Defensive Adaptations

While almost everyone has some personal experience with the main forms of hymenopteran defense (the biting mouthparts and seemingly omnipresent stinger), some hymenopterans have developed an ingenious method of defense directly dependent on their endothermic properties.

Heat Tolerance as a Weapon

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 (Ono et al 1995).  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 (Schmidt-Nielsen 2001).  Instead, the bees heat themselves up to 47 degrees C very quickly using their flight muscles.  As the hornetís upper lethal temperature is 44-46 degrees C, it is killed quickly, effectively baked to death by the large clump of bees.  The Japanese honeybee displays an amazing defensive adaptation, using its already extant endothermic qualities as an effective defense mechanism against their natural predator, the giant hornet (Ono et al 1995).