open access

https://hdl.handle.net/2115/56855

Differences in Pollen Resource Usage and Foraging Periods between the Exotic Bumblebee Bombus terrestris and the Native B. pseudobaicalensis and B. hypocrita sapporoensis in Hokkaido, Japan

英語

interspecific competition

2014

Hokkaido University Forests, EFRC

Eurasian Journal of Forest Research

17(1)

1-10

Bombus terrestris Linnaeus is an exotic bumblebee species that has recently been naturalized in Hokkaido, Japan. Some studies have suggested that the naturalization of this species has caused a decline in the native bumblebee populations. The present study focuses on differences in plant resource usage between coexisting exotic (B. terrestris) and native (B. pseudobaicalensis and B. hypocrita subsp. sapporoensis) bumblebee species in the Ishikari lowland region of Hokkaido. We observed the workers of the three species that came to forage in the investigation area during an approximately five-month period. In addition, we captured some of the bees carrying pollen to analyze the pollen grains attached to their body surfaces. The pollen grains were identified at the genus or species level. Compared with the two native species, B. terrestris workers were relatively abundant during the investigation period. This species also exhibited a relatively long duration of foraging activity and a larger foraging range than the other two native species. The patterns of pollen resource usage were generally different among the three species, suggesting that these species have different flower preferences. Cluster analysis based on use of pollen species by each worker revealed that the cluster compositions overlapped among the three species in July, but this overlap disappeared in August. The usage in pollen species tended to differ through the season.

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