Menaced by Homicide Hornets, Bees Adorn Their Hives With Poop

Giant hornets of the Vespa genus do not play around when hunting.

These matchbox-sized horrors – a group that includes the infamous “murder hornets” – will invade beehives, brutally decapitate residents, and return the mutilated carcasses to their young. A small hangry hornet cavalry can wipe out a colony of bees in a matter of hours.

But even the most powerful monster can be stopped. And a great way for honeybees to stave off public insect enemy # 1 might be to serve them a # 2 serving.

To fend off huge hornet attacks, honeybees in Vietnam will decorate the entrances to their nests with droppings from other animals, a defense behavior known as droppings staining. This emerges from an article published in PLoS One magazine on Wednesday. The hideous ornamentation appears to repel – or at least seriously eradicate – the wasps, and offers the intriguing possibility that honeybees could use the stool as some sort of rudimentary tool.

Decorating your own home with manure may sound incorrect, especially to the docile bees that so many people associate with candy. “We think of bees visiting pretty flowers and collecting sweet nectar,” said Rachael Bonoan, a Providence College bee biologist who was not involved in the study. “This is the complete opposite.”

But the scat-based strategy seems to benefit from an attributable trend: most creatures are not interested in messing their meals with someone else’s garbage.

A team of researchers, led by Heather Mattila, who studies bees at Wellesley College in Massachusetts, was first made aware of the confusing behavior almost a decade ago while working in the field in Vietnam, where honey bees are being terrorized by Vespa Soror Hornets, a nearby sister species Asian giant hornet Vespa mandarinia, which terrified people in the Pacific Northwest earlier this year.

The local beekeepers had spied on a piece of gray-brown mass at the entrances to honey bee colonies, which seemed to adorn the insects in a frenzy after hornet attacks. Nobody was sure what the substance was, but “it didn’t smell good,” said Dr. Mattila. A zookeeper noticed bees buzzing around some water buffalo droppings and wondered if this was the source of the stench.

Dr. Mattila and her colleagues began exploring local farms, crouching in pigsties and chicken coops. Over time, Dr. Mattila a honey bee that landed on a mess of chicken droppings. The bee was busy pulling on some of the dirt with its mouth parts and then carrying it away. “I remember running back to the apiary and yelling, ‘It’s true, it’s finally true!'” Said Dr. Mattila.

Hours of video footage proved that the insect’s action was not an anomaly. When the researchers placed buffets of animal manure near several apiaries, the bees harvested clumps from it and dabbed their nests in carefully heaped up clumps, each roughly the size of a sesame or poppy seed. The spots seemed to sharpen in the days following the hornet attack. In their most adorned form, the colony entrances looked “like an all-bagel,” said Dr. Mattila.

Honey bees are typically demanding creatures who keep their households spotlessly clean. “Bees don’t even poop in their own hives,” said Dr. Bonoan. Carrying around the feces of another animal could put the risk of illness or even death.

But hornets spent less time lurking at the entrances of freckled nests with feces, and they were less likely to band together to invade colonies.

Recognition…Heather Mattila

It is not yet clear how much recognizing affects survival. Honeybees have a number of tactics they use when there is danger, including a sneaky and sometimes self-sacrificing move called balling, which involves a phalanx of worker bees swarming a hornet to choke or overheat it. In the long run, crap couldn’t make much of a difference.

The researchers also don’t know how the droppings stop the hornets from doing so. One way is for them to avoid the harmful botanicals that remain in some feces. Dr. Mattila noticed that the bees seemed to be going crazy, mostly because of the chicken droppings.

And of course, “poop really stinks,” said Dr. Bonoan. Poop could act like an inverted deodorant, layering its foul stench over the seductive waxy, floral scent that usually wafts from more pristine nests.

Since detection involves intentional manipulation of slurry, Dr. Mattila that this could qualify as a tool use. Dr. Bonoan said she was not yet convinced of the idea and noted that the droppings may not have been changed enough along the way.

Known tool users like humans may be tempted to thwart giant hornets with feces slag, especially as concerns about invasive Vespa species continue to attract national attention. While Asiatic giant hornets don’t usually pay much attention to humans, they can occasionally give off painful, poison-laced stings.

But there’s no guarantee that all giant hornets will shy away from dung, said Margarita López-Uribe, an entomologist at Pennsylvania State University who wasn’t involved in the study. Beekeepers should also not rush to spray their beehives with droppings, which could contaminate the precious honey inside.

Bees could benefit from poop stains, said Dr. Bonoan. But “if you’re human, don’t use poop to protect yourself from a murder horror.”

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