Habitat preference influences response to changing agricultural landscapes in two long-horned bees

Abstract

Agricultural intensification and urban development have drastically influenced pollinators living in semi-natural grasslands. Pollinators are likely to have different responses to more intensive land uses; some decline rapidly, whereas others maintain or increase their populations. We predicted that differences in interspecific responses to different land uses are partly attributed to differences in habitat preference. We examined the distribution and flower use patterns of two closely related Eucera species with different habitat preferences. Study sites were narrow belt-like meadows within traditional, intensified, and urbanised agricultural lands in the Osaka-Kobe metropolitan area, Japan. Forest-associated Eucera nipponensis were significantly fewer in consolidated and urbanised meadows than in traditional meadows, whereas open land-associated E. spurcatipes exhibited the opposite pattern. A significant negative relationship between their abundance was also found. Both species foraged on legume flowers most frequently (83.5%), but their floral use patterns differed significantly in traditional and consolidated meadows. The bee species that preferred stable habitats were vulnerable to land consolidation and urbanisation, while the species associated with disturbed habitats maintained or increased its population size in meadows with these intensive land uses. Thus, recent land-use changes may have different impacts on species with different habitat preferences.