Tag Archives: Bumblebees

Did you know that bumblebees find efficient ways to move a ball to a target?

Have you ever watched a bumblebee collecting nectar from flowers? At first sight, this does not seem like a very difficult task, requiring sophisticated cognitive skills.

However, bumblebees have an amazing ability to learn. Not only where to find the nectar, but also how to perform human-designed tricks that require behaviours not needed in nature. For example, bumblebees have learned to pull strings, pull caps aside, and rotate disks to get to a reward.

Not so long ago, scientists (and bumblebees) have taken it a step further. The scientists, in various ways, demonstrated to their subjects that moving a ball into a target (a circle drawn on the experimental platform) led to a reward. The bumblebees quickly learned to do so themselves, and even improved their tactic to be more efficient than those demonstrated.

Teachers

First, the researchers trained the bumblebees to move a wooden ball, larger than them, to a target – the demonstrator was an artificial insect (on a stick held by the experimenter) pushing the ball. The bumblebees quickly got the idea, but preferred pulling the ball while moving backwards over pushing it. These bumblebees were the demonstrators in the next phase.

Students

In the main experiment, new, untrained bumblebees were divided into three groups. Each insect in the first group could watch another bumblebee dragging one of three available balls to a target and they both received a reward – a drop of sugar water. Insects in the second group saw a ball that moved “by itself” to the target (with help of a researcher-directed magnet under the platform). When the ball reached its destination, the watcher would get a reward. Insects in the third group simply found the ball already at the target with the reward next to it. Each demonstration/trial was conducted only three times.

Then the bumblebees were tested without further demonstration and only got a reward if they brought the ball to the target themselves. Virtually all bumblebees that had had a live demonstrator successfully dragged the ball to the target and did so faster than the other two groups. Those that had seen the ball moving by itself completed about 8 out of 10 trials. Finally, those bumblebees that had simply found the ball next to the reward were successful on average in only 3 or 4 of 10 trials and took the longest.

The student has become the master

Interestingly, the bumblebees did not simply copy what they observed early on. The bumblebee-demonstrator and magnet-using scientist always moved the farthest ball to the target. The student bumblebees usually moved the one closest to the target, even if it had a different colour than the one in the demonstration. And it was not a result of closest ball being pushed accidentally to the target, because the bumblebees usually dragged the ball actually being in-between the ball and the target.

To sum up: firstly, the bumblebees quickly learned a new task requiring the use of a tool (ball) and behaviour that has little to do with normal bumblebee foraging. And secondly, they did not blindly copy a previously observed behaviour, but used a more efficient method – moving the ball closest to the target.

Such unusual experiments show how great a capacity for learning and flexibility in problem solving these common insects have.

Did you know that bumblebees give up sleep to care for their siblings?

I still remember months of sleep deprivation after my children were born. In the evenings my husband would take care of them and I would go to bed at eight. Still, I would feel like a zombie in the morning, after waking up every few hours to feed my babies.

If you have children, you probably know what I’m talking about. If you don’t, maybe you will find out one day…

A recent study shows that bumblebees also sleep less when they have offspring to take care of, even though the young are not their own offspring, but siblings. The large earth bumblebee (the species in the study I’m discussing here) is a social insect. In the spring, the queen lays eggs that develop into workers that will take care of their mother and their younger brothers and sisters.

When workers were kept with their younger siblings – in the larvae or pupae stages – they slept much less than if they were kept with a similarly-sized piece of wax (used as a control – so that all the bees had something with them and potentially something to do). And while larvae need feeding, pupae do not. But even pupae need grooming and temperature control – and workers did that. When researchers removed pupae from their cocoon and gave the workers an empty cocoon, at first the workers slept as little as workers with live pupae, but with time they started sleeping as much as the control bees. Most likely pupae release substances that make workers give up sleep in order to tend for the young. When pupae case is empty substances slowly evaporate or degrade.

After the pupae were removed (effect of larval removal was not checked), workers started to sleep more. Where they catching up on sleep? Maybe partially, but researchers speculate that the presence of young modulates the long-term sleep needs of the nurses. That’s because even though workers slept longer after pupae was removed, they still slept less than workers that never had pupae to take care off. If they would be catching up on sleep, they should sleep more.

It’s as of yet not certain whether reduced sleep has just as negative an effect on bumblebees’ performance, cognition or even health as it does on humans. Perhaps like some migrating birds, bumblebees can perform well even under long-term sleep deprivation. If so, I’m jealous!


Polską wersję tego wpisu możesz znaleźć tutaj.