Long-term environmental risk assessment of glufosinate-tolerant GM zoysiagrass ( <i>Zoysia japonica</i> Steud.) on non-target arthropod communities

Environmental risk assessment (ERA) of genetically modified (GM) crops is essential for evaluating their potential impact on non-target organisms under field conditions. In this study, a long-term field assessment was conducted to evaluate the ecological effects of glufosinate-tolerant GM zoysiagrass (Zoysia japonica Steud.; events JG21 and JG21-MS1) on non-target arthropod communities at two geographically distinct living modified organism isolation sites in South Korea (Jeonju and Seogwipo). A total of 528,796 arthropods were collected and classified into three functional groups: pests (45.73%), natural enemies (14.51%), and other arthropods (39.76%). Arthropod community composition exhibited clear regional and temporal variations. Linear mixed-effects model (LMM) analyses indicated that arthropod abundance and diversity indices were primarily influenced by the year and region, whereas treatment effects, defined as differences between GM events and non-GM controls, were not significant. Although occasional statistical differences were detected, post hoc comparisons confirmed that arthropod communities associated with GM treatments were ecologically comparable to those of non-GM controls within each region and year (p > .05). Non-metric multidimensional scaling (NMDS) ordination revealed clear clustering by region and year, with substantial overlap among treatments. Permutational multivariate analysis of variance showed that year explained the largest proportion of the variation (R2 = 0.640), whereas treatment effects were negligible (R2 = 0.006). Overall, these results provide robust field-based evidence that glufosinate-tolerant and male-sterile GM zoysiagrass does not adversely affect non-target arthropod communities, supporting its environmental safety in perennial agroecosystems.