Suicidal defense is an important and effective attribute of some highly social animals. It has been suggested that the defensive behavior of biting onto raiders is suicidal in stingless bees; however, the mechanisms causing death are unclear. We conducted the first test of the effect of agonistic encounters on death and injury rates of guards of a stingless bee, Tetragonisca angustula, that bit both conspecific and heterospecific invaders within plastic tubes. Tetragonisca angustula guards bit and immobilized invading bees for long durations and had the ability to release their hold, but rarely did so unless the other bee died. In our assays, which lasted hours to up to 1 day, the probability of death during nest defense by T. angustula was 5–7%. Bitten invading bees fought back, often causing injury and sometimes death of the biting T. angustula. Tetragonisca angustula foragers can survive for 7 days without food and so death by starvation of guards during day-long encounters seems unlikely. Death rates of biting guards holding non-nestmates on the ground may be higher in the field due to susceptibility to predation. Defensive biting of stingless bees effectively protects the nest, and most guards likely are able to return to their tasks after a raid is thwarted, though studies in a more naturalistic setting are needed.

中文翻译：

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Tetragonisca angusula 的防御性咬伤是危险的，但不会自杀

自杀防御是一些高度社会化动物的重要而有效的属性。有人提出，在无刺蜜蜂中，咬住入侵者的防御行为是一种自杀行为；然而，导致死亡的机制尚不清楚。我们进行了第一次激动性遭遇对无刺蜂（Tetragonisca angustula）守卫的死亡率和受伤率的影响的测试，它们在塑料管内同时咬住同种和异种入侵者。Tetragonisca angustula 守卫长时间咬住入侵的蜜蜂并使其无法移动，并且有能力释放它们，但除非另一只蜜蜂死亡，否则很少这样做。在我们的分析中，持续数小时至 1 天，T. angustula 在巢穴防御期间死亡的概率为 5-7%。被咬的入侵蜜蜂进行反击，经常导致咬人的 T. angustula 受伤，有时甚至死亡。Tetragonisca angustula 觅食者可以在没有食物的情况下存活 7 天，因此在一天的遭遇中被守卫饿死似乎不太可能。由于对捕食的敏感性，咬人守卫在地面上抱着非同窝者的死亡率可能更高。防御性咬伤无刺蜜蜂有效地保护了巢穴，大多数守卫在突袭被挫败后很可能能够返回他们的任务，尽管需要在更自然的环境中进行研究。