Ruhr University Bochum, Universitätsstr. 150, Bochum 44780, Germany.
Ruhr University Bochum, Universitätsstr. 150, Bochum 44780, Germany.
Curr Biol. 2019 Mar 4;29(5):717-725.e3. doi: 10.1016/j.cub.2019.01.007. Epub 2019 Feb 14.
Living in the African savanna is dangerous, especially for plants. Many plants therefore engage in mutualism with ants, in which plants provide food and shelter in exchange for protection against herbivores. Ants become alarmed when the plant takes on some sort of damage. They immediately emerge from their plant shelter and aggressively defend the plant. Mammalian herbivores can have devastating effects on trees by browsing, breaking tree branches, stripping bark, and pushing over entire trees. However, mutualistic ants substantially reduce the amount of damage. To efficiently protect the tree, ants need to rapidly react together when the tree is under attack. Here, we show that the acacia ant Crematogaster mimosae defends its host tree by exploiting plant-borne vibrations caused by browsers feeding on the tree. Experiments with controlled vibrations show that ants discriminate browser-induced vibrations from those induced by wind, become alarmed, and patrol on the branches. Browser-induced vibrations serve as a long-distance alarm cue. The vibrations propagate through the whole acacia tree and trigger ants' defensive behavior, even on the other side of the tree. Furthermore, the ants make use of tropotactic directional vibration sensing to orient to the attacked part of the tree and fight back the attacker.
生活在非洲大草原是很危险的，尤其是对植物来说。因此，许多植物与蚂蚁形成互利共生关系，植物为蚂蚁提供食物和住所，以换取免受食草动物侵害的保护。当植物受到某种损害时，蚂蚁会发出警报。它们会立即从植物庇护所中出来，积极保护植物。食草哺乳动物通过啃食、折断树枝、剥树皮和推倒整棵树，会对树木造成破坏性的影响。然而，互利共生的蚂蚁会大大减少损害。为了有效地保护树木，当树木受到攻击时，蚂蚁需要迅速共同做出反应。在这里，我们发现金合欢蚁 Crematogaster mimosae 通过利用食草动物在树上进食时产生的植物传播的振动来保护其宿主树。对受控振动的实验表明，蚂蚁可以区分食草动物引起的振动和风吹引起的振动，当它们感到警报时，就会在树枝上巡逻。食草动物引起的振动充当远距离警报信号。振动会传遍整棵金合欢树，并触发蚂蚁的防御行为，即使在树的另一侧也是如此。此外，蚂蚁利用趋触振动感知来确定树的受攻击部分，并反击攻击者。
