Honey bees are fascinating insect societies,
throughout evolution, they develop several ways to defend their nest from pathogens,
thieves, and predators. Against microorganisms, honeybees rely on innate immunity and some
socially immune behaviors as discussed in another video in this channel. Against bigger enemies
like varroa mites and small hive beetles they rely on social immunity behaviors like grooming
hygienic behavior and the use of propolis to isolate intruders apart from the nest, however,
when the opponent is much bigger and stronger like a giant hornet honeybees can become very creative.
Normally honeybees collect resources from plant sources, nectar and pollen from flowers, and
propolis from tree buds however, this Apis cerana honey bee is collecting something very different,
animal poop yes you heard it right poop.
One of the most dramatic interactions between honeybees and hornets involves honeybees and the
famous Vespa mandarinia the murder hornet as it becomes known in the united states
the hornet can easily overtake colonies of the European honeybees Apis mellifera however,
they cannot do the same with Apis cerana, the Asian honey bee it is known that in the presence
of the hornet Apis cerana workers start vibratory signals to be prepared to hit ball scouting hornet
an impressive defensive behavior where honeybees attack the invader by engulfing them in a bowl of
honey bees not only trapping them but also killing them using heat and suffocation.
In 2018 a group of researchers led by Dr. Heather Matilla from Wesley college in Massachusetts
investigated claims from local beekeepers in Vietnam about the use of an unknown material
being collected by bees and use it at the entrance of the hives when another
giant hornet was present Vespa soror a close cousin of the Vespa mandarinia
that also preys on honeybees and masses. After several experiments and a lot of hard work,
the researchers conclude that the material was poop collected by bees intentionally used at
the entrance of the hives to protect the colony against the hornet this was the first description
of honeybees collecting no plant material and the first description of honeybees using tools.
The research got a lot of attention out there it was featured on a youtube channel Scishow
on CNN, Scientific American and all of them described the results of this fantastic
use of the scientific method however none of them described how the science was done. How
do the scientists know the spots at the entrance of the hive were the results of honeybee activity?
to answer this question the researchers clean up 339 honeybee hives and on top of that they
record those heights activity for 10 days. Can you imagine yourself cleaning up poop from 339 hives
to fulfill your research duties? By monitoring these colonies the researchers could confirm
that fresh material was indeed deposited at the entrance of the hives by bees and it increases
over time as you can see in this graphic right here. After 5 days 25% of the hives have the
poop spot back and on day 10 some apiaries have reached 80 percent so now the researchers
know that over time there is an accumulation of spots and the bees are responsible for the spot
but how the heck the researchers know or figured it out the spots are poop?
The researchers marked several workers and with the video recording from the bees in the field
researchers could observe several Apis cerana worker bees not only investigating animal feces
but also carrying it back to their colonies and then applying it as a texture spot in front of
the hives confirming that the mysterious material is in fact poop. Again a lot of respect for the
researchers here can you imagine yourself in front of a pile of poop for hours marking bees and then
recording them and then going back and matching them with the painting that you did just to
confirm that whatever they collected is the thing they put in front of the hive... a lot of work
Okay now the researchers know the spots are made by bees now the researchers know the spots are
poop but how do they know the spots the presence of the spots is a reaction to the presence
of the Vespa soror specifically or not any Vespa?
Researchers hypothesized that poop spots at the entrance of the hives
were reactions to the presence of Vespa soror the initial claim from local beekeepers to prove it
they separated two sets of hypes in the same apiary one set of hives exposed to the hornet
in another set of hives where the researchers were waving them away and then they recorded the number
of poop spots at the entrance of each hive over time and the results show a strong correlation
as you can see here the number of spots increased overtime only on the hives exposed to Vespa soror
this is a strong result in favor of the hypothesis that the phenomenon
is a defense mechanism against Vespa soror, however, to make sure the behavior was not
triggered by any other hornets the researchers also performed the same experiment using Vespa
velutina and in this experiment, there was no correlation at all observed
meaning that Vespa velutina do not trigger the same defense mechanism.
So now the researchers know the spots are made by bees the spots are poop there is
a correlation when you have Vespa soror only that so the behavior is triggered
by the presence of the Vespa soror but now the question is what triggers the behavior uh is a
visual effect or there is any smell or anything else that triggers the effect? to answer this
question the researchers dissect Van der Vech's glands from Vespa soror the putative source of
pheromones that hornets use to mark target colons prior to a mass attack and exposed these extracts
to one set of Apis cerana honeybee colonies and the control contains only ether the extraction
solvent to another set of hives and documented the number of poop spots over time. As you can
see here the hives exposed to ether control has less than five poop spots on average at
the beginning and at the end of the test however, the hives exposed to the gland extract have more
than 15 poop spots on average at the end of the test much more than the eater controls itself,
showing that the gland extract is, in fact, a key factor to trigger the defense mechanism.
So many experiments right now, very exciting we learned a lot, but there is one question
that's still remaining does the poop at the entrance to the hive get rid of the hornet? does
it work? to answer this question the researchers measured the total visit duration of the hornets,
how long the hornets stay after landing, how long the horns stay landed at the entrance of the hive,
and last but not least how long the hornets chewed the entrance of the hive
all of that in three different levels of poop spots light, moderate, and heavy. The
total duration of a hornet visit on a hive with the light load of poop was around 100 seconds
and this time was reduced almost by half on hives with moderate and heavy loads of poop the hornets
stay landed on hives with a light load of poop for around 80 seconds and this time was reduced to
only 30 seconds on hives with moderate and heavy loads of poop the hornet landed at the interest
of the hive with the light poop load for around 35 seconds but this time was reduced almost 80
percent on hives with moderate and heavy loads of poop and finally, likely the most exciting result
the hornets were able to chew the entrance of the hive with the light load to poop for around 25
seconds and this time was dramatically reduced to almost zero on hives with moderate and heavy poop
loads this is definitely strong data showing how hard it is for the hornets to stay around in the
presence of poop basically the hornets can't stand chewing poop which is kind of funny.
I don't know about you but I learned a lot so far and I got a lot of respect for the researchers
can you imagine everything they have passed in Vietnam I'm very curious about not only science,
I have more questions about science, but I also have questions about the travel, the adventure,
the excitement of doing the research on location. Lucky us i invite the authors of the paper for my
next live stream it's gonna be held on February 3rd at 7 pm eastern time and all of you are
welcome to join us it is free to everybody I'll leave a link in the description of this video so
you can register to know more about the event if you like this video please consider subscribing
to the channel and also supporting us on Patreon I also want to invite you to watch this next video
right here thanks for watching inside the hive. tv the show of about bees, see you guys next week