Honey bee lifespan: the critical role of pre-foraging stage

Assessing the various anthropogenic pressures imposed on honey bees requires characterizing the patterns and drivers of natural mortality. Using automated life-long individual monitoring devices, we monitored worker bees in different geographical, seasonal and colony contexts creating a broad range of hive conditions. We measured their life-history traits and notably assessed whether lifespan is influenced by pre-foraging flight experience. Our results show that the age at the first flight and onset of foraging are critical factors that determine, to a large extent, lifespan. Most importantly, our results indicate that a large proportion (40%) of the bees die during pre-foraging stage, and for those surviving, the elapsed time and flight experience between the first flight and the onset of foraging is of paramount importance to maximize the number of days spent foraging. Once in the foraging stage, individuals experience a constant mortality risk of 9% and 36% per hour of foraging and per foraging day, respectively. In conclusion, the pre-foraging stage during which bees perform orientation flights is a critical driver of bee lifespan. We believe these data on the natural mortality risks in honey bee workers will help assess the impact of anthropogenic pressures on bees.要评估施加于蜜蜂的各类人为压力，需先明确其自然死亡的模式与驱动因素。本研究采用自动化终身个体监测设备，在不同地理、季节与蜂群背景下对工蜂进行监测，以此构建多样化的蜂箱环境条件。我们测定了其生活史性状，并重点探究了觅食前飞行经历是否会影响蜜蜂寿命。研究结果表明，首次飞行日龄与觅食起始时间是在很大程度上决定蜜蜂寿命的关键因素。尤为关键的是，本研究发现有高达40%的蜜蜂会在觅食前阶段死亡；而对于存活下来的个体而言，首次飞行至觅食起始之间的时长与飞行经历，对最大化其觅食天数至关重要。进入觅食阶段后，工蜂的死亡率恒定：每小时觅食时段的死亡率为9%，每觅食日的死亡率则为36%。综上，蜜蜂进行认巢飞行的觅食前阶段，是影响蜜蜂寿命的关键驱动因素。我们认为，这些关于工蜂自然死亡风险的研究数据，将有助于评估人为压力对蜜蜂的影响。