Abstract: Intercropping patterns shape insect community structure and contribute to the suppression of insect pests. Based on systematic field investigations, we examined the changes in species composition and population dynamics of major insect pests and their natural enemies in maize fields intercropped with different companion crops. The aim of this study was to provide a scientific basis for ecological pest management in maize fields. The results showed that the major pests were Ostrinia furnacalis, Pseudaletia separata, Spodoptera litura, and Spodoptera frugiperda. The dominant natural enemies included Orius similis, Harmonia axyridis, Trichogramma chilonis, and Trichogramma ostriniae. Compared to maize monoculture, the abundance of O. furnacalis and P. separata was lower (with peak <45 individuals per 100 plants), while the abundance of T. chilonis and T. ostriniae was higher (with peak > 40 individuals per board) in the konjacmaize intercropping system. A high niche overlap index was observed between O. similis and S. litura (0.962), and the population dynamics of the two insect species were significantly positively correlated. In shallot-maize fields, the peak density of S. litura population was suppressed. Additionally, there was a strong niche overlap between T. ostriniae and O. furnacalis (0.971) and between H. axyridis and P. separata (0.969). There was significant positive correlation between the populations of T. ostriniae and O. furnacalis, as well as H. axyridis and P. separata. In pepper-maize intercropping system, peak abundances of T. chilonis and T. ostriniae were relatively higher (exceeding 40 individuals per board). There were higher niche overlaps between T. chilonis and S. litura (0.891), between T. ostriniae and O. furnacalis (0.921), and between H. axyridis and P. separata (0.933). There was significant positive correlation between the populations of T. chilonis and S. litura, T. ostriniae and O. furnacalis, as well as H. axyridis and P. separata. These results demonstrate that intercropping maize with konjac, shallot, or pepper can effectively reduce pest pressure and enhance the regulatory efficacy of natural enemies. Thus, these systems are recommended as effective ecological planting patterns for sustainable pest management in maize fields.

Key words: maize, intercropping, pest, natural enemy, ecological niche