In the boundless meadows of Southern and Eastern Asia, a small but captivating creature takes the centre stage. Today we explore the fascinating world of 𝘉𝘰𝘮𝘣𝘶𝘴 𝘦𝘹𝘪𝘮𝘪𝘶𝘴 (Smith, 1852), the orange-legged bumble bee. With its vibrant appearance and vital ecological role, this remarkable insect invites us into a realm where nature’s beauty intertwines with its intricate mechanisms.
Our story begins in the sun-drenched fields and fragrant blooms of Asia, where the orange-legged bumble bee reigns supreme. Despite a relatively short head, our orange-legged bumble bee emerges as a true titan among its peers, boasting a size of approximately 18 mm for workers and drones (males), and an impressive span of nearly 30 mm for the queens. With its distinctive orange legs contrasting against its fluffy black and yellow body, our bumble bee is undoubtedly the embodiment of cuteness. However, appearances can be deceiving for our bumble bee which is also a brave little warrior. Its striking colouration serves as an aposematic signal - a warning to potential predators, signalling the presence of its fierce defence mechanism to deter lurking predators.
When it comes to nesting, the bumblebees are true masterminds, and each colony is a fortress meticulously designed to shield their kin. They showcase a spectrum of colony sizes, from gatherings of a few dozen workers to bustling communities teeming with thousands. Their nesting choice often favours subterranean realms like deserted mammal burrows or cleverly repurposed human-made structures such as PVC pipes or the covert spaces beneath buildings, all crafted to cloak their precious home and their queen from prying eyes. To further defend their sanctuary, the entrances of these underground bases are often found to be concealed with vegetation, be it dried or living - to potentially thwart any unwelcome detection.
As the orange-legged bumble bee ventures into the world, it is immediately drawn to the vibrant and nectar-rich flowers that dots the landscape. Tasked with gathering nectar as a food source for the nest and pollen to supply the young with protein, our bumble bee worker is well-equipped for this mission. With its long proboscis, a straw-like feeding tube, it delicately probes into the depths of flowers, extracting the sweet nectar hidden within and collecting pollen grains that cling to its fluffy body. But what if some of the pollen is firmly stuck inside the flower? Well fear not; the orange-legged bumble bee has a spectacular trick up its sleeve – buzz pollination. By vibrating its flight muscles at an impressive frequency of up to 400 Hz (that’s 400 times per second )- akin to the pitch of a car horn - as it grips onto a flower’s anthers, this action produces the distinctive buzzing sound that prompts the flower to release a burst of pollen. This specialized method allows the orange-legged bumble bee to efficiently extract pollen from flowers that would otherwise be difficult to access, solidifying its role as an invaluable partner in the reproductive cycle of these plants.
In the mist of its feeding adventure, the orange-legged bumblebee faces yet another challenge – cold! Unlike endothermic creatures that internally regulate their body temperature, insects are ectothermic, relying on external sources to manage their warmth. While many insects become sluggish or unable to fly when the air turns cool, our bumblebee possesses an exceptional adaptation - our industrious fella can produce internal heat, sustaining a relatively high body temperature even in chilly environments. Before taking flight, the bumble bee engages in a pre-flight warm-up routine, much like athletes warming up before a race, ensuring its flight muscles are ready for action in the chilly air. This impressive ability has intrigued scientists, who have been investigating the mechanism behind such heat generation, with hypotheses ranging from internal chemical reaction to shivering – similar to how humans cope with a cold environment.
Surprisingly, the orange-legged bumblebee is not just prepared for moderately cold temperatures – but also possesses strategies for more extreme conditions. When the temperature drops too low, the bumble bee can enter a state of chill-coma. Resembling a deep sleep, its bodily functions will slow down and become temporarily paralysed. But don’t worry, as temperature returns to normal, it gradually awakens from its chilly slumber, regaining full functionality and resuming its vital pollination duties.
Now, if your heart has been stirred by the captivating journey of the orange-legged bumble bee, come and witness our cute little fella firsthand in the Hong Kong Biodiversity Museum! If you enjoyed this post, feel free to share it with your friends and follow us every week for more posts.
Text: Nick Lin
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