Bumblebees, with their fuzzy appearance and buzzing flight, are a familiar sight in various environments. They are found globally and are an integral part of many ecosystems and agricultural settings.
Their Role in Pollination
Bumblebees are highly effective pollinators for wild plants and agricultural crops. Their large, hairy bodies readily collect and transfer pollen. They can also fly in cooler temperatures and lower light conditions than many other bee species, extending their foraging hours.
Bumblebees use a specialized technique called “buzz pollination,” or sonication. For certain flowers, such as tomatoes, peppers, blueberries, and cranberries, pollen is tightly held within the anthers. A bumblebee grasps the flower and vibrates its wing muscles, causing vibrations that dislodge the pollen. This action is crucial for pollinating these plants, which honeybees often cannot perform. They are often two to four times more effective per bee than honeybees for some crops, due to a faster working rate and longer foraging days.
Bumblebees contribute to entire ecosystems and agricultural economies. They pollinate numerous wild flowering plants, which provide food for birds and small mammals. In agriculture, bumblebees contribute to the production of a wide range of fruits and vegetables, including strawberries, curcurbits, and various orchard fruits. This service has substantial economic value, contributing billions of dollars annually to agricultural economies.
Life in a Bumblebee Colony
Bumblebees are social insects living in colonies, with a structure different from honeybees. Most colonies are annual, lasting a single season, unlike perennial honeybee colonies. A new colony begins in the spring when a single queen emerges from hibernation.
The queen, having mated the previous autumn, searches for a suitable nesting site, often an abandoned rodent burrow, a tussock of grass, or another sheltered cavity. She then provisions the nest with nectar and pollen and lays her first batch of eggs. These first offspring develop into female worker bees, which take about four to five weeks to emerge as adults.
Once the first workers appear, they take over the tasks of foraging, caring for subsequent broods, and maintaining the nest. The queen remains in the nest, focusing on laying eggs. As the season progresses, the colony grows, typically reaching a size of 50 to 500 individuals, though this can vary by species. In late summer, the queen lays unfertilized eggs that become male drones and fertilized eggs that become new queens, ensuring species continuation.
Everyday Activities and Adaptations
Bumblebees have specific behaviors and adaptations for their daily tasks. They collect nectar for carbohydrates and pollen for protein from flowering plants. Their long, hairy tongues allow them to access nectar from various flower shapes, including those with deep corollas. As they forage, pollen adheres to their dense body hairs, facilitating transfer between flowers.
Bumblebees regulate body temperature, remaining active in cooler conditions. To warm flight muscles for takeoff, they shiver, uncoupling wing muscles to vibrate their thorax. This shivering can raise their thoracic temperature to between 30°C and 40°C. Their fuzzy fur acts as insulation, maintaining body heat.
While generally not aggressive, female bumblebees can sting to protect themselves or their colony. Unlike honeybees, a bumblebee’s stinger is smooth, allowing it to sting multiple times without dying. Male bumblebees do not have a stinger. When threatened, some bumblebees drop to the ground, pulling their attacker with them.