BEHAVIOUR OF BUMBLEBEES
1. Foraging
A returning bumblebee forager communicates to other workers to ensure that they leave the nest and forage on flowers that have the same scent as the returned bee. Unlike the honeybees, bumblebees do not provide positional information of the location of certain food source.
Their communication system is less complex as compared to the honeybees. This form of communication produces a pheromone signal which contains terpenes eucalyptol, farnesol and ocimene. The release of these compounds stimulate workers to leave the nest to forage, which can help to increase the rate of foraging interval. This method can be applied commercially in greenhouses to enable pollination in crops, especially the ones that do not produce nectar, such as tomatoes.
Their communication system is less complex as compared to the honeybees. This form of communication produces a pheromone signal which contains terpenes eucalyptol, farnesol and ocimene. The release of these compounds stimulate workers to leave the nest to forage, which can help to increase the rate of foraging interval. This method can be applied commercially in greenhouses to enable pollination in crops, especially the ones that do not produce nectar, such as tomatoes.
Foraging bees often avoid flowers that were visited by other bumblebees. They are able to scent mark the flowers that they have visited. This allows the bees to spend less time on less profitable flowers.
Learning how to reach the nectar of certain complex flowers requires time and energy.
An example of complicated flower, with deep lying nectar, is the Monkshood (Aconitum napellus).
Figure 6.1 Aconitum napellus
Learning how to reach the nectar of certain complex flowers requires time and energy.
An example of complicated flower, with deep lying nectar, is the Monkshood (Aconitum napellus).
Figure 6.1 Aconitum napellus
In return, these bumblebees will be rewarded with large amount of nectar if they have successfully learn how to reach and obtain the nectar. Therefore bumblebees tend to obtain nectar from the same flowers if they are able to continue providing food to the bees. This behaviour is known as flower constancy.
2. Nectar robbing
Bumblebees are famously known as nectar robbers. They are able to ‘rob’ nectar by piercing a hole in the corolla of the flower to reach the deep lying nectar of some complex flowers, in which the nectar is hard to reach. BY doing so, they ‘rob’ the nectar, without pollinating the flower, which defeat the biological purpose of their visit. Nectar robbers can be either primary or secondary robbers. Primary nectar robbers are individuals who made holes in the corolla by biting, whereas secondary nectar robbers are individuals who use the holes that are previously made by primary nectar robbers.
3. Thermoregulation
At rest, a bumblebee’s temperature will decrease. In order to raise the temperature to 30 °C (temperature required to fly), they generate body heat by shivering their flight muscles. When warming up, the wings contract to generate more heat. The increase in the speed of contraction allows more heat to be generated.
The queen have about 2 to 7 months to find a nest to brood. Incubation of immature stages is required to increase the rate of development. Once the queen lays the first batch of eggs, she spends a lot of time incubating the eggs. The temperature of an established nest is kept between 29 to 31°C.
The queen have about 2 to 7 months to find a nest to brood. Incubation of immature stages is required to increase the rate of development. Once the queen lays the first batch of eggs, she spends a lot of time incubating the eggs. The temperature of an established nest is kept between 29 to 31°C.
As the colony grows, active incubation will no longer be necessary as large colonies can produce enough heat to keep the nest warm. If overheating occurs or if carbon dioxide levels increase in the nest, the worker bees will station themselves at the entrance to fan the brood with their wings.
Figure 6.3 A group of red tailed bumblebee (Bombus lapidarius) fanning their nest to cool it during hot weather