The first time Kiyohito Morii saw a Japanese honeybee whooping an ant was on YouTube. The bee's chosen tactic appeared to be kicking, according to the video, but Morii would later learn this was a mistake. A few months later, he got a chance to observe the whooping behavior in-person and recognized the bees thwacked the ants not with their tiny black legs, but with their wings.
"I intuitively felt that this was a specialized defensive behavior against ants," Morii, a behavioral ecologist at the National Institute for Environmental Studies in Tsukuba, Japan, wrote in an email. Morii and his entomologist colleagues Yugo Seko and Yoshiko Sakamoto recently described this new defense mechanism in a paper in Ecology.
Honeybees are born fighters; they have to be. Their colonies teem with eggs, larvae, and adults—all delectable food for many predators and parasites. Many different bees and other eusocial insects have evolved particular defensive behaviors to protect their hives from predators. Some of these behaviors are stunning to witness and a testament to working together as a collective. When Japanese honeybees confront a giant hornet threatening to raid the nest, the honeybees swarm around the hornet in a bee ball, where hundreds of bees vibrate together to cook the hornet to death. When a predator approaches the open nests built by giant honeybees, the bees coordinate to flip their abdomens upward, creating the illusion of a giant, shimmering hive.
But sometimes bees must fight their battles alone. After watching the honeybee's smackdown, Morii looked for past research on interactions between honeybees and ants. He found observations of one defensive behavior called fan-blowing, in which bees fan their wings to shoo ants away from the entrance to the hive. But he found no papers describing a defense in which bees use their wings to actually hit the intruder ants, meaning this behavior was new to science.
Morii, Seko, and Sakamoto suggested various names for this behavior, including "hitting," "batting," and the names of techniques from sumo and kendo, Morii said. But they decided "wing-slapping" was the most accurate and nuanced term for the bee's moves. The slaps are certainly powerful—enough to send a grown ant pinwheeling through the air.
To film wing-slapping in action, the researchers conducted experiments in two Japanese honeybee colonies in Tsukuba City. They identified each hive's guard bees, which monitored the entrance to the hive, with a daub of paint. And then they collected three ant species known to invade Japanese honeybee hives—Japanese queenless ants, Japanese pavement ants, and Japanese wood ants—and placed the ants by the entrance to the hive.
It wasn't easy filming such itty-bitty slaps. For one, not all the ants cooperated. The Japanese wood ants "move so quickly that they scatter in all directions and disappear from the hive entrance in a short time," Seko wrote in an email. And Morii, who had set up above the hive with a high-speed camera, struggled to get clean footage of the whizzing guard bees, which constantly moved around the hive entrance.
But after reviewing their footage, the researchers observed that wing-slapping was a guard bee's most common defensive behavior against an intruding ant. More than half the time, a wing-slap successfully repelled a queenless or pavement ant. (The wood ants, which are longer and move more quickly, were better at evading the slaps.) The researchers suggested this behavior offers the bees a low-lift method of defense, requiring far less energy than fan-blowing or shimmering. But the paper left them with questions for future research, such as if some bees are better wing-slappers than others, and if they get better at wing-slapping the more they do it.
The researchers were so inspired by the wing-slapping that they created an accompanying music video for the bees—a first for the National Institute for Environmental Studies. They selected a song by the guitarist MIYAVI, who is known for his finger-slapping style of guitar. "Among many candidates, we couldn't think of a better song than 'Slap It' to highlight this behavior because the song perfectly matches the behavior (including lyrics) and features the guitar slapping technique," Sakamoto wrote in an email. The scientists faced challenges obtaining permission to include the copyrighted music. "However we are delighted that we ultimately succeeded and hope to share the greatness of this behavior with as many people as possible," Sakamoto added.
May these researchers' hard work inspire more scientists to add music videos to promote their papers! Could you imagine a slow-motion video of the leaping leech over the wistful guitar of Tom Petty's "Free Fallin'," or the the matador bug's leg-waving set to Lucian Piane's "Legs"? Either would surely be a better music video than whatever this is.
