Honey Bees 'Scream' for Help When Attacked by Giant Hornets

Honey Bee Swarm - Sputnik International, 1920, 11.11.2021
According to scientists, it is still unclear whether these "distress calls" alter the behaviour of honey bees. The current observations reveal that the "chatter" inside a hive increases more than eight times during a hornet attack. Interestingly, the bees also smear animal faeces at the entrance to the hive to repel the hornets.
Asian honey bees (Apis cerana) have a unique defence mechanism against their predators, something which was unheard of earlier: they have managed to adapt to protect themselves from brutal attacks and invasion by giant hornets (Vespa soror) who are existential threats to the bees' colonies.
According to new research published in the journal Royal Society Open Science, these Asian bees have an alarm that is similar to a distress call.
As per the scientists, giant hornets can destroy an entire beehive in just a few hours and their "nasty" attack involves killing the defender bees, occupying their nest, and taking away the broods to feed their own larvae.

"It's alarming to hear! It's characterised by rapid bursts of high-pitched sounds that change unpredictably in frequency — they're quite harsh and noisy", Heather Mattila, a co-author of the study and a researcher at Wellesley College was quoted by Gizmodo as saying.

Per the study, this "shriek" by bees is an "acoustic trait with alarm shrieks, fear screams, and panic calls of primates, birds, and meerkats".

"It's exciting to learn that the sound properties of the honey bees' alarm signal are really similar to the properties of signals used by mammals that also live in social groups and share information about the danger around them", Mattila said.

Mattila and her team have been studying the interactions as well as natural instincts of honey bees and their predators for the last seven years. They would place microphones inside the beehives and examine the various sound effects.
The team recorded over 1,300 minutes of "conversations" inside the beehives in Vietnam. However, they found that the newly detected audio signal - antipredator pipe - was isolated from other sounds, as they also examined the visual representations of sound known as spectrograms.

"We have images which show the different properties of the sounds that the bees make, even if they overlapped in time because many bees were signaling at once. We looked through all of our recordings to get good examples of antipredator pipes that were clear of other sounds so that we could characterise their acoustic properties", Mattila said.

She also said that the visual representations helped them to easily recognise anti-predator cries in more chaotic moments when lots of sounds were being made.
The scientists also said they are excited about these preliminary observations and these findings could become the foundation stone for future research.
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