Captured on video: Bees set off alarms to warn of ‘deadly hornet’ attacks

Researchers at Wellesley College have identified a sound that Asian bees use to warn the hive of a ‘deadly hornet’ attack.

Asian bees (Apis cerana) produce a unique alarm sound to alert hive members of an attack by giant “murderous hornets”, according to a new article published in the journal Royal Society Open Science. For the first time, scientists at Wellesley College have documented these so-called “anti-predator hoses,” which serve as bugle calls to beehive members to initiate defensive maneuvers. You can hear a sampling in the (rather disturbing) video, embedded above, of bees being attacked by a hornet.

“The [antipredator] pipes share common traits with many mammalian warning signals, so when a mammal hears them, there is something that is immediately recognizable as communicating danger, ”said co-author Heather Mattila of Wellesley College , who said the alarm signals gave her chills when she first heard them. “It sounds like a universal experience.”

As I wrote previously, the so-called murderous hornets became infamous after November 2019, when a Blaine, Washington beekeeper named Ted McFall was horrified to discover thousands of tiny mutilated bodies littering the ground – a entire colony of its bees. had been brutally beheaded. The culprit: the giant Asian hornet species Vespa mandarinia, native to Southeast Asia and parts of the Russian Far East. Somehow, these so-called “murderous hornets” had found their way to the Pacific Northwest, where they now pose a serious ecological threat to North American honey bee populations.

There are also other species of Asian giant hornets. They are advanced predators and sport huge mandibles that they use to rip the heads off their prey and remove the tasty thorax (which includes the muscles that power the bee’s wings to fly and move). A single hornet can behead 20 bees in a minute, and just a handful can wipe out 30,000 bees in 90 minutes. The hornet has a poisonous and extremely painful sting, and its stinger is long enough to pierce traditional beekeeping combinations. And while Asian bees have developed defenses against the deadly hornet, North American bees have not, as the McFall colony massacre clearly demonstrated.

Mattila has studied bees for 25 years, fascinated by their organization and ability to communicate, and she turned to Asian bees in 2013. “They have evolved in a much more frightening predatory landscape,” she said. declared to Ars, pointing to the 22 species of hornets in the world for which Asia is a particular hot zone. Many of these species depend on insects like bees to grow their colonies, so they are among the most relentless predators of bees. The deadliest of all are the giant hornets (aka “murderous hornets”) as they coordinate in groups to attack beehives.

“As humans, I think there’s something fundamentally appealing about understanding predator-prey interactions,” Mattila said. “Humans are both predators and prey, depending on the situation, so we have evolved under bee-like circumstances. We can recognize their plight in the face of giant hornets.”

Last year, Mattila and her team documented the first example of bee use of tools in Vietnam. Researchers found that Asian bees forage on animal droppings and use it to line the entrances to their hives, a practice called “fecal spotting.” It serves as a sort of chemical weapon to ward off giant hornets. Mattila and her team found that hornets were much less likely to land or find their way into beehives with entrances lined with animal droppings.

How bees use animal droppings as a chemical weapon to protect beehives from giant ‘killer hornets’.

While Mattila and her team were in Vietnam to study the droppings, they noticed that the noise levels in the hives increased dramatically whenever the giant hornets approached. “We could hear the sounds of bees from several meters away,” she said. “So we started to install microphones in the settlements so that we could listen to them.” They also made numerous video recordings of the activities in the apiaries of the local beekeepers.

In the end, they collected some 30,000 signals emitted by the bees over 1,300 minutes, then translated those sounds into spectrograms for analysis. Bees produce a surprisingly complex range of sounds, which they perceive either as movements of air particles which they detect with their antennae, or as vibrations which they detect via special organs in their legs. Bees’ signals are therefore “vibroacoustic” and are transmitted within colonies both in the form of airborne sounds and vibrations.

There are whistles, for example, usually made by all bees at once as they lower their bodies and move their wings in near synchrony, Mattila said. They hiss constantly, but more so when hornets are present, and the exact purpose of the hiss is not yet fully understood.

“Hissing in other animals is often used to intimidate a predator, but that is probably not the case with bees, mainly because they hiss a lot without predators as well,” Mattila said. “One idea that has been proposed (not by us) is that the hissing helps momentarily silence the colony because the bees remain motionless for a while after a whistle. It might help the workers to perceive other sounds in the nest. so most bees stop moving for a second. “


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