Japanese Honeybee thermal defence against Japanese giant hornet

Japanese Honeybee thermal defence against Japanese giant hornet

The Japanese honeybee (Apis cerana japonica) has a defense against the Japanese Giant Hornet (Vespa mandarinia japonica) attacks. When a hornet approaches the hive to release pheromones, the bee workers will retreat back to the hive, leaving an opening to allow the hornet scout to enter. At a given point, the bees emerge from their hiding places in an angry cloud formation containing some 500 individuals. They form a tight ball around the hornet that acts like a convection oven when the bees vibrate their wings to direct air over their bodies, warmed by their muscular exertion, into the inside of the ball. The interior temperature of the ball rises to 47 °C (117 °F). The hornet can survive maximum temperatures of 44–46 °C (111–115 °F), but the bees can survive up to 48–50 °C (118–122 °F), so the hornet is killed and the bees survive. It was found that the hornet can survive temperatures of up to 47°C, and temperature alone is not sufficient in killing the hornet via bee ball. The combined carbon dioxide concentrations increasing inside the bee ball coupled with the temperature increase causes the hornet to expire. The ability to withstand heat for the hornet decreases as carbon dioxide concentrations increase.

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