Previously we suggested the significance of some of the hymenopteran (Andrenidae, Apidae, and Halictidae) and dipteran (Syrphidae) families in Japanese pear pollination. However, they might contribute differentially to the pollination reflecting their pollination efficiencies. For this study, we investigated the pollination efficiency of three insect pollinator groups at an insect-pollinated Japanese pear orchard: (Hymenoptera: Apidae), solitary bees (Hymenoptera), and flies (Diptera). First, we examined the contribution of the insect pollinator groups to the fruit-set ratio of inflorescences. Results indicated that the floral visits of had a positive effect on the fruit-set ratio. Then, for two consecutive years, the numbers of pollen grains deposited on the stigma after a single floral visit by insects were examined. The obtained results were not consistent, but data in one year showed that and spp. (Hymenoptera: Andrenidae) deposited more pollen grains than (Hymenoptera: Andrenidae) did. Third, we examined the presence of pollen grains derived from the pollinizer variety among those removed from the body surfaces of the flower-visiting insects. Results indicated the involvement of the three pollinator groups in pollen grain transfer of the pollinizer variety. Finally, we recorded the abundance of flower-visiting insects by walking around the study site. Results demonstrated that flies were observed stably irrespective of temperatures during the survey period, unlike and solitary bees, which exhibited little flower-visiting activity under low temperatures. Results also demonstrated that solitary bees were abundant at the study site in the late flowering period. These results suggest that hymenopterans and dipterans contribute differentially but mutually complementarily to open insect pollination in the Japanese pear orchard.

中文翻译：

---

昆虫授粉的日本梨园中蜜蜂（膜翅目：蜜蜂科）、独居蜂（膜翅目）和苍蝇（双翅目）的授粉效率

之前我们提出了一些膜翅目（Andrenidae、Apidae 和 Halictidae）和双翅目（Syrphidae）科在日本梨授粉中的重要性。然而，它们对授粉的贡献可能有所不同，这反映了它们的授粉效率。在本研究中，我们调查了昆虫授粉的日本梨园中三个昆虫传粉媒介群体的授粉效率：（膜翅目：蜜蜂科）、独居蜂（膜翅目）和苍蝇（双翅目）。首先，我们研究了昆虫传粉媒介群体对花序坐果率的贡献。结果表明，花期对坐果率有积极影响。然后，连续两年检查昆虫单次造访花后沉积在柱头上的花粉粒数量。获得的结果并不一致，但一年的数据表明，spp。 （膜翅目：Andrenidae）比（膜翅目：Andrenidae）沉积更多的花粉粒。第三，我们检查了从访花昆虫体表取出的花粉粒中是否存在来自传粉者品种的花粉粒。结果表明，三个授粉媒介群体参与了授粉媒介品种的花粉粒转移。最后，我们通过在研究地点走动来记录访花昆虫的丰富程度。结果表明，在调查期间，无论温度如何，都能稳定地观察到苍蝇，这与独居蜜蜂不同，独居蜜蜂在低温下很少表现出访花活动。结果还表明，在开花后期，研究地点的独居蜂数量较多。这些结果表明，膜翅目和双翅目对日本梨园的开放昆虫授粉的贡献不同，但相互补充。