Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Flower-visiting bees collected in Kagawa Prefecture, Japan and the possibility of unusual pollination by the large carpenter bee (Hymenoptera: Apoidea).

Abstract

The adults of bees (Hymenoptera: Apoidea) visiting on or flying around flowers of indigenous or cultivated plants have been observed and collected for three years (1996-1998) in Kagawa Prefecture, Japan. Fifty-four species belonging to 22 genera represented by 6 families were collected, and two introduced species of Apidae, Apis mellifera and Bombus terrestris were included in them. Among indigenous species, only two species, Xylocopa appendiculata and Apis cerana were confirmed to be active in open field for more than 6 months a year. Although social bees belonging to Apidae tended to visit wider spectrum of plant species than those visited by solitary bees, the widest spectrum was observed in the solitary carpenter bee, X. appendiculata. Nectar robbing was observed in X. appendiculata and Bombus ignitus, and buzz pollination in X. appendiculata, B. ardens, B. diversus and B. ignitus. When female X. appendiculata buzzed on the male flowers of a dioecious tree plant, Mallotus japonicus, pollens were instantaneously dispersed in the air. As no visitors on the female flowers of M. japonicus have been observed, it was supposed that M. japonicus was pollinated by the dispersed pollens. The possibility of this hypothetized pollination named "buzz and airborne pollination" was discussed in comparison with some hypothesized manners of pollination having been submitted to explain pollination systems in tropic dioecious tree plants. Possible evolutionary pathway of Xylocopa in relation to their flower-visiting activities was also briefly discussed.