Data from: The carry-over effects of pollen shortage decrease the survival of honeybee colonies in farmlands

1.Many studies have reported honeybee colony losses in human-dominated landscapes. While bee floral food resources have been drastically reduced over past decades in human-dominated landscapes, no field study has yet been undertaken to determine whether there is a carry-over effect between seasonal disruption in floral resource availability and high colony losses. 2.We investigated if a decline in the harvest of pollen by honeybees in spring affected managed honeybee colony dynamics (brood size, adult population and honey reserves) and health (Varroa mite loads and colony survival) throughout the beekeeping season. 3.A decline in pollen harvest was associated with a direct reduction in brood production, leading to a negative effect on the adult population size later in the season, and lower honey reserves before the onset of winter. Furthermore, the decline in pollen harvest negatively impacted the health of the colony, resulting in higher Varroa mite loads and higher seasonal and winter colony losses. 4.Early warning signs of these carry-over effects were identified, showing that preferential investment in honey reserves instead of brood production early in the season increased the decline in pollen harvest and its associated carry-over effects. 5.Synthesis and applications. The results suggest that the decline in pollen harvest may have been overlooked as a cause of pollen shortage and associated bee colony losses. Strategies to avoid such losses in intensive farmland systems include i) limiting or avoiding honey harvests in spring, ii) monitoring colonies for early warning signals of colony failure, and iii) increasing the amount of floral resources available through wise land-use management.

1. 诸多研究均已报道，在人类主导的景观中存在蜜蜂蜂群损失的现象。尽管近几十年来人类主导景观中的蜜蜂蜜粉源食物资源已大幅缩减，但目前尚无野外研究探明，蜜粉源可获得性的季节性中断与严重蜂群损失之间是否存在遗留效应。
2. 本研究探究了春季蜜蜂花粉采集量下降，是否会影响整个养蜂季中人工饲养蜜蜂蜂群的动态参数（幼虫数量、成年蜂种群规模及蜂蜜储备）与健康状况（瓦螨寄生载荷及蜂群存活率）。
3. 花粉采集量下降与幼虫繁育量的直接减少存在显著关联，进而在养蜂季后期对成年蜂种群规模产生负面影响，并在冬季来临前导致蜂蜜储备量降低。此外，花粉采集量下降还会对蜂群健康造成负面影响，致使瓦螨寄生载荷升高，同时加剧了养蜂季及冬季的蜂群损失率。
4. 本研究还识别出了这些遗留效应的早期预警信号，结果表明，养蜂季初期优先储备蜂蜜而非开展幼虫繁育的管理策略，会进一步加剧花粉采集量的下降及其相关的遗留效应。
5. 综合分析与应用建议：研究结果表明，花粉采集量下降作为花粉短缺及关联蜂群损失的诱因，此前可能未得到足够重视。在集约化农田系统中，可通过以下策略规避此类蜂群损失：①限制或避免春季蜂蜜采收；②定期监测蜂群，以识别蜂群衰竭的早期预警信号；③通过合理的土地利用管理，提升区域内蜜粉源资源的总供给量。