Department of Zoology, Stockholm University, Stockholm, 11418, Sweden.
Department of Zoology, Stockholm University, Stockholm, 11418, Sweden; Department of Animal Physiology, Zoological Institute and Museum, University of Greifswald, D-17489, Greifswald, Germany.
J Therm Biol. 2024 Apr;121:103830. doi: 10.1016/j.jtherbio.2024.103830. Epub 2024 Apr 5.
Over the past decades, increasing environmental temperatures have been identified as one of the causes of major insect population declines and biodiversity loss. However, it is unclear how these rising temperatures affect endoheterothermic insects, like bumblebees, that have evolved thermoregulatory capacities to exploit cold and temperate habitats. To investigate this, we measured head, thoracic, and abdominal temperature of bumblebee (Bombus terrestris) workers across a range of temperatures (24 °C-32 °C) during three distinct behaviors. In resting bumblebees, the head, abdomen, and thorax conformed to the environmental temperature. In pre-flight bumblebees, the head and abdominal temperatures were elevated with respect to the environmental temperature, while the thoracic temperature was maintained, indicating a pre-flight muscle warming stage. In post-flight bumblebees, abdominal temperature increased at the same rate as environmental temperature, but the head and the thoracic temperature did not. By calculating the excess temperature ratio, we show that thermoregulation in bumblebees during flight is partially achieved by the active transfer of heat produced in the thorax to the abdomen, where it can more easily be dissipated. These results provide the first indication that the thermoregulatory abilities of bumblebees are plastic and behavior dependent. We also show that the flight speed and number of workers foraging increase with increasing temperature, suggesting that bees do not avoid flying at these temperatures despite its impact on behavioral performance.
在过去的几十年中，不断升高的环境温度被认为是导致主要昆虫种群减少和生物多样性丧失的原因之一。然而，目前尚不清楚这些不断升高的温度如何影响具有体温调节能力以利用寒冷和温带生境的内生异温昆虫，例如熊蜂。为了研究这一问题，我们在三种不同行为下测量了熊蜂（Bombus terrestris）工蜂在一系列温度（24°C-32°C）下的头部、胸部和腹部温度。在静止的熊蜂中，头部、腹部和胸部与环境温度一致。在预飞行的熊蜂中，头部和腹部温度相对于环境温度升高，而胸部温度保持不变，表明存在预飞行肌肉升温阶段。在飞行后的熊蜂中，腹部温度以与环境温度相同的速度升高，但头部和胸部温度没有升高。通过计算多余温度比，我们表明熊蜂在飞行过程中的体温调节部分是通过将胸部产生的热量主动转移到腹部来实现的，在腹部热量更容易散发。这些结果首次表明，熊蜂的体温调节能力是可塑的，并取决于行为。我们还表明，随着温度的升高，蜜蜂的飞行速度和觅食工蜂的数量增加，这表明尽管飞行对行为表现有影响，但蜜蜂不会避免在这些温度下飞行。
