Diversity and composition of flower-visiting insects and related factors in three fruit tree species.

Animal-mediated pollination is an essential ecosystem service for the production of many fruit trees. To reveal the community composition of flower-visiting wild insects which potentially contribute to fruit production and to examine the effects of geographic location, local meteorological conditions and locally introduced domesticated pollinators on them, we investigated the community composition of insects visiting the flowers (hereafter, "visitors") of apple, Japanese pear and Oriental persimmon for 1‒3 years at 20 sites around Japan. While most of the variation (82%) of the community composition was explained by tree species with a slight contribution by geographic distance (2%), maximum temperature and tree species contributed 62% and 41% of the variation in total abundance of the visitors, respectively. Though the dominant families of the visitors varied spatiotemporally, the community composition of the visitors of apple and Japanese pear clearly differed from that of Oriental persimmon. While Andrenidae and Syrphidae together accounted for 46%‒64% of the visitors of apple and Japanese pear, Apidae represented 57% of the visitors of Oriental persimmon. The taxonomic richness, diversity and evenness of the visitors were best predicted by locally introduced domesticated pollinators and local meteorological conditions of wind speed and maximum temperature. Amongst these selected factors, locally introduced domesticated pollinators could have the largest impact. It seemed to be strongly related to the reduction of taxonomic richness, diversity and evenness of the visitors, accounting for 41‒89% of the variation. Results suggested that the community composition and total abundance of potential pollinators were predominantly determined by tree species and temperature, but locally introduced domesticated pollinators could have a determinantal pressure on the taxonomic diversity of the community.
Competing Interests: No conflict of interest to declare Disclaimer: This article is (co-)authored by any of the Editors-in-Chief, Managing Editors or their deputies in this journal.
(Shoko Nakamura, Hisatomo Taki, Tomonori Arai, Ken Funayama, Shunsuke Furihata, Yuki Furui, Takamasa Ikeda, Hiromitsu Inoue, Kiyohiko Kagawa, Hidenari Kishimoto, Mitsuko Kohyama, Michiyo Komatsu, Akihiro Konuma, Ken Nakada, Suguru Nakamura, Nobuo Sawamura, Shoji Sonoda, Masahiro Sueyoshi, Seishi Toda, Katsuhiko Yaginuma, Shunsuke Yamamoto, Koki Yoshida, Tomoyuki Yokoi, Masatoshi Toyama.)