Abstract

Background: Parasitic mistletoes infect a wide range of host plants, and when infestation density is high, they alter host resource allocation and canopy structure, thereby affecting ecosystem components including light regimes and understory vegetation. In South Korea, research has primarily focused on their bioactive properties, with limited attention to host associations or ecological traits. This study examined the host plant diversity and preference of Korthalsella japonica (Thunb.) Engl. and predicted its potential habitats to provide baseline data for conservation planning. Results: Korthalsella japonica was found on 26 host species belonging to 11 families and 18 genera, including 15 newly recorded host plants. A clear preference for warm-temperate evergreen broad-leaved trees was observed, particularly Eurya japonica Thunb. and Camellia japonica L. This pattern indicates that host selection is shaped not only by parasitic opportunism but also by physiological compatibility and the spatial structure of densely distributed evergreen assemblages. Predicted suitable habitats were primarily concentrated in gently sloping areas near streams within the lower mid-mountainous regions of Jeju Island, aligning well with actual vegetation structures and host plant distributions. Conclusions: The distribution of K. japonica reflects an intermediate level of host specificity, closely associated with warm-temperate evergreen broad-leaved forests. These findings advance understanding of the ecology of K. japonica by revealing its host diversity, habitat preferences, and key environmental determinants, and they provide valuable baseline data to guide future conservation planning and management strategies.