Abstract
Artificial light at night (ALAN) can influence plant growth, defence, interactions with herbivores and invasion by exotic plants. However, studies assessing the interactive effects of ALAN, nutrient enrichment and herbivory on invasive and native plant species remain limited. We conducted a greenhouse experiment to investigate the interactive effects of ALAN (no-ALAN versus ALAN), nutrient enrichment (low versus high) and herbivory by a generalist Spodoptera litura (without versus with) on the growth, root allocation and defence of six congeneric pairs of invasive and native plant species. Nutrient enrichment increased total biomass more in native plants than in invasive plants. ALAN enhanced total biomass in both groups of plants without herbivory, but increased native plant biomass and decreased that of invasive plants under herbivory. ALAN reduced root mass fraction, especially under low-nutrient conditions without herbivory. Native plants exhibited greater tolerance to herbivory and higher net photosynthetic rates under ALAN compared to invasive species. Moreover, S. litura larvae grew faster on invasive plants but slower on native plants under ALAN. These findings suggest that ALAN may weaken the competitive advantage of invasive species by enhancing the defence mechanisms and physiological performance of native plants, potentially shifting competitive dynamics in favour of native flora.