Comparison of Coleopteran Occurrence Patterns and Feeding Guild Composition between Grassland and Forest Plots on the Yeungnam University Campus, South Korea

Habitat heterogeneity in vegetation structure and ground-surface conditions can influence biological communities by altering resource availability and microhabitat conditions. This study compared Coleoptera community structure and feeding guild composition between two sampling plots with contrasting vegetation structure on the Yeungnam University campus, South Korea: a grassland plot and a forest plot. Coleopteran insects were collected using pitfall traps from 19 April to 19 May 2022, and vegetation was surveyed monthly from April to June 2022. Collected species were classified into herbivorous, predatory, and detritivorous guilds, and differences in species richness and abundance between plots were tested using the Mann-Whitney U test. In total, 32 species and 236 individuals were collected: 21 species and 163 individuals in the grassland plot and 11 species and 73 individuals in the forest plot. Open-habitat and dry-surface-associated taxa dominated the grassland plot, whereas taxa associated with litter layers, fungi, and concealed organic substrates occurred in the forest plot. Overall species richness and abundance were significantly higher in the grassland plot. Predatory beetles showed significantly greater species richness and abundance in the grassland plot, while detritivorous beetles showed significantly greater abundance but not species richness. Herbivorous beetles did not differ significantly in trap-level species richness or abundance. These patterns suggest that differences between the two plots were reflected not only in overall richness and abundance but also in feeding guild composition. Predatory and detritivorous beetles appeared to respond to vegetation structure, ground-surface openness, and resource exposure, whereas herbivorous beetles may have been more closely related to local host plants and floral resources. Feeding guild-based analysis can help interpret resource use patterns of coleopteran communities between sampling plots with contrasting vegetation structure.