What does the “Whoop” sound really mean?

Honeybees make a “whoop” sound. Is this a sound a tells other bees to stop looking for food in a certain area?

Or it is simply a sound of surprise?

Bee-apisHoney By Maciej A. Czyzewski – Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=8786717

By using accelerometers to record vibrations inside hives for a year, researchers from Nottingham Trent University managed to isolate the sound. You can hear it in the sound cloud below.

Lots of interesting ideas to why the honeybees make the “whoop” sound has been put forward. Yet, it seems that these whoops happen rather frequently. The bees made these whooping sound more frequently than would be expected if they were trying to tell other bees not to look for nectar or other types of food in a certain area. The whoops sounds happen mostly night. When the bees bumped into each other they were startled. So perhaps the whoop sound is a sound of being surprised when you bump into a bee in the middle of the night.

The insight could help us to monitor how healthy a bee hive is. A stressed colony would most likely not react to small stimulus such as the bumping into another bee in the middle of the night. Considering the many challenges that bees around the world are currently facing it is indeed important to find out ways to monitor their health.