Are honey bees (Apis mellifera ssp. carnica) in South Tyrol (Italy) choosing their pollen resources in apple orchards (Malus domestica)?

Apple tree (Malus domestica) production in South Tyrol (Italy) is a very important economic sector with more than 3,500 beekeepers managing 38,000 honey bee colonies (Apis mellifera). Here, we elucidate to what extend apple orchards were used by honey bees in 2016–2020, especially outside the blooming period, performing palynological analyses of pollen pellets and combined with vegetation surveys. The results indicate that apple orchards were the major pollen source for honey bees during the apple blossom. However, before and after the apple blossom, apple orchards played a minor role for the pollen supply of honey bees, as a wide range of insect pollinated or anemophilous flowers, such as from broadleaved trees, were the main pollen sources, even when not offering nectar to honey bees. Strikingly, herbaceous plants were less attractive to honey bees, which actively selected for the availability of blooming plants throughout the blossom and foraging season.

意大利南蒂罗尔地区的苹果（Malus domestica）种植业是当地极为重要的经济支柱产业，辖区内共有超过3500名养蜂人，管理着38000群西方蜜蜂（Apis mellifera）。本研究旨在阐明2016—2020年间，西方蜜蜂对苹果园的利用程度，特别是花期以外时段的利用情况；研究通过对花粉团开展孢粉学分析（palynological analyses）并结合植被调查完成。研究结果表明，在苹果花期内，苹果园是西方蜜蜂的核心花粉来源。但在苹果花期前后，苹果园在西方蜜蜂的花粉供给中仅扮演次要角色：此时多种虫媒或风媒开花植物（如阔叶树）构成了其主要花粉来源，即便这些植物无法为蜜蜂提供花蜜。值得注意的是，草本植物对西方蜜蜂的吸引力相对较弱；蜜蜂会主动选择在整个开花与觅食季内均可开花的植物资源。