Plant architecture shapes arthropod communities and mediates indirect defense in maize landraces

Maize ( Zea mays L.) is a globally critical cereal. In Mexico, a significant portion of its annual production is derived from rainfed landraces cultivated by smallholders, but yields are threatened by insect pests, such as the fall armyworm ( Spodoptera frugiperda ). This study evaluated how functional traits of three maize landraces (Nal tel, Nal xoy, Dzit bacal) influence the associated arthropod community and its relationship with S. frugiperda damage. A randomized complete block design was used to assess morphological traits, insect diversity, and foliar damage. The landrace Dzit bacal exhibited superior development in height, stem diameter, leaf area, and leaf dry mass. While no significant differences in pest damage were found among landraces, Nal xoy and Dzit bacal supported arthropod communities with higher ecological diversity (q = 1) and dominance (q = 2), indicating greater evenness. Path analysis identified plant architecture, specifically leaf dry mass, leaf area, and height, as the primary factor structuring the insect community. These results suggest that morphological diversity among landraces acts as a bottom-up driver, shaping arthropod assemblages and favoring natural enemies, such as Ichneumonidae, which may enhance the biological control potential against pests.