Buzz the Alarm! 'Stop Signals' in Bees Discovered

A recent study in the PLOS journal described different types of vibration-based "stop signals" produced by certain species of Asian honey bees when they are attacked by hornets.

According to the findings, the alarm signals have varying effects depending on the threat, its level and its context. One typical signal is given by a bee to another by a brief pulse sent through a head-butt.

The research was a collaboration between American scientists from the University of California and Chinese scientists from Xishuangbanna Tropical Botanical Garden, Chinese Academy of Science.

The biologists measured and monitored the vibrations, and took notes on the various parameters, such as the frequency, pitch and duration of pulse.

As quoted in a Science Daily report, Professor James Nieh, the team leader, said that they were surprised by the way specific messages based on the type of danger were encoded in the signals.

As mentioned in its abstract, alarm communication is an important form of adaptation in social groups. It is significant in fighting predators and it is a defensive strategy that allows a group of social organisms to respond to predation.

The scientists used two species of hornets, namely, the largest hornet species, Vespa mandarinia, and the smaller hornet species, Vespa velutina. They alternately introduced these species into colonies of Asian honey bee species, Apis cerana.

They discovered that the bees responded differently depending on the species of hornet. The attacks of the larger hornets triggered higher alarm signals among the bees.

To date, the alarm signals produced by the bees are the most sophisticated type of alarm in social insects. Nieh previously discovered that a species of European honey bees, Apis mellifera, also produced alarm signals when they are attacked.