2019, we investigated the occurrence dynamics of pests and natural enemy populations on spring maize intercropped with needle leaf pea, spring maize intercropped with common vetch, and monocropped spring maize. The results revealed that throughout the growing season, the average population numbers of Tetranychus urticae and Rhopalosiphum maidis respectively reached up to 8300.00 and 1611.33 individuals per 100 plants on spring maize intercropped with needle leaf pea, whereas the population number of Helicoverpa armigera declined to 40.00 individuals per 100 plants. In contrast, we detected no T. urticae and R. maidis individuals on spring maize intercropped with common vetch, although the population number of H. armigera reached up to 66.67 individuals per 100 plants. Furthermore, we established that the period of parasitic wasp emergence was earlier and the population number was greater on spring maize intercropped with either needle leaf pea or spring maize intercropped with common vetch. Our findings indicate that intercropping spring maize with common vetch can be an effective strategy for controlling the occurrence of T. urticae and R. maidis, although was not entirely effective in the control of H. armigera. Conversely, whereas intercropping spring maize with needle leaf pea was found to be effective in controlling the occurrence of H. armigera, it was less effective in controlling T. urticae and R. maidis.