Queen bees ‘toot’ to instruct colony to keep them safe

The study has shed new light on how honeybees communicate in the hive

Held captive in their queen cells by the workers to prevent infighting, the rival ‘virgin queens’ then respond to this tooting with a ‘quack’ – which the researchers say is their signal to the colony that they are ready and waiting to replace the queen as soon as she leaves.

While it has long been known that queen bees ‘pipe’ loudly in the hive, the study has shed new light on the reason behind it.

Scientists at the university – who have been studying honeybee communication in the hive – say that as well as preventing conflict, the important signal is linked to the swarming behaviour of the bees.

They found that when up to half the honeybees swarm to form a new colony –led by the mobile queen – the tooting stops immediately, which is perceived by the remaining workers as a cue to release a new leader, who stops quacking and begins to toot her arrival.

The findings also suggest that when the quacking stops completely, the colony knows that there are no virgin queens left and the honeybees must not swarm again or they will be left without a queen.

The study involved placing ultra-sensitive vibrational sensors called accelerometers into the heart of hives to non-invasively investigate the vibrational signals produced by the bees, to look for clues which might help to monitor and predict the honeybee swarming process. Vibration is one of the forms of communication that honeybees use to preserve the cohesion of the colonies.

Using this information they were able to compare it alongside the use of toots and quacks of honeybees across the entire swarming season.

The researchers, writing in the journal Scientific Reports, found that queen tooting started between four and seven days after the initial swarming and a ‘duet’ of tooting and quacking then persisted until the exit of the final swarm, when the last queen remains.

They say the findings show for the first time that the absence of tooting is the trigger for the colony to release a new queen.

“The previous common interpretation of this duet is that it is a sizing-up exercise between the mobile and captive queens”, said Dr Martin Bencsik, lead researcher and a scientist in the university’s School of Science and Technology.

“Our work provides strong evidence that the queen tooting and quacking is actually a colony-level communication to aid the worker population in the orderly co-ordination of the release of queens.

“The piping back and forth informs the colony that one queen is free-running and how many are encapsulated in their queen cells and this allows the worker bees to behave accordingly. Specifically, they work at avoiding direct competition between them.

“If it was not for the worker bees keeping the virgin queens captive, two or more queens would be heard tooting simultaneously, something that is never observed in our recordings.

“The quacking indicates to the colony that queens are still available for further swarms. The mobile queen and half the colony can swarm away, because they know that further queens are still to be released. When the quacking ceases, it indicates to the colony that the pool of captive queens is exhausted, and all bees must remain where they are.”

Using the vibrational data the researchers say that by monitoring the hive over a period of about ten days, they are also able to predict whether swarming will occur or not, with a high degree of accuracy.

Dr Michael Ramsey, a Nottingham Trent University scientist involved in the study, said: “Our methods that use vibrational spectra obtained from the heart of honeybee hives have shown tremendous potential as a useful tool for beekeepers to monitor the likelihood that their colonies will swarm.

“By providing them with continuous information about swarming preparations, beekeepers will be able to prioritise their efforts, saving them both time and money, and adjust swarm-prevention measures to minimise disruption to their colonies, allowing them to develop more naturally.”

Dr Yves Le Conte, senior scientist and Research Director at INRAE, said: “When we look at a honeybee colony, it is always fascinating to see thousands of individuals working together to develop their nest. The big question is how do they do it?

“Our work has demonstrated the complexity and the beauty of chemical and acoustical communication among honeybees and given us greater insight into their ability to communicate together as a colony.

“We believe there is much more to discover on this topic.”

The study also involved the National Research Institute for Agriculture, Food and Environment (INRAE) in France and the Beekeeping Centre of Research and Information (CARI) in Belgium.