This was a fascinating research project! I have gathered some
information about the way that groups of bees can mount a "thermal"
attack on a hornet or wasp. Initially I wondered how bees could heat a
hornet, but I've found several explanations of the phenomenon, which
is called "heat-balling."
"The Japanese honeybee (Apis cerana japonica) has a unique way of
defeating its sympatric predator, the giant hornet (Vespa mandarinia
japonica). The Japanese honeybee is a small creature with a
correspondingly small sting; as its primary means of defense cannot
inflict much damage against such a large predator as the giant hornet,
it requires another method of defense... Instead of utilizing its
stinger against the pack-hunting hornet, the honeybee instead waits
for the predator, having earlier detected traces of its pheremonal
hunting signals. As a hornet approaches the nest in an attempt to kill
honeybees, a hundred or so will guard the nest entrance in an attempt
to draw it on. When the hornet enters the nest, it is immediately
mobbed by a clump of approximately 500 honeybees, which, surprisingly,
do not sting the hornet to death as previously thought... Instead, the
bees heat themselves up to 47 degrees C very quickly using their
flight muscles. As the hornet?s upper lethal temperature is 44-46
degrees, it is killed quickly, effectively baked to death by the large
clump of bees."
Defensive Adaptations: Heat Tolerance as a Weapon
http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2001/Thawley/defense.htm
"Although a handful of Asian giant hornets can easily defeat the
defenses of honeybees, whose correspondingly small sting cannot
inflict much damage against such a large predator as the giant hornet,
the Japanese honeybee (Apis cerana japonica) has evolved an ingenious
method of defending against the much larger predator.
When a hornet scout locates a Japanese honeybee hive and approaches
the nest, the scout will emit specific pheromonal hunting signals.
When the honeybees detect these pheromones, a hundred or so honeybees
will gather near the entrance of the nest, apparently to draw the
hornet further into the hive. As the hornet enters the nest, a large
mob of about five hundred honeybees surround the hornet, completely
covering it and preventing it from moving, and begin quickly vibrating
their flight muscles. This has the effect of raising the temperature
of the honeybee mass to 47 °C (116.6 °F). Though the honeybees can
tolerate such a temperature, it is fatal to the intruder, which can
handle a maximum temperature of about 45 °C/113 °F, and is effectively
baked to death by the large mass of vibrating bees."
Wikipedia: Asian giant hornet
http://en.wikipedia.org/wiki/Asian_giant_hornet
"Body heat can be so powerful that some honeybees in Asia use it as a
deadly weapon. A few dozen bees sometimes swarm around attacking wasps
and heat them to death. The bees that collect into a ball to kill a
wasp or some other invader seem to regulate how hot it gets to keep
from cooking themselves, says an international team of scientists. The
team studied this heat-balling behavior in two species of honeybees.
One species is native to Asia. The other species, the European
honeybee, was brought to Asia about 50 years ago...
To further study this defense behavior, the scientists tied down 12
wasps and moved one wasp close to each of six colonies of European
bees and six colonies of Asian bees. All of the defender bees from
each colony surrounded its wasp immediately. The researchers then used
a special sensor to measure temperatures inside the bee clumps.
Within 5 minutes, the temperature at the center of an average ball
rose to around 45 degrees C (113 degrees F). That's high enough to
kill a wasp. Within 5 minutes, the temperature at the center of an
average ball rose to around 45 degrees C (113 degrees F). That's high
enough to kill a wasp. In separate tests, the researchers checked to
see how close the bees came to cooking themselves. There's a margin of
safety, they say. Asian honeybees die at 50.7 degrees C (123 degrees
F) and European honeybees die at 51.8 degrees C (125 degrees F)."
Science News for Kids: Bee Heat Cooks Invaders
http://www.sciencenewsforkids.org/articles/20050928/Note2.asp
"Honeybees that defend their colonies by killing wasps with body heat
come within 5°C of cooking themselves in the process, according to a
study in China. At least two species of honeybees there, the native
Apis cerana and the introduced European honeybee, Apis mellifera,
engulf a wasp in a living ball of defenders and heat the predator to
death. A new study of heat balling has described a margin of safety
for the defending bees, says Tan Ken of Yunnan Agricultural University
in Kunming, China...
Heat balling is the flip side of bees nursing larvae in a nest, says
Seeley. To keep the youngsters at the right temperature in cool
weather, honeybees space themselves around the nursery and shiver
their powerful flight muscles to generate heat. Seeley notes, however,
that the nursemaids don't raise the temperature above 36°C, so the
brood stays safe."
Science News: Balls of Fire: Bees carefully cook invaders to death
http://www.sciencenews.org/articles/20050924/fob5.asp
These articles provide some details about the endothermic properties
of bees, and "shivering thermogenesis," in which the vibration of the
flight muscles produces heat:
Department of Biology, Davidson College: Flight Adaptations
http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2001/Thawley/flight.htm
The Journal of Experimental Biology: Endothermic heat production in
honeybee winter clusters
http://jeb.biologists.org/cgi/content/full/206/2/353
My Google search strategy:
Google Web Search: bees heat hornet
://www.google.com/search?hl=en&q=bees+heat+hornet
Google Web Search: bees hornet endothermic
://www.google.com/search?hl=en&q=bees+hornet+endothermic
Google Web Search: bees hornet OR wasp heatballing OR "heat balling"
://www.google.com/search?hl=en&q=bees+hornet+OR+wasp+heatballing+OR+%22heat+balling%22
I hope this is helpful. If anything is unclear or incomplete, please
request clarification; I'll be glad to offer further assistance before
you rate my answer.
Best regards,
pinkfreud |
