Journal of Insect Conservation

, Volume 12, Issue 2, pp 135–146

Displacement of Japanese native bumblebees by the recently introduced Bombus terrestris (L.) (Hymenoptera: Apidae)

Original Paper

DOI: 10.1007/s10841-007-9071-z

Cite this article as:
Inoue, M.N., Yokoyama, J. & Washitani, I. J Insect Conserv (2008) 12: 135. doi:10.1007/s10841-007-9071-z

Abstract

The introduced Bombus terrestris has recently been naturalized in Japan and become dominant in some local communities. We investigated potential niche overlaps between introduced and native bumblebees in terms of morphological characteristics, seasonal flight activity, foraging and nesting habitat use, and plant species visited. There were considerable niche overlaps in flower resource use between B. terrestris and B. hypocrita sapporoensis/B. pseudobaicalensis. Bombus terrestris also potentially competes for nest sites with B. hypocrita sapporoensis. During 3-year monitoring, B. pseudobaicalensis showed no noticeable change, but B. hypocrita sapporoensis decreased while B. terrestris increased. Abundant flower resources provided by exotic plants may buffer native bumblebees from competition for food with introduced species. By contrast, the number of nest usurpers found in B. terrestris nests increased between 2003 and 2005, indicating that availability of nest sites was limiting and queens strongly competed for nest sites. Our findings suggest that competition for nest sites rather than flower resources is the major ecological mechanism for displacement of native bees. The large reduction of B. hypocrita sapporoensis queen indicates that B. terrestris may cause local extinction of native bumblebees. Control of established B. terrestris populations and prevention of further range expansion are urgently needed.

Keywords

Biological invasionCompetitive displacementInterspecific competitionNest siteNiche overlap

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.Laboratory of Conservation Ecology, Department of Ecosystem Studies, Institute of Agricultural and Life SciencesThe University of TokyoBunkyo-kuJapan
  2. 2.Department of Ecology and Evolutionary Biology, Graduate School of Life SciencesTohoku UniversityMiyagiJapan