Introduced Western Honeybees Dramatically Reduce the Abundance of Wild Bees in Alpine Meadows, Eastern Tibet Plateau

Over the past few decades, the western honeybee (Apis mellifera) has been widely introduced throughout China. Introduced honeybees have often been observed to pose a significant threat to native bee species diversity through competition for floral resources. However, the specific impact on native pollinator communities is not well understood, especially in alpine meadows, where bee diversity is particularly high. In this study, we determined the difference in species abundance and diversity of native bees between nearby and distant plots relative to apiaries in alpine meadows on the eastern Tibetan Plateau. We constructed a plant-bee network and calculated perceived apparent competition (i.e., the feeding niche overlap) between the introduced honeybees and each of the native bee species. Furthermore, we determined the relationship between the relative change in species abundance and the perceived apparent competition and species abundance across bee species. Among the 15 native bee species, 9 bee species were significantly lower in abundance in the nearby plots compared to the distant plots, and, in particular,, 5 rare species were not found in the nearby plots. For the other six species, the abundance difference was statistically non-significant. Data analysis reveals that the species abundance of native bees in distant plots, along with the feeding niche overlap between introduced bees and native bees in distant plots, explains the variation in the relative change in species abundance across bee species. However, the feeding niche overlap between introduced bees and native bees in nearby plots does not account for this variation. Our findings demonstrate that rare native bee species with greater feeding niche overlap have been significantly impacted by the introduced western honeybees. These results highlight important implications for pollinator management in natural ecosystems and the conservation of wild bees.