How Vietnamese bees use animal poop to protect themselves from hungry hornets
New honeybee study is the 1st evidence of bees using tools, says University of Guelph scientist
Scientists have documented the first evidence of honeybees using tools to defend themselves. And by tools, they mean poop.
It all started a few years ago when University of Guelph entomologist Gard Otis was visiting a beekeeping development project in Vietnam and noticed many of the hives were covered in dark spots.
"Having had experience with honeybees in Asia in several other countries, I'd never seen this before," he told As It Happens host Carol Off.
"One particular beekeeper who really knew his bees said, 'Oh, it's water buffalo dung.' And when I pressed him on that ... he said, 'Well, I've watched them collect it.' And I'd never heard of a report of honeybees collecting animal manure, animal dung. So that was, like, a first."
Otis and his colleagues from Canada and Vietnam have since recorded the beekeeper's observations in action, and learned the bees collect animal dung and smear it on their nests to ward off hornet attacks. Their findings were published Wednesday in the journal PLOS ONE.
White balloons and a 'little poo shop'
The bees, he said, were under regular attack from swarms of giant Asian hornets, whose invasive North American cousins have been dubbed "murder hornets." They are the size of golf tees, and their stings pack seven times the venom of a regular honeybee.
"If they can get in, they go in and they attack the bees and ... just start chomping them to bits," Otis said.
"All those little baby bees, the larvae and the pupae, are all the protein and fat [the hornets would] ever want. Plus they've got like a bonanza of honey that's left in there to keep them going for a week or so."
To study the phenomenon, the scientists needed to protect some beehives from the hornets, while allowing others to come under attack.
"We were positioned all through the apiary, and at some of the hives, we would station people with balloons on sticks. This was really high-tech," Otis said.
"They would wave the white balloon at the hornet when it arrived and it would fly away and they could prevent the hornets from visiting certain hives. And then other hives, we would allow them to go ahead and visit."
Meanwhile, the scientists needed to make sure they had plenty of animal feces on hand.
"One assistant … really wasn't enthusiastic about going around to the neighbouring farms and collecting shovelfuls of poo, and so we set up our own little poo shop, and we had chicken, pig, water buffalo and cattle," Otis said.
Sure enough, the nests that were raided by hungry hornets made use of the animal dung to protect their nests. The nests protected by balloon-wielding scientists, meanwhile, did not.
"At the end of the day, about 140 bees visited our little poo shop and we got to watch them collect the dung in their mouths and then fly off with it."
The researchers claim this the first documented instance of bees using tools.
What constitutes tool use is a controversial idea in science. The study's authors defined it using four established criteria: A creature must use an external object (the dung), alter its form (making the hive spots), manipulate the tool (carrying and forming it with their mandibles), and "effectively orient the tool" (strategically placing it around their hive).
The bees seemed to particularly favour the chicken and pig droppings, Otis said, perhaps because they have a more pungent smell.
"They also collected one really weird thing. They collected human urine, and the hive just reeked," Otis said. "So it isn't just poo they're collecting, but I think it's a variety of sorts of strong-smelling substances."
More work needs to be done to determine exactly why this stink defence is so effective against the hornets.
But Otis suspects it has something to do with the fact that the giant hornets — both the ones in Asia and the invasive species in North America — are the only types of wasp that attack bee colonies in swarms.
"The others all forage individually, but these guys get to, like, bring their nest mates back and do a mass attack," he said.
"And all we can imagine is somehow these strong odours interfere with that recruitment process. We have a little bit of data that suggests that's what's going on, but we can't definitively say that from our study."
The Vietnamese honeybees have lived alongside the giant hornets for millions of years, Otis said, and this is just one of several defence strategies they've developed to protect themselves.
But the hornets that are now showing up in North America aren't native to the continent, and scientists say they pose a risk to both humans and local honeybees, who lack the experience to ward off attacks.
"Sadly, our European bees that we keep in North America have no defences and they get slaughtered," he said.
Written by Sheena Goodyear. Interview produced by Chloe Shantz-Hilkes.
